Mitochondrial DNA variation and the origin of the Europeans.

Sequences from the mitochondrial DNA (mtDNA) control region were analyzed in nine European and West Asian populations. They showed low genetic heterogeneity when compared to world populations. However, a Caucasoid population tree displayed a robust east-west gradient. Within-population diversity (ascertained through various parameters) and mean pairwise differences declined from east to west, in a pattern compatible with ancient population migration and expansion from the Middle East. Estimated expansion times indicate a Paleolithic event with important differences among populations according to their geographical position and thus a slower tempo than previously believed. The replacement of Neanderthals by anatomically modern humans, fully compatible with the present results, may have been a slower and more complex process than cultural change suggests.