Human accelerated regions (HARs) have been linked to human brain evolution, but their function has not been well understood — until now. A study by NOMIS researcher James Noonan and colleagues indicates that HARs — segments of DNA that are highly conserved across many species but show significant changes in humans — have shaped brain evolution by fine-tuning the activity of existing gene networks, rather than introducing entirely new genes. Their findings, published in Cell, provide valuable insights into the basis of human cognitive development.
The researchers identified nearly 3,000 genes regulated by HARs that are conserved (shared) between humans and chimpanzees, many of which are involved in neurodevelopment. These genes show altered expression in neural stem cells and specific cell types in the developing human brain. In contrast, species-specific HAR targets do not share a common function. The findings suggest that rather than introducing entirely new genes, HARs contribute to brain evolution by fine-tuning the activity of existing gene networks, shedding light on the molecular basis of human cognitive development.
Read the Cell publication: Resolving the three-dimensional interactome of human accelerated regions during human and chimpanzee neurodevelopment
Read the related Yale news story: Study sheds light on the genetic changes that shaped human brain evolution
