Neanderthal (Homo neanderthalens) is an ancient human being active in Europe 200,000 years ago. They began to rule the entire European , Western Asia and Northern Africa . But surprisingly, about 35,000 years ago, the living scope of Neanderthals began to shrink rapidly and eventually became completely extinct about 30,000 years ago.
It is worth noting that 35,000 years ago, it was Homo sapiens (Homo sapiens), which is the time when we modern humans came to Europe. Therefore, it is not difficult to speculate that the disappearance of the Neanderthals is inseparable from Homo sapiens .
Many scholars also believe that it was the arrival of Homo sapiens that brought disaster to the Neanderthals. In contrast, how can Homo sapiens, who are weaker in , defeat the stronger Neanderthals and become the only existing species in the genus?
On September 9, 2022, winner of the 2022 Nobel Prize in Physiology or Medicine, from the Max Planck Institute of Molecular Cell Biology and Genetics in Germany, Svante Pääbo (Svante Pääbo) and others published a research paper titled: Human TKTL1 implies greater neurogenesis in frontal neocortex of modern humans than Neanderthals in the international top academic journal Science.
The study found that the difference between an amino acid on a key protein, TKTL1, gave us humans a significant advantage over Neanderthals, increasing the production of brain nerve cells , which may be the basis of cognitive differences between modern humans and other extinct ancient humans.
neocortical (Neocortex) is an external region of the cerebral cortex. It is an evolutionarily more advanced brain structure and is widely believed to give us humans unique and extraordinary cognitive abilities. However, fossil evidence suggests that Neanderthal brains are similar in size to modern humans, and how they may differ in function or structure are still unknown.
human brain (left) and Neanderthal brain (right)
In this latest study, the research team compared the genome sequences of modern humans with those of Neanderthals and other apes. The comparison results show that the TKTL1 gene of modern humans encodes a unique amino acid substitution. lysine (Lysine) in Neanderthals and apes was replaced in humans with arginine (Arginine) .
Next, the research team started from two aspects and studied whether the TKTL1 gene plays a role in the development of the brain neocortex and affects the number of neural progenitor cells, as well as whether the ancient TKTL1 gene (aTKTL1) and the modern TKTL1 gene (hTKTL1) have similar effects on neural progenitor cells during neocortex development.
study overexpressing the TKTL1 gene in mice and ferret brains and brain organoids. The results show that compared with aTKTL1, the overexpression of hTKTL1 produces more neural progenitor cells - basal radial glial cells (bRG) , thereby promoting the proliferation of neocortical neurons.
Inhibiting hTKTL1 expression in human fetal neocortical tissues and brain organoids, or replacing hTKTL1 with aTKTL1, will lead to a decrease in bRG and neuronal production.
research team said that the research results determined that a single specific amino acid substitution of a gene in modern humans plays a role in controlling the abundance of neural progenitor cells during neocortical development. It suggests that there are differences in the composition of neural progenitors in the cerebral cortex between Neanderthals and modern humans.
In humans, the TKTL1 gene encodes transketolase-like protein 1, an enzyme involved in the metabolic pathway of acetyl-CoA, which is used for fatty acid production. However, basal radial glial cells (bRG) require a large amount of fatty acids, so the TKTL1 gene in modern humans promotes the proliferation of bRG. This mechanism may represent a key driver of brain evolution between ancient and modern humans.
Paper link :
https://www.science.org/doi/10.1126/science.abl6422
