Researchers in Germany and Japan introduced a human-specific gene to the fetuses of common marmosets, Callithrix jacchus. In turn, that gene, displayed at typical human levels, caused the monkeys’ brains to grow larger than usual. This extraordinary finding was published [June 18] in the journal Science.
“We had certain hopes — what the gene, ideally, could do and should, if it had the function that we had postulated it should have,” lead study author Wieland B. Huttner tells Inverse. Huttner is the director of the Max Planck Institute of Molecular Cell Biology and Genetics.
“The very satisfying answer is that the gene did exactly everything that you could have hoped for.”
Huttner breaks the results down into four parts. Inserting the gene:
- Increased size of the monkeys’ neocortex.
- Induced folding of the brain, similar to how a human brain is folded.
- Increased the relevant pro-generative cell type, which produces neurons.
- Specifically, increased upper-layer neurons, which are the neurons that increase during evolution.
Essentially, the gene did everything in the marmoset fetus that you might expect an evolutionarily important gene to do: It’s as if the researchers re-created the same evolution that happened in the brains of ancient Homo sapiens. That genetic evolution, researchers believe, is part of the basis for the brains we have today.