An ancient skeleton from an underwater Mexican cave sheds light on early Americans
Nearly 10,000 years ago, the body of a young woman ended up in a dry cave in southern Mexico. Her bones, discovered by divers in the now-submerged cave, are revealing clues to a short, hard life as well as the history of the first Americans. Traditionally, scientists thought just one group of humans crossed a land bridge connecting Asia to North America around 12,000 years ago. But sinkhole caves in the Yucatán Peninsula have yielded nine other skeletons, including a teenage girl linked to modern native Americans (SN: 5/15/14), that suggest humans had already reached that far south by roughly 12,000 years ago. Explorers mapping a Yucatán cave called Chan Hol found this new female skeleton, dubbed Chan Hol 3, in 2016. Salty cave water degrades collagen in bones, stymieing usual radiocarbon dating methods. But low levels of uranium and thorium in calcite mineral deposits from stalactites that dripped onto Chan Hol 3’s...