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 ...

Natural selection is the process by which some organisms in a population survive and reproduce, while others do not, based on their bodies and behaviour. It is one of the processes by which species ...

The Indigenous peoples of the Bolivian highlands are survivors. For thousands of years they have lived at altitudes of more than two miles, where oxygen is about 35 percent lower than at sea level.