SANTA CRUZ, CA--Scientists have discovered a gene that has undergone accelerated evolutionary change in humans and is active during a critical stage in brain development. Although researchers have yet to determine the precise function of the gene, the evidence suggests that it may play a role in the development of the cerebral cortex and may even help explain the dramatic expansion of this part of the brain during human evolution.
"At this point, we can only speculate about this gene's role in the evolution of the human brain, but it's exciting to find a new gene involved in brain development, and it's especially exciting for us because it validates our approach of letting evolution guide us and tell us what are the important parts of the human genome," said David Haussler, director of the Center for Biomolecular Science and Engineering (CBSE) at the University of California, Santa Cruz, and a Howard Hughes Medical Institute (HHMI) investigator.
The study, published by Nature on August 16 as an advance online publication, was led by CBSE researchers Katherine Pollard and Sofie Salama, who worked with an international team of collaborators including neuroscientists in Belgium and France. Pollard, now an assistant professor of statistics at UC Davis, performed an extensive computational analysis, comparing the genomes of humans, chimpanzees, and other vertebrates to identify elements of the human genome that have undergone accelerated evolutionary changes.
This computer-intensive bioinformatics approach produced a list of the most rapidly evolving regions of the human genome, and subsequent work focused on the top hit, a region called HAR1. Salama, a HHMI research biologist, led the "wet lab" investigations, using the laboratory techniques of molecular biology to characterize the gene, identify the tissues in which it is active, and begin the search to understand its function.