The groans of pain as we get up from the sofa or the sound of crunching cartilage when taking the stairs are all too familiar. Many of us look down at our aching knees and curse them — wondering why they seemingly evolved to hurt so much. But the human knee has a complex evolutionary history. And new research is showing how misunderstood it is.

The knee has undergone major changes to its size and shape, not only to allow early humans to walk upright, but also to differentiate us (Homo sapiens) from our extinct genetic relatives, such as Homo erectus and Homo neanderthalensis (Neanderthals).

Natural selection, acting with other evolutionary forces, like random mutation or genetic heritage, probably shaped the knee to help us walk on two legs more efficiently and for longer than our relatives.

Many of the knee problems we face today are new problems our ancestors did not experience. For example, in 2017, research suggested that the sedentary lifestyle of the post-industrial world may have led to a 2.1-fold increase in the rate of knee osteoarthritis, the most common form of arthritis of the knee.

When the researchers studied the remains of hunter gatherers who lived up to 6,000 years ago, they discovered that knee osteoarthritis was probably not a problem at all back then. In the U.K. today, over a third of people over 45 have sought treatment for osteoarthritis — primarily for the knee.

Weaker muscles for stabilizing and protecting joints and relatively weaker cartilage to cushion the scraping of bones are probably the result of humans moving a lot less than they used to — sitting in an office or running on a treadmill builds less muscle than hunting deer for most of the day in challenging terrain. For us to evolve osteoarthritis-free knees, sedentary people with "good" knees would need to have more children than sedentary people with "bad" knees for many generations.

But it gets more complicated. The knee is an intricate piece of biological machinery that scientists don't fully understand.

This is particularly the case for sesamoid bones — small bones that are embedded in tendons or ligaments like the kneecap. These bones can be present throughout the mammalian skeleton. This means some mammals may have sesamoid bones when even members of the same species don't. One such example is the lateral fabella, which is behind the knee and can be found in an average of 36.8% of human knees today.

Despite hundreds of years of research, little is understood about sesamoid evolution, growth, development and why they are present in some species and not others. This is so much so that sesamoids are often missing from the articulated skeletons you see in museums, thrown away with the muscles they are embedded in.

Related: Does evolution ever go backward?

New work from my colleagues and I has shown that two of these often misunderstood bones, the medial and lateral fabellae, which are behind the knee, could have evolved in multiple ways in primates and helped early humans learn to walk upright.

The research was a systematic review of three sesamoid bones in 93 different species of primate, including other hominids and common ancestors to humans.

Our work showed that humans have a distinct form of evolution for these bones that may have begun at the origin of hominoids, a group of primates that include apes and humans.

Scientists think that using the existing fabella bone for a new purpose, something called an exaptation, may have helped early humans go from walking on four limbs to two. Interestingly, this bone is also linked to higher rates of osteoarthritis. People who have it are twice as likely to develop the condition. Evolution is not a simple road to biomechanical efficiency.

This picture gets even more complicated when we realize that, unlike teeth, knees are "plastic," meaning they shift and change depending on factors like nutrition and usage. Teeth on the other hand (once grown) don't adapt and simply become damaged. This is why it is so important to exercise as we age — to keep our bones strong.

Knees change and adapt in response to their use, or lack thereof. A global increase in nutrition causing humans to be taller and weigh more is the leading hypothesis as to why fabellae are becoming more common, for example. The presence of the fabella has trebled in the past 100 years or so, with some variation worldwide.

We know that the evolution of the knee in humans hasn't been straightforward, and instead had branching paths. We also know that we are living in a way that our bodies are poorly adapted to, and lifestyle changes are probably the culprit of knee issues that have become more severe with time. The knee didn't evolve for the age in which we find ourselves and the bone that may have helped us walk in the first place may be part and parcel of those problems.

So, when your knees buckle on the treadmill or feel sore when you're sitting down, spare a thought for them because evolution isn't as easy as it seems.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

The human body is a complex network of systems that work together to keep life-sustaining processes running smoothly. These systems break down food for fuel, clear away waste, repair damaged tissues and DNA, fight infectious germs and monitor the outside world so we can move through it safely. 

Many scientists spend their days working to understand how each bodily system performs its jobs, how the systems interact, and what can happen when one or more of them falter. Such malfunctions can stem from aging or disease, for instance, and through medical care, doctors aim to get derailed systems back on track. 

Here's a quick rundown of the systems of the human body, its vital organs and its "vestigial" organs, as well as a few fascinating facts about how the body works.

What are the different systems of the human body? 

Our bodies consist of a number of biological systems that carry out specific functions necessary for everyday living. Some organs and tissues play roles in multiple systems at once.

Related: Strange, two-faced brain cells confirmed to exist, and they may play a role in schizophrenia 

Circulatory: The job of the circulatory system is to move blood, nutrients, oxygen, carbon dioxide and hormones around the body. It consists of the heart, blood, blood vessels, arteries and veins. According to the Cleveland Clinic, the adult human body's network of blood vessels is more than 60,000 miles (around 100,000 kilometers) long. 

Digestive: The digestive system consists of a series of connected organs that together allow the body to break down and absorb nutrients from food and remove waste. It includes the mouth, esophagus, stomach, small intestine, large intestine, rectum and anus. The large intestine is home to microorganisms that are collectively called the gut microbiome and influence our health in various ways. The liver and pancreas also have roles in the digestive system because they produce digestive juices filled with enzymes to break down the components of food, such as carbohydrates, fats and proteins, according to the National Institute of Diabetes and Digestive and Kidney Diseases.

Endocrine: The endocrine system consists of a network of glands that secrete hormones — long-range chemical messengers that regulate how cells and tissue function — into the blood. These hormones, in turn, travel to different tissues and regulate many bodily functions, such as metabolism, growth and sexual function, according to Johns Hopkins Medicine. For example, the pancreas releases the hormones insulin and glucagon to regulate blood sugar. Conditions like diabetes and insulin resistance arise from the body having too little insulin or not responding to it adequately. 

Related: Meet the 'exclusome': A mini-organ just discovered in cells that defends the genome from attack

Immune: The immune system is the body's defense against bacteria, viruses and other pathogens that may be harmful. Components of the system include the lymph nodes, which contain infection-fighting cells called lymphocytes. These lymphocytes are one of many types of leukocyte, or white blood cell. The immune system also includes the spleen, the bone marrow and a gland called the thymus. The immune system can learn to recognize antigens — proteins on the surface of bacteria, fungi and viruses — and alert the body to their presence. Some immune cells make proteins called antibodies that attach to these antigens and mark invaders for destruction. 

Lymphatic: The lymphatic system includes the lymph nodes, lymph ducts and lymph vessels and is considered part of the immune system. Its main job is to make and move lymph, a clear fluid that contains white blood cells. The lymphatic system also removes excess lymph fluid from the body's tissues and returns it to the blood.

Nervous: The nervous system controls both voluntary actions, such as conscious movements, and involuntary actions,like breathing, and it sends signals to and detects signals from different parts of the body. Conscious actions are controlled by the somatic nervous system, while involuntary actions are controlled by the autonomic nervous system. The autonomic nervous system dictates whether we're in "rest and digest" or "fight or flight" mode. The nervous system can further be split up into the central nervous system (CNS), which includes the brain and spinal cord, and the peripheral nervous system, or the nerves connecting the CNS to every other part of the body.

Muscular: The body's muscular system consists of hundreds of muscles that aid movement, blood flow and other bodily functions, according to the Library of Congress. There are three types of muscle: skeletal, which is connected to bone and helps with voluntary movement; smooth, which is found inside organs and helps to move substances through them; and cardiac, which is found in the heart. The body's largest muscle by mass is the gluteus maximus, but the two latissimus dorsi are the largest in terms of surface area.

Related: Why is it harder for some people to build muscle than others?

Reproductive: The reproductive system allows humans to produce offspring. The male reproductive system includes the penis and the testes, which produce sperm. The female reproductive system includes the vagina, uterus and ovaries, which produce eggs. During fertilization, a sperm cell will fuse with an egg cell that, in a successful pregnancy, will then implant in the uterus. The fertilized egg will then mature into what's called a blastocyst, then an embryo and, finally, a fetus. A placenta forms to support this process. 

Skeletal: Our bodies are supported by the skeletal system, which contains between 206 and 213 bones in an adult human body, due to slight variations in people's anatomy, according to the medical resource StatPearls. These bones are connected by tissues called tendons, ligaments and cartilage. As infants, humans have about 300 bones, but some fuse together as the child grows. The skeleton not only helps us move but is  also involved in the production of blood cells and the storage of calcium. The teeth are also part of the skeletal system, but they aren't considered bones. The smallest bones in the body are found in the ear, and the largest is the femur, or thigh bone, which is also one of the heaviest body parts.

Respiratory: The respiratory system allows us to take in oxygen and expel carbon dioxide through breathing. It includes the lungs; trachea, or windpipe; and the diaphragm, a muscle that pulls air into and pushes air out of the lungs.

Urinary: The urinary system helps eliminate a waste product called urea, which is produced when certain foods are broken down. The system includes the two kidneys; two ureters, or tubes leaving the kidneys; the bladder; two sphincter muscles; and the urethra. The kidneys filter blood in the body to make urine that then travels down the ureters to the bladder and exits the body through the urethra.

Integumentary: The skin, hair and nails make up the integumentary system. Skin is the body's largest organ. It protects our innards from the outside world, serving as our first defense against bacteria, viruses and other pathogens, for instance. Our skin also helps regulate body temperature and eliminate waste through perspiration, or sweat. 

Related: Scientists discover new way humans feel touch 

What are the body's vital organs?

Click the purple circles to learn about the body's vital organs, including the brain, lungs, heart, liver and kidneys. They're considered vital because you need a functioning brain, heart, liver, at least one kidney and at least one lung to survive. That said, there are medical devices and treatments that can make up for a loss of function in these organs, at least temporarily — for example, ECMO machines can do the work of the heart and lungs, and dialysis can filter the blood of people with kidney failure.

Fast facts

• The average adult male body contains about 36 trillion cells, the average adult female body contains 28 trillion cells and a 10-year-old has about 17 trillion. 
• It's often said that there are 78 organs in the human body, but the number actually differs depending on whom you ask. 
• There's a popular idea that the body replaces itself every seven years. But that's not really true, because tissues renew themselves at different rates. 
• Oxygen is the most common element in the human body, followed by carbon. 
• The average adult body contains about 1.2 to 1.5 gallons (4.5 to 5.5 liters) of blood. 
• Humans' average body temperature has fallen slightly over time, so it's no longer 98.6 degrees Fahrenheit (37 degrees Celsius). 
• The most detailed map of the human brain to date contains more than 3,300 types of brain cells. 

What are vestigial organs?

There are arguably some parts of the human body that don't serve any useful purpose, such as the male nipple. That said, the usefulness of some organs is still up for debate, as scientists have often judged the worth of body parts before discovering their purposes. 

Broadly speaking, vestigial body parts are defined as those that have lost their original physiological significance to humans over the course of evolutionary history. The idea is that, while we inherited them from an ancient ancestor, we could really do without them in the modern day. 

Wisdom teeth are held up as one example of a vestigial body part, as the modern human jaw is often too small to accommodate a third set of molars. Some people also carry remnants of a vomeronasal organ that is largely thought to be nonfunctional in humans; animals use equivalent organs to detect each other's pheromones. 

Some scientists consider the human tailbone, or coccyx, vestigial because it's no longer a full-blown tail. But it's far from useless, as it still anchors many muscles, ligaments and tendons. And the appendix has gotten a bad rap for supposedly being both vestigial and useless, but more recently, scientists have uncovered possible functions for the long-maligned body part. 

Ever wonder why some people build muscle more easily than others or why freckles come out in the sun? Send us your questions about how the human body works to community@livescience.com with the subject line "Health Desk Q," and you may see your question answered on the website!

Editor's note: This page was last updated on April 5, 2024.

The human skeletal system is not quite as simple as the popular children's song suggests. The "head bone" (actually made up of 22 separate bones) is not connected to the "neck bone," but rather to a series of small bones that go all the way down the back. And the "toe bone" is actually made up of several bones that connect to another set of bones that provide structure for the foot. In total, the human skeleton consists of a whopping 206 bones.

In addition to all those bones, the human skeletal system includes a network of tendons, ligaments and cartilage that connect the bones together. The skeletal system provides the structural support for the human body and protects our organs. Our bones also serve several other vital functions, including producing blood cells and storing and releasing fats and minerals, according to the National Center for Biotechnology Information (NCBI).

Development and structure of the skeleton

Infants are born with about 300 separate bones, according to Nemours, a nonprofit children's health provider. As a child grows, some of those bones fuse together until growth stops, typically by the age of 25, leaving the skeleton with 206 bones. 

Our bones are separated into two categories based on the purpose and location of the bones: The axial skeleton and the appendicular skeleton, according to the SEER program of the National Cancer Institute.

The axial skeleton contains 80 bones, including the skull, spine and rib cage. It forms the central structure of the skeleton, with the function of protecting the brain, spinal cord, heart and lungs.

The remaining 126 bones make up the appendicular skeleton; they include the arms, legs, shoulder girdle and pelvic girdle. The lower portion of the appendicular skeleton protects the major organs associated with digestion and reproduction and provides stability when a person is walking or running. The upper portion allows for a greater range of motion when lifting and carrying objects.

Bones are further classified by their shape: long, short, flat, irregular or sesamoid, according to SEER. 

• Long bones are found in the arms, legs, fingers and toes. These bones are longer than they are wide and are cylindrical. They move when the muscles around them contract, and they are the most mobile parts of the skeleton.
• Short bones are found in the wrists and ankles and are about equal in their length, width and thickness. 
• Flat bones make up the skull, shoulder blades, sternum and ribs. These curved, thin bones protect internal organs and provide an anchor for muscles.
• Irregular bones are those in the spinal cord and face, which, because of their unique dimension, don't fit in any of the other shape categories.
• Sesamoid bones are found in the hands, wrists, feet, ears and knees. These small, round bones are embedded in tendons and protect them from the great pressure and force they encounter.

There are some variations between male and female skeletons. For example, the female pelvis is typically more broad, thin, and round than the male pelvis, according to the National Museum of Natural History. [Image Gallery: The BioDigital Human]

What's inside your bones?

Three main types of material make up every bone in your body: compact bone, spongy bone and bone marrow, according to the School of Life Sciences at Arizona State University.

Approximately 80% of every bone is compact bone, which is the hardest and strongest type of bone and is what allows the body to support its weight. Compact bone makes up the outer layers of the bone and protects the inner parts of the bones where many vital functions occur, such as bone marrow production. Compact bone consists primarily of cells called osteocytes. Microscopic passages in between the cells to allow nerves and blood vessels to pass through.

About 20% of each bone is spongy bone, which is filled with large holes and passages. Most often found toward the ends of individual bones, the spongy bone material is filled with bone marrow, nerves and blood vessels. 

Two types of bone marrow fill the pores in spongy bone. Approximately half is red bone marrow, which is found mainly within flat bones such as shoulder blades and ribs. This is where all red and white blood cells and platelets (cells that help a cut stop bleeding) are made. Infant's bones contain all red bone marrow to produce enough blood cells to keep up with the youngsters' growth. 

The other half of marrow is yellow bone marrow, which is found in long bones, such as thigh bones, and consists primarily of fat. Blood vessels run through both types of bone marrow to deliver nutrients and remove waste from the bones.

There are four main types of cells within bones: Osteoblasts, osteocytes, osteoclasts and lining cells, according to the NCBI.

Osteoblasts are cells that create new or repair existing bone material as the bones grow or break. The cells create a flexible material called osteoid and then fortify it with minerals to harden and strengthen it. When osteoblasts successfully finish their job, they retire to become osteocytes or lining cells.

Osteocytes, found in the compact bone, are responsible for exchanging minerals and communicating with other cells in the vicinity. They are formed from old osteoblasts that have gotten stuck in the center of bones.

Osteoclasts break down existing bone material and reabsorb it. These cells often work with osteoblasts to heal and reshape bone after a break (the osteoclasts break down the extra callus formed by the healing process) to make room for new blood vessels and nerves and to make bones thicker and stronger.

Lining cells are flat bone cells that completely cover the outside surface of bones. Their primary function is controlling the movement of minerals, cells and other materials into and out of the bones.

Diseases of the skeletal system

As with any part of the human body, bones are susceptible to injury and disease.

Some of the most common diseases that can affect the skeletal system include:

• Osteoporosis is a disease that causes the density and strength of bones to decrease because bone loss occurs faster than bone growth. It can be caused by genetics or unhealthy lifestyle habits (such as lack of calcium or vitamin D, and heavy smoking or drinking with little exercise).
• Leukemia is a type of cancer that starts in the bone marrow and the lymphatic system, according to the Mayo Clinic. Several types of leukemia affect various blood cells and other systems of the body.
• Osteoarthritis is a disease that causes the breakdown of the cartilage that protects the ends of bones in joints. This lack of cartilage leads to bone-on-bone rubbing, which can cause significant pain, damage to the bones and connective tissues, inflammation of the surrounding tissue and restricted motion, according to the Mayo Clinic. 

Additional resources:

• Learn more about the skeletal structure and function from Khan Academy. 
• Check out some pictures of cool animal skeletons from the Oxford University Museum of Natural History.
• Learn more about the differences between the male and female skeleton, from the Smithsonian Institution. 

This article was updated on Oct. 18, 2021, by Live Science contributor Ben Biggs. 

This article is for informational purposes only, and is not meant to offer medical advice. 

A Pictish man with a rugged face who was brutally murdered 1,400 years ago may have been royalty, new research finds.

After his murder, the approximately 30-year-old man's remains sat undisturbed in a cave on the Black Isle of the Scottish Highlands for more than a millennia. Archaeologists found the man's skeleton in a strange position; rocks pinned down his arms and legs, his skull was fractured, and his legs were crossed. Forensic artists published a virtual reconstruction of his face in 2017, catapulting him into internet fame.

Now, a new analysis indicates that this fellow, known as Rosemarkie Man, was likely a prominent person in his community, perhaps a member of royalty or a chieftain, according to news sources. [Photos: See the Ancient Faces of a Man-Bun-Wearing Bloke and a Neanderthal Woman] 

The Picts were a group of tribes that lived in what is now Scotland during the Iron Age and Medieval times. They routinely fought against the Romans, who dubbed these tribes "Picts," likely from the Latin word "picti," which means "painted ones," as the Picts had distinctive tattoos and war paint.

This particular Pict was well off, according to an analysis of his remains. "He was a big, strong fella — built like a rugby player — very heavily built above the waist," Simon Gunn, a professor of urban history at the University of Leicester, who is studying the man's remains, told The Scotsman.

The 5-foot-6-inch-tall (167 centimeters) man ate a high-protein diet (it's almost like he was "eating nothing but suckling pigs," Gunn said), which was rare for people in that region during that time, The Scotsman reported.

A radiocarbon-dated bone sample shows that the man died between A.D. 430 and 630, Gunn said. Moreover, piles of animal bones found near the man's remains suggest that there was a celebration or ritual in honor of his passing, Gunn said.

There were other clues that Rosemarkie Man was royal. Besides his head wounds, there were no other injuries on his body, suggesting that he wasn't a warrior or someone who labored for his livelihood. What's more, his burial in the cave may have been purposeful; perhaps his undertakers placed him at a place they believed was an entrance to the underworld, Gunn said.

Gunn said he and his colleagues plan to continue looking for new finds, as part of the Rosemarkie Caves Project. So far, they have evidence that these caves were used as long as 2,300 years ago, he said.

• Photos: The Reconstruction of Teen Who Lived 9,000 Years Ago
• In Photos: Scotland's Cave of the Dead
• In Photos: Intricately Carved Stone Balls Puzzle Archaeologists

Originally published on Live Science.

Revolutionary War hero Casimir Pulaski was a dashing young officer who served under George Washington. But a new examination of his remains reveals that he wasn't exactly the gentleman that he appeared to be.

Pulaski, an exiled Polish nobleman, founded America's first cavalry division. He died in battle in 1779 and his remains were entombed inside a monument in Savannah, Georgia, in 1854. But when the tomb was opened more than a century later, experts made a startling discovery: Some features of the skeleton were female.

At that time, scientists were unsure if the body was Pulaski's or that of an unknown woman whose remains were mistakenly placed in Pulaski's tomb. However, new DNA analysis confirms that the skeleton belongs to Pulaski, raising intriguing questions about the general's gender. [The Truth About Genderless Babies]

Details of this incredible story were recently described in "The General Was Female?," an episode in the series "America's Hidden Stories" that premiered yesterday (April 8) on the Smithsonian Channel. 

Born in Poland in 1745, Pulaski's military expertise fueled his rise to the role of Brigadier General during America's struggle for independence. He formed a legion that combined cavalry and infantry, called the Pulaski Legion; the generalis known as "The Father of the American Cavalry," according to the National Parks Service.

When the Pulaski monument in Savannah was opened in 1996, experts determined that the skeleton inside was female based on the shape of the pelvis and features in the skull, "such as a delicate midface, with the jaw at more of an obtuse angle," Virginia Estabrook, an assistant professor of anthropology at Georgia Southern University, told Live Science.

But did that mean that Pulaski was actually a woman — or was the body not Pulaski's? Experts conducted genetic tests, comparing DNA from the skeleton with DNA collected from a deceased Pulaski relative. Though the forensic team's results were inconclusive, the body was reburied in 2006 as Pulaski's, Estabrook said.

A portrait of the Revolutionary War general Count Casimir Pulaski, engraved by H.B. Hall and published in 1871. Credit: National Archives at College Park

Recently, Estabrook and other experts revisited this historic mystery, analyzing mitochondrial DNA by using a database not available in 2006. They found that DNA from Pulaski and from a maternal relative matched each other more closely than DNA of 27,000 other genetic profiles in the database. This strongly suggested that the two were related — and that the remains in the monument were Pulaski's, Estabrook said.

What's more, the skeleton also preserved known details from Pulaski's life, such as height and build; an old heel injury; and wear in the hip sockets consistent with long-term horseback riding.

