|20 October 2015
Teeth from China reveal early human trek out of Africa
Teeth from a cave in Hunan Province, southeastern China, show that Homo sapiens reached there around 100,000 years ago, a time when most current researchers thought our species had not moved far beyond Africa.
Recent excavations of an extensive cave system in Daoxian County discovered 47 human teeth, as well as the remains of hyenas, extinct giant pandas, and dozens of other animal species, but no stone tools; it is likely that humans never lived in the cave.
Maria Martinon-Torres, a palaeo-anthropologist at University College London who co-led the study, says the overall shape of the teeth is barely distinguishable from those of both ancient and present-day humans.
The team dated various calcite deposits in the cave, and used the assortment of animal remains to deduce that the human teeth were probably between 80,000 and 120,000 years old.
Those ages challenge the conventional wisdom that Homo sapiens from Africa began colonising the world only around 50,000 to 60,000 years ago. Older traces of modern humans have been seen outside Africa, such as the roughly 100,000-year-old remains from caves in Israel, but many had argued those remains are from an unsuccessful migration.
Without DNA from the teeth, it is impossible to determine the relationship between the Daoxian people and other humans, including present-day Asians, but Jean-Jacques Hublin, a palaeo-anthropologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, thinks that later waves of humans replaced them. Other genetic evidence suggests that present-day East Asians descend from humans who interbred with Neanderthals in western Asia some 55,000 to 60,000 years ago.
It is not clear why modern humans would have reached East Asia so long before they reached Europe, where the earliest remains are about 45,000 years old. Martinon-Torres suggests that humans could not gain a foothold in Europe until Neanderthals there were teetering on extinction. The frigid climate of Ice Age Europe may have been another barrier.
Hublin says that although the Daoxian teeth may be older than 80,000 years, several of the teeth have visible cavities, a feature uncommon in human teeth older than 50,000 years. "It could be that early modern humans had a peculiar diet in tropical Asia," he says. "But I am pretty sure that this observation will raise some eyebrows." Martinon-Torres says her team plans to look more closely at the cavities and the diet of the Daoxian humans by examining patterns of tooth wear.
Edited from Nature (14 October 2015)
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