A cave is "a natural opening in the ground extending beyond the zone of light and large enough to permit the entry of man," according to the U.S. Geological Survey. Caves can range in size from single rooms to large formations with winding passageways that extend for miles. Caves typically form in types of rock, such as limestone, that dissolve in water. It can take tens of thousands to hundreds of thousands of years for caves to form. The study of caves is called speleology, and the exploration of caves is called spelunking. Caves are famous of their dripstone features called speleothems, the most well-known of which are stalactites and stalagmites. Many of the strange creatures found in caves have adapted to live in near or total darkness — some are blind to visible light. See cave pictures and read about the latest cave discoveries and speleological research below.
Human cannibals likely took a big bite out of their fellow humans about 10,000 years ago, according to a study that examined prehistoric bones with scratch and bite marks on them.
A newfound, 400,000-year-old hominin skull has a few telltale features suggesting that it's more of a Neanderthal than a Homo sapiens relation, a new study finds.
A new species of land snail that lives underground in Brazil was named for a character in the popular role-playing tabletop game, Dungeons & Dragons.
Hikers exploring caves in southern Israel recently made an unexpected discovery: engravings of a cross and a menorah located close together on a cistern wall.
Glowworms create dazzling threads to trap unsuspecting insects. And now, researchers think they may have found the secret ingredient in the worms' traps: urea from their guts.
Stone tools dating back 14,550 years provide rare physical evidence that places humans in the Americas earlier than previously suspected — by more than 1,000 years.
Tooth marks on the leg bone of a hominin, an ancient human relative, suggest that the poor soul had a gristly end, a new study finds.
Hawaii just doubled the number of known land mammal species that are native to the islands, thanks to the discovery of a number of fossils representing a tiny bat.
Deep beneath the surface of the Earth, in a dank and dismal cave, lives Hades, the invertebrate king of hell.
Shattered cave formations in the central and eastern United States preserve one of the longest records of powerful earthquakes in these regions.
While spelunking in northern Israel, cavers stumbled upon a hidden stash of ancient coins and jewelry from the era of Alexander the Great, the Israel Antiquities Authority announced.
Bacteria aren't just tenants inside Sweden's Tjuv-Ante's Cave. The microbes are building calcite dripstones on the ceiling.
A 3D modeling technique allows researchers to stay dry while studying skeletons found in a deep underwater cave on the Yucatan Peninsula.