GENETICS
D. ROBERTS/SCIENCE PHOTO LIBRARY/GETT
CHIMPS AND BONOBOS—OUR CLOSEST RELATIVES, EVOLUTIONARILY SPEAKING—SHARE ABOUT 99 PERCENT OF OUR DNA. GORILLAS clock in at 98 percent. So what genes distinguish humans? In the journal Cell, researchers at the University of California, Santa Cruz, report their discovery of three nearly identical genes, found only in humans, that seem to play a critical role in one of our unique features, the development of a larger brain. About 3 million or 4 million years ago, just when our ancestral brains enlarged, the triplet of genes, called Notch (named after the shape of a fruit fly’s wings), appeared. They help guide the slow maturation of the human brain and the profusion of neurons in the neocortex, two features that proved key to the evolution of higher functions like reasoning and language. These genes may also play a part in neurological disorders, including microcephaly, autism and schizophrenia. Continued research of the human-only Notch genes could improve our understanding of these conditions, as well as brainpower in general. —Jessica Wapner