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Researchers: Homo erectus survived longer than thought

russell ciochon

Russell Ciochon holds one of a series of skull caps. Photo by Tim Schoon.

Up to 100 000 years ago:

Homo erectus evolved around two million years ago, and was the first known human species to walk fully upright.

New dating evidence shows that it survived until just over 100,000 years ago on the Indonesian island of Java – long after it had vanished elsewhere.

This means it was still around when our own species was walking the Earth …

The findings further underline the shift in thinking this field of study has undergone over the decades. We used to think of human evolution as a progression, with a straight line leading from apes to us. This is embodied in the so-called March of Progress illustration where a stooping chimp-like creature gradually morphs into Homo sapiens, apparently the apex of evolution.

These days, we know things were far messier. The latest study highlights a mind-boggling truth: that many of the species we thought of as transitional stages in this onward march overlapped with each other, in some cases for hundreds of thousands of years.

Paul Rincon, “Homo erectus: Ancient humans survived longer than we thought” at BBC News

Actually, the progression was more like homo Darwin-and-his-upper-crust-set but oh, never mind. No need to rehash all that just now.

Other takes on this find:

At New Scientist, the betting is that the BBC’s “it” met the Denisovans:

Currently there is no evidence that modern humans were in Java that early. “That might change in a few years if somebody finds a much older modern human site,” says Westaway. Still, for now it seems the two didn’t meet. That means they cannot have interbred, and there is no reason to think humans were responsible for the extinction of H. erectus.

“But the age does open up the opportunity that there could have been potential overlap with the Denisovans,” says Westaway. The Denisovans are known from a handful of remains, which have yielded DNA. They roamed Asia and interbred with the ancestors of people in China and South-East Asia.

Homo erectus lived recently enough that it may have met Denisovans” at New Scientist


Why they’re sure:

The researchers time-stamped the site by dating animal fossils from the same bonebed where 12 Homo erectus skull caps and two tibia had been found, and then dated the surrounding land forms—mostly terraces below and above Ngandong—to establish an accurate record for the primeval humans’ possible last stand on Earth.

“This site is the last known appearance of Homo erectus found anywhere in the world,” says Russell Ciochon, professor in the Department of Anthropology at Iowa and co-corresponding author on the study. “We can’t say we dated the extinction, but we dated the last occurrence of it. We have no evidence Homo erectus lived later than that anywhere else.”

The research team presents 52 new age estimates for the Ngandong evidence. They include animal fossil fragments and sediment from the rediscovered fossil bed where the original Homo erectus remains were found by Dutch surveyors in the 1930s, and a sequence of dates for the river terraces below and above the fossil site.

Richard C. Lewis, “Researchers determine age for last known settlement by a direct ancestor to modern humans” at Iowa Now

Well, they don’t have later evidence yet, anyway.

Added: Climate change is blamed:

These specimens confirm that the species likely went extinct due to climate change, study coauthor Russell Ciochon, a biological anthropologist at the University of Iowa, tells CNN. “The open woodland was replaced by a rainforest. No Homo erectus fossils are found after the environment changed, so Homo erectus likely was unable to adapt to this new rainforest environment,” he says.

Emily Makowski, “Reanalyzed Fossils Could Be Last Known Homo erectus Specimens” at The Scientist

Here’s the paper at Nature. (paywall)


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