Enlarge / Lida Ajer modern human tooth (left top) with its corresponding scanned image (left bottom) compared to an orangutan tooth (right) (credit: Tanya Smith and Rokus Awe Due)
In the Padang Highlands of western Sumatra, a large island in Indonesia, there is a small cave called Lida Ajer that has long offered up clues about human history. Dutch paleoanthropologist Eugene Dubois first excavated the cave before 1890, and Lida Ajer has turned up plenty of preserved animal remains since, including teeth that were identified as human in 1948.
It’s only now that the cave has been carefully and thoroughly dated, providing a new line of evidence that our species was in the region more than 60,000 years ago. That’s 20,000 years older than the previous oldest skeletal evidence of humans in the area. But these new dates line up with existing genetic evidence, as well as with reconstructions of the climate and sea levels at the time.
In a paper published in Nature this week, Kira Westaway of Macquarie University in Australia and her colleagues report what they found when they revisited the discoveries of Lida Ajer. They re-examined the teeth, pointing to all the evidence that the teeth did indeed belong to anatomically modern humans rather than orangutans or other primates. And they carefully dated the cave site to establish how old the teeth were likely to be.
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