Natural selection is accelerating, massive DNA study finds
For years, the story of recent human evolution looked relatively quiet. Scientists studying ancient human DNA had found only a few dozen clear cases where natural selection appeared to strongly favor one version of a gene over another. As a result, it made it seem as though the most forceful kind of selection had played only a limited role after modern humans spread out of Africa. In addition, they formed distinct populations around the world. A new analysis upends that picture. Drawing on DNA from nearly 16,000 ancient people across West Eurasia, researchers found that directional selection, the kind that pushes certain genetic variants to rise or fall in frequency because they help or hurt survival and reproduction, has been far more common than once believed. Moreover, the team identified hundreds of such cases over the past 10,000 years. Selection appears to speed up after the rise of farming. The work, led by researchers at Harvard, was published in Nature. David Reich (left), Ali Akbari (right), and colleagues studied thousands of ancient genomes from West …
