A new study published in Science offers a clue as to why Neanderthals, a species that lived in Europe, are no longer with us. Apparently, there is a genetic mutation in Homo sapiens that allowed the development of more neurons in the neocortex. This area is responsible for cognition.
Although Homo sapiens is the only remaining human species on Earth today, thousands of years ago the planet witnessed the coexistence of representatives of nine other human species. This reduction is a reason for questioning on the part of the scientific community, which has sought to try to understand what happened to other humans.
Known as TKTL1, the gene differs from the Neanderthal version by just one amino acid building block. All modern human beings are endowed with this change. However, those that disappeared, such as Neanderthals, Denisovans and other primates, did not carry the mutation.
It is not yet clear whether this change interferes with the production of better tools, weapons, adequate language, art, symbolism, or even better brains, evolutionary characteristics that have theoretically ensured survival. of Homo sapiens compared to other species.
A specific amino acid promoted the positive evolutionary trait
In this study, the researchers inserted both the version of TKTL1 found in Neanderthals and the version found in modern humans, into developing rodents. Those who received the Neanderthal gene produced fewer progenitor cells, which give rise to neurons. To see if development would be different in humans, the researchers decided to use the TKTL1 gene in human fetal brain tissue. The result was the same: fewer progenitor cells.
When they applied the gene to a slightly more complex brain system, made up of laboratory-grown brain mini-structures created from human stem cells, the same pattern repeated itself. University of Liège neurobiologist Rodrigo Pérez Ortega said “this discovery is really a breakthrough” because it shows that “a single amino acid change is extremely important and has incredible consequences in relation to the brain. “.
Studies of 96 other genetic differences
According to the Times, while a brain with more neurons does not necessarily result in higher intelligence, the findings may indicate that a change in brain structure had beneficial cognitive repercussions that ensured the survival of the species.
In order to complete this result, scientists must continue their research on the other 96 differences found between the human and Neanderthal genomes that modify the structure of a protein.
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