Did we split from Neanderthals 400,000 years earlier than we thought?

Fossil teeth could change our understanding of human evolutionAida Gomez-Robles, Ana Muela and Jose Maria Bermudez de Castro By Ruby Prosser ScullyAn analysis of fossil teeth suggests that the shared ancestor of modern humans and our Neanderthal cousins may have lived more than 800,000 years ago. Previous studies have used DNA to calculate how long…


Fossil teeth could change our understanding of human evolution

Fossil teeth could change our understanding of human evolution

Aida Gomez-Robles, Ana Muela and Jose Maria Bermudez de Castro

An analysis of fossil teeth suggests that the shared ancestor of modern humans and our Neanderthal cousins may have lived more than 800,000 years ago.

Previous studies have used DNA to calculate how long ago these two types of humans split from each other, estimating this to have taken place around 400,000 years ago.

But fossils from the cave site of Sima de los Huesos, in Spain, don’t fit with this estimate. The hominin remains discovered there are thought to be those of early Neanderthals, but dating indicates they are around 430,000 years old, which hints that the most recent common ancestor of Neanderthals and modern humans must have lived before this time.

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To estimate how much earlier this ancestor may have lived, Aida Gómez-Robles of University College London analysed the shape of these fossilised teeth and the teeth of seven other types of hominin, includingAustralopithecus afarensisandParanthropus robustus, and compared how they have changed over time.

Because these chewing teeth appear to evolve steadily in hominin species, Gómez-Robles could use modelling to estimate when different branches of the human family tree must have had to split from each other to lead to the different kinds of fossil teeth.

The only way the teeth found at Sima de los Huesos would have had time to evolve its particular features would have been for Neanderthals and early humans to have diverged at least 800,000 years ago, she says.

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If Gómez-Robles is right, it would suggest thatHomo heidelbergensis, an ancient human that lived 700,000 to 300,000 years ago, could be ruled out as a possible common ancestor with the Neanderthals.

However, her analysis only included Neanderthal fossils from the Sima de los Huesos site. The relationship of these hominins to other Neanderthals throughout Europe is not clear yet.

Whether we split from Neanderthals 400,000 or 800,000 years ago, we know from genetic analysis that modern humans in ancient Europe later interbred with Neanderthals several times before our cousins went extinct around 30,000 years ago.

Journal reference:Science Advances, DOI: 10.1126/sciadv.aaw1268

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