A new study published in the journal Cell sheds light on the genetic changes that shaped human brain evolution, revealing how the process differed from chimpanzee evolution. Researchers at Yale focused on a class of genetic switches known as Human Accelerated Regions (HARs), which regulate gene expression during evolution.
The study found that HARs fine-tune the expression of genes already shared between humans and chimpanzees, influencing neuronal development and communication. Advanced techniques allowed researchers to track how HARs interact with genes and human neural stem cells, identifying targets for nearly all HARs – a significant advance in understanding human evolution.
According to Dr. James Noonan, lead author of the study, “HARs largely regulate the same genes in both species, particularly those involved in brain development.” However, HARs adjust gene expression levels differently in humans, suggesting that evolutionary changes to brain function emerged not by reinventing genetic pathways but by modifying their output.
The discovery expands knowledge about how HARs contribute to unique human brain features. Previous studies had only identified targets for 7-21% of HARs, likely due to less precise methods and limited data. The new study used advanced techniques to map the genome in three dimensions, tracking how HARs interact with genes in human and chimpanzee neural stem cells.
The findings suggest that many HAR gene targets are active in developing human brain cells and linked to processes such as neuron formation and communication. Some are associated with conditions like autism and schizophrenia, highlighting the potential role of HARs in shaping normal brain function and neurological disorders.
The study provides a fuller picture of genetic changes that shaped human brain evolution, significantly advancing knowledge about what genes HARs controlled and their biological functions.
Source: https://phys.org/news/2025-02-genetic-human-brain-evolution.html