The Body: A Guide for Occupants

by Bill Bryson

Indigenous populations in South America, for instance, are lighter-skinned than would be expected at the latitudes they inhabit. That is because in evolutionary terms they are recent arrivals. “They were able to get to the tropics quite quickly and had lots of gear, including some clothing,” Jablonski told me. “So in effect they thwarted evolution.” Rather harder to explain have been the KhoeSan people of southern Africa. They have always lived under a desert sun and have never migrated any great distance, yet have 50 percent lighter skin than would be predicted by their environment. It now appears that a genetic mutation for lighter skin was introduced to them sometime in the last two thousand years by outsiders—but who these mysterious light-skinned outsiders