Each week we uncover the most interesting and informative articles from around the world, here are 10 of the coolest stories in science this week.
POWs and Slaves
At an ancient site of human sacrifice in China, war captives may have been kept as slaves for years before they were killed, a new study finds.
Archaeologists have previously uncovered evidence of ritual human sacrifice in many ancient societies, including the ancient Greeks, the Vikings, the ancient Maya, and the Aztecs and the Incas, as well as in ancient China. [Read more about the doomed lives.]
Not a Comet
An astronomer thinks he's pinpointed the source of a mysterious radio signal from space: a passing comet that nobody knew about. But his colleagues said they're still skeptical of the explanation, noting that comets don't emit radio waves in the right way.
Others aren't so sure. "We do not believe the two-comets theory can explain the Wow! signal," Jerry Ehman, the astronomer who discovered the Wow! signal in 1977, told Live Science. [Read more about the 'WOW!' signal.]
Tanning by Pill
A new drug can give human skin a "natural" tan — it activates the same process that causes skin to darken in the sun, without exposure to harmful ultraviolet (UV) rays, according to early research.
Much more research is needed to determine if the drug is safe before it could be used in people, the researchers said. But they are hopeful that the drug might actually protect people against skin cancer, because the presence of melanin in the skin is linked with a lower risk of skin cancer. [Read more about sunless tanning.]
A Chinese satellite has split pairs of "entangled photons" and transmitted them to separate ground stations 745 miles (1,200 kilometers) apart, smashing the previous distance record for such a feat and opening new possibilities in quantum communication.
Quantum entanglement has interesting applications for testing the fundamental laws of physics, but also for creating exceptionally secure communication systems, scientists have said. That's because quantum mechanics states that measuring a quantum system inevitably disturbs it, so any attempt to eavesdrop is impossible to hide. [Read more about hack-proof communications.]
Charging on the Go
A new wireless power system could help people avoid the inevitable jumbled mess of tangled cords and offer a more efficient way to charge electric vehicles on the go, according to a new study.
The problem lies in the design of these wireless power systems. They typically consist of a source, which is the charging pad, and a receiver, which could be a phone or an electric car. [Read more about wired roads.]
A Severe Condition
When doctors in China removed 30 inches of a young man's colon, they also removed nearly 29 lbs. (13 kilograms) of his feces.
Temple to a Wind God
An ancient ceremonial ball court and an Aztec temple dedicated to the wind god Ehécatl have been identified in what is now a modern section of Mexico City.
And close by the ball court lay a grisly surprise: sets of neck bones representing about 30 individuals, all infants and children, INAH officials said in the statement. [Read more about the gruesome find.]
Sex in Space
If humanity is serious about colonizing Mars, we need to get busy studying how to get busy in space.
Off-Earth reproduction isn't a completely ignored topic, of course. Just last month, for example, a group of researchers in Japan announced that freeze-dried mouse sperm that was stored on the International Space Station for nine months gave rise to healthy pups. [Read more about the final frontier.]
The identity of Leonardo da Vinci's mother has eluded historians for years, but now one scholar said he's found the woman behind the Renaissance man.
After digging through overlooked records in Italy, Martin Kemp, a leading Leonardo expert, claimed that the artist was born to Caterina di Meo Lippi, a 15-year-old orphan, on April 15, 1452. [Read more about Da Vinci's mom.]
Work and Sexism
The recent case of man in a powerful position making a sexist comment — during a company meeting aimed partly at addressing discrimination against women — raises the question of why gender issues in the workplace are so difficult to quash.
Companies don't talk about things such as masculinity and the role it plays in gender inequality, Pascoe told Live Science. But dominance over women is a "central part of the contemporary understanding of masculinity," and that extends beyond the workplace, she said. [Read more about workplace sexism.]