Researchers have identified a mutated gene that appears to be responsible for a large disparity between Neanderthal and human brains.
Their paper, published in Science, explains how human brain cells can be ‘Neanderthal-ised’ with very small changes to their DNA.
Led by Alysson R Muotri, the research team compared the human and Neanderthal genomes for differences that might affect brain formation. Out of 61 altered genes, one – called NOVA1 – was chosen for closer inspection because it affects several other genes in early brain development.
The team then used CRISPR to modify human stem cells, so that they carried the NOVA1 mutation. These stem cells were grown into brain organoids – small clusters of brain cells.
The differences were clear. Aside from being distinct in shape, the Neanderthal-ised cells grew and multiplied differently, and had notably altered synapses (the connections between neurons). Electrical impulses within the brain organoids changed as well.
Muotri says these changes are similar to changes in other non-human primate brains, which allow those primates to learn faster than human newborns. His team has previously used stem cells to study modern primates, including chimpanzees and bonobos, but this is the first time the technique has been tested on an extinct species.
We know Neanderthals have a lot in common with humans. But Muotri highlights that small discrepancies in the genome can have a huge effect.
“It’s fascinating to see that a single base-pair alteration in human DNA can change how the brain is wired,” he says. “We don’t know exactly how and when in our evolutionary history that change occurred. But it seems to be significant, and could help explain some of our modern capabilities in social behavior, language, adaptation, creativity and use of technology.”
According to Muotri, it’s difficult to study evolutionary brain development and function, because brains do not fossilise. This new stem-cell method can be used to study other extinct species, and the team will be using it to examine the other 60 genetic differences they identified.