Pulaski was almost certainly not a woman living secretly as a man; the general's entire life was conducted as a male identity, and he was christened Casimir — a man's name — as an infant, Estabrook said. However, the researchers proposed something that was not seriously considered when the skeleton was examined 15 years ago: the possibility that Pulaski was intersex, possessing both male and female characteristics.

Intersex is a blanket term for a number of conditions in which development patterns don't all fit neatly into exclusively male or female categories. For instance, babies that are genetically female (two X chromosomes) may have an enlarged clitoris that resembles a penis, while babies that are genetically male (one X and one Y chromosome) may have an abnormally small penis and no testicles, according to the Mayo Clinic.

For Pulaski, one possible explanation could be a condition called congenital adrenal hyperplasia (CAH), which can cause females to develop genitals that look more male than female, Estabrook said. Increased androgen production from CAH could also cause someone who was chromosomally female to have a slightly receding hairline and facial hair — as evident on Pulaski in portraits of the general.

Many cultures recognize more than two genders, and some include as many as five, according to Estabrook. Yet remains in archaeological sites are typically interpreted as either male or female, even when a body is buried with gendered objects that aren't consistent with the skeleton's biological sex. Such was the case of the so-called Viking warrior woman, who appeared to be biologically female and was buried with an array of weapons that are usually found in the graves of men.

"What we haven't really thought about is that maybe some of these individuals may have been some form of intersex as well," Estabrook said.

• Men vs. Women: Our Key Physical Differences Explained
• Why Is Pink Associated with Girls and Blue with Boys?
• Photos: Viking Warrior Is Actually a Woman

Originally published on Live Science.

Peek inside a few animal mouths and you'll see evidence of evolution's finest work. Take snakes, whose teeth are needle-thin and spiked with venom — excruciatingly efficient instruments for killing prey. Or walruses, which use their massive teeth like ice picks to haul their heavy bodies along the ground. In hagfish, hook-like teeth that line the gullet are ideal for macerating the flesh into which they burrow, headfirst.

But, fancy fangs aside, when it comes to numbers, which animal on earth boasts the most?

As it turns out, there's some stiff competition for the title of toothiest creature, depending on where you look — and what you define as a "tooth." Here are some of the best contenders. [Why Are Teeth Not Considered Bones?] 

On land

Deep in South America's rainforests, the giant armadillo (Priodontes maximus) tops the land mammal tooth count, at 74 teeth. That number may not seem wildly impressive, but it's high for mammals, who are actually some of the least toothy creatures on Earth.

Egg-laying mammals like platypuses have no teeth, marsupials like opossums have around 50, while humans have a measly 32, said Robert Voss, curator in the Department of Mammalogy at the American Museum of Natural History in New York City. In this context, "the giant armadillo is definitely an anomaly," he told Live Science.

There's an interesting reason behind this. Most mammals are 'heterodonts,' meaning their teeth have more than one shape and are complex, enabling precise interactions between the upper and lower jaw. This equips mammals to really mash up their food, which increases the food's surface area and enables them to absorb more energy and nutrients. "Fewer teeth mean[s] they can focus on very precise types of contacts, and interactions, between opposing teeth" and thus maximize on energy consumption, said Peter Ungar, a paleoanthropologist at the University of Arkansas who studies how mammal teeth evolved.

But, unlike other mammals, giant armadillos are homodonts, meaning their teeth are less complex: "At the front, their teeth look sort of like sharp chiclets. Towards the back they look like pegs," Voss said. These simpler gnashers suit a diet of soft-bodied invertebrates, which require only a little crushing to release energy. "Think of it like bubble tea: You don't really need to chew those knobs up," Voss said. Evolutionarily speaking, having simpler teeth means more can fit in the mouth. Add to that the giant armadillo's long jaw, and the combination explains why these mammals are able to pack in more teeth than most.

At sea

Giant armadillos, however, "can't hold a candle to some fish, which can have hundreds, even thousands of teeth in the mouth at once," Ungar told Live Science. That revelation takes us plunging into the ocean — and into the jaws of requiem sharks, which are most likely the toothiest of all vertebrate animals, according to Gavin Naylor, director of the Florida Program for Shark Research.

This comes down to their rotational teething system — a smart biological hack that all shark species have. Instead of just one line of teeth rooted in the jaw, sharks grow multiple rows inside their mouths. These are tethered only to the skin covering the jaw, allowing them to move forward to replace lost teeth. Asked why sharks have this system, Naylor said, "I think a better question is, why don't we? No dentist required!" Crucially, this perpetual conveyor belt enables sharks to replace the teeth they frequently lose in ferocious battles with their prey: "Teeth are important for feeding, so replacing them continuously could confer tremendous advantages," Naylor said. [What Animal Is the Fastest Swimmer?]

So, what kind of numbers are we talking about? At any given time, requiem sharks will have a few hundred active teeth in their mouths. But over the course of their lifetime, "estimates suggest some species of requiem sharks may grow and shed 30,000 teeth," Naylor told Live Science. That's threefold more than the great white (Carcharodon carcharias), which goes through about 10,000 during its lifetime.

And yet, that's still overshadowed by one small creature whose toothiness outstrips us all.

The winner is ...

Peer through a microscope inside a sea slug's mouth, and you will find a forest of spikes so fearsome that they could be the inspiration for Ridley Scott's 1979 film, "Alien." These are slug teeth, and some species have several hundred thousand enclosed within their mouths.

Slugs belong to the class of animals called gastropoda, a generally toothy bunch that also includes limpets and snails. Their spikes don't fit the strict definition of "teeth": traditional ones like ours are made from calcium phosphate, and are typically found in vertebrate animals. Gastropod teeth — also known as "radula" — "are essentially ribbons of chitin, the same material as insect exoskeletons," Ungar told Live Science.

But, technicalities aside, gastropod radula still have the same function: They help slugs, snails and limpets to eat. "The radula is used by both carnivorous and herbivorous molluscs to rasp fragments of food into their mouth — hence the Latin name 'radula' [which means] 'little scraper,'" said Tom White, senior curator of noninsect invertebrates at the Natural History Museum in London. "Essentially, animals with radulae extend them — a bit like sticking out their tongue — and scrape at whatever they are feeding from," he told Live Science.

As the teeth wear down (creatures like sea slugs spend a lot of time scraping at rocks for food), "they are replaced by new ones that form at the back of the radula and move forward, similar to the continuously growing conveyor-belt rows of teeth in sharks," White said. (You can see a photo of it here.)

As for the species that takes the ultimate prize for most teeth: Those are the umbrella slugs (Umbraculum umbraculum), colorful sea-dwelling slugs that go through an unbelievable 750,000 of these chitinous teeth in a lifetime.

Compared with this array of fascinatingly toothy animals, our own human gnashers simply don't cut it, Ungar said. "Our teeth are boring!"

• Why Do We Grind Our Teeth?
• Why Do Your Teeth Feel Weird After Eating Spinach?
• Why Do Teeth Turn Yellow?

Originally published on Live Science.

In medieval Sicily, a man was stabbed multiple times in the back, buried in a really weird way and ostensibly lost to history.

Now, hundreds of years later, archaeologists have excavated evidence of this ancient crime in the Piazza Armerina, Sicily. The researchers found the man's skeleton lying face-down in a shallow pit, empty of any funerary objects typical of ancient burials. The body was buried in a position that was unusual for that time period, they reported last month in the International Journal of Osteoarchaeology.

The evidence suggests that the man, lived in the 11th century and was between 30 and 40 years old when he died. Using CT scans and 3D reconstructions, the researchers set out to determine how he died and why his burial was so unusual. [25 Grisly Archaeological Discoveries]

According to the report, there was evidence of six cuts on the individual's sternum (breastbone) that were indicative of stab wounds likely inflicted by a knife or dagger. On the right side of his sternum, the researchers found a chop mark where a piece of the bone had been removed, likely by a twisting motion from the weapon.

There was no evidence of other injuries on the man's vertebrae or ribs that would suggest that the man was involved in some kind of "uncontrolled" fight, said lead author Roberto Miccichè, an archaeologist at the University of Palermo in Italy.

The goal of the man's killer, it seems, was to attack the victim in a "very effective and rapid way," Miccichè said; in addition, the assailant likely knew human anatomy "very well." In fact, the cuts were so clean and smooth, that the man may have been immobilized, perhaps with binding, Miccichè said. The man's feet were also squished together in the burial space, which further supports the idea that his feet were bound together.

Using CT scans, the researchers were able to determine the the angle and size of the man's stab wounds, information that the investigators then used to create a 3D reconstruction of where the sharp object dug into the sternum and chest cage.

Because the blade of the knife would have entered the man's upper back at an angle, the researchers think that the man was kneeling on the ground at the time of the stabbing, Miccichè said. Since the knife pierced through the thorax (the part of the body between the neck and the abdomen) and into the man's breastbone, Miccichè said the weapon likely punctured the man's lung and heart repeatedly — so he probably died very quickly.

And then there's the weirdness of the burial — the first, well-documented case of a deviant burial in Sicily.

"The burial is atypical because [it] does not follow any religious prescription in the arrangement of the body," Miccichè said. During this time in Sicily, three major monotheistic religions coexisted: Judaism, Christianity and Islam. Each had different traditions in burying its dead — Jews and Christians of the Middle Ages buried their dead face-up, while Muslims buried the body lying on its right side, so that the head faced southeast, toward Mecca.

This skeleton, on the other hand, was buried face-down.

Atypical burials tend to be the result of superstitious beliefs (such as if people think the dead person is a vampire or has returned from the dead) or an indication that the person was an outlaw, Miccichè said. He said he thinks, in this case, that it's the latter. If in "his life, the individual was not aligned to the social order of the community, [his] burial should reflect this lack of conformity in death," Miccichè said.

All of this is to say that the man was likely an exile of sorts who was executed.

What's more, this was a time of "crisis and social reorganization" that occurred right after the Norman conquest of Sicily in 1061. "As everywhere and anytime during a period of sociopolitical rearrangement, it is possible to note an increase in violent acts among people," Micciché said.

Now, Miccichè and his team are looking through medieval archaeological records to find evidence of weapons that could be compatible with the marks on the skeleton and move a step closer to solving this ancient game of Clue.

Editor's Note: This article was updated at 12:23 p.m. on Feb. 21 to correct when the time of crisis occured. It was right after the Norman conquest of Sicily, not the Norman conquest of England.

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Originally published on Live Science.

A grim discovery

Archaeologists unearthed the skeleton of a man who may have met a tragic end on the banks of the Thames River in London 500 years ago. [Read more about the discovery]

Sewer construction

The grave was found during construction for the Thames Tideway Tunnel, which is designed to keep London's sewage from overflowing into the Thames River, and expected to be completed in 2024.

Dirty boots

The man's thigh-high leather boots survived some 500 years buried in the waterlogged soil.

Labor left its mark

The man's teeth had deep groves, which might be an indication that he had to hold ropes in his mouth for work, perhaps in a job as a sailor or a fisherman.

Boots made for water

If the man indeed worked on the water, that would also explain why he was wearing boots that would have kept his legs dry past his knees. The shoes had reinforced soles and extra padding, perhaps to keep him warm or to make the boots fit better.

Clues in the bones

An analysis of the man's bones suggests he may have been younger than 35 but he likely suffered osteoarthritis, perhaps from a life of repetitive work.

A tragic death?

Archaeologists may never be able to know how exactly the man died and how he ended up buried in the muck on the shore of the Thames. However, his splayed position and the fact that he was still wearing expensive boots suggest that his death might have been an accident, perhaps a drowning.

Archaeologists in Pompeii just unearthed the headless skeleton of an unfortunate man who appears to have died in the great explosion of Mount Vesuvius in A.D. 79. The man was decapitated by a large, 1-meter-long rock, researchers found.

The man, who was at least 30 years old, was the first victim to be found in a new, unexplored excavation site called Regio V, north of the city, according to a statement from the Pompeii Archaeological Park.

"We are digging all around," trying to find the head, said Massimo Osanna, the archaeological park's general director. The rock appears to have crushed the man's chest and head. Though the man died while trying to flee the aftermath of the eruption, he probably wasn't killed by the rock, but rather by the dense layer of hot ash, lava and gas, or "pyroclastic flow," that poured into the area, Osanna said.

Archeologists found his body on the first floor of a building, above a layer of "lapilli," or small rock fragments from the volcano. The skeleton was in a position that indicated that the man had been thrown back by force, probably from the pyroclastic flow, Osanna said. Since the man's tibia bone had lesions in it, the scientists suspect he may have had a bone infection that prevented him from quickly escaping, the statement said. [25 Grisly Archaeological Discoveries]

Last February, at another excavation site, scientists also discovered the skeleton of a 7- or 8-year-old child who they think was seeking safety in a public bath, but was suffocated by clouds of ash, according to The Telegraph.

The man and child were just two of thousands of people thought to have perished in the catastrophic Mount Vesuvius explosion that took place nearly 2,000 years ago, burying Pompeii beneath 19 to 23 feet (6 to 7 meters) of volcanic ash. These layers of ash preserved skeletons and have been giving scientists a glimpse of life and death in the ancient Roman city since excavations began in the 18th century.

But with new excavation techniques, such as drones, laser scanning and photogrammetry (making measurements from photographs), new skeletal discoveries can provide a more detailed story of ancient Pompeii and its demise, Osanna said. With all the different technologies, "now we can document everything," he said.

As the only active volcano on mainland Europe, scientists still worry about Mount Vesuvius' potential to inflict serious damage on nearby Naples and other towns, Live Science previously reported. After all, it did destroy Pompeii in just 25 hours.

Originally published on Live Science.

Some 2,000 years ago, a ragtag troop of about 400 Germanic tribesmen marched into battle against a mysterious adversary in Denmark, and they were slaughtered to the last man.

Or at least that's the story their bones tell. Exhumed from Alken Enge — a peat bog in Denmark's Illerup River Valley — between 2009 and 2014, nearly 2,100 bones belonging to the dead fighters have given archaeologists a rare window into the post-battle rituals of Europe's so-called "barbarian" tribes during the height of the Roman Empire. In a new study published online May 21 in the journal Proceedings of the National Academy of Sciences, a team of researchers from Aarhus University in Denmark dug into the bloody details.

"The ferocity of the Germanic tribes and peoples and their extremely violent and ritualized behavior in the aftermath of warfare became a trope in the Roman accounts of their barbaric northern neighbors," the authors wrote in the new study. Despite these historical accounts, little evidence of these practices has ever been discovered in archaeological finds — until now. [See Photos of the Mutilated Iron Age Skeletons]

"Comprehensive slaughter"

In the Alken Enge find, archaeologists unearthed 2,095 human bones and fragments from the peat and lake sediment across 185 acres of wetlands in East Jutland. These bones belonged to 82 distinct people — seemingly all men, most of them 20 to 40 years old — but likely account for just a fraction of the bones initially deposited in the area, the researchers wrote. After analyzing the geographic distribution of the bones, the team estimated a minimum of 380 skeletons were originally interred in the water.

This population "significantly exceeds the scale of any known Iron Age village community," the researchers wrote, suggesting the men were recruited from a large area to participate in a common battle.

Using radiocarbon analysis, the team dated the bones to between 2 B.C. and A.D. 54 — sometime between the reigns of the Roman emperors Augustus (27 B.C. to A.D. 14) and Claudius (A.D. 41 to 54). During this time, Rome expanded its empire north into Europe but met fierce resistance from the scattered tribes who lived in modern-day Germany and Denmark. Some tribes allied with the Empire, and infighting between tribes was common.

The bones of the men at Alken Enge are thought to be the casualties of one such tribal battle. Ancient weapons like axes, clubs and swords were found scattered about the site, and it was clear to the researchers that many of the skeletons had sustained critical battle wounds before dying.

"The relative absence of healed sharp force trauma suggests that the deposited population did not have considerable previous battle experience," the researchers wrote. Indeed, the scrappy group of soldiers met "comprehensive slaughter."

Ritual burial or hasty cleanup?

Finding boneyards of dead soldiers is no rarity in archaeology; what truly excited the researchers about Alken Enge was the seemingly ritualistic way in which the skeletons were buried. [25 Grisly Archaeological Discoveries]

For starters, it appears that the skeletons were deposited in the lake after they had decomposed in the wild for anywhere between six months and a year. Nearly 400 of the bones were hatched with gnawing tooth marks probably left by scavenging animals such as foxes, wolves or dogs. Moreover, the absence of bacterial decay on the bones suggests that the men's inner organs were removed, decomposed or eaten by scavengers before their ultimate burial, the researchers wrote.

Whether it was a friend or foe who did the burying is still unclear. The men's arm and leg bones were severed from their torsos. Few intact skulls were present, but many cranial fragments appeared to have been smashed with a club or other bludgeoning tool, the researchers said. Four pelvic bones hung around a single tree branch with deliberate intent.

"Alken Enge provides unequivocal evidence that the people in Northern Germania had systematic and deliberate ways of clearing battlefields," the researchers concluded. The find certainly "points to a new form of postbattle activities" in Germanic tribes at the dawn of the current era — but what it all means is still a mystery.

Originally published on Live Science.

Army Pvt. Shamika Burrage's left ear is unlike other ears, though you might not realize it at first. Like her right ear, it is made from Burrage's own cells, and connected to her head by her own blood vessels. She can hear perfectly well out of it, and feel perfectly well when you touch it. And yet, until a few days ago, Burrage's left ear was not on her head — it was on her arm.

Burrage lost her left ear during a single-car crash in Odessa, Texas, in 2016. Now, she is the latest recipient of a cosmetic reconstruction procedure called prelaminated forearm free flap surgery — a sci-fi-sounding operation that involves "growing" new tissue by implanting a patient's cartilage under their forearm skin. While many civilians around the world have successfully undergone the procedure, Burrage is the first American soldier to receive the novel reconstruction process, according to a statement from the U.S. Army. [The 27 Oddest Medical Cases]

"The whole goal is, by the time she's done with all this, it looks good, it's sensate and in five years if somebody doesn't know her they won't notice," Lt. Col. Owen Johnson III, chief of plastic and reconstructive surgery at William Beaumont Army Medical Center in El Paso, Texas, said in the statement. "As a young active-duty soldier, they deserve the best reconstruction they can get."

To lend an ear

So how does prelaminated forearm free flap surgery work? First, surgeons create a mold of the new prosthetic ear by harvesting some of the patient's cartilage — usually from the patient's ribs. The cartilage is shaped, sometimes with the help of a 3D-printed mold, and then inserted under a flap of skin cut open on the patient's forearm. (In another variant of the surgery, patients have had cartilage implanted under their forehead skin to grow new noses.)

Because the molded cartilage comes from the same cells as the patient's arm tissues, the skin will begin to grow around the mold. New blood vessels begin to form inside the transplanted tissue and, after several months of healing, the newly formed ear can be safely transplanted to the head. In Burrage's case, extra skin from her forearm was also used to cover scar tissue around her jawline.

"[The ear] will have fresh arteries, fresh veins and even a fresh nerve so she'll be able to feel it,"  Johnson said. In addition, Burrage will even be able to hear out of it, because surgeons were able to reopen her ear canal following the trauma of her accident.

"I didn't lose any hearing and [Johnson] opened the canal back up," Burrage said in the statement. "It's been a long process for everything, but I'm back."

A growing field

While this sort of transplant may be a first for the Army, similar operations have been performed successfully on civilians around the world. In 2017, a team of Chinese plastic surgeons led by Dr. Guo Shuzhong completed a similar surgery on a man who lost his ear during a traffic accident. (The forearm-ear transplant took about 7 hours to complete.) Guo told the Daily Mail that he and his team perform similar procedures on about 500 children each year.

Famously, not all recipients of the surgery have been human. In 1995, perhaps the first patient to "grow" a human ear using transplanted cartilage was a laboratory mouse at the University of Massachusetts Medical School. The mouse — nicknamed the "earmouse" or the "Vacanti mouse," after lead researcher Charles Vacanti — carried the ear on its back and spurred a wave of controversy about genetic engineering.

In fact, the Vacanti mouse was not genetically engineered at all: He was a regular (albeit hairless) mouse who had simply received what is fast becoming a standard — and life-changing — plastic surgery procedure.

Originally published on Live Science.

Shucking oysters can be tricky, but no one expects to get sick from doing it. But that's what happened to a North Carolina man who developed a rare bacterial infection after prying open one of the mollusks, according to a report of the man's case.

The culprit was Mycobacterium szulgai, a bacterium found in soil and water. People typically don't become sick when exposed to this organism, but when they do, the bacteria usually infect the lungs and, in some cases, can cause infections in the skin, bones and sheaths surrounding tendons.

The bacteria can get into a person's body through cuts in the skin, which is precisely what happened to the 66-year-old man, who was shucking oysters with a cut on his hand, said case report lead author Dr. Amir Barzin, an assistant professor of family medicine at the University of North Carolina School of Medicine who treated the man. [27 Oddest Medical Cases]

The bacteria were likely on the shellfish and probably entered the man's skin through his cut, Barzin told Live Science. Other animals that are known to carry the bacteria include certain fish, other shellfish and turtles, according to the case report, which was published online last December in the journal BMJ Case Reports.

But infections with M. szulgai are rare, so when the man first went to the doctor because of mild swelling in his right index finger, doctors didn't suspect the bacteria were the cause. Indeed, he could move the finger without experiencing any pain, and X-rays of his hand didn't show anything unusual.

An unlikely culprit

But when the swelling in the man's finger did not go away, he was sent to an orthopedic specialist because his medical history made him more vulnerable to infections. In particular, the man had received a kidney transplant years earlier and was taking medications to suppress his immune system and prevent rejection of the donor kidney, according to the case report.

The orthopedist suspected the man had "stenosing tenosynovitis," or inflammation within the protective sheath surrounding the tendon in his index finger. (Tendons connect muscle to bone.) He was given a shot of steroid medication to relieve the swelling, but his symptoms returned a few months later.

At that point, the man was sent for an MRI, which suggested he might have an infection in the tendons of his finger. He also needed a surgical procedure known as a "flexor tenolysis," which is done to release any areas along a tendon that are stuck, or "adhesed," Barzin said. This was necessary because the man was unable to bend his finger normally, Barzin said.

