Summary: A new study reveals that human accelerated regions (HARs)—segments of DNA that evolved much faster than expected—may be key to the brain’s advanced cognitive abilities. Researchers compared human and chimpanzee neurons and found that HARs drive the growth of multiple neural projections, which enhance communication between brain cells.

When human HARs were introduced into chimp neurons, they also grew more projections, suggesting a direct link between HARs and neural complexity. However, these same genetic changes may also contribute to neurodevelopmental disorders like autism, highlighting the delicate balance of human brain evolution.