Summary in Seconds: Scientists may have uncovered the evolutionary roots of human right-handedness. A recent study comparing 41 primate species suggests that two major developments in human evolution—walking upright on two legs and growing larger, more specialized brains—were the key drivers of our strong preference for using the right hand. As bipedalism freed the hands for tool use and other complex tasks, natural selection likely favored individuals with greater hand specialization. Over millions of years, increasing brain lateralization reinforced this tendency, resulting in the approximately 90 percent rate of right-handedness seen in modern humans. The findings also provide new insights