During the procedure, surgeons collected a sample of the infected tissue and sent it to a lab for analysis. That's when doctors discovered that the cause of his infection was the bacterium M. szulgai. It was only after the bacterium was identified that the man recalled getting a cut on his hand while shucking oysters, because his finger became swollen.  

Barzin noted that it's unlikely that people with healthy immune systems would get sick from these bacteria. But the immune-suppressing medications that the man was taking gave the rare infection a chance to flourish, he added.

Had the man delayed seeking medical attention, he might have developed lasting damage to his finger, Barzin said, and there would have been a small chance for the infection to spread to other tendons.

The man took antibiotics for about four months to clear the infection. When doctors last saw him, the range of motion in his right finger was almost back to normal, Barzin said.

Originally published on Live Science.

Fifteen-hundred years ago, a single mighty blow crashed down upon a man in Italy, severing his right hand. The wound should have killed him — if not from immediate blood loss, then from an infection for which there were no antibiotics. But he survived.

The man's severed bones healed. He lived for many years, possibly even decades longer, until he was nearly 50. Eventually, he replaced his missing hand with a long knife buckled to his arm with leather straps. Today, his body lies in a necropolis in northern Italy, surrounded by more than 200 fellow Italian skeletons and one headless horse interred as an animal offering. [The 5 Strangest Prosthetic Limbs]

Does this story fill you with a warm, fuzzy feeling?

Maybe it should, said the anthropologists who documented the unusual skeleton's discovery in the newest issue of the Journal of Anthropological Sciences. Grim details aside, the blade-armed man lost his hand during a time when an amputation could be a death sentence. His survival well into middle age represents not just a personal triumph, the researchers wrote, but also a human one.

"This [find] shows a remarkable survival after a forelimb amputation during pre-antibiotic era," the team, led by researchers from the University of Rome, wrote. "The survival of this [man] testifies to community care, family compassion and a high value given to human life."

Body and blade

The man's skeleton was exhumed about 20 years ago from the Longobard necropolis of Povegliano Veronese near Verona in northern Italy. The site, which dates roughly to between the sixth and eighth centuries A.D., has so far yielded 164 tombs holding 222 individuals (plus a burial pit containing two greyhound dogs and the aforementioned horse).

Researchers discovered the blade-handed skeleton alone in a tomb, with its right arm bent at the elbow and draped over the chest. This alone was unusual enough to get researchers' attention; while various other men in the necropolis had been buried with weapons, their arms all hung straight down at their sides. Further analysis revealed that the man's right hand was missing, that it had been amputated from his forearm by a single blow and that the bones in his arm had ample time to heal before he died (which was likely sometime in his late 40s).

In the spot where the man's right hand should be, researchers found a prosthetic limb fashioned from leather straps, a bronze buckle and a long, iron knife, which the team dated to the end of the 6th century. Dental analysis showed that one of the man's upper incisors was worn down significantly compared to surrounding teeth, suggesting he had used that tooth for something other than chewing — perhaps for tightening the straps on his prosthetic, the researchers said.

How the man lost his hand is another mystery. One big clue: that he even survived a limb amputation before antibiotics existed.

"This highlights a community-level effort to provide an ideal setting for healing to take place," the researchers wrote. "This suggests a clean environment and intensive care during the early stages of healing, with the ability to prevent death from blood loss."

Based on these findings, the researchers said, it's likely the man lost his hand in the line of battle or during a medical procedure. If his hand had been lopped off as punishment, he probably wouldn't have received such effective medical care, they said. Their full report is available on the Journal of Anthropological Sciences website.

Originally published on Live Science.

In a cramped stone grave beneath the medieval town of Imola, Italy, a 1,300-year-old woman lies dead with a hole in her skull and a fetus between her legs.

The fetus, now just a collection of tiny bones trailing below the mother's skeletal pelvis, was likely delivered in the grave through a phenomenon called "coffin birth" — essentially, when an unborn child is forced out of its mother's womb by posthumous gases after both mother and child have died.

It's a rare sight in archaeology — but rarer still might be the peculiar circular wound bored into the mother's skull. [The 8 Most Grisly Archaeological Studies]

Archaeologists from the University of Ferrara and University of Bologna attempted to unwind the mystery of this mother's and child's deaths in a new study published in the May 2018 issue of the journal World Neurosurgery. According to the researchers, these remarkable skeletal remains may present a rare Middle Ages example of a primitive brain-surgery technique called trepanation. This procedure involved drilling or scraping a hole into the patient's skull to relieve pressure and (theoretically) a whole host of medical ailments. In this case, sadly, that relief may not have been enough.

"Our hypothesis is that the pregnant woman incurred preeclampsia or eclampsia [two pregnancy conditions involving high blood pressure] and she was treated with a frontal trepanation to relieve the intracranial pressure," the researchers wrote in the new paper. "Despite the intervention, she did not survive, and died with the fetus in her womb."

Reading human remains

The grave in question was discovered in 2010, during an excavation of the town of Imola in northern Italy, near the city of Bologna. The skeletal remains of the mother were found among several other burials that researchers dated to the Lombard period (lasting from the 7th to 8th century A.D.). Because the woman's remains were found face-up and surrounded by cut stones, the researchers concluded that she was intentionally buried and likely hadn't been moved or altered (before now).

The woman was likely in her mid-20s to 30s and appeared to be nearing the end of her pregnancy when she was buried. Although the baby's sex was impossible to determine, leg measurements suggested that it was near the 38th week of gestation.

At the top of the woman's skull, researchers detected a small, circular hole measuring 4.6 millimeters (0.2 inches) in diameter — a little smaller than the diameter of a pencil. The puncture was precise and round, suggesting that it didn't result from violence or a single, extreme blow, the researchers wrote. Rather, the wound appeared consistent with repetitive drilling directly into the bone — a hallmark of some trepanation surgeries, the study said.

Because the skull showed early signs of healing near the wound, it was likely that the hole was inflicted at least one week before the woman's death, not posthumously, the scientists said. The researchers also found a linear cut mark a few centimeters above the hole, measuring less than 3 mm (0.12 inches) in length. This, they said, could indicate an area where the scalp was cut or peeled away to prepare the skull for surgery.

A rare cut

The researchers concluded that there was suitable evidence to suggest the wound in the woman's head was caused by a medical procedure similar to trepanation.

Why drill into a pregnant woman's head weeks before she's due? One possible reason was to reduce symptoms related to pregnancy, such as high blood pressure, the researchers said.

"Because trepanation was once often used in the treatment of hypertension to reduce blood pressure in the skull,we theorized that this lesion could be associated with the treatment of a hypertensive pregnancy disorder, such as preeclampsia," the researchers wrote. "This finding is one of the few documented cases of trepanation in the European early Middle Ages, and the only one featuring a pregnant woman in association with a postmortem fetal-extrusion phenomenon."

While trepanation wounds have been documented in more than 1,500 skulls dating to the Neolithic period, this possible example from Middle Ages Italy remains a unique mystery. Further study is required to help answer how and why the surgery was conducted, and why similar examples are so hard to find.

Originally published on Live Science.

The skeleton, with a dramatically elongated skull and an underdeveloped jaw and face, was uncovered in Chile's Atacama Desert in 2003, and mystified scientists when it was first found.

Research published in 2013 offered some clues about the skeleton's bizarre appearance, but five additional years of genetic analysis have provided even more answers. Examination of the skeleton's entire genome revealed that it was Chilean and female, and that its misshapen skull and other deformities might be linked to a host of genetic mutations that affect bone development. Together, those mutations shaped an array of abnormalities that gave the remains an alien-like form. [Image Gallery: Odd Alien-Looking Skeleton Poses Medical Mystery]

Though the skeleton is the size of a 22-week-old fetus, it was initially thought to be a 6- to 8-year-old child with severe deformities. Nearly a decade later, a highly detailed analysis — including X-rays, computed tomography (CT) scans and DNA sequencing — showed that it was a fetus (and that it was definitely human).

It's hard to tell how old the skeleton is just by looking at it, but prior examinations found it to be about 40 years old, scientists explained in a new study. Despite the skeleton's minuscule size, previous analysis cast doubt on whether it was a fetus because its "advanced bone age" more closely resembled that of a young child, particularly in the structure of the skeleton's skull, with sutures that were already fused.

But that feature was a byproduct of a genetic mutation — one of many that caused its numerous skeletal deformities. And, in fact, the premature fusing of skull plates in the fetus is what gave the skull its pointed shape, the researchers reported.

The scientists extracted DNA from one of the skeleton's ribs — another anomaly that previously had fueled speculation about alien origins, as there were 10 pairs, rather than the 12 normally found in humans.

However, alien hunters will likely be disappointed to hear that "the specimen is shown here to have a purely earthly origin," the study authors reported.

Genetic anomalies, not extraterrestrial DNA

While the scientists found no evidence of alien DNA, they did find mutations in seven of the fetus's genes: COL1A1, COL2A1, KMT2D, FLNB, ATR, TRIP11 and PCNT. Mutations in these genes are known to play roles in premature joint fusion, abnormalities in rib development, malformed skulls, and diseases that inhibit the development of bone and cartilage, according to the study.

Taken together, the mutations expressed by these genes would explain all of the fetus's skeletal abnormalities, the scientists concluded. However, finding so many mutations that specifically affect skeletal development is unusual; in fact, it's never been reported before, and it is unknown what triggered this cascade of mutations, study lead author Garry Nolan, a professor of microbiology and immunology at Stanford University, told Live Science in an email.

As bizarre as this skeleton may appear, it isn't the first example of remains that look mostly human but nevertheless invite comparisons to popular images of creatures from science fiction.

In 1999, excavations in a 1,000-year-old cemetery in Mexico yielded 13 human skeletons — many of them children — with skulls that were stretched and pointed in the back, bearing a distinctly alien appearance. But researchers determined that the skulls' unusual shapes stemmed from cultural practices that deliberately deformed the bone, similar to those seen in pre-Hispanic cultures in Central America.

And 14 elongated, alien-like skulls in Bavarian graves dating to 1,500 years ago also were traced to cultural practices of cranial shaping, this time in tribes from southeastern Europe, Live Science previously reported.

However, five so-called "alien mummies" from Peru — mummified humanoids with three-fingered hands — were widely denounced by experts as fabrications, perhaps even cobbled together from looted body parts belonging to real human remains. [In Photos: 'Alien' Skulls Reveal Odd, Ancient Tradition]

Genes working together

The bigger story is not about the skeleton's debunked "alien" origins but what its analysis reveals about how genes shape our skeletons as they develop and grow, and how they interact with each other to do so — successfully or not, Nolan told Live Science in an email.

"The era of single gene/single disease is just about over — it's now time to look at the more subtle effects when genes interact," Nolan wrote. "In isolation, a gene might have no effect ... but combined with other genes, the outcomes can be dramatic."

The idea of gene collaboration is not new to geneticists; it has been well studied for years in models derived from fruit flies, plants and yeasts, Nolan said. But now, researchers are compiling enough data to understand these genetic interactions in humans, and are exploring how they affect our biology.

"These studies show that certain gene mutations can 'vote' towards a given body plan or disease," Nolan said.

And the new study's findings about genetic control of bone development could help researchers reverse-engineer solutions to disorders that affect how bones grow, Nolan told Live Science in an email.

"Deeper knowledge about bone growth disorders will point to how normal growth must develop," he said. "It might offer understandings of how we can (say, with drugs) stimulate bone growth in cases of catastrophic accidents to help patients."

The findings were published online today (March 22) in the journal Genome Research.

Original article on Live Science.

He might not be a sailor or have a girlfriend named Olive Oyl, but a man in Japan did share something in common with the cartoon character named Popeye — a bulging biceps in his left upper arm, a new report of the man's case reveals.

The 79-year-old man's visible bulge in the middle of his left upper arm, known medically as a "Popeye sign" or Popeye deformity, was not obtained after downing a can of spinach. Instead, it happened after he lifted an object and immediately felt a sharp pain in his left shoulder, according to the case report, published today (Nov. 15) in The New England Journal of Medicine.

And although Popeye's bulging biceps are considered a sign of strength, the appearance of a Popeye sign may instead be caused by weakness in the shoulder and elbow. [27 Oddest Medical Cases]

In the man's case, the Popeye sign occurred because the man tore one of his biceps tendons. Tendons are the tissues that connect muscle to bone; the biceps muscle is attached to the shoulder bone by two tendons, and to the elbow bone by one tendon.

An MRI showed he had a complete tear of the long head of the biceps tendon, according to the case report.

The "long head" of the biceps tendon is the longer of the two biceps tendons attached at the shoulder, said Dr. Dominic King, an orthopedic physician at The Cleveland Clinic in Ohio, who was not involved in treating the man's case.

When this tendon tears, the biceps muscle, which is no longer pulled as strongly toward the shoulder, sags toward the elbow.

The result is a big, balled-up muscle in the middle of the arm, which produces the characteristic bulge in the biceps, King told Live Science. This bulge is more noticeable when the arm flexes at the elbow, and may appear thinner when the arm is at rest, he said.

These tendon tears are more common in older adults, as wear-and-tear over time weakens the muscles and tendons, according to the report. But the injury can still occur in younger people, especially in body builders and weightlifters, when they lift something heavy too quickly, King said. 

King noted that surgery typically isn't needed to fix this type of injury, because a person still has one biceps tendon attached to the shoulder.

Indeed, in the man's case, the patient was treated with nonsteroidal anti-inflammatory medications, and four months later, he told doctors that his pain no longer affected his daily life, according to the case report.

Originally published on Live Science.

Simply put, your body can't turn fat into muscle. And the reverse is also true: Your body can't turn muscle into fat, either.

The reason? Fat and muscle are two different types of tissue, and one cannot be converted directly into the other, said Brad Schoenfeld, an assistant professor of exercise science at the City University of New York's Lehman College.

"The best analogy I can use is, you cannot turn an orange into an apple," Schoenfeld told Live Science. What a person can do instead, however, is lose fat and gain muscle as two separate processes, he added. 

Related: Why do men gain weight in their bellies?

To lose fat, you have to lose weight, Schoenfeld said, and losing weight requires burning more calories than you consume.  

"It's a basic extrapolation of the first law of thermodynamics," Schoenfeld said, which states that energy, including the calories you eat, is conserved; it does not appear or disappear but simply changes form, whether it is burned to fuel bodily functions or stored as fat.  

"That has been shown over and over again in highly controlled … studies," Schoenfeld said.

But to lose fat without also losing muscle, you have to eat the right foods: If you cut your calorie intake and don't eat enough protein, weight loss can result in a decrease in not only fat but also muscle.

"It's been shown over and over that low protein intake [while cutting calories] leads to an accelerated loss of muscle," Schoenfeld said. To make up for the lack of protein in the diet, the body burns not just stored fat but also muscle, which is made of protein. When this happens, your muscle cells shrink.

To prevent this from happening, Schoenfeld said he recommends that people who are trying to lose fat but not muscle consume about 0.8 grams of protein per pound of body weight per day. For example, a person who weighs 150 lbs. should eat about 120 grams of protein per day, equivalent to the amount of protein found in about three cups of chopped chicken, or 3.5 four-ounce chicken breasts. (Of course, not all your protein has to come from one source!)This is the amount of protein required for anyone lifting weights, Schoenfeld said, an activity that is essential for losing weight without also losing muscle.

Lifting weights builds muscle

To gain muscle, you have to do two things: eat a sufficient amount of protein, and engage in resistance training (in which your muscles oppose a force), such as lifting weights, to tax the muscles and thus stimulate growth. In addition to weight lifting, other forms of resistance training include working with resistance bands and resisting one's own body weight, through exercises such as squats and push ups, Schoenfeld said.

Resistance training is essential for gaining muscle while losing fat, Schoenfeld said. "You certainly should lift [weights] a minimum of twice a week, working all your major muscle groups, to [slow] any loss of muscle," he said. (Always check with a doctor before starting a new exercise routine.) As your muscles get stronger, your muscle fibers get bigger in a process called hypertrophy.

While aerobic exercise is generally healthy, it's not good for building muscle, at least not beyond the very early stages of working out, Schoenfeld said. "The only way, really, to keep gaining muscle is to push your body over time," he said. During aerobic exercise, however, there's a limit to how much a person can tax his or her muscles, and it's not enough to make the muscles bigger, he said.

Muscle into fat?

You may worry that if you take time off from the gym, you'll get flabby. And that's a valid concern, Schoenfeld said.

But this doesn't happen because your muscle is turning into fat. Rather, if you're not lifting weights or doing some kind of resistance training, then you're not combatting age-related muscle loss, called sarcopenia.

Starting between ages 30 and 40, people naturally begin to lose muscle. More specifically, a person's individual muscle cells, called muscle fibers, begin to die, Schoenfeld said. [11 Surprising Facts About the Skeletal System]

So, as people get older, if they exercise less and continue to eat the same amount, or eat more, then they will also gain fat as they lose muscle.

However, age-related muscle loss "can be attenuated and completely obliterated if you lift weights, especially if you start lifting early," Schoenfeld said. Other forms of resistance training can also counteract sarcopenia, he said. "It is a function of the use-it-or-lose-it principle, and if you use it, you will not lose it."

Original article on Live Science.

More than 40 million years ago, on a small island that has since coalesced with other islands to become modern-day Turkey, an odd beast the size of a domestic cat lived in the trees: a bone-crushing marsupial relative. Now, in a new study, researchers have described the near-complete skeleton of this ancient creature.

The remains of the marsupial relative, called Anatoliadelphys maasae, were found in the Turkish Uzunçarşıdere Formation, according to the scientists.

While today the most beloved and, arguably, most thrilling marsupials such as kangaroos and wallabies live in Australia, this isn't the only place they're found now — a slew of mouse-size opossums currently populate the Americas. Some insect-eating marsupials the size of mice or rats were also around in the Northern Hemisphere — North America and Europe — during the middle Eocene period, 43 million to 44 million years ago. [10 Extinct Giants That Once Roamed North America]

Still, Murat Maga, a coauthor of the recent study and assistant professor of pediatric medicine at the University of Washington, was surprised to have found a marsupial relative in that spot at all, he told Live Science. For Robin Beck,study coauthor and a lecturer in biology at the University of Salford, in the United Kingdom, the size of this creature was one of the big shocks.

"Here you have, at this site in Turkey, an animal that's much bigger — it's about 10 times bigger than the biggest marsupial relative from Europe or North America at about this time," Beck told Live Science. "And it has these big, big jaws [with] big crushing teeth ... The teeth are very worn, as well, so it was obviously crunching away at something pretty hard."

Marsupials — and their closely related marsupial relatives — are thought to have trouble competing against placental carnivores. But, the researchers think that this tree-climbing oddball, which may have been a bone-eating scavenger or a carnivore that fed on hard-shelled invertebrates such as snails (or both), didn't actually have to outcompete them.

It may simply be that this island didn't have any placental carnivores, they said.  

As far as Beck and Maga know, no placental carnivores have yet been discovered on the island that Anatoliadelphys maasae inhabited. And so, this creature may have been able to fill the ecological niche on the island for a predator, according to Chris Beard, a professor of ecology and evolutionary biology at the University of Kansas, who was not involved in this research.

This may also explain why the marsupial relative is no longer alive. Once Turkey came together 25 million years ago to form a land bridge, Anatoliadelphys maasae would have been subject to predation by the placental carnivores from Asia and the Middle East.

Consider this thought experiment, proposed by Beard: What would happen to lemurs, primates that live only on the island of Madagascar and nearby islands, if Madagascar became attached to continental Africa? Would lemurs continue to survive in a new world pulsing with leopards, baboons and pythons?

"If I would make a prediction, I would predict that they would probably all go extinct just because they can't compete with the African mammals, which have been evolving on a much larger landmass," Beard told Live Science.

The study was published Aug. 16 in the journal PLOS ONE.

Original article on Live Science.

First, the bad news: Divers stole a prehistoric human skeleton from an underwater cavern near Tulúm on Mexico's Yucatán Peninsula five years ago. Police have yet to solve the case. But the good news? The looters didn't take everything. Some bits of bone were preserved under stalagmites, mineral growths shaped like upside-down icicles on the cave floor.

By analyzing what's left of this ice age grave site, researchers determined that the skeleton could be up to 13,000 years old, making it "one of the oldest human skeletons from America," study author Wolfgang Stinnesbeck, an earth scientist at Heidelberg University in Germany, said in a statement.

Stinnesbeck and his colleagues first became aware of the skeleton in a submerged cave called Chan Hol in February 2012 from photos on social media. Unfortunately, 90 percent of the skeleton was looted a month later. [The 25 Most Mysterious Archaeological Finds on Earth]

The researchers used pre-robbery photos to reconstruct the skeleton, determining that the person had likely been male, and that he likely died in the cave at a time in the ancient past when the site was dry. The researchers also collected the bone fragments remaining in the cave, including part of a hip bone that was stuck under a stalagmite.

Often, to determine the age of human remains, scientists look at bone collagen and measure a radioactive isotope of carbon that decreases at a regular rate once a living thing dies. In this case, carbon dating wasn't possible, however; the collagen in the skeleton had completely degraded after years of exposure to tropical water, the researchers said.

As an alternative, the researchers looked at the relative levels of uranium and thorium isotopes in the stalagmite growing on top of the bone. Those results showed a minimum age of 11,300 years. But Stinnesbeck and his colleagues speculated that the skeleton could be even older, based on another sediment deposit located between the bone and the stalagmite. The researchers estimated that the remains could be as old as 13,000 years.  

Jim Chatters, an archaeologist with Applied Paleoscience in Bothell, Washington, who was not involved in the study, said he wasn't convinced by this extrapolation, adding that deposits under the stalagmite could have formed more rapidly.

"I could buy that skeleton being over 11,000 years old," Chatters told Live Science, "but not 13,000, at least not with the evidence presented."

Even at 11,000 years old, the bones would still join a special class of human skeletons from the Americas. "We don't have very many individuals from that age range," Chatters said.

