Human Neurons Evolve Faster Than Chimps, Boosting Cognition But Increasing Disease Risk

A study at UC San Francisco reveals that certain regions of human chromosomes, known as human accelerated regions (HARs), have evolved at a rate 10 times faster than expected in mammals. This rapid evolution gives humans an advantage in brain development over apes, but may also increase susceptibility to brain disorders. The research, published in Nature and supported by the National Institutes of Health, compared artificial neurons derived from human and chimpanzee cell lines. Human neurons grew multiple neurites ["wiry projections that help the nerve cells send and receive signals"], while chimp neurons grew only single neurites. When human HARs were engineered into artificial chimp neurons, the chimp neurons grew many more neurites. According to Yin Shen, PhD, professor at UCSF, "More neurites during development could mean more complexity in our neural networks... These networks facilitate the transmission of signals in the nervous system and support our higher cognitive functions. But disruptions in their development may contribute to neurodevelopmental disorders like autism."