Neanderthals and modern humans have diverged at least 800,000 years ago, which is significantly earlier than most estimates based on DNA suggest, according to a new study. a UCL scholar.
The research, published in Progress of science, analyzed the rates of dental evolution in different species of hominins, focusing on early Neanderthals. It shows that the hominin teeth of Sima de los Huesos, Spain – the ancestors of the Neanderthals – diverged from the modern human lineage earlier than expected.
Sima de los Huesos is a cave located in the mountains of Atapuerca, Spain, where archaeologists have recovered fossils of nearly 30 people. Previous studies date back about 430,000 years (Middle Pleistocene), making this site one of the oldest and largest collections of human remains discovered so far.
Aida Gomez-Robles (UCL Anthropology) said: "Any divergence of time between Neanderthals and modern humans under 800,000 years would have resulted in a rapid and unexpected evolution of the tooth in the Neanderthals of Sima de los Huesos.
"Different factors could potentially explain these findings, including a strong selection to change the teeth of these hominins or their isolation from other Neanderthals on the European continent.However, the simplest explanation is that the divergence between Neanderthals and the modern man was older 800 000 years.This would make the evolution rates of the early Neanderthals of Sima de los Huesos roughly comparable to those observed in other species. "
Modern humans share a common ancestor with the Neanderthals, the extinct species that was our closest prehistoric parent. However, the details of when and how they have diverged are the subject of intense debate within the anthropological community.
The old DNA analyzes generally indicate that the two lineages diverged about 300,000 to 500,000 years ago, which strongly influenced the interpretation of the fossil record of the hominin.
This divergence time, however, is not compatible with the anatomical and genetic similarities of Neanderthal observed in the hominins of Sima de los Huesos. The Sima fossils are considered probable ancestors of Neanderthal based on anatomical features and DNA analysis.
Dr. Gomez-Robles said: "The hominins of Sima de los Huesos are characterized by very small posterior teeth (premolars and molars), which have many similarities to classical Neanderthals, and more primitive teeth present in the last ancestor. Neanderthals and modern humans. "
The shape of the teeth evolved at very similar speeds in all hominins, including those with very dilated and very reduced teeth. This new study examined when Neanderthals and modern humans should have moved away to make the evolutionary rhythm of the primitive Neanderthals of Sima de los Huesos similar to that seen in other hominins.
The research used quantitative data to measure the evolution of dental form from one hominin species to the other by assuming different periods of Neanderthal man and of modern man, and taking into account the uncertainty surrounding the evolving relationships between different species of hominin.
"The teeth of the Simas are very different from those we hoped to find in their last ancestral species common to modern humans, suggesting that they have evolved separately for a long time to develop such differences."
The study has important implications for the identification of the last common ancestral species of Homo sapiens with the Neanderthal because it allows to eliminate all groups after 800 000 years.
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