Prehistoric human skeletons could help scientists understand how and when the Americas were first settled — still a subject of much debate in archaeology. Stinnesbeck told Live Science that the new finding is further evidence that humans were settled in the Americas before the Clovis culture, long thought to be the first to arrive to North America via a land bridge from Asia about 13,000 years ago. The "Clovis first" hypothesis has been challenged by recent findings at sites like Monte Verde in Chile, where scientists have found traces of human occupation at least 14,800 years old, and an underwater sinkhole known as the Page-Ladson site in Florida where scientists have found 14,550-year-old stone tools.

The Yucatán Peninsula has emerged as one of the most important sites for pre-Clovis findings. Once-dry caves like Chan Hol flooded with rising water when glaciers melted at the end of the last ice age, preserving human remains as well as extinct animals like giant sloths and saber-toothed cats. "The area appears to be [a] prime site and paleontological and paleoanthropological bonanza, with so many finds from the late Pleistocene in a really small area," Stinnesbeck told Live Science in an email.

In 2007, divers found the skeleton of a teenage girl, nicknamed Naia, in Hoyo Negro, another submerged Yucatán cave; in 2014, Chatters and his colleagues determined that the teenager likely died 12,000 to 13,000 years ago, based on radiocarbon dating and uranium-thorium dating.

Chatters said it was unfortunate that the Chan Hol site was looted, and noted that archaeologically rich caves in the region are becoming more accessible to divers, which puts the sites at greater risk of being disturbed or plundered.

"Carelessness and lack of skill, even notwithstanding looting, are real threats to the integrity of these finds," Chatters said, adding that he's found bones moved or broken at Hoyo Negro since the site's discovery.

The results from the Chan Hol remains were published online Aug. 30 in the journal PLOS One.

Original article on Live Science.

The face of a 1,400-year-old murder victim is seeing the light of day, now that scientists have digitally reconstructed his features.

The victim, a young Pictish man, met a grisly end when he was brutally murdered in what is now modern Scotland. Archaeologists found the man's remains — placed in an odd, cross-legged position with rocks pinning down his arms and legs — during the excavation of a cave in the Black Isle, Ross-shire, in the Scottish Highlands.

The archaeologists sent the man's bones to the Centre for Anatomy and Human Identification (CAHID) at the University of Dundee in Australia. The team there, led by forensic anthropologist Sue Black, analyzed the bones and identified the horrific injuries the man had sustained, including five impacts that led to the fracturing of the man's face and skull. [The 25 Most Mysterious Archaeological Finds on Earth]

And then, they created a digital reconstruction of his face, Black said.

"This is a fascinating skeleton in a remarkable state of preservation, which has been expertly recovered," Black said in a statement. "From studying his remains, we learned a little about his short life, but much more about his violent death. As you can see from the facial reconstruction, he was a striking young man, but he met a very brutal end, suffering a minimum of five severe injuries to his head."

The man's injuries indicate that a tool with a circular cross section made the first injury "that broke his teeth on the right side," Black said. "The second may have been the same implement, used like a fighting stick, which broke his jaw on the left. The third resulted in fracturing to the back of his head as he fell from the blow to his jaw with a tremendous force, possibly onto a hard object, perhaps stone."

The fourth impact was likely meant to end the man's life, she said. The attacker, or attackers, drove the same weapon through the man's skull, "from one side and out the other as he lay on the ground," Black said. "The fifth was not in keeping with the injuries caused in the other four, where a hole, larger than that caused by the previous weapon, was made in the top of the skull."

Radiocarbon dating of a bone sample showed that the man died between A.D. 430 and 630, a time known as the Pictish period in Scotland.

In addition, workers surveying the cave where archaeologists found the man's body unearthed hearths and iron-working debris, suggesting that the cave was used for iron smithing during the Pictish period, Black said. But the murdered man's body puts a new perspective on how ancient people used the cave, Black and her colleagues said.

"Having specialized in prehistoric cave archaeology in Scotland for some years now, I am fascinated with the results," Steven Birch, the excavation leader, said in the statement. "Here, we have a man who has been brutally killed, but who has been laid to rest in the cave with some consideration — placed on his back within a dark alcove and weighed down by beach stones."

"While we don't know why the man was killed," Birch added, "the placement of his remains gives us insight into the culture of those who buried him. Perhaps his murder was the result of interpersonal conflict; or was there a sacrificial element relating to his death?"

Researchers may soon learn more about the doomed man; the goal of the Rosemarkie Caves Project is to search more caves in the Black Isle, continuing to survey caves along the isle's coast.

Several other small excavations that were done in the past few years show that these caves were occupied or utilized in some way from about 1,500 to 2,000 years ago.

What's more, the caves have artifacts that date from about 200 to 300 years ago, likely left behind by temporary travelers or more permanent occupants. Some of these more recent occupants were likely making or repairing leather shoes for local communities, evidence suggests.

Black and her colleagues plan to continue to study the skeleton and artifacts left in the cave, with the hope of learning more about the man's place of origin, she said.

Original article on Live Science.

"Lucy," an early human ancestor that lived 3 million years ago, walked on two legs. But while she had her feet firmly planted on the ground, her arms were reaching for the trees, a new study shows.

High-resolution computed X-ray tomography (CT) scans of long bones in Lucy's arms reveal internal structures suggesting that her upper limbs were built for heavy load bearing — much like chimpanzees' arms, which they use to pull themselves up tree trunks and to swing between branches.

This adds to a growing body of evidence that although Lucy's pelvis, leg bones and feet supported bipedal walking, her upper body was adapted for at least partial life in trees — far more so than in modern humans. [Human Ancestor 'Lucy' Was A Tree-Climber, Bone Scans Reveal | Video]

Lucy was discovered in 1974 in Ethiopia, and for decades she represented the only known skeleton of the hominid species Australopithecus afarensis. Scientists knew from other fossil finds that females of the species were smaller than males, according to the Smithsonian National Museum of Natural History, and the size of Lucy's skeleton indicated that she was female.

While her skeleton was only 40 percent complete, it included long bones from her arms (humerus) and legs (femur), a partial shoulder blade and part of her pelvis, which helped scientists determine she was bipedal.  

But scientists have argued that anatomical features also suggest that Lucy was partly arboreal — a tree dweller.

The researchers delved into a digital archive of more than 35,000 CT "slices" — single images of bone cross-sections — to peer inside Lucy's left and right humerus and her left femur, to see what they might reveal about her tree-climbing habits. They then compared the internal structures to bones from other fossil hominids, chimpanzees and modern humans.

Load-bearing arms

The study is grounded in mechanical engineering principles, lead author Christopher Ruff, a professor of functional anatomy and evolution at the Johns Hopkins University School of Medicine, said in a statement.

He explained that bones required to support a lot of heavy lifting are bulkier in order to bear the extra strain. Other studies have even shown that bones can bulk up over time in response to high-stress demands, according to study co-author John Kappelman, a paleoanthropologist with the University of Texas at Austin.

"It is a well-established fact that the skeleton responds to loads during life, adding bone to resist high forces and subtracting bone when forces are reduced," Kappelman said in the statement. "Tennis players are a nice example: Studies have shown that the cortical bone in the shaft of the racquet arm is more heavily built up than that in the non-racquet arm," he added.

Structural proportions in Lucy's bones told the scientists that she was far more adapted for climbing than modern humans. And like chimpanzees, she likely spent a good portion of time in trees, perhaps to escape from predators or to find food.

An ape-like shoulder

Before this study, there was some debate among scientists about how Lucy may have divided her time between the ground and the trees, according to Will Harcourt-Smith, an associate professor of anthropology at Lehman College in the City University of New York, and a research associate in the vertebrate paleontology department at the American Museum of Natural History.

"The argument about whether Lucy was a full committed biped was heavily challenged in the 1980s by a number of studies," Harcourt-Smith told Live Science. "When you look at the anatomy — an ape-like shoulder joint, aspects of the wrist, elbow and foot — there are all these features that indicate she was still climbing in trees a significant part of the time."

Lucy's shoulder joint, in particular, hinted that she was probably a tree climber, he added. "The orientation of the joint essentially indicates she would have had a range of motion more conducive to pulling herself up in the trees," Harcourt-Smith explained.

Another A. afarensis discovery in 2012 — a 3-year-old girl called "Selam" — offered additional evidence that this species was at least partly arboreal. Selam's shoulder blades were angled like apes', suggesting that her arms were adapted for active climbing, even at this early age. [Image Gallery: 3-Year-Old Human Ancestor Revealed]

"And then along comes this new study, looking at cross-sectional profiles of the long bone, and the stress and strain that would have gone through those bones," Harcourt-Smith said.

"I think it's a very strong biomechanical argument that they had these strong upper limbs that were outside the range of variations seen in humans, and were much more like an ape. So it's very complementary to that initial work on the shoulder bones," he added.

The findings were published online Wednesday (Nov. 30) in the journal PLOS ONE.

Original article on Live Science.

Swiss researchers may have solved the mystery over the identity of a 17th-century man who was buried face-down with a knife and purse filled with coins.

X-ray computer tomography of the coins has revealed the man was likely a merchant, but the reason for his prone burial continues to puzzle the archaeologists.

Unearthed in 2013 in the Bernese Lakeland region of Switzerland during the construction on a new underground garage, the skeleton was found along 342 bodies laid to rest between the 8th and 17th centuries. The individual was among the last 15 bodies to be buried at the ancient cemetery.

The face-down skeleton stood out from all the other graves.

"It is certainly a deviant burial, in the sense that the burial practices here seem to be very unusual for the time," Christian Weiss, a numismatic expert with the Archaeological Services of Canton Bern, told Discovery News. "The individual was facing to the ground; moreover, a knife and a purse were found within the burial where we normally don't find any grave goods in this time," Weiss said.

RELATED: Anti-Demonic Burial Found in Poland

Under the individual's chest, the archaeologists found what remained of a leather purse. Over time, the leather had decomposed and the coins it contained had corroded together to form a solid block of metal.

Unable to separate the coins, the researchers turned to a powerful X-ray computer tomograph, a new instrument called µDETECT. Used in conjunction with a high resolution detector, the µDETECT revealed the presence of 24 coins.

"The astonishing fact about these coins is that they belong to three different coin circulation areas, the Fribourg-Bern-Solothurn, Basel-Freiburg in Breisgau and Luzern-Schwyz regions," Weiss said.

The finding suggests the individual was moving in these three areas, which had their own coins in local circulation at that time.

"It is possible he was a traveling merchant," Weiss said.

With one exception, a heavily worn silver coin from France, all the coins in the purse are of rather low value.

"They are really just small change," Weiss said. "The most interesting to me isn't really one particular coin, but the ensemble all together. We rarely get such a big ensemble of small value coins from this time."

RELATED: Medieval 'Witch Girl' Suffered From Scurvy

The latest among the coins in the purse dates from 1629, indicating the man must have been buried after then. The reason behind the face-down burial remains a mystery.

Like other deviant burials, in which the dead were buried with a brick in the mouth, nailed or staked to the ground, the prone burial aimed to humiliate the dead and prevent the individual from rising from the grave, since it was believed that the soul left the body through the mouth.

Usually these rare burials were meant as an act of punishment and in extreme cases the victim was interred alive.

In the case of the Swiss merchant, there is no conclusive answer. 

"It is likely they buried the man intentionally facing downwards. Whether the burial was meant to prevent him from returning to the living, or to face him to hell is just speculation. There could be other, rather unspectacular reasons behind this," Weiss said.

Originally published on Discovery News.

A well-preserved 2,000-year-old skeleton of a young man found on the famous Antikythera shipwreck could provide the first DNA evidence recovered from an ancient sunken boat, archaeologists reported.

Divers discovered the skeletal remains of the man, possibly a crewmember of the ship, on Aug. 31 during an excavation of the Antikythera shipwreck. This is where the mysterious Antikythera mechanism (an astronomical calculator) was found, in the Aegean Sea, near the Greek island of Antikythera. The submerged ruins date to 65 B.C and are thought to belong to a Greek ship that was used for trading or cargo.

Many precious artifacts as well as human remains have emerged from the wreckage of this ancient seafaring vessel since the ship was first discovered, in 1900. But for the first time, scientists are capable of conducting genetic analysis of a recovered skeleton, a procedure that was not yet available for bones found during a 1976 expedition, according to a Sept. 19 statement released by Woods Hole Oceanographic Institution (WHOI) in Massachusetts, whose researchers co-led the recent excavation. [Photos of Famed Antikythera Shipwreck and Antikythera Mechanism]

The bones, which were found buried beneath sand and bits of pottery, included rib pieces, two femurs, two arm bones and parts of a skull with three teeth still attached, and were described in a Sept. 19 news story published in the journal Nature. The bones' condition was described as "incredible" in a statement by Hannes Schroeder, an expert in ancient DNA at the Natural History Museum of Denmark in Copenhagen.

Schroeder traveled to Antikythera to view the bones after they were collected, determining that they likely all belonged to the same person — a young man, Schroeder said.

The skull pieces looked especially promising for DNA extraction, because they contained petrous bone, or a pyramid-shaped part of the temporal bone, Schroeder noted in the statement. Located at the base of the skull, this area contains some of the densest bone material in the body and is considered one of the best places for finding preserved DNA, which could inform researchers about what the young man looked like, or what part of the world he came from.

Since the shipwreck was first spotted by sponge divers more than 100 years ago, numerous objects have been brought to the surface. The first expeditions, in 1901, found treasures galore: dozens of marble statues, skeletons belonging to the long-dead crew and the spectacular bronze "computer" dubbed the Antikythera mechanism.

This peculiar device, described by the Hellenic Ministry of Culture and Sports as the most complex ancient item ever discovered, was found in 80 pieces. It contained wheels, dials and more than 30 gears. The complexity and intricate design intrigued and puzzled experts for decades; they eventually discovered that it was capable of showing lunar phases and the positions of the sun, moon and planets on a given date.

Other objects that emerged from the shipwreck appeared to be luxury goods belonging to people who enjoyed a lavish lifestyle: board-game pieces, musical instruments and even the arm of what may have been a bronze throne.

But while objects found at the site provide important information about how people lived thousands of years ago, the newly discovered skeleton represents a vital link to humans from the distant past — particularly those who crewed this ancient vessel, said Brendan Foley, a WHOI marine archaeologist who participated in the 2016 excavation.

"We can now connect directly with this person who sailed and died aboard the Antikythera ship," Foley said in the statement. "We don't know of anything else like it."

Original article on Live Science.

Move over, Nessie! There's a new ancient sea monster in town: the Storr Lochs Monster, a fierce, dolphin-like predator that lived 170 million years ago, during the age of dinosaurs.

Found on a beach in 1966 near the SSE Storr Lochs Power Station by the facility's manager, Norrie Gillies, the fossil is the most complete skeleton of a Jurassic-era, sea-living reptile that has ever been found in Scotland.

The ancient reptile, which belongs to an extinct family of marine reptiles known as ichthyosaurs, measured around 13 feet (4 meters) in length. It had a long, pointed head filled with hundreds of cone-shaped teeth. According to researchers, ichthyosaurs thrived in prehistoric seas, feeding on fish and squid. [In Images: Graveyard of Ichthyosaur Fossils Found in Chile]

"Ichthyosaurs like the Storr Lochs Monster ruled the waves, while dinosaurs thundered across the land," Steve Brusatte, a paleontologist at the University of Edinburgh, said in a statement. "Their bones are exceptionally rare in Scotland, which makes this specimen one of the crown jewels of Scottish fossils."

A fossilized skeleton of the Storr Lochs Monster was discovered 50 years ago, but until recently, it was sitting in the National Museums Scotland's storage facility. Thanks to a new research partnership, the fossil has been extracted from the rock that encased the skeleton for millions of years, so that it can now be studied.

"It's all thanks to the keen eye of an amateur collector that this remarkable fossil was ever found in the first place, which goes to show that you don't need an advanced degree to make huge scientific discoveries," Brusatte said.

Brusatte studied another fossil of the prehistoric marine-reptile found in Scotland, also discovered by an amateur fossil collector. That ichthyosaur specimen was incomplete — consisting of an arm bone and vertebrae — and was smaller than the Storr Lochs Monster.

The fossil record, which Brusatte noted is scarce, shows that sometime during the Middle Jurassic, smaller ichthyosaurs went extinct, while the larger, more advanced ones continued to thrive until their extinction about 95 million years ago, in the early stages of the Late Cretaceous period, the researchers said. The reason for this turnover, however, is unknown.

As paleontologists continue to study the Storr Lochs Monster, it could shed light on the Middle Jurassic Period, which lasted from about 176 million to 161 million years ago, Brusatte said.

"We don't have that many fossils from that time period anywhere in the world," Brusatte told National Geographic. "That's what makes this potentially an internationally important specimen. It's one of the few good fossils of an ichthyosaur that comes from this 'dark' period."

The Isle of Skye, where the Storr Lochs Monster was discovered, is one of the few places in the world where fossils from the Middle Jurassic Period can be found, the researchers said.

Original article on Live Science.

Arthritis is far from just a modern malady, said scientists who discovered the condition in the elbow of a 70-million-year-old duck-billed dinosaur.

The finding is the oldest recorded case of septic arthritis — a condition in which a joint becomes inflamed, often from bacteria or fungus — the researchers said.

"Our [duck-billed dinosaur] seems to have been afflicted with septic arthritis, which completely destroyed the elbow joint," said study lead researcher Jennifer Anné, a recent doctoral graduate from the School of Earth and Environmental Sciences at the University of Manchester in England. "There are signs of both bone destruction and excess bone growth that resulted in [a] possible fusion of the elbow. [Photos: Duck-Billed Dinosaurs Found in Alaska]

David Paris, a curator at the New Jersey State Museum, found the fossilized specimen in New Jersey a number of years ago, but he didn't have the tools needed to sufficiently study the fossil because it was fragile and full of pyrite (fool's gold), Anné said.

However, once Anné and her colleagues got access to a micro computed tomography (micro-CT) scanner, they decided to move forward and study the fossil. A micro-CT scanner uses X-rays that are more powerful than those used in CT scanners found in hospitals, providing higher-resolution images, Anné said.

"The X-rays are much more powerful, so they can punch through the dense fossil," she told Live Science in an email. "Medical CTs don't want to be that powerful, or they would cause damage to the patient. [But] fortunately, our patient [was] already dead."

The detailed micro-CT images helped the researchers diagnose the duck-billed dinosaur (or hadrosaur) with a bad case of septic arthritis. The condition likely gave the dinosaur a limp, and could have "possibly been severe enough for the animal to not use that arm at all," Anné said.

The hadrosaur was hardly alone in its misery. Septic arthritis also affects humans, as well as the living relatives of dinosaurs: crocodiles and birds, Anné said.

"I think it's a bit humbling to realize that a hadrosaurus that lived 70 million years ago could have had the same problems that affect the pigeons in the city," she said.

It's rare to find a dinosaur fossil with a malady. However, other researchers have found a few select remains indicating that the beasts experienced benign tumors and deformed fingers. 

The new study was published online today (Aug. 3) in the journal Royal Society Open Science.

Original article on Live Science.

Scientists have coaxed stem cells to grow new cartilage on a scaffold shaped like the ball of a hip joint. This is a major step toward being able one day to use a patient's own cells to repair a damaged joint, thus avoiding the need for extensive joint-replacement surgery.

In addition, the scientists used gene therapy to grant this new cartilage the ability to release anti-inflammatory molecules when needed. If done in patients, this technique could help prevent a return of arthritis, if that was what damaged the joint in the first place.

The new technique may be ready to test in humans within three to five years and may ultimately work with other joints, such as knees, said Farshid Guilak, a professor of orthopedic surgery at Washington University School of Medicine in St. Louis, who co-led the project. [5 Amazing Technologies That Are Revolutionizing Biotech]

The work, a collaboration between researchers at Washington University in St. Louis and researchers from Cytex Therapeutics, Inc. in Durham, North Carolina, appears today (June 18) in the journal Proceedings of the National Academy of Sciences.

The researchers said that the stem cell therapy might be particularly useful to younger people who have advanced osteoarthritis. In this degenerative joint disease, the cartilage that cushions the joint between two bones wears thin due to injury, excessive use or genetic susceptibility.

More than 27 million Americans have osteoarthritis, according to the Centers for Disease Control and Prevention (CDC). The prevalence of the condition is rising and is significantly higher among obese adults; weight loss of as little as 11 lbs. (5 kilograms) reduces the risk of developing knee osteoarthritis by half, according to CDC data. [Special Report: The Science of Weight Loss]

Doctors often recommend joint-replacement surgery for severe osteoarthritis when preventive measures such as weight management, exercise and medication fail. But doctors are reluctant to perform joint-replacement surgery on patients under the age of 50, because prosthetic joints typically last for less than 20 years, and a follow-up joint-replacement surgery is risky, Guilak said.

Some doctors in private practice began to treat osteoarthritis with stem cells as early as 2008. Mostly, doctors did this by simply injecting stem cells directly into the affected area with the hope that the cells would latch onto the joint, turn into cartilage and provide cushioning for the joint. But this method has never been shown to have a benefit, and the Food and Drug Administration (FDA) has questioned the safety and efficacy of the untested therapy, which can cost thousands of dollars per injection. The method has, however, been popular among athletes.

In 2014, a U.S. Court of Appeals decision upheld the FDA's authority to regulate stem cell treatment. That decision prevented U.S.-based clinics from offering these stem cell injections. Meanwhile, researchers have sought more-legitimate ways in which stem cells could be used for regenerative medicine. [11 Body Parts Grown in the Lab]

"Our study has made several major advances," Guilak told Live Science. "One important breakthrough has been to create cartilage that has the same load-bearing properties as normal cartilage but … [is] grown outside the body using stem cells from fat."

Most previous studies targeted small defects in the cartilage, an approach that was like trying to fix "a pothole in the road," he said. But in the new study, the researchers created a replacement that is the size of the entire joint. "We have the potential to resurface the whole hip in the case of osteoarthritis, which is much more common than a small defect," he said.

Guilak said the procedure is straightforward: Stem cells are extracted from a patient's fat and seeded on an external woven scaffold, designed to fit over the ball of the patient's joint. Using a "cocktail of proteins," Guilak said, stem cells are coaxed into turning into cartilage cells, before spreading throughout the woven scaffold over a period of six weeks.

