A pair of wide-ranging genetic studies, published yesterday in the journal Nature, back up the idea that humanity first evolved in Africa before migrating elsewhere, Reuters reports. DNA testing of African Americans and European Americans found that people with African roots had much more genetic diversity. Other tests discovered that DNA diversity decreased the farther away populations were from Africa.
Researchers believe that as early humans migrated out of Africa tens of thousands of years ago, a "bottleneck" effect occurred when many failed to survive, leaving a smaller gene pool among those who remained to reproduce and spread out across the world. Native Americans and Pacific Islanders had the least diverse DNA, and consequently the highest risk of harmful mutations.