For decades, the human genome could only tell us what we already suspected about the evolution of certain traits. Researchers were able to trace the genetic origin stories of lactose tolerance (as opposed to lactose intolerance), malaria resistance, and more only after observing these successful traits in specific populations. Now, the study of positive selection – the ability to determine which genetic changes have conferred an evolutionary advantage – has reached a turning point: the genome itself can be used as a starting point to guide scientists to important genetic locations, leading to hypotheses about human health and disease.