CLOCK Gene May Hold Clues to Human Brain Evolution

Scientists have long sought to unravel the molecular mysteries that make the human brain special: What processes drove its evolution through the millennia? Which genes are critical to cognitive development? A new study provides insight on the matter by demonstrating that a gene controlling our biological clocks also plays a vital role in regulating human-specific genes important to brain evolution. The findings from the University of Texas (UT)) Southwestern O’Donnell Brain Institute open new paths of research into how CLOCK proteins produced by the CLOCK gene affect brain function and the processes by which neurons find their proper place in the brain. “People have been searching for genes that are important for brain evolution, within the context of our larger, folded brains,” said Dr. Genevieve Konopka (photo), a neuroscientist with UT Southwestern’s Peter O’Donnell Jr. Brain Institute. “We now have evidence that CLOCK regulates many genes outside of circadian rhythms, so we can place it as a key point in the hierarchy of important molecular pathways for human brain development and evolution.” Human brains are notably bigger than the brains of our closest relative, the chimpanzee. But because size alone doesn’t account for cognitive abilities – mammals such as whales and dolphins have larger brains than humans – scientists have sought to understand what makes the human brain smarter. Dr. Konopka’s research has focused on the neocortex, an area of the brain with distinctive folds that is associated with sight and hearing and considered the most recently evolved part of the cortex. Her lab released a study in 2012 that found CLOCK has increased expression in the human neocortex compared to that seen in other primate brains.
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