The plan is to remove the worn-out cartilage from the ball of the joint and replace this with a "living joint" to resurface the hip, Guilak said. This plan hasn't been performed on humans yet but will be tested now in animals.

"Unlike a standard metal and plastic prosthesis, the bone of the hip is kept intact, and the surgery is much less invasive," Guilak said.

The scaffold in which the cartilage cells grow is a unique structure consisting of approximately 600 biodegradable fiber bundles woven together to create a high-performance fabric that can function like normal cartilage.

"The woven implants are strong enough to withstand loads up to 10 times a patient's body weight, which is typically what our joints must bear when we exercise," said Franklin Moutos, vice president of technology development at Cytex and the first author on the journal article.

Guilak said that the ultimate success of this new technique may depend on the gene-therapy element, which would help thwart new damage to the new cartilage. "We have modified the stem cells genetically to give them the ability to release anti-inflammatory drugs on demand, which has not been done in bioartificial cartilage previously," he said.

In this way, the joint would have a built-in medicine cabinet and perhaps be better than new, Guilak said.

Follow Christopher Wanjek @wanjek for daily tweets on health and science with a humorous edge. Wanjek is the author of "Food at Work" and "Bad Medicine." His column, Bad Medicine, appears regularly on Live Science.

The origins of a man who lived some 8,500 years ago, and whose skeleton was discovered in 1996 in Kennewick, Washington, have finally been pinned down. The ancient remains are most closely related to modern Native Americans, a new study led by the U.S. Army Corps of Engineers confirmed.

Now that the skeleton's Native American link has been confirmed — a 2015 analysis of Kennewick Man found similar results — the re-burial of the remains must follow the guidelines of the Native American Graves Protection and Repatriation Act (NAGPRA), the Army Corps said.

Currently, five Native American tribes claim the Kennewick Man is a relative, and they will work together to re-bury the remains, The Seattle Times reported.

"Obviously, we are hearing an acknowledgment from the corps of what we have been saying for 20 years," JoDe Goudy, chairman of the Yakama Nation, told The Seattle Times. "Now we want to collectively do what is right, and bring our relative back for re-burial." [In Photos: Human Skeleton Sheds Light on First Americans]

The saga of Kennewick Man

The Kennewick Man skeleton was found along the banks of the Columbia River and is considered one of the oldest and most complete ancient skeletons found in North America. In fact, tribes refer to Kennewick Man as the "Ancient One."

An arrow tip was lodged in the skeleton's pelvis, which led the coroner to surmise Kennewick Man was of European descent and was killed by a Native American. The identity of the Kennewick Man soon became contentious, and many researchers investigated the skeleton.

First efforts at analysis were unsuccessful in extracting and amplifying DNA, so researchers looked to qualitative evidence of what the man's life would have been like.

Physical anthropologist Douglas Owsley of the Smithsonian Institution and others reviewed the perplexing nature of these discoveries, according to the Smithsonian Magazine. Although Kennewick Man's grave was located 300 miles (483 kilometers) inland, studies concluded the man may have lived along a coast, because evidence shows his diet consisted largely of marine animals, according to that review. The water he drank was glacial meltwater, though 8,500 years ago, the closest water of this kind would have been in Alaska. Researchers determined that Kennewick Man was a traveler; evidence of developed muscles and possible work-related injuries show the man worked hard during his life.

Final resting place

Now, with the DNA determination of the man's relation to Native Americans in the U.S., the Kennewick Man's final journey will be to his final resting place.

Reburial would traditionally be at a site as close as possible to the skeleton's original grave. However, as multiple tribes claim relation, spokesperson for the Corps Northwestern Division Michael Coffey told The Seattle Times, it may be next February before they can confirm cultural ties for the reburial.

In the meantime, the tribes can continue to visit the Kennewick Man where he currently resides at the Burke Museum of History and Culture.

Follow Kacey Deamer @KaceyDeamer. Follow Live Science @livescience, on Facebook & Google+. Original article on Live Science.

The mystery of how a lung from ancient French royalty became mummified has been solved after decades of uncertainty, according to an international team of researchers.

In 1959, a preserved lung was uncovered by archaeologist Michel Fleury inside a stone sarcophagus in the Basilica of St Denis, Paris, the site where the kings of France have been buried for centuries. The lung was found with a skeleton, a strand of hair, jewelry and several fragments of textiles and leather.

On a gold ring, the inscription "Arnegundis" around a central monogram "Regine" revealed the remains belonged to the Merovingian Queen Arnegunde (about 515–about 580), one of the six wives of King Clotaire I (511-561) and the mother of King Chilpéric I (about 534-584).

Photos: Mummies' Faces, Hairdos, Revealed in 3D

Since the discovery, the fine preservation of the lung raised questions over whether her lung had naturally mummified or had been embalmed.

"From a macroscopic point of view, the lung appears nicely preserved, while the body is completely skeletonized," Raffaella Bianucci, a bio-anthropologist in the Legal Medicine Section at the University of Turin, told Discovery News.

It turns out an elaborate copper belt played a key role in the lung's mummification.

Photos: Signs of Incest in Famous Mummies

The international team led by Bianucci presented the results of their investigation at the International Conference of Comparative Mummy Studies in Hildesheim, Germany.

Scanning electron microscopy on the lung biopsies revealed a massive concentration of copper ion on the surface of the lung tissue. Other analysis turned up massive concentrations of a copper oxide throughout the lung biopsies.

Further biochemical analysis showed the presence of benzoic acid and related compounds in the lung, although at low levels.

Optical Illusion: Child Mummy Opens And Closes Her Eyes

"These substances are widespread in the plant kingdom and similar profiles have been already reported in the balms of Egyptian mummified bodies," Bianucci said.

According to the researchers, the findings support the theory that, as suggested by historians, Arnegunde might have undergone an oral injection of a fluid made of spices/aromatic plants.

"Since Arnegunde was wearing a copper alloy ... belt around her waist, we speculate the copper oxide in the lungs is from weathering of the belt," Bianucci said.

"The preserving properties of copper, combined with the spice embalming treatment, might have allowed the preservation of the lungs," she added.

Mystery Mummies: Who Are They? Photos

Historical accounts indicate that artificial mummification, based on the use of spices and aromatic plants, was used in sixth century France to treat the bodies of kings, queens, holymen and holywomen.

The Merovingians embalmed these elite individuals following a procedure they had learned from the Romans, which they, in turn, had adopted from Egypt.

"Clearly the Merovingian mummification was much less sophisticated," Bianucci said,

"It was essentially based on the use of oil and resin-soaked linen strips used with spices and aromatic plants such as thyme, nettles, myrrh and aloe," Bianucci said.

Ancient Egyptian Mummy Wearing Jewels Found

"Queen Arnegunde is a particularly complex case," Bianucci said. "Since she was exhumed in 1959, her remains underwent several displacements, disappearing in the 1960s to finally resurface in 2003."

Investigations on Arnegunde' skeletal remains revealed the queen was 5'1" tall and around 61 years old when she died of unknown causes.

Albert Zink, Head of the EURAC Institute for Mummies and the Iceman in Bolzano, found the research to be similar to the case of a Coptic mummy, dating from about 600-1000 A.D.

"During the study of this mummy we discovered the body did not undergo organ and brain removal. Instead, it appears that an embalming solution was injected through the mouth," Zink told Discovery News.

"Just like in the case of the Merovingian queen, the liquid agglomerated in the lung, which is the only organ that is well preserved," Zink said.

Mummy Identification Still Uncertain Science

Queen Arnegunde represents one of the few specimens from the Early Middle Ages for whom researchers have both an historical account, human remains and artifacts. Moreover, Arnegunde belonged to Merovingian royalty.

Distinctive for their shoulder-length hair, these Frankish kings ruled in parts of France and Germany from the fifth to the eighth centuries, establishing the most successful post-Roman kingdom in western Europe.

More recently, the Merovingians became popular with the publishing of Dan Brown's "Da Vinci Code," which revived the story that Jesus Christ and Mary Magdalene had married and their bloodline survived in the Merovingian dynasty.

3,400-Year-Old Necropolis Found in Egypt

In 2006, DNA analysis of a sample from Arnegunde' skeletal remains was arranged and filmed in a documentary.

The aim was to check whether she had a Middle Eastern haplo type. She did not. A princess of Thuringia, daughter to King Baderic, Arnegunde had married into the dynasty and was not a direct descendant of the Merovingian line.

Bianucci and colleagues were not interested in conspiracy theories but rather focused on the mummified lung.

Originally published on Discovery News.

One odd-looking creature

Since the so-called Tully monster's discovery in 1958, fossils of the odd-looking creature have mystified scientists. Now, two 2016 studies using cutting-edge technologies and a team of collaborative experts have announced that the approximately 307-million-year-old fossils — which, incidentally, are the state fossil of Illinois — are vertebrates. one study found that they were are jawless fish, similar to modern lampreys.

The other found that they were vertebrates, and likely "a type of very weird fish."

Tully monster, envisioned

An illustrator's interpretation of the Tully monster (Tullimonstrum gregarium). Notice its hammerheadlike eyes and its toothy mouth at the end of its proboscis.

Fishy swimmer

The Tully monster likely used its tail to propel it forward in the water.

First Tully monster fossil

The first fossil ever found of the Tully monster. Notice its proboscis folded over its head at the top.

Open wide

The toothy mouth at the end of the long proboscis. The dark spot on the right might be the remnants of an organ, the researchers said.

Eye bar

A sideways view of a Tully monster specimen. Notice its long eye bar pointing diagonally on the right side of the fossil.

Folded tail

A fossil with a folded tail, with the dorsal fin extending from the fifth skeletal muscle in the middle of the specimen.

Oh, that face!

This specimen shows a clear view of the Tully monster's eyes (right), proboscis (middle) and mouth (left).

Follow Laura Geggel on Twitter @LauraGeggel. Follow Live Science @livescience, Facebook & Google+.

It's all in the eyes

An microscopic image of Tully monster's peculiar eyes.

Tully Hunt

Thomas Clements and Sarah Gabbott search for the Tully monster in Illinois, where Tully is the state fossil.

A star is born

The Tully Monster is so famous in Illinois, that it's even featured on U-Haul trucks.

In 1958, amateur fossil collector Francis Tully found a prehistoric creature so strange that even scientists called it a monster. The beast has perplexed researchers ever since, with some calling the so-called "Tully monster" a worm and others classifying it as a shell-less snail.

But now, an analysis of more than 1,200 Tully monster (Tullimonstrum gregarium) fossils has uncovered the monster's true identity. It's a 307-million-year-old jawless fish, a creature in the lineage leading to modern-day lampreys, the researchers found. 

"It's a very unusual animal," study co-author Scott Lidgard, curator of invertebrate paleontology at the Field Museum of Natural History in Chicago, told Live Science. [See Images of the Bizarre Tully Monster]

The roughly foot-long (0.3 meters) monster had a narrow body with eyes like a hammerhead's on the top of its head and a long, slender snout ending in a toothy jaw.

Scientists formally described it in 1966, and in 1989, Illinois designated it as the official state fossil. But experts still couldn't make heads or tails of it. They couldn't even place it in a phylum, a big-picture category that includes about 30 broad subcategories, and explains the origins of almost every living thing on Earth.

Researchers have found thousands of Tully monster specimens in Illinois over the years. Many of them were digitally scanned into The Field Museum's electronic database, so scientists had plenty of samples to examine while undertaking the new study.

"Basically, nobody knew what it was,” study co-author Derek Briggs, a professor of geology and geophysics at Yale University and a curator of invertebrate paleontology at the Yale Peabody Museum of Natural History, said in a statement. "The fossils are not easy to interpret, and they vary quite a bit. Some people thought it might be this bizarre, swimming mollusk. We decided to throw every possible analytical technique at it."

The researchers combed through the database and also used synchrotron elemental mapping, a technique that uses a powerful light source to determine the chemistry within a fossil.

Although soft-bodied, the Tully monster is a vertebrate that likely used its tail to propel itself forward in the water. Moreover, analyses showed that "the monsters are related to the jawless fishes that are still around today by a unique combination of traits, including primitive gills [and] rows of teeth," Paul Mayer, The Field Museum's fossil invertebrates collections manager, said in the statement.

It also has "traces of a notochord, the flexible rodlike structure along the back that's present in chordate animals — including vertebrates like us," Mayer said.

The big-eyed and pointy-toothed fish was likely a predator, said study lead author Victoria McCoy, who conducted the research as a Yale graduate student and is now at the University of Leicester in the United Kingdom. However, it's unclear when the animal first developed and when it went extinct, she said.

The study was published online today (March 16) in the journal Nature.

Follow Laura Geggel on Twitter @LauraGeggel. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

When it comes to genuinely cringe-inducing feeding adaptations, you'd be hard-pressed to find an example more hard-core than the hydra, which rips itself a new mouth at every feeding time.

Yes, a hydra literally "tears itself a new one," opening a gap in its own skin to make a feeding slit and sealing it back up afterward, when the meal is done.

And now, for the first time, researchers have examined exactly what happens on a cellular level during this unusual (and arguably horrifying) process. [Watch: Tiny Tentacled Creature Rips Itself Open to Eat Prey]

Hydra vulgaris is a tiny, tentacled freshwater invertebrate. It has a tubular body measuring less than 0.5 inches (1.3 centimeters) in length, with a grasping footlike appendage at one end and a ring of tentacles covered in sharp barbs at the other. If a small shrimp touches those tentacles, the hydra's barbs paralyze the prey. That's when the smooth expanse of skin at its head rips open to expose a mouth, which gulps down the prey and then reknits itself closed without a seam to show that there was ever a mouth at all.

"Because [the] mouth opening is so dramatic, it was suggested that cells need to rearrange to allow for the hydra mouth to open," study senior author Eva-Maria Collins, an assistant professor in physics and cell and developmental biology at the University of California, San Diego, told Live Science in an email.

Rip, heal, repeat

The researchers quickly discovered that the cells weren't rearranging — they were deforming.

"When the mouth is closed, the cells have a roundish appearance," Collins said. "As [the mouth] opens, cells stretch dramatically, going from a roughly spherical to an ellipsoidlike shape."

And the transformation was dramatic — even the cell nuclei were warping, Collins said in a statement.

A hydra would trigger the stretching with electrical signals, which then cued muscular pulses that pulled its mouth open, Collins said. The muscle contraction was a key part of the mouth-opening process, the researchers found — if a hydra was given a muscle relaxant, its mouth wouldn't open.

While scientists may have revealed the cell-deforming process that opens and closes the hydra's peculiar temporary mouth, the benefits of this adaptation are yet to be discovered, Collins told Live Science.

"At this point in time, we do not have a good answer for this," she said. "It is an exciting question to study in the future."

The findings were published online today (March 8) in the Biophysical Journal.

Follow Mindy Weisberger on Twitter and Google+. Follow us @livescience, Facebook & Google+. Original article on Live Science

The tombs of Alexander the Great's extended family, first excavated in the 1970s, are a perennial source of controversy and frustration in the archaeological community. The debate centers around two tombs: Tomb I, which held human remains but had been looted in antiquity; and Tomb II, which was filled with treasure and armor, as well as the burnt bones of a man and a woman.

Tomb II has been identified as the final resting place of Philip II, Alexander the Great's father. But that identification is hotly contested. Some archaeologists believe that the bones actually belong to Philip III Arrhidaeus, Alexander's half-brother and a short-lived figurehead king. Philip II, they say, may actually rest in the looted Tomb I.

The debate has become entrenched and politicized, given the famous names involved. The Macedonian tombs near the city of Vergina, where the bones were found, are a UNESCO World Heritage site. Any new research paper on the tombs is met with skepticism from the opposing faction. Some observers despair of ever finding the truth.

The following images show the fragile bones and bone fragments around which this controversy swirls. Whether they belong to Philip II, Philip III, their wives or some other person, these bones represent the last physical link to ancient Macedonian royalty. [Read full story about the controversial bones]

Injured leg

The left leg of an adult male skeleton found in Tomb I at Vergina. The thigh bone (femur) and one of the bones of the lower leg (the tibia) are fused, and hole at the knee suggests a devastating penetrating injury. The injury matches some historical accounts of a leg wound suffered in battle by Philip II, the father of Alexander the Great. After the wound, Philip II limped until his death by assassination. (Photo Credit: Image Courtesy Javier Trueba)

Philip II

In a paper published in the journal PNAS on July 20, 2015, researchers argue that this leg wound is the "smoking gun" identifying the male skeleton in Tomb I as Philip II. This artist's impression reveals how the fused bones would have set the king's leg in a permanent bent position. He could have walked, albeit with difficulty. (Photo Credit: Image Courtesy Arturo Asensio)

Male jaw

The lower jaw of an adult male found in Tomb I. This jaw may belong to Philip II, father of Alexander the Great. Philip II was assassinated by one of his bodyguards in 336 B.C., possibly as part of a complicated revenge plot involving several of the king's male lovers.

The story, as recorded by ancient historian Diodorus of Sicily, goes like this: Philip's bodyguard and lover Pausanias became jealous that the king was doting on another man (also, confusingly, named Pausanias). The first Pausanias taunted the second so much that he committed suicide.

In revenge, the second Pausanias' friend Attalus (uncle of one of Philip II's wives), got the first Pausanias drunk and had him sexually assaulted. Pausanias brought the matter to Philip II, who promoted him but did not punish Attalus. Pausanias then assassinated Philip II to avenge his own honor.

The tale may or may not be true. Scholars have suggested that Alexander the Great's mother, Olympias, may have been involved, and the king had no shortage of enemies. (Photo Credit: Image Courtesy Javier Trueba)

Cleopatra's jaw?

If the male bones in Tomb I do belong to Philip II, the female skeleton found in the tomb is almost certainly his wife, Cleopatra. She was a teenager when she wed Philip, and was his seventh known wife. Cleopatra gave birth to the couple's child just days before Philip was assassinated. Days after his death, Olympias killed the child in Cleopatra's lap, according to the Latin historian Justin. She then forced Cleopatra to hang herself. (Photo Credit: Image courtesy of Javier Trueba)

Whose legs?

The leg bones of the female skeleton found in Tomb I. Antonis Bartsiokas and colleagues, reporting in the journal PNAS on July 20, 2015, argue that these bones belong to Philip II's wife Cleopatra. She was a robust woman who stood about 5 feet 4 inches (165 centimeters), according to the measurement of these bones. (Photo Credit: Image courtesy of Antonis Bartsiokas)

Teensy bones

Tiny newborn bones found in Tomb I belong to a child only one to three weeks past its due date. (It is impossible to know the baby's exact age, as it isn't clear from bones alone when an infant was born.) Anthropologists aren't sure of this infant's sex, but it may have been the murdered newborn child of Philip II and his seventh wife Cleopatra. (Photo Credit: Image courtesy of Antonis Bartsiokas)

An ancient mystery

In 1977, archaeologists near Vergina, Greece, cracked open a lavish Macedonian tomb containing two skeletons. The grave goods made it clear that the researchers had discovered the royal resting place of relatives of Alexander the Great, the conqueror who created an empire spanning from Greece into modern-day India. 

But the identity of the two skeletons remains hotly contested, even decades later. This male skeleton is likely to be either Philip II, Alexander the Great's powerful father, or Philip III Arrhidaios (also spelled Arrhidaeus), Alexander's reportedly feeble-minded half-brother. Philip II died in 336 B.C., and Philip III in 317 B.C. (Photo Credit: Jonathan Musgrave)

A mystery woman

Alongside the male skeleton found in the tomb at Vergina were the burnt bones of a young woman. Her bone fragments fill two trays, one of which is seen here. The woman's identity is also unknown. If the tomb belongs to Philip III Arrhidaios, she is probably his wife, Eurydice. Intermarriage was common among ancient Macedonian royals, so Eurydice was also Philip III's niece (she was the daughter of Philip III's half-sister). 

Philip II had somewhere in the range of seven wives. Archaeologists who believe the tomb is his have long suggested that the woman buried there is his last wife, Cleopatra (not the famous Egyptian queen, who lived centuries later). However, a study to be published in the International Journal of Osteoarchaeology suggests that the woman could be another wife, name unknown, from the nearby kingdom of Scythia, which covered the area roughly where Kazakhstan, Uzbekistan, Turkmenistan, Afghanistan, most of Pakistan and some of Eastern Europe are today. (Photo Credit: Jonathan Musgrave)

A hot debate

A view of the male skeleton from the Vergina tomb. Over the years, much of the debate about the bones' identity has focused on whether they were cremated dry or with flesh still clinging to them. Philip III Arridaios was ordered executed by one of his father's wives, Olympias, in the succession wars that followed Alexander the Great's death. (Olympias was Alexander the Great's mother.) Eurydice was forced to commit suicide. According to ancient histories, the couple was then buried unceremoniously, only to be exhumed months, or perhaps more than a year, later for a royal burial to shore up legitimacy for the next king. At this royal burial, the bodies would have been cremated. 

Philip II, on the other hand, would have been cremated right away. Thus, archaeologists reasoned, if the bones were cremated "fleshed," they were probably Philip II's. If they were cremated dry — the flesh having rotted off — they were probably Philip III's. But that line of thinking has been largely abandoned in recent years, given that a few months in the ground probably would have left Philip III Arridaios with some flesh still clinging to his bones. Thus, either body would have been cremated with flesh on. (Photo Credit: Jonathan Musgrave)

Proof of death

Fragments of the femoral (upper leg) bones from the woman in the Macedonian tomb. These pieces are the upper part of the femurs, and the knob is the joint where these bones connect to the pelvis. A 2010 article by University of Bristol anatomist Jonathan Musgrave noted the curved fractures in the bones and argued that these features indicated that the bones were burned with flesh still clinging to them. Bones warp differently in heat if burned dry versus burned with flesh on. (Photo Credit: Jonathan Musgrave)

Powerful woman

Limb bone fragments from the female skeleton found in the Vergina tomb. One candidate for the woman's identity is Eurydice II of Macedon, wife (and niece) of Philip III Arrhidaios. Eurydice was a warrior queen, as was her mother, Cynane (Alexander the Great's half sister). In the succession crisis that followed Alexander the Great's death, Cynane was determined to marry off her daughter to the new king, Philip III. In the process, Cynane was put to death by Alexander the Great's former generals, who were vying for power in the vacuum left by the conqueror's death. Eurydice, however, did marry Philip III and carried on her mother's ambitions, trying to grab real power for her figurehead husband. Ultimately, she led an army against the regent Polyperchon, but was stymied by the sudden appearance of Olympias, Alexander the Great's mother. Eurydice's troops refused to fight against the mother of Alexander the Great, who was backing Polyperchon, and she was forced to flee. She and her husband were both captured. He was executed, and she ordered to commit suicide by Olympias. (Photo Credit: Jonathan Musgrave)

Warped bones

This photograph of the male skeleton from Vergina was taken in 1983 at the Archaeological Museum in Thessaloniki, Greece. Arrows point to warping in the arm and leg bones caused by postmortem cremation. (Photo Credit: Jonathan Musgrave)

Debated facts

Part of the skull of the mystery male from Vergina. A large flange of bone is peeled outward, an effect of cremation. The question of whether these bones were burned dry or fleshed remains a contentious one: Musgrave argues that they were fleshed, while a 2000 paper in the journal Science by Antonis Bartsiokas, a paleoanthropologist at the Anaximandrian Institute of Human Evolution in Greece, argued that the bones were not warped enough to have been burned fleshed. 

