Scientists at the University of California San Francisco have discovered that parts of human chromosomes evolved rapidly to enhance brain development compared to apes. The “human accelerated regions” (HARs) made up 1% of the genetic difference between humans and chimpanzees, resulting in more complex neural networks. However, this rapid evolution may also contribute to uniquely human brain disorders such as autism.
Researchers led by Yin Shen studied HARs in artificial neurons derived from human and chimpanzee cell lines. They found that human neurons developed multiple neurites, allowing for more efficient signal transmission, while chimpanzee neurons only grew single neurites. When human HARs were engineered into chimp neurons, they produced many more wires, suggesting a link between rapid evolution and increased brain power.
The findings imply that the development of complex neural networks may be crucial to our higher cognitive functions, but disruptions in this process could lead to neurodevelopmental disorders like autism. The study appears in Nature and highlights the importance of understanding the role of HARs in human brain evolution.
Source: https://medicalxpress.com/news/2025-02-human-chromosomes-evolved-hyperspeed-brains.html