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D'après des chercheurs, la modification d'un seul acide aminé de la protéine TKTL1 entre Néandertal et l'humain moderne a participé à l'augmentation des neurones du néocortex, en particulier dans le lobe frontal. © Neandertal Museum, Mettmann, Allemagne, CC-BY-SA 4.0

One produces more neurons than the other

Changing a single amino acid in a protein can have significant effects. By this means, neuronal production would be more important in the frontal lobe during brain development in modern humans than in Neanderthals.

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Neanderthals lived between 250,000 and 28,000 years before our era. Carnivorous, he has developed many tools to capture and defrost game. Inrap (National Institute for Preventive Archaeological Research) follows in the footsteps of this ancestor in a documentary, Experts of the Past, that traces captivating hunting practices.

What makes modern man unique? The answer lies partly in The frontal lobe The neocortex (space brain), according to New study featured in Science. It is recognized that the sound The internal structure of the cranium of modern humans and Neanderthals was not different, indicating a similar size of the brain and neocortex. But it was not yet known whether a similar size of the neocortex meant the same production nervous cells.

Few proteins show differences in their amino acid sequences between Homo sapiens and our ancestors. Neanderthals. However, this is the case with TKTL1, which differs from only one Amino acid from a primitive alternative. Institute researchers Max Planck From Cell biology molecular and hereditary From Dresden (Germany) I found this protein An increase in a type of brain progenitor cell called radial basal glia, which generates the majority of neurons in the developing neocortex.

More neurons formed with the modern human variant of TKTL1

Next, the study authors wanted to know the importance of amino acid modification in the development of the neocortex. They have introduced a modern human variant or primitive variant of TKTL1 into the neocortexembryos from mouse. Result: radial basal glia increased with the modern human variant of TKTL1, but not with the . variant Neanderthals. Thus, the brains of mice embryos with the modern human variant of TKTL1 contained more neurons.

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In order to see if these same effects were found to develop brain Humans, the researchers used human brain organelles – miniature structures that mimic the structure and key functions of the brain and were cultured in the laboratory from Stem Cells Human. And so they replacedarginine From TKTL1 to the modern man before Lysine than Neanderthal TKTL1 and found that fewer radial basal glia were produced and therefore fewer neurons.

In more detail, Homo sapiens TKTL1 functions through modifications to Metabolismby one Energizing From the pentose pathway phosphate followed by an increase in installation fatty acids. Indeed, modern human TKTL1 increases the synthesis of some Fats Membranes needed to generate the long process of radial basal glia, and thus to increase the production of neurons.

Impact on cognitive abilities associated with the frontal lobe?

If the study indicates that neocortical neurons in modern humans were larger than in Neanderthals (particularly in the frontal lobe), the authors speculate that this may be a virtue. Cognitive abilities of modern humans associated with the frontal lobe. Thus, our genetic evolution Ocean It may have contributed to the development of language and voluntary motor coordination.

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