The debate may be the result of too little information, according to Maria Liston, an anthropologist at the University of Waterloo in Ontario who studies cremated remains in Greece. Not enough is known about how bones respond when cremated after partial decomposition of the body, as would have occurred with Philip III, Liston told Live Science in June. (Photo Credit: Jonathan Musgrave)

Battle scars?

A view of part of the skull of the male skeleton from Vergina. An arrow points to a notch in the eye socket that the University of Bristol's Musgrave interprets as a remnant of a known battle wound of Philip II's. However, a 2000 paper in the journal Science argued that this notch is an effect of postmortem handling and cremation. An upcoming study in the International Journal of Osteoarchaeology also failed to find evidence of a pre-mortem eye wound — though those researchers did discover a healing hand fracture that could have matched one of Philip II's known injuries. (Photo Credit: Jonathan Musgrave)

Wounds or illness?

The jaw bone of the male skeleton from Vergina. The University of Bristol's Musgrave and Theodore Antikas of Aristotle University in Greece both noted, in separate studies, signs of inflammation in the jaw and sinuses of the skull. The inflammation could be the result of battle trauma, or chronic infection. For example, damage to the jaw could be caused by chronic gum disease. (Photo Credit: Jonathan Musgrave)

Dental work

The remnants of the teeth and hard palate of the man buried in the Macedonian tomb at Vergina. The arrows show shallow molar sockets; when a tooth is removed, bone breaks down in the empty space in the jaw in a process called resorption. This process permanently changes the shape of the jaw bone. In the modern day, dentists use bone grafts or synthetic materials to preserve the socket after a tooth is removed, enabling them to place a false tooth later.  (Photo Credit: Jonathan Musgrave)

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A California man tore a tendon in his thumb after playing a puzzle game on his smartphone too much, according to a new report of the case.

The case is interesting because such injuries are usually quite painful, but the man appeared to not notice any pain while he played, according to the doctors who treated him. The case shows that, in a sense, video games may numb people's pain and contribute to video game addiction, they said.

"We need to be aware that certain video games can act like digital painkillers," said Dr. Andrew Doan, a co-author of the case report and head of addictions research at the Naval Medical Center San Diego. "We have to be very cognizant that that can be abused," Doan said.

The 29-year-old went to the doctor because his left thumb hurt and he was having trouble moving it. He told doctors that he had played the puzzle game "Candy Crush Saga" on his smartphone all day for six to eight weeks. The man had played the game with his left hand while he used his right hand for other things, the report said.

"Playing was a kind of secondary thing, but it was constantly on," the man was quoted as saying in the case report. 

After examining the man and performing magnetic resonance imaging (MRI) on his hand, doctors determined that the man had ruptured a tendon involved in moving the thumb, and they said he needed surgery to repair the tendon. [9 Odd Ways Your Tech Devices May Injure You]

Typically, when people rupture this tendon, the tear occurs at the point where the tendon is thinnest, or where it attaches to the bone, Doan told Live Science. But in this man's case, the rupture occurred at the point where the tendon was thickest, which would usually cause pain prior to the rupture, Doan said.

But the man said he didn't feel pain while he played the smartphone game. This may be because, when people play video games, they can feel pleasure and excitement that are tied to the release of natural painkillers in the body — the same thing that happens when a person feels a "runner's high," Doan said.

This may lead to reduced perceptions of pain, but it may also play a role in the addictive nature of video games, Doan said.

In this particular case, the man was not addicted to "Candy Crush." Rather, he was playing the game as a way to pass time, Doan said. (The man had recently left the military and was between jobs.) But video game addictions can occur, and they sometimes cause problems in people's relationships, finances and work, Doan said.

People should try to limit gaming to about 30 minutes a day, Doan said. Studies show that about one hour or less of video game play a day can have social and emotional benefits, but too much gaming can have the opposite effect, Doan said.

People who experience problems in their lives as a result of too much video-game play should seek help, and can visit the support group On-Line Gamers Anonymous, Doan said.

It's well-known that smartphones and other devices can cause injuries — the phrase "BlackBerry thumb" refers to repetitive strain injuries that result from the overuse of thumbs to press buttons on mobile devices. And a recent review of Nintendo injuries found that the video games have been linked with a number of injuries over the last three decades, including muscle injuries, and cuts and black eyes linked with playing Nintendo Wii.

But despite the potential for video games to be abused and lead to injuries, their "painkiller" effect might have benefits in the right circumstances, such as for people in pain, the researchers said.

"Although this is only a single case report, research might consider whether video games have a role in clinical pain management and as nonpharmacologic alternatives during uncomfortable or painful medical procedures," the researchers wrote in the April 13 issue of the journal JAMA Internal Medicine. "It may be interesting to ascertain whether various games differ in their ability to reduce the perception of pain," they said.

Follow Rachael Rettner @RachaelRettner. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

About 3.5 million years ago, carnivorous birds with hooked beaks standing 10 feet (3 meters) tall roamed parts of South America in search of prey. Now, researchers have found a nearly complete skeleton of a new species of these so-called terror birds, and are learning surprising details about their hearing and anatomy.

Researchers found the fossil in 2010 on a beach in Mar del Plata, a city on the eastern coast of Argentina. To their delight, the fossil is the most complete skeleton of a terror bird ever found, with more than 90 percent of its bones preserved, said the study's lead researcher, Federico Degrange, an assistant researcher of vertebrate paleontology at the Centro de Investigaciones en Ciencias de la Tierra and the Universidad Nacional de Córdoba in Argentina.

The scientists named the new species Llallawavis scagliai: "Llallawa" because it means "magnificent" in Quechua, a language native to the people of the central Andes, and "avis," which means "bird" in Latin. The species name honors the famed Argentine naturalist Galileo Juan Scaglia (1915-1989). [Images: 25 Amazing Ancient Beasts]

Given its extraordinary condition, the fossil has helped researchers study the terror bird's anatomy in detail. The specimen is the first known fossilized terror bird with a complete trachea and complete palate (the roof of the mouth). It even includes the intricate bones of the creature's ears, eye sockets, brain box and skull, providing scientists with an unprecedented look at the flightless bird's sensory capabilities.

An analysis of L. scagliai's inner ear structures suggests the terror bird likely heard low-frequency sounds, an advantage for predators that hunt by listening for the low rumble of their prey's footsteps hitting the ground, the researchers said. The new findings also suggest that the terror bird communicated using low-frequency noises, the researchers added.

"That actually tells us quite a bit about what the animals do, simply because low-frequency sounds tend to propagate across the environment with little change in volume," said Lawrence Witmer, a professor of anatomy
at Ohio University
 who has worked with Degrange before, but was not involved in the new study.

"Low-frequency sounds are great for long-[distance] communication, or if you're a predator, for sensing the movements of prey animals," Witmer told Live Science.

This skill puts L. scagliai in good company. Other animals that can or could hear low-frequency sounds include Tyrannosaurus rex, crocodiles, elephants and rhinos, Witmer said.

The researchers also looked at the bird's skull, and found that it was more rigid than in other birds. This could have been to the bird's advantage, the scientists said, since a rigid skull could have helped the terror bird slam prey with its large beak.

"Terror birds didn't have a strong bite force, but they were capable of killing prey just by striking up and down with the beak," Degrange said.

The incredible, near-complete fossil shows that terror birds were more diverse in the Late Pliocene epoch than had been previously thought — an interesting fact given that the Late Pliocene falls toward the end of the birds' reign. Terror birds emerged about 52 million to 50 million years ago, and lived until about 1.8 million years ago, Degrange said. (Some scientists say that terror birds lived until 17,000 years ago, but evidence for this is dubious, he said.)

The researchers plan to study the terror bird's eye bones, brain case and skull in the coming years, with hopes of learning more about the animal's vision and other sensory capabilities, the scientists said.

The findings were published today (April 9) in the Journal of Vertebrate Paleontology.

Follow Laura Geggel on Twitter @LauraGeggel. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

The relatively lightly built skeletons of modern humans developed late in evolutionary history, and may have been the result of a shift away from a nomadic lifestyle to a more settled one, according to a new study.

These findings may shed light on modern bone conditions such as osteoporosis, the scientists said.

Bone is one of the strongest materials found in nature. Ounce for ounce, bone is stronger than steel, since a bar of steel of comparable size would weigh four or five times as much. In another comparison, a cubic inch of bone can in principle bear a load of 19,000 lbs. (8,620 kilograms) or more — roughly the weight of five standard pickup trucks — making it about four times as strong as concrete. [Bone Basics: 11 Surprising Facts About the Skeletal System]

Still, modern humans have a relatively lightly built skeleton compared with those of chimpanzees — the closest living relatives of humans — as well with those of extinct human lineages.

"Throughout our skeleton, our joints are about three-quarters to one-half as dense as those of our early human ancestors and those of other modern primate species," study co-author Brian Richmond, curator of human origins at the American Museum of Natural History in New York City, told Live Science. "That raises the question of when this happened in humans."

Much remains uncertain about when this unique modern human feature evolved. To shed light on this mystery, scientists examined the density of trabecular, or spongy, bone throughout the skeleton of modern humans and chimpanzees, as well as fossils of extinct human lineages spanning several million years, including Australopithecus africanus, Paranthropus robustus, Neanderthals and early Homo sapiens.

"We initially suspected that a more gracile, lightly built skeleton might be a characteristic of modern humans in general, compared to Neanderthals or our ancestors," Richmond said.

Instead, the researchers discovered that the arms and legs of recent modern humans are lightly built compared not only with other living primates and with extinct human species, but also with modern humans from before the present Holocene Epoch, which began about 12,000 years ago. Rather than shifting gradually over time, bone density remained high throughout the history of human evolution, until the appearance of recent modern humans, when it decreased dramatically. [Top 10 Mysteries of the First Humans]

Despite centuries of research on the human skeleton, this is the first study that shows that modern human skeletons have a substantially lower density in joints throughout the skeleton than compared to thei predecessors, Richmond said. "We've only discovered this now because our imaging technology is much higher-resolution than before, and is computationally capable of handling such images," he said.

The discovery that lightly built modern human skeletons evolved late in evolutionary history suggests that this change may have been linked to a reduction in activity due to a shift from a foraging lifestyle to a sedentary one. This idea is supported by the fact that the decrease in recent modern human bone density is more conspicuous in the lower joints of the hip, knee and ankle than in the upper joints of the shoulder, elbow and hand.

"Much to our surprise, throughout our deep past, we see that our human ancestors and relatives, who lived in natural settings, had very dense bone. And even early members of our species, going back 20,000 years or so, had bone that was about as dense as seen in other modern species," Richmond said in a statement. "But this density drastically drops off in more recent times, when we started to use agricultural tools to grow food and settle in one place."

In a related study, paleoanthropologists Timothy Ryan at the University of Pennsylvania and Colin Shaw at the University of Cambridge compared the hip joints of four groups of humans — two agricultural groups and two foraging groups — that once lived in what is now Illinois. They found that the mobile-forager groups possessed significantly thicker and stronger bones in their hip joints compared with the sedentary agriculturalist groups, and the bone strength and structure of the foragers' hip joints were comparable to that of great apes. This supports the idea that changes in physical activity may explain the lightly built modern human skeleton.

"There are other things that could account for some of the differences between early agriculturalists and foragers — the amount of cultivated grains in the diet of the agriculturalists — in this case maize — as well as possible deficiencies in dietary calcium [that] may also contribute to lower bone mass," Ryan said in a statement. "However, I think the key appears to be higher physical activity and mobility from a very young age that makes the bones of nonhuman primates and human foragers stronger."

This research could yield insights into modern conditions such as osteoporosis, a bone-weakening disorder that may be more prevalent in contemporary populations, due partly to low levels of walking activity.

"This is really important for understanding our skeletal health today," Richmond said. "It's clear our skeletons evolved in a context where our species was wide-ranging and experienced lots of activity. Something we have to grapple with today is what are the consequences of our relative lack of activity. It points to the importance of exercise, especially when growing up."

The scientists detailed their findings online today (Dec. 22) in two studies in the journal Proceedings of the National Academy of Sciences.

Follow us @livescience, Facebook & Google+. Original article on Live Science.

An archaeological dig in northern Italy has unearthed the remains of a 13-year-old-girl buried facedown -- evidence, archaeologists say, that despite her young age, she was rejected by her community and seen as a danger even when dead.

Dubbed by Italian media as “the witch girl,” the skeleton was unearthed at the complex of San Calocero in Albenga on the Ligurian Riviera, by a team of the Pontifical Institute of Christian Archaeology at the Vatican.

The site, a burial ground on which a martyr church dedicated to San Calocero was built around the fifth and sixth centuries A.D., was completely abandoned in 1593.

PHOTOS: Great Archaeological Discoveries Ahead

The prone burial, which has yet to be radiocarbon dated, is thought to date from the late antiquity or the early Middle Ages.

“These rare burials are explained as an act of punishment. What the dead had done was not accepted by the community,” said Stefano Roascio, the excavation director. Like other deviant burials, in which the dead were buried with a brick in the mouth, nailed or staked to the ground, or even decapitated and dismembered, the facedown treatment aimed to humiliate the dead and impede the individual from rising from the grave.

“In particular, the prone burial was linked to the belief that the soul left the body through the mouth. Burying the dead facedown was a way to prevent the impure soul threatening the living,” anthropologist Elena Dellù told Discovery News.

In extreme cases, a facedown burial was used as the ultimate punishment, with the victim horrifically buried alive.

BLOG: Skeletons Shed Light On Ancient Earthquake In Israel

It wasn’t a treatment used on the teenage girl, however.

“The skeleton’s position rules out this possibility,” Dellù said.

Found with her hands placed on the pelvis and straight and parallel legs, the girl showed no apparent signs of a violent death in her bones. However, Dellù noticed porotic hyperostosis on the skull and orbits. These areas of spongy or porous bone tissue are the result of a severe anaemia.

“She could have suffered from an inherited blood disorder such as thalassemia or from hemorrhagic conditions. More simply, it could have been an iron lacking diet,” Dellù said.

PHOTOS: Ancient Quake Revealed By Remains 

Standing just under 5 feet tall, the young girl somehow scared the community -- perhaps it was just her pallor, her possible hematomas and fainting.

Intriguingly, her disrespectful burial was found in a privileged area, just in front of the church.

“This makes the finding even more unusual. A similar case of a teenager buried facedown in front of a church was found at the archaeological site of Pava near Siena,” Roascio told Discovery News.

“A precise dating of the skeleton and further research on similar burials might help in finding more clues,” Roascio said.

Originally published on Discovery News.

A gargantuan, long-necked dinosaur as big as a two-story house and weighing as much as 12 elephants once stalked a flower-dotted earth some 77 million years ago in what is now Argentina. 

That's where paleontologists discovered the beast's bones, naming it Dreadnoughtus schrani after steel warships. The dinosaur is a sauropod, a type of long-necked, four-legged dinosaur that only ate plants.

"I think the big herbivores don't get their due for being" intimidating, said study lead author Ken Lacovara, an associate professor of paleontology and geology at Drexel University in Philadelphia. "I thought it should have a fearsome name." [See Images of the Massive Dreadnoughtus Dinosaur and Dig]

Lacovara named the dinosaur after dreadnaughts, warships that were created in the early 20th century. "For a time, they were basically impervious to attack," Lacovara told Live Science. "I thought that Dreadnoughtus would be a good name for these dinosaurs, which does two things: It means 'fears nothing,' and this dinosaur would have had nothing to fear. It also connotes something big like a battleship."

The species name, schrani, honors Adam Schran, an Internet entrepreneur and financial supporter of the project.

The big dig

Lacovara stumbled across Dreadnoughtus in February 2005, when he unearthed a small patch of bones in Patagonia, which is in southern Argentina.

"It turned into a 6-foot-plus-long [1.8 meters] femur, which was nice, but I kind of figured that this was going to be an isolated bone," Lacovara told Live Science. "And then we uncovered the tibia, and then we uncovered the fibula. By the end of the day, we had 10 bones exposed. And four years later, we had 145 bones exposed."

In fact, they had found two dinosaurs. The remains of the large Dreadnoughtus, the one the researchers examined in their new study, included 115 bones, and the smaller dinosaur's remains included 30 bones.

To the researchers' delight, much of the skeletons had stayed in place, revealing how the bones connected with one another. In many cases, dinosaur bones are found splayed apart, leaving much guesswork for paleontologists trying to piece the remains together, Lacovara said.

The researchers uncovered about 45 percent of the Dreadnoughtus' total skeleton and about 70 percent of the bones in its body, providing a rare glimpse of the anatomy and biomechanics of one of the largest dinosaurs to ever live. [Video: 'Astoundingly Huge' Dinosaur Discovered]

"To finally get to see what a really big sauropod looks like is fantastic," Steve Salisbury, a paleontologist from the University of Queensland in Brisbane, Australia, who was not involved in the study, told Live Science in an email. "Although we've known that there are a few really big sauropods out there, particularly among the titanosaurs [a group within sauropod dinosaurs], most have been known from fairly incomplete fossils."

These partial skeletons lead to speculative estimates about the animals' overall size and body proportions, Salisbury added. Before this new discovery, the most complete super-massive titanosaur fossil came from the Futalognkosaurus dukei, which was also discovered in Pategonia. These remains included about 15 percent of the animal's total skeleton and approximately 27 percent of the types of bones in its body, Lacovara said.

The new fossils, including a single, 2-inch-long (5 centimeters) tooth, are now in Lacovara's lab at Drexel University, on research loan from the Province of Santa Cruz, Argentina, which owns the dinosaur. The excavation team never found the dino's head, which would have been small and lightweight because it sat at the end of a 37-foot (11 m) neck.

"It's kind of a joke that sauropods don't have heads, because you almost never find a head," Lacovara said. "When they die, their heads pop off and you don't find them."

When the dinosaurs roamed

Dreadnoughtus lived about 77 million years ago, during the Late Cretaceous. The planet was likely warm and ice free, meaning that ocean levels were about 200 feet (61 m) above what they are today, Lacovara said. Flowering plants blossomed everywhere. [In Images: A Baby Dinosaur Unearthed]

Australia, Antarctica and South America were still connected during this period. In fact, fossils can help researchers piece together how the continents were joined together in the past. It's too difficult to dig for dinosaurs in the Antarctic ice, but Lacovara said he wonders if Dreadnoughtus fossils could be found in Australia — a project for another time, he said.

Still, complete skeletons of super-massive dinosaurs — those weighing 40 tons or more — are rarely found. At 65 tons, Dreadnoughtus is 85 feet (26 m) long, and two stories high at its shoulder. Estimates of the weight and length of other super-massive dinosaurs are typically based on only a handful of bones, the researchers said.

For example, estimates for the size of the Argentinosaurus, one of the largest dinosaurs on record, are based on just 13 of about 250 bones from its skeleton, Lacovara said.

He speculates that the two Dreadnoughtus dinosaurs found in Argentina died when a river flooded after suddenly breaking through a natural levee. This would have turned the ground into a soupy mess of sand and water, and led to the rapid burial of the dinosaurs.

"This needs to happen before the bones are heavily scavenged and/or break down naturally," Salisbury said. "I suspect that in most instances, the carcasses of some of the larger sauropods were just so big that unless they were in the right place at the right time, their carcasses were probably heavily scavenged, and in most instances, large parts of the skeleton probably never got preserved,"

The large Dreadnoughtus dinosaur has a few tooth marks on its vertebra, likely from a meat-eating scavenger that chewed on the dinosaur around the time of its death, the researchers said.

"If you put 65 tons of meat on the table, some scavengers are going to show up," Lacovara said. "We have some teeth of the meat[-eating] dinosaurs. They typically lose teeth as they feed."

"But," he added, "it's not the kind of injury that would kill Dreadnoughtus. It looks like something you would put a Band-Aid on."

Further analysis of the bones suggests that the large Dreadnoughtus was not yet fully grown. The shoulder bones are not fused together as they would be in a mature adult, and a section of the fossils show that the animal's bone-growing cells look like that of a youthful individual, Lacovara said.

The team did a "great" job examining the bones — which they scanned into 3D PDF files that are available to the public — and fitting them into the dinosaur family tree, said Patrick O'Connor, professor of anatomy at Ohio University in Athens, Ohio

"Many people are going to be very excited to see a dinosaur this complete coming out," O'Connor said. "A lot of times, we'll have a dinosaur based on a humerus or a couple parts of a vertebrae. This is a great because it's a lot of material to work with."

The study was published today (Sept. 4) in the journal Scientific Reports.

