Brain Gene Tops the List for Making Humans, Human
by Courtney Sexton/Smithsonianmag.com
Why do humans have such large brains? This evolutionary mystery has challenged scientists for ages, but some researchers are using genetics, specifically those genes that can only be found in Homo sapiens, for an answer.
ARHGAP11B, a gene found only in humans, is known for its role in expanding neocortex, the part of the brain responsible for higher cognitive functions such as language and planning. In experiments detailed in a new study published today in the journal Science, researchers inserted the gene into the fetuses of marmosets, who, like humans, are primates, but don’t carry the gene. The team found that after 101 days, the neocortices of the monkeys’ developing brains were larger and had more folds in the tissue than normal monkey fetuses without the gene.
Having more folds in this part of the brain is important because those folds increase the surface area available for brain cells, or neurons, without making the brain too big for the skull. Demonstrating that the human gene fulfills a similar purpose in the brain of another primate provides new insight into how humans may have evolved and may point the way to future treatments for brain disease.