"... the great majority of genetic differences can be found between individuals from any one of the major continents, and, on average, only a small proportion of additional differences will be found between individuals from two different continents. Furthermore, [given the comparatively low diversify of the human genome, and] because human history is a history of population movement, and because humans are extraordinarily adept at sharing their DNA, the genetic boundaries between populations are typically indistinct."
-L.B. Jorde, USM