Improvement of the human brain could be the result of doubling the gene
Last reviewed: 16.10.2021
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The increase (and improvement) in the human brain in the process of evolution could be the result of a doubling of the gene that helps brain cells move from place to place.
At least twice in the past three million years, the SRGAP2 gene has been duplicated, says Megan Dennis of the University of Washington, USA, who along with colleagues showed that additional copies of the gene may be responsible for thickening the cerebral cortex.
Previously, the same group of scientists found that SRGAP2 is among the 23 genes that have a second copy of only one species of primates - humans. Ms. Dennis concluded that the ancient form of this gene located in the first chromosome was partially duplicated on the same chromosome about 3.4 million years ago. This partial copy is responsible for producing a shorter version of the SRGAP2 protein.
Then, about 2.4 million years ago, a copy of that partial copy was created. She entered the short shoulder of the first chromosome.
However, the appearance of additional copies does not mean that the gene played an important role in evolution. Therefore, researchers studied more than 150 people and found out that a duplicate, created 3.4 million years ago, some do not, while a younger version is reliably fixed in the human genome (in other words, it is for everyone). A couple of millions of years with a tail is quite a short time to fix duplicate genes, notes Ms. Dennis. Such rapid assimilation may indicate a large value of the gene for evolution.
With the help of colleagues from other universities, specialists have found that a shortened version of the protein SRGAP2 prevents brain cells from creating filopodia, with which they move. Reducing the number of these pseudopods did not allow the cells to migrate actively and, possibly, led to the appearance of new layers of the cerebral cortex.
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