Humans and Neanderthals evolved from a common ancestor mystery, a considerable analysis suggests

Modern humans and Neanderthals may have diverged at least 800,000 years ago, according to an analysis of nearly 1,000 teeth from humans and close relatives.

This new estimate is much older than the previous ones, based on old DNA analyzes, which indicates the separation between humans and Neanderthals as it occurred between 500,000 and 300,000 years.

However, even though outside researchers have described the new dental analysis as impressive, they note that this is based on a fundamental assumption: this form of tooth is constantly evolving, especially among Neanderthals. If the shape of the teeth does not evolve at a steady pace, "then the construction of this paper will collapse," said Fernando Ramirez Rozzi, director of human evolution research at the National Research Center. scientist from Toulouse, France. study. [Photos: See the Ancient Faces of a Man-Bun Wearing Bloke and a Neanderthal Woman]

That said, it is quite possible that teeth (and Neanderthal teeth in particular) are changing at a predictable rate, which means that the calculation of the new study could be consistent with the objectives. "At the moment, there is the idea of ​​a constant evolutionary change in the shape of the teeth," said Ramirez Rozzi.

Tons of teeth

The researchers examined 931 teeth belonging to a minimum of 122 people belonging to eight groups, including humans and our close relatives. Of these, 164 came from the first Neanderthals at the Sima de los Huesos ("bone-to-bone") site in Spain, a sample comprising nearly 30 individuals who lived about 430 000 years ago, during the time of the Middle Pleistocene.

By comparing the differences in tooth shape between samples, researcher Aida Gomez-Robles, a paleoanthropologist at University College London, was able to calculate the rates of change in dental shape change, and then Estimate the time of divergence between the last common ancestor between man and Neanderthal man. .

The result – Neanderthals and modern men probably diverged more than 800,000 years ago – shows that the last common ancestor of these two groups is probably not Homo Heidelbergensisas some scientists think.

"H. heidelbergensis Gomez-Robles told Live Science in an email: "That means we have to look at older species when we are looking for this common ancestral species."

The discovery "also has profound implications for how we interpret the fossil record and evolving relationships among species," said Gomez-Robles.

Take out

Pushing away the divergence between Neanderthals and modern humans "opens a new door", as it suggests that the two groups have separated much longer than expected, Ramirez Rozzi said.

However, this raises a question, he said. Neanderthal humans and humans met about 60,000 years ago, when modern humans left Africa. (This miscegenation explains why the genomes of some modern humans contain nearly 3% of Neanderthal DNA.) But if humans and Neanderthals broke down at least 800,000 years ago, it's amazing that they are still able to cross 60,000 years ago, said Ramirez Rozzi.

"In other words, nearly a million years of evolution has not been enough to establish barriers (genetic, endocrinological, behavioral, etc.) to separate definitely these two species? " He asked.

The argument is well exposed by Gomez-Robles, who is "a recognized specialist in the dental morphology of the Neanderthal lineage," said Bruno Maureille, director of research at the National Center for Scientific Research (CNRS), in Paris . not involved in the study.

But, it seems that the dental remains of Neanderthals from different pockets of Europe each 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 May 16 in the journal Science Advances.

Originally published on Science live.