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Modern humans and Neanderthals may have split apart 1
This new estimate is much older than previous estimates based on ancient DNA analysis, the the split between humans and Neanderthals between 500,000 and 300,000 years ago.
Outstanding researchers cited the new dental analysis as impressive, noting that it is based on a broad assumption that the shape of the teeth, especially in Neanderthals, is constantly evolving. If the tooth shape does not develop at a steady pace, "the construction of this paper collapses," said Fernando Ramirez Rozzi, research director of human evolution at the French National Center for Scientific Research in Toulouse, who was not involved in the study. [Photos: See the Ancient Faces of a Man-Bun Wearing Bloke and a Neanderthal Woman]
Nevertheless, it is quite possible that teeth (and especially Neanderthal teeth) may develop at a predictable rate, meaning that the calculation of the new study may be within the target range. "Right now, there is the idea of a steady change in the rate of molar development," said Ramirez Rozzi.
Tons of Teeth
Researchers studied 931 teeth from at least 122 individuals from eight groups, including humans and our close relatives. Of these came 164 teeth from the early Neanderthals from the Spanish Sima de los Huesos ("pit of bones"). This sample included nearly 30 individuals living in the middle Pleistocene around 430,000 years ago.
Comparing the differences in tooth shape between specimens, study researcher Aida Gomez-Robles, a paleoanthropologist at University College London, calculated evolution rates for tooth shape changes and then estimated the time difference from the last common ancestors between humans and Neanderthals.
The result – that Neanderthals and modern humans probably diverged more than 800,000 years ago – shows that the last common ancestor of these two groups is probably not Homo heidelbergensis as some scientists think.
" H. heidelbergensis can not adopt this evolutionary position because it traces the divergence between Neanderthals and modern humans," Gomez-Robles said in an e-mail to Live Science. "That means we have to look at older species when looking for this common ancestor species."
The finding also has profound implications for the way we interpret the fossil record and the evolutionary relationships between the species, "said Gomez-Robles.
Delaying the divergence between Neanderthals and modern humans "opens a new door" because it suggests that the two groups were separated from each other for much longer than previously thought.
That raises a question, he said, that humans and Neanderthals mingled about 60,000 years ago as modern humans Leaving Africa (This cross explains why the genomes of some modern humans contain nearly 3% Neanderthal DNA.) However, when humans and Neanderthals broke apart at least 800,000 years ago, it is surprising that they were able to cross 60,000 years ago, Ramirez Rozzi said
"In other words, nearly 1 million years of evolution were not enough to break down barriers (genetically, endok rhinologically, behaviorally, etc.) to finally separate these two species? "he asked.
The argument is well set out by Gomez-Robles, who is "a well known specialist in the dental morphology of the Neanderthal line," said Bruno Maureille, research director at the National Center for Scientific Research (CNRS), in Paris, who did not attend the Study was involved.
However, it appears that the remains of Neanderthals from different parts of Europe "have their own peculiarities," Maureille told Live Science. "Can we just try to draw such global scenarios? [I’m] not so sure."
The study was published online on May 16 in the journal Science Advances.
Originally published on Live Science