The unmistakable work of prehistoric humans was found etched into the mammoth's hide. Yuka the mammoth may have been killed by cave lions. Image credit: Zhuravlev Andrey/Shutterstock.com Often hailed as the best-preserved woolly mammoth corpse ever discovered, the body of a young female specimen named Yuka has just yielded a staggering surprise. By analyzing cut marks on the animal's hide, researchers have now determined that the beast was butchered by humans 39,000 years ago, thus providing the earliest evidence for the presence of people in the Arctic. Discovered in 2010 in the extreme north of Siberia, Yuka is thought to...