Not just genes: Environment also shaped population variation in first Americans
(PHYSorg.com Biology)

The first Americans-humans who crossed onto the North American continent and then dispersed throughout Central and South America-all share common ancestry. But as they settled different areas, the populations diverged and became distinct. A new study from North Carolina State University shows that facial differences resulting from this divergence were due to the complex interaction of environment and evolution on these populations and sheds light on how human diversification occurred after settlement of the New World.