Follow Laura Geggel on Twitter @LauraGeggel and Google+. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

Big and Small

The bones of a gargantuan long-necked dinosaur, as big as a two-story house and weighing as much as 12 elephants, were discovered in Patagonia. Here, an illustrator's rendering of two Dreadnoughtus schrani dinosaurs next to a small meat-eating dinosaur. With a 37-foot-long neck, a 30-foot tale and a weight of 65 tons, the dinosaur likely had to eat massive amounts of plants to fuel its body. [Read full story]

Big dig

Lead researcher Kenneth Lacovara, an associate professor of paleontology and geology at Drexel University in Philadelphia, at the Dreadnoughtus site. [Read full story]

Heavy lifting

Between 2005 and 2009, researchers excavated the dinosaur bones (shown here in 2006), revealing 45 percent of dinosaur's total skeleton and about 70 percent of the bones in its body. [Read full story]

Large Dino

Paleontologist Kenneth Lacovara relaxes next to 234 plaster jackets holding the dinosaur bones of his and his colleagues' big find. [Read full story]

Teaming together

Former Drexel students Jessica Battisto (left) and Alison Moyer (right) jacket a single neck vertebra from Dreadnoughtus. [Read full story]

Dino Drawing

An artist's representation of Dreadnoughtus schrani, a dinosaur researchers discovered in Patagonia in 2005. The enormous dinosaur lived some 77 million years ago, during the Late Cretaceous, when Earth was warm and ice-free, dotted with flowering plants. [Read full story]

Tail of a tale

A portion of the 29-foot (8.7 meter) long tail of Dreadnoughtus schrani at the excavation site in Patagonia. [Read full story]

Towering tibia

Lacovara sits next to the right tibia, or shinbone, of Dreadnoughtus. [Read full story]

Chevron spotlight

These bones, called a chevron, are found at the bottom of the tail. The chevrons in Dreadnoughtus tail have a large surface for muscle attachment, suggesting that the tail was muscular and powerful. [Read full story]

Stormy skies

The landscape of Patagonia in Southern Argentina where the group excavated the dinosaur. [Read full story]

3D imaging

Lacovara’s team scanned the bones in 3D using lasers and are making them available to both researchers and the public. Here, doctoral candidate Anna Jaworski works on the Dreadnoughtus femur. [Read full story]

Fossils galore

Lacovara stands next to the Dreadnoughtus schrani fossils at Drexel University. [Read full story]

When European explorers landed in the Americas, they brought tuberculosis (TB) and a wave of other deadly diseases with them. However, some strains of TB may have already been lurking in South America, a new study finds.

In fact, these strains may have been brought to the Americas by seals and sea lions, researchers say.

A new analysis of three ancient Peruvian human skeletons that date to between A.D. 1028 and 1280 — well before Europeans landed on American shores — shows evidence of tuberculosis, including skeletal lesions and curved spines. [8 Grisly Archaeological Discoveries]

"It looked as though tuberculosis was present in the New World before [European] contact, based on these skeletons," said Kirsten Bos, the study's lead researcher and a postdoctoral fellow in paleogenetics at the University of Tübingen in Germany.

However, when the researchers reconstructed the genomes of the tuberculosis samples, they found the strains didn't fit into any branches of the disease that are commonly associated with human infection. Instead, "it was branching with the animals'" strains of TB, Bos told Live Science.

The new study also suggests that the common ancestor of the M. tuberculosis complex is just 6,000 years old, which is much earlier than the date suggested in a study published just last year. The previous study, whose authors included six of the same authors as the more recent study, concluded that the most recent common ancestor of TB was 70,000 years old, according to the paper, published in the journal Nature Genetics.

"These dates are worked out by measuring the amount of genetic diversity among all known strains of TB bacteria, and then using a molecular clock — based on the rate at which genetic changes occur during evolution — to work out how much time was needed for all that diversity to evolve," said Terry Brown, a life sciences faculty member at the University of Manchester in England, who was not involved in the study.

A popular theory suggests that tuberculosis started in Africa tens of thousands of years ago and followed humans as they migrated out of the continent. But the earlier date prompted the question, "How on Earth did TB get to the New World less than 10,000 years ago?" Bos said. The Bering Land Bridge, a stretch of land that connected Russia to Alaska during the previous Ice Age, had already disappeared under the Bering Strait, she noted.

A colleague helped to answer the question. Sebastien Gagneux, an expert on modern tuberculosis at the Swiss Tropical and Public Health Institute, suggested that the three Peruvians caught the disease from seals that had once lived in Africa, and had swum to the New World.

"We all laughed; we were all thinking that was kind of a joke," Bos recalled. "Then, we got our hands on some seal TB sequences. We plugged them into our TB family tree, and wouldn't you know: They were branching with our Peruvian samples." [Gallery: Seals of the World]

TB is known to jump across species, and there have been cases of people who have caught bovine TB, Brown told Live Science in an email.

"The reason why there are fewer reports of humans catching TB from seals is because we don't come into contact with seals so much," Brown said. "There have been previous speculations among archaeologists that this might have been a source of TB infections in coastal areas of South America, where seals were hunted and possibly even farmed."

But with only three human skeletons, it's unclear whether the seal strains of tuberculosis infected many people, or just an isolated few. More human archeological evidence is needed to determine whether the strains transmitted from seals and sea lions were widespread in the early Americas, experts agreed.

What's more, the 6,000-year-old birth date of tuberculosis needs further scrutiny, researchers said. 

"This estimate is, I think, the youngest estimate I've ever read," said Ruth Hershberg, an assistant professor of microbial evolutionary genomics at the Ruth and Bruce Rappaport Faculty of Medicine at the Technion (Israel Institute of Technology), who was not involved in the study.

Perhaps the bacteria that cause TB do not diversify at a constant rate, but rather have a pattern that speeds and slows over time, Hershberg said. "In order to address this, people will have to sequence more ancient samples to have more calibration points," she said.

Regardless of their age, the marine tuberculosis strains appear to have been completely replaced by European strains following contact, Bos said.

The study was published today (Aug. 20) in the journal Nature.

Follow Laura Geggel on Twitter @LauraGeggel and Google+. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

This Research in Action article was provided to Live Science in partnership with the National Science Foundation.

These tiny woven fibers make up a scaffold that is part of a framework for growing cartilage. 

Each of the scaffold’s seven layers is about as thick as a human hair, with the finished product about 1 millimeter thick. 

Humans and animals suffering from deteriorated articular cartilage — tissue that cushions bone joints — may one day find relief from the new synthetic material that mimics the suppleness and strength of natural cartilage tissue.

Articular cartilage is a durable, load-bearing tissue. Although it can withstand great stress while remaining lubricated enough to support thousands of joint movements, it wears away with overuse, injury or disease. Unfortunately, the uniqueness of this remarkable organic substance makes it difficult to replace. 

Nevertheless, Duke University engineers Farshid Guilak and Xuanhe Zhao developed a flexible, durable tissue that can model the functionality of natural cartilage  They created the synthetic tissue by uniting a 3-D fabric scaffold that Guilak and his team developed in 2007 with a hydrogel that Zhao and a team from Harvard University engineered in 2012. Hydrogels are composed of many molecule chains, called polymers, suspended in water. Just as a steel framework may provide stability for concrete poured over it, the 3-D fabric creates a lattice scaffold that provides stability for the malleable hydrogel.

Zhao’s resilient, lubricating hydrogel integrates with the durable fabric, resulting in a synthetic material that may be injected with stem cells and grown into articular cartilage tissue.

While this new artificial tissue does not serve as an exact replica of natural articular cartilage, it is a highly advanced synthetic material. The technology proves that a functional biomaterial simulating the pliable support of joint cartilage can be produced in the laboratory. "From a mechanical standpoint, this technology remedies the issues that other types of synthetic cartilage have had," says Zhao. "It is a very promising candidate for artificial cartilage in the future."

The National Science Foundation supported the Triangle Center of Excellence for Materials Research and Innovation involvement in this collaborative project, as well as the development of Zhao’s lubricating hydrogel in 2012. The research was described in the December 17, 2013 issue of the journal  Advanced Functional Materials.

Editor's Note: Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author and do not necessarily reflect the views of the National Science Foundation. See the Research in Action archive.

A sip of unpasteurized sheep or goat's milk may have spelled doom for a medieval Italian man.

A new genetic analysis of bony nodules found in a 700-year-old skeleton from Italy reveal that the man had brucellosis, a bacterial infection caught from livestock, when he died. It's not clear if the disease killed the man, but he likely would have suffered from symptoms such as chronic fatigue and recurring fevers, according to the researchers who analyzed the bones.

This medieval Italian man joins many other long-dead people in getting a postmortem diagnosis of brucellosis. Signs of the disease have been found in skeletons from the Bronze Age and earlier. In fact, the disease predates modern humans: In 2009, researchers reported possible signs of brucellosis in a specimen of the human ancestor Australopithecus africanus, who lived more than 2 million years ago. [10 Deadly Diseases That Hopped Across Species]

Disease hunters

The brucellosis-infected Italian came from Sardinia. He was buried in a medieval village called Geridu, which was abandoned sometime in the late 1300s, and was probably between 50 and 60 years old when he died.

Archaeologists found 32 bony nodules scattered in the man's pelvic region, the largest about 0.9 inches (2.2 centimeters) in diameter. Such nodules are often a sign of tuberculosis, a lung infection caused by the bacterium Mycobacterium tuberculosis. Tuberculosis is the most common culprit in cases of calcified nodules, study leader Mark Pallen, a microbial genomist at Warwick Medical School in England, said in a statement.

Pallen and his colleagues sampled one of the nodules and subjected it to a process called "shotgun metagenomics." Instead of searching for a particular DNA signature, shotgun metagenomics takes the approach of simply sampling all the DNA present, just to see what turns up.

To the researchers' surprise, the man did not have tuberculosis. Instead, the bony nodule held the DNA signature of the bacterium Brucella melitensis, the microbe that causes brucellosis.

Animal malady

Brucellosis can be transmitted from livestock to humans in several ways. One possibility is that the man caught the disease from direct contact with animals — perhaps while slaughtering a sheep or delivering a newborn lamb. Or he could have gotten the disease from drinking unpasteurized milk or eating unpasteurized cheese. The Brucella strain that infected the man was a close relative of modern Italian strains, the researchers found, and sheep and goat herding have long histories in the region.

Brucellosis is also called Mediterranean fever. It still affects more than 500,000 people around the world yearly, though livestock vaccination and dairy pasteurization have hampered its spread.

Today, antibiotics are used to treat people with brucellosis, and no more than 2 percent of infected people die from the disease, according to the Centers for Disease Control and Prevention. In its chronic, untreated form, the disease causes muscle and joint pain, fatigue and depression. The deadliest symptom of the disease is endocarditis, the swelling of the lining of the heart.

The method of diagnosing the medieval man's brucellosis could be used to uncover other ancient diseases, the researchers said. By not honing in on specific DNA signatures, researchers can cast a wider net, they wrote in their report of the case published today (July 15) in the journal mBio.

The team is now using the technique to test an array of samples, from ancient Hungarian and Egyptian mummies to the lung tissue of an early medieval French king, the researchers said in a statement.

"We're cranking through all of these samples, and we're hopeful that we're going to find new things," Pallen said.

Follow Stephanie Pappas on Twitter and Google+. Follow us @livescience, Facebook & Google+. Original article on Live Science.

A robot powered by muscle tissue could improve how engineers design future robots for disaster-relief operations, exploration or construction, new research finds.

The 3D-printed "bio-bot," created by researchers at the University of Illinois at Urbana-Champaign, has more precise control over its movements and a more dramatic range of motion, so it can navigate and change its movement in response to its environment. The rectangular robot measures about 0.2 inches (6 millimeters) long, and is constructed from a flexible, jelly-type material and fitted with two strips of engineered muscle tissue on either end.

This type of skeletal muscle tissue could eventually replace conventional motors in robots, said Carmel Majidi, a robotics professor at Carnegie Mellon University in Pittsburgh, who is not involved in the study. [The 6 Strangest Robots Ever Created]

"It could create an artificial muscle for limbs in a soft robot — like an artificial jellyfish or octopus — which can be used in search-and-rescue operations, underwater explorations, natural disaster relief — any scenario where we need a robot to squeeze into tight spaces," Majidi told Live Science. "Basically, you want a robot that's more lifelike."

Skeletal muscle tissue is what drives human movement. It covers the bones and is attached by springy tendons that we can consciously control. When we contract skeletal muscles in certain parts of the body, we move — whether it's a thigh while running or a slight twitch of the finger.

The researchers integrated skeletal muscle tissue engineered from a mouse cell line into a 3D-printed soft robot. Soft robots— a type of robot in bio-engineering inspired by the strong yet stretchy structure of starfish — is made from flexible rather than rigid material, allowing it to move and adapt in new environments.

By integrating skeletal tissue into a soft robot, the researchers created a machine that can carry out more complex motor tasks and is capable of freer and more dynamic motion. The new soft robots would be lightweight, bio-compatible and match the elastic properties of natural muscle tissue, the researchers said.

When the scientists tested the robot's movement, they found that the bio-bot moved only when given an electric shock — giving operators more control over its movement compared to previous bio-bots engineered with cardiac tissue. Robots with cardiac tissue twitch continuously, making it difficult to control their movements, according to the researchers.

If humans can control the robots to move only when they desire them to, that robot would thrive even better in sensitive or unpredictable work scenarios. These bots could potentially mimic the way our bodies move in response to our changing environments — whether it's dodging a taxi or moving into our downward dog yoga pose.

In the study, the researchers write that "cell-based soft robotic devices could transform our ability to design machines and systems that can dynamically sense and respond to a range of complex environmental signals."

Majidi said this type of integration of biological tissue with robotics could potentially lead to improving the design of prosthetic limbs, but such a feat is still far off into the future. "This is still early work and the potential advantages are speculative based on our current practical understanding/experiences," Majidi said. "There's much that remains to be done in tissue engineering and materials integration to have truly untethered and autonomous soft biohybrid robots."

Currently, DARPA has expressed interest in soft robots for a variety of military uses, including for its Maximum Mobility and Manipulation (M3) program launched in 2011, which is designing robots to assist warfighters on the ground.

Follow Jillian Rose Lim @jillroselim& Google+. Follow us @livescience, Facebook & Google+. Original article on Live Science.

The bones of ground sloths, saber-toothed cats and other creatures of the Ice Age have been discovered in a deep underwater cavern on Mexico's Yucatan Peninsula, but the exploration of the site is actually happening on the surface, hundreds of miles away, in a lab in San Diego.

Spelunkers first discovered the cave, called Hoyo Negro, seven years ago, but it was accessible only to specially trained cave divers. Now, a technique that combines photos to create 3D maps is providing a way for archaeologists to get a good look inside, without making the dangerous descent into the depths of the cave.

"If we can document all the artifacts, make a photo map of the bottom of the pit and create a 3D visualization that puts the archaeologists and paleontologists there — without ever getting wet — those discoveries and interpretations are made possible," Dominique Rissolo, a visiting scholar at the University of California, San Diego (UCSD), said in a statement. [See Photos of the Underwater Cave]

So far, explorers in this cave have discovered a human skeleton from the Ice Age, and remains of gomphotheres (ancient elephant-like animals), prehistoric ground sloths and saber-toothed cats. Archaeologists think Hoyo Negro holds more remains and could provide valuable insight into Native American history; they just need a way to get their hands on the bones.

Hoyo Negro — which, appropriately, means "Black Hole" — is part of the underwater labyrinth known as the Sac Actun cave system. The cave is more than 100 feet (30 meters) deep, and divers get only an hour of bottom time on each dive, further complicating the exploration of the site.

But researchers at the UCSD's Center of Interdisciplinary Science for Art, Architecture and Archaeology (CISA3) have come up with a solution: By tracking and lining up features in a series of photos of the cave taken by divers, researchers can create what are called 3D structure-from-motion models.

The imaging technique can even be used to create models of the artifacts in the cave. The dive team brought a a small mount into the cave and photographed the skull of the skeleton discovered there. Then, back on the surface, scientists at CISA3 stitched together the photos and created a 3D model for archaeologists to study.

"The in-depth post-expedition analysis happens digitally, in the form of 3D models that can be studied interactively and collaboratively, as well as precise physical replicas created on CISA3's 3D printers," Falko Kuester, director of CISA3, said in a statement. "Meanwhile, the original artifacts can remain undisturbed where they were originally discovered."

Even though the underwater cavern was discovered in 2007, the first study detailing what the cave holds was not published until this year. The biggest discovery is a 13,000-year-old skeleton of a Paleoamerican teenage girl that might provide some insight into the genetic history of Native Americans.

The archaeologists studying the site nicknamed the skeleton Naia, and believe she probably fell to her death while collecting water during the Pleistocene age, long before the cave filled with water. 

Scientists analyzed DNA from Naia's teeth and discovered that her genes came from an Asian lineage only seen before in Native Americans. The DNA supports the theory that Native Americans descended from a group of Siberians who entered America by crossing a land bridge that used to exist over the Bering Strait.

The team of researchers and divers exploring the cave are now considering ways to use acoustic mapping and imaging sensors to help create even more detailed visualizations of Hoyo Negro.

Follow Kelly Dickerson on Twitter. Follow us @livescience, Facebook & Google+. Original article on Live Science.

The ancient skeleton of a teenage girl found in an underwater cave in Mexico may be the missing link that solves the long-standing mystery behind the identity of the first Americans, researchers say.

These findings, the first time researchers have been able to connect an early American skeleton with modern Native American DNA, suggest the earliest Americans are indeed close relatives of modern Native Americans, scientists added.

The newfound skeleton was named "Naia," after Greek water spirits known as naiads. The bones are the nearly intact remains of a small, delicately built teenage girl who stood about 4 feet 10 inches (149 centimeters) tall and was about 15 or 16 years old at the time of her death, based on the development of her skeleton and teeth. [See Images of the Ancient Human Skeleton Discovery]

Naia reveals that despite any differences in the face and skull between the earliest Americans and modern Native Americans, they were, in fact, significantly related, probably deriving from the same gene pool.

"Naia is a missing link filling in a gap of knowledge we had about the earliest Americans and modern Native Americans,"lead study author James Chatters, owner of Applied Paleoscience, an archaeological and paleontological consulting firm in Bothell, Washington, told Live Science. Chatters is best known for his work on Kennewick Man, an ancient skeleton found in Kennewick, Washington, in 1996, whose origins were debated, because his skull was markedly different from those of modern Native Americans.

Cave discovery

Naia was hidden in a deep submerged pit known as Hoyo Negro. This underwater chamber is reachable only by divers in the Sac Actun cave system, a web of flooded tunnels beneath the jungles of Mexico's Eastern Yucatán Peninsula.

"Hoyo Negro is a more than 100-foot-deep (30 meters), bell-shaped, water-filled void about the size of a professional basketball arena deep inside a drowned cave system," Chatters said. "Only technical cave divers can reach the bottom. First they must climb down a 30-foot (9 m) ladder in a nearby sinkhole. Then they swim along 200 feet (60 m) of tunnel to the pit rim before making a final 100-foot (30 m) drop. The divers are the astronauts of this project; we scientists are their mission control."

Divers first discovered Hoyo Negro in 2007 during their exploration of underwater caves in the region. "We had no idea what we might find when we initially entered the cave, which is the allure of cave diving," said study author Alberto Nava of Bay Area Underwater Explorers in Berkeley, California. "The moment we entered the site, we knew it was an incredible place. The floor disappeared under us, and we could not see across to the other side."

"We pointed our lights down and to the sides — all we could see was darkness," Nava recalled. "We felt as if our powerful underwater lights were being destroyed by this void, so we called it 'Black Hole' (a cosmic object that absorbs all light), which in Spanish is Hoyo Negro." [Photos: The 7 Longest Caves of the World]

Buried with beasts

Naia was found in 2007 buried alongside the bones of beasts such as saber-toothed cats, coyotes, pumas, bears, sloths and bobcats. "It is like a miniature version of the La Brea Tar Pits, only without the tar and with better preservation," Chatters said. "It is a time capsule of climate, and plant, animal and human life at the end of the last ice age." (Located in Los Angeles, the La Brea Tar Pits hold the world's richest deposits of ice age fossils.)

The scientists think Naia and the animals fell into this cave long ago and died in this "inescapable natural trap," as the investigators called it. As glaciers worldwide started melting about 10,000 years ago, the cave filled with water — sea levels were as much as 360 feet (120 m) lower then.

Based on direct radiocarbon dating of tooth enamel and indirect uranium-thorium dating of flowerlike crystalline deposits on Naia's bones, the researchers suggest her remains are 12,000 to 13,000 years old. This hinted that she could help reveal a long-standing controversy regarding the mysterious relationship between the earliest Americans and modern Native Americans.

Genetically, modern Native Americans resemble Siberians. This suggests that modern Native Americans are the descendants of people who moved between 26,000 and 18,000 years ago into Beringia, the landmass that once connected Asia and North America and is now divided by the Bering Strait. These people then migrated southward into North America sometime after 17,000 years ago.

Who were the first Americans?

However, despite widespread support for the idea that the earliest Americans are the ancestors of modern Native Americans, the ancestry of the first people to inhabit the Americas was long debated, because the face and head features of the oldest-known American skeletons do not look much like those of modern Native Americans. [Human Origins: How Hominids Evolved (Infographic)]

"Modern Native Americans closely resemble people of China, Korea, and Japan, but the oldest American skeletons do not," Chatters said. The earliest American skeletons have longer, narrower skulls than modern Native Americans, and smaller, shorter faces.

All in all, the earliest Americans more closely resemble modern peoples of Africa, Australia and the Southern Pacific Rim. "This has led to speculation that perhaps the first Americans and Native Americans came from different homelands, or migrated from Asia at different stages in their evolution," Chatters said.

Moreover, it has been very difficult unearthing intact skeletons of the earliest Americans that might help resolve this controversy.

"Paleoamerican skeletons are rare for several reasons," Chatters said. "The people themselves were few; they were highly nomadic and seem to have buried or cremated the dead where they fell, making the locations of graves unpredictable; also, geologic processes have destroyed or deeply buried their graves."

Until now, the skeletal remains of the earliest Americans that scientists discovered were typically only fragments. In addition, most were estimated to be younger than 10,000 years old — the earliest Americans reached the Americas long before that.

Examining Naia's skull

To help solve the puzzle regarding the origins of the first people to reach the Americas, Chatters and his colleagues retrieved Naia's skull from Hoyo Negro. This operation was complicated by how divers who visited Hoyo Negro without authorization had almost knocked Naia's skull into a deep chasm.

"The floor of that cave is a mess, littered with boulders, some of which are room-sized, and the skull could have dropped another 5 meters (16 feet) into a gap where there would have been no room for a diver," Chatters said. "The area is now fenced off."

Moreover, "the divers had never picked up Naia's skull before, so we didn't know how strong it was," Chatters recalled. "We were praying that it would not just shatter in their hands. It turned out, she's as solid as a rock."

Naia's skull had the face and head features one would expect of the earliest Americans. To learn more about Naia's potential links to modern Native Americans, the scientists extracted DNA from her upper right wisdom tooth. They focused on genetic material from her mitochondria — the powerhouses of the cell, which possess their own DNA and get inherited from the mother. People have far more copies of mitochondrial DNA than chromosomal DNA, making it easier for researchers to study. [Top 10 Mysteries of the First Humans]

"We tried a DNA extraction on the outside chance some fragments might remain," Chatters said. "I was shocked when we actually got intact DNA.

"We were lucky to find a tooth that did not have an opening in the crown, so DNA still happened to be inside," Chatters added.

This DNA from her molar revealed that Naia possessed genetic mutations common to modern Native Americans. This genetic signature is found only in the Americas, probably first developing in Beringia after populations there split from Asians.

"This project is exciting on so many fronts — the beautiful cave, the incredibly well-preserved animal skeletons, the completeness of the human skeleton, the success of our innovative dating approach," Chatters said. "But for me, what is most exciting is that we finally have an answer, after 20 years, to a question that has plagued me since my first look at Kennewick Man — 'Who were the first Americans?'"

"These discoveries are extremely significant," said study author Pilar Luna, director of underwater archaeology at Mexico's National Institute of Anthropology and History. "Not only do they shed light on the origins of modern Americans, they clearly demonstrate the paleontological potential of the Yucatán Peninsula and the importance of conserving Mexico's unique heritage."

The differences seen in the face and head between the earliest Americans and modern Native Americans are probably due to evolutionary changes that happened during or after the colonization of the Americas.

"The changes that make northernmost Native Americans look most like East Asian people are adaptations to cold environments — for instance, a flatter face and lower nose means there are less parts of the body projecting out and potentially freezing off," Chatters said. "Afterward, evolutionary changes that were advantageous during the expansion into the Americas were not necessarily so advantageous after people settled down, so other traits came to dominate."

The researchers now hope to sequence Naia's entire genome. "Current technology permits this, but it will still be challenging," said study author Brian Kemp, a molecular anthropologist at Washington State University in Pullman.

The researchers also hope to find more skeletons that support their findings.

"You don't prove an argument based just on one example in science," Chatters said.

The scientists detail their findings in tomorrow's (May 16) issue of the journal Science. The research was supported, in part, by the National Geographic Society.

Follow us @livescience, Facebook & Google+. Original article on Live Science.

Watery skeleton

A near-complete human skeleton has been discovered, buried alongside saber-toothed cats, pumas and bobcats, at the bottom of Hoyo Negro, deep beneath the jungles of the eastern Yucatan Peninsula. Here, divers Nava and Susan Bird transport the Hoyo Negro skull to an underwater turntable so that it can be photographed in order to create a 3D model.

[Read the full story on this 'missing link' skeleton]

Cave find

Diver Susan Bird working at the bottom of Hoyo Negro, a large dome-shaped underwater cave on Mexico's Yucatan Peninsula. She carefully brushes the human skull found at the site while her team members take detailed photographs.

Ancient teen girl

Divers Susan Bird and Alberto Nava search the walls of Hoyo Negro, an underwater cave on Mexico's Yucatan Peninsula where the remains of "Naia," a 12,000- to 13,000-year-old teenage girl, were found.

Naia Skull

Cave diver Alexandro Alvarez inspects the newly discovered skull of Naia, the nearly complete human skeleton of a teen girl who fell into a Yucatan sinkhole some 12,000 to 13,000 years ago. Studying her DNA, researchers are learning about the origins of the first people to inhabit the Americas along with their connection to native people today. [Read the full story on this 'missing link' skeleton]

Hoyo Negro

The skull of Naia, the teen girl who died 12,000 to 13,000 years ago, on the floor of Hoyo Negro, an underwater cave on Mexico's Yucatan Peninsula, as it appeared in December 2011, having rolled into a near-upright position.

Skull and Arm

The skull of Naia, the teen girl who died 12,000 to 13,000 years ago, on the floor of Hoyo Negro, an underwater cave on Mexico's Yucatan Peninsula, as it was discovered in 2007, resting against the left humerus (upper armbone).

Shasta ground sloth

Alberto Nava at 145-foot depth in the underwater cave Hoyo Negro (on the Yucatan Peninsula), inspecting a forelimb of an extinct Shasta ground sloth, one of two sloth species found in the cave. The Shasta ground sloth has not previously been found so far south in the Americas.

In a new light

A broad view of Hoyo Negro, an underwater cave on Mexico's Yucatan Peninsula where the near-complete human skeleton of a teen girl was found, shot from the floor near the south edge, showing the immensity of the chamber and the complexity of the boulder-strewn bottom. One access tunnel can be seen near the ceiling at top left. (This photo was taken by the "painting with light" method on a 30 second exposure.)

Teen molar

The upper right third molar of Naia (the skeleton of a teen girl who died 12,000 to 13,000 years ago), which was used for both radiocarbon dating and DNA extraction. The tooth is held by ancient genetics expert Brian Kemp of Washington State University, who led the genetic research on the skeleton.

Why bother to manufacture materials if you can grow them organically?

Researchers have produced "living" materials by nudging bacteria to grow biological films. In turn, this process could lead to the development of more complex and interactive structures programmed to self-assemble into specific patterns, such as those used on solar cells and diagnostic sensors, and even self-healing materials that could sense damage and repair it, a new study finds.

"In contrast to materials we use in modern life, which are all dead, living materials have the ability to self-heal, adapt to the environment, form into complex patterns and shapes, and generate new functional materials and devices from the bottom up," said study lead author Timothy Lu, a biological engineer at the Massachusetts Institute of Technology.

Such "living materials" are essentially hybrids that have the best of both worlds: the benefits of both living cells, which can organize and grow on their own, and nonliving materials, which add functions such as electricity conduction or light emission. [Biomimicry: 7 Clever Technologies Inspired by Nature]

For instance, other researchers have looked at the possibility of organizing viruses into new materials. But Lu said his team's approach is different. "Previous systems do not leverage the characteristics of living organisms," he told Live Science. "Also, most modern materials' synthesis processes are energy-intensive, human-intensive endeavors. But we're suggesting to use biology to grow materials from the bottom up in an environmentally friendly fashion."

Learning from bones

To create the materials, Lu's team took inspiration from natural materials, such as bone and teeth, which contain a mix of minerals and living cells. Bones grow when cells arrange themselves into specific patterns and then excrete special proteins to produce the calcium phosphate structures.

Lu's team tried to do the same by reprogramming Escherichia colibacterial cells using genetic engineering to produce the proteins.

E. colinaturally produce biofilms that contain a special type of protein called curli fibers that help the bacteria attach to surfaces, and are known to have the strength of steel. Each curli fiber is composed of a chain of identical protein units called CsgA, which can be changed by adding protein fragments called peptides. These peptides can capture nonliving materials, such as gold nanoparticles, and incorporate them into the biofilms.

The researchers' goal was to get the bacteria to secrete the protein matrix in response to specific stimulants.

To do so, the researchers disabled the bacterial cells' natural ability to produce CsgA and replaced it with an engineered genetic code that produces CsgA proteins only under certain conditions — when a molecule called AHL is present.

The scientists could then adjust the amount of AHL in the cells' environment, and when AHL was present, the cells produced CsgA, making curli fibers that merged into a biofilm.

The team then modified E. coli in a different way, to make it produce CsgA with a specific peptide with many histidine amino acids, but only when a molecule called aTc was present.

"This allowed us to control the materials that were made by the bacteria using external signals," said Lu. Just by increasing or decreasing the amount of AHL and aTc in the modified E. coli's environment, they were able to modify the production and composition of the resulting biofilms.

The team then modified the proteins to make inorganic materials, such as gold nanoparticlesand quantum dots, to grow on the biofilms. By doing so, the researchers engineered self-growing E. coli biofilms that could conduct electricity or emit fluorescence.

"Talking" cells

The researchers also modified E. coli so the cells could "talk" to each other and coordinate the formation of materials whose properties change over time, without requiring human input. "Ultimately, we hope to emulate how natural systems, like bone, form. No one tells bone what to do, but it generates a material in response to environmental signals," Lu said. [Bone Basics: 11 Surprising Facts About the Skeletal System]

"One can imagine growing materials using sunlight rather than needing to have very energy-intensive processes for top-down materials' synthesis," he added.

Lu also envisions living cellular sensors that change their properties when they detect specific environmental signals, such as toxins.

Finally, by coating the biofilms with enzymes that catalyze the breakdown of cellulose, this work could lead to materials that convert agricultural waste into biofuels.

The research is not limited to E. coli. "We are considering the use of photosynthetic organisms and fungi as other fabrication platforms," Lu said. "In addition, we have only demonstrated the interface of biology with gold and semiconductor nanocrystals, but there are many other materials that can be interfaced."

Ahmad Khalil, a biomedical engineer at Boston University who was not involved in the study, applauded the work.

"This work presents, to my knowledge, one of the first demonstrations of using synthetic biology approaches to rewire or engineer these cellular mechanisms to precisely control how inorganic materials are assembled or synthesized on a molecular bio-template, thus providing an avenue for genetically encoded materials engineering," Khalil told Live Science.

The study was detailed in the March 23 issue of the journal Nature Materials.

Follow us @livescience, Facebook & Google+. Original article on Live Science. Follow the author on Twitter @SciTech_Cat.

Surprise!

An adult's skeletal system consists 206 bones, 32 teeth and a network of other structures that connect the bones together. This system performs a number of vital functions, such as giving the body its form, assisting with bodily movements and producing new blood cells.

Here are 11 surprising facts about the skeletal system.

Babies have more bones than adults.

Adults have 206 bones in their bodies, but the same is not true for infants.

The skeleton of a newborn baby has approximately 300 different components, which are a mixture of bones and cartilage. The cartilage eventually solidifies into bone in a process called ossification — for example, the kneecaps of newborns start off as cartilage and become bone in a few years.

Over time, the "extra" bones in infants fuse to form larger bones, reducing the overall number of bones to 206 by adulthood.

The hands and feet contain over half of the body's bones.

Bones come in all shapes and sizes, and are not evenly distributed throughout the body; some areas have far more bones than others. Coming out on top are your hands and feet.

Each hand has 27 bones, and each foot has 26, which means that together the body's two hands and two feet have 106 bones. That is, the hands and feet contain more than half of the bones in your entire body.

Some people have an extra rib that can cause health issues.

Most adults have 24 ribs (12 pairs), but about one in every 500 people has an extra rib, called a cervical rib. This rib, which grows from the base of the neck just above the collarbone, is not always fully formed — it's sometimes just a thin strand of tissue fibers.

Regardless of its form, the extra rib can cause health issues if it squashes nearby blood vessels or nerves. This results in a condition known as thoracic outlet syndrome, which is marked by pain in the shoulder or neck, loss of limb feeling, blood clots and other problems.

Every bone is connected to another bone — with one exception.

The hyoid is a horseshoe-shaped bone in the throat, situated between the chin and the thyroid cartilage. It's also the only bone in the human body not connected to another bone.

The hyoid is often considered the anatomical foundation of speech; because of where it's located, it can work with the larynx (voice box) and tongue to produce the range of human vocalizations. Neanderthals are the only other species to have hyoids like humans, and its presence in those hominids has led scientists to speculate that the Neanderthals had complex speech patterns similar to modern humans.

Ancient Egyptians developed the world's first functional prosthetic bone.

Prostheses are artificial devices that take the place of missing or injured body parts. Some prosthetic body parts are merely cosmetic — artificial eyes, for example — but prostheses that replace bones, such as prosthetic limbs or joints, have a functional purpose.

About 3,000 yeas ago, ancient Egyptians developed the first functional prosthesis: an artificial big toe. In 2011, researchers showed that Egyptians with the fake toes would have had a much easier time walking around in sandals than people who were missing their big toes but didn't get prostheses.

Human species have been dealing with bone tumors for 120,000 years.

Bones are made of active, living cells. And like the other cells in your body, the cells of your bones are susceptible to benign tumors and even cancer. But this is nothing new: Modern humans and their relatives have dealt with tumors for thousands of years.

In 2013, scientists found a tumor in a Neanderthal rib bone dating back 120,000 to 130,000 years. It is the oldest human tumor ever discovered.

Animals with internal, bony skeletons are in the minority.

The bony skeletal system in humans is hidden under layers of skin and muscle. The same is true for other vertebrates, or animals with backbones, including amphibians, birds, reptiles and fish. But vertebrates only account for 2 percent of the animal species on the planet; the other 98 percent are invertebrates, including insects, arachnids and mollusks.

This means that the vast majority of the animal species on the planet lack an internal or external skeleton made of bones. Some invertebrates have exoskeletons made of a fibrous substance called chitin, while others have a fluid-filled skeletal structure, as do jellyfish and worms.

Sharks lose thousands of teeth in their lifetimes.

Teeth are not counted as bones, but they are considered to be part of the skeletal system. Most people have 52 teeth in a lifetime — 20 "baby" teeth that fall out during childhood and 32 permanent teeth that grow in afterwards.

Sharks, on the other hand, have serrated front teeth and multiple rows of replacement teeth, which steadily move forward as the front teeth fall out. The teeth are sometimes replaced as frequently as once every 8 to 10 days, according to the Marine Education Society of Australasia, an organization that seeks to improve the understanding of marine environments. This high rate of replacement means that some sharks go through about 30,000 teeth in a lifetime.

Bones are not the hardest substances in the body.

Bones are strong and rigid, and built to withstand a lot of force — pound for pound, they are stronger than steel. But, surprisingly, they are not the hardest substance in the body.

That title goes to another part of the skeletal system: tooth enamel. This substance protects the crown of teeth and owes its strength to its high concentration of minerals (calcium salts in particular), according to the National Institutes of Health.

People don't directly control their bones.

One of the staples of Halloween costumes and horror movies is the walking skeleton. Of course, such a creature is pure fiction because it has no brain or nervous system to control its movements. But even if it did have these vital components, the undead monster would still be unable to walk around.

When people move their arms, legs or any other part of their bodies, it's not because they tell their bones to move — it's because they tell their muscles, which are attached to their bones, to move.

People have known how to deal with bone fractures for thousands of years.

Humans have, no doubt, suffered from broken bones for as long as the species has been around. But people have known how to deal with such fractures for a very long time, too, according to a 2009 review in the journal Clinical Orthopaedics and Related Research.

For example, in ancient Egypt's Edwin Smith Papyrus, which dates back to around 1600 B.C., the authors describe how to treat bone fractures, including a broken upper arm. Their recommendation: Realign the bone fragments (a process called reduction) and bandage the injury with linen.

And in the Hippocratic Collection, a Greek medical document circa 440–340 B.C., the authors fully describe their technique for reduction, which involves soaking linen bandages in oil and wax.

Hierakonpolis

The excavation site at an elite cemetery in the ancient Egyptian city of Hierakonpolis. Among the many animals buried in the cemetery are six newly discovered cats, including four kittens.

Excavating Skeletons

Bioarchaeologist Wim Van Neer excavates a small pit containing 6 cat skeletons at Hierakonpolis.

Cat Skeletons

A pit about 20 inches (50 cm) in diameter holds the remains of two adult cats and four kittens.

Cat Close-Up

Cat skeletons found in an elite cemetery in Hierakonpolis may have been sacrified and buried as part of some religious ritual.

Felis silvestris

Bone measurements suggest the cats belonged to the species Felis silvestris, the European wildcat shown here. These cats are the likely ancestors of modern housecats.

Mummified Kitten

In later periods, cats were an indisputable part of Egyptian life. This mummified kitten dates to between 332 B.C. and 30 B.C. It was likely bred to be sacrificed to the feline goddess Bastet, according to a 2012 study.

By the time relatives found 19-month-old DeVarion Gross concealed inside an 18-gallon storage container in his mother's closet, his body was too decomposed for investigators to determine how he had died.

They did, however, find other damning evidence that contributed to his mother's 2010 conviction in North Carolina: DeVarion had three rib fractures at different stages of healing — evidence of a history of abuse.

"If he hadn't been decomposed, we probably would not have seen any of them," said Ann Ross, an anthropologist at North Carolina State University who examined DeVarion's remains. "Most likely they would not have shown up on regular X-ray."

Rib fractures indicate abuse, since children DeVarion's age rarely suffer this injury in any other way, Ross said.

With fellow anthropologist Chelsey Juarez, Ross has published an overview of forensic research on child abuse and starvation with a focus on skeletal injuries. The goal: justice for victims and protection for others, whose abuse can be identified and stopped before the child arrives on an autopsy table. [The 7 Biggest Mysteries of the Human Body]

About 9.2 children per 1,000 in the United States were victims of child abuse in 2012, while 2.1 per 100,000 lost their lives to it in 2011, according to annual data. But some researchers think these numbers don't tell the whole story.

Child abuse and neglect can be difficult for doctors and forensic investigators to catch. For instance, bone injuries like DeVarion's are difficult to diagnose, particularly in young children, because these injuries heal quickly. What's more, abused children usually don't get medical attention until they are seriously injured, and, if they do get treatment, a doctor must determine if a caretaker's explanation is plausible given the injuries, Ross said.

DeVarion's rib fractures fit into one of the common abuse patterns — thoracic, or upper torso, injuries — described by Ross and Juarez. Rib fractures in children under 3 years old are rare, partly because a young child's thoracic region is extremely flexible. As a result, rib fractures in young children are a strong sign of abuse.

For DeVarion, two rib fractures had nearly healed and one was in a very early state of healing. These injuries would likely have escaped X-ray detection while he was still alive, and an X-ray scan done after the discovery of his body, while it was still covered in plastic bags, did not reveal any acute injury. But the advanced state of decomposition of his body allowed Ross to examine his bones directly, where she found the three healing fractures.

Another common pattern, called shaken baby syndrome, is associated with bleeding and swelling of the brain as well as hemorrhages in the retina at the back of the eye. However, there is a controversy over shaken baby syndrome; some argue that shaking alone cannot produce these injuries and that some other form of impact must also be a factor, according to Ross.  

In addition to violence, the researchers address another form of abuse: neglect, specifically starvation. This kind of abuse typically accompanies so-called medical neglect. As a result, children suffering these abuses almost never show up in doctors' offices.

Ross and Juarez recommend using bone mineral-density scans, in which X-rays measure how much calcium and other minerals a section of bone contains, to determine if a child experienced starvation before dying. Bone mineral density normally increases with age, but malnourishment reduces bone density.

As a forensic anthropologist and a mother, Ross finds children's cases completely consuming. "These are little, innocent children that didn't have a choice. They didn't have a choice on who their mother was. They didn't have a choice on their circumstances," she said. An investigator's job is to present the facts, "so you are speaking for that innocent" child.

Ross and Juarez's work was published online Jan. 28 in the journal Forensic Science, Medicine and Pathology. 

Follow us @livescience, Facebook & Google+. Original article on Live Science.

Parents dying to know their baby's sex before birth can typically find out with an ultrasound at 20 weeks. But if baby doesn't provide a full frontal view — or if parents can't stand to wait 20 weeks — any number of old wives' tales promise to give answers.

The latest of these, "skull theory," looks to the shape of the fetal skull. Supposedly, boys have larger, blockier foreheads, while girls' heads are rounder.

As fun as the guessing game might be, however, skull theory is for entertainment value only. There's no way to judge the sex of a fetus from the shape of a skull on a grainy ultrasound. [11 Big Fat Pregnancy Myths]

"It makes no sense," said Kristina Killgrove, a bioarchaeologist at the University of West Florida. Anthropologists and archaeologists can, in fact, tell the difference between adult male and female skulls — sometimes. But the skeletons of baby boys and baby girls just don't look that different.

"Until you get to maturity or at least puberty you just don't get these sexually dimorphic features of the skulls in males and females," Killgrove told LiveScience.

Strange theory

It's hard to say how skull theory got started. A few baby blogs mention it, but most of its online fame comes from pregnancy message boards, where moms-to-be post ultrasound pics and challenge each other to guess the baby's sex from the skull. Increasing use of early ultrasound may drive the trend: Many pregnant posters put up scans from before the 20-week appointment when sex is usually determined.

The ideas underlying skull theory, as found in various online posts explaining the methods, appear to be drawn from anthropological studies of adult skeletons. Male skulls are larger and blockier, while female skulls are more delicate and rounded. The forehead is more prominent in males, and the jaw squarer.

This is all true, to some extent, Killgrove said. The problem with applying it to fetuses is that the differences develop at maturity. Men are bigger than women, on average, with larger muscles, so the bony attachments that anchor these muscles are larger, too.

Sex mysteries

But even in adults, experts can't look at a skull and know sex for sure; they have to compare careful measurements of these features to averages across the entire population. Ethnicity matters, too. Modern Chinese men, for example, will be smaller and more slightly built than modern men from the Netherlands, the country with the tallest men, on average, Killgrove said. And there are grey areas. A particularly small man or especially bulky woman is hard to differentiate from skeletal remains alone, she said.

Even when examining adult remains, the skull isn't the best place to start looking for sex. It can provide useful information, Killgrove said, but the pelvis usually makes the strongest case for male or female.

"With the pelvis, there are certain features that seem to correlate with the different anatomy," she said.

To determine the sex of ancient remains of children and babies, researchers must turn to DNA analysis, Killgrove said.

Skull theory is not the strangest method people have come up with to guess at a baby's sex in utero. Many a mom-to-be has been told she must be carrying a boy because her baby bump sits so high; they also try to extract information from pregnancy cravings. (The old wives' tale holds that sweet cravings presage a baby girl.) Perhaps the strangest method is one suggested in the book " "Do Chocolate Lovers Have Sweeter Babies?" (Souvenir Press, 2013), which posits that moms carrying girls will watch their breasts swell larger than will moms carrying boys.

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