Selective sweeps in humans


Jason Collins


July 24, 2012

From a new paper in PLOS Genetics:

[R]efined analyses of modern human genomic data have changed our view of evolutionary forces acting on our genome. While most people assumed that the out-of-Africa expansion had been characterized by a series of adaptations to new environments leading to recurrent selective sweeps, our genome actually contains little trace of recent complete sweeps and the genetic differentiation of human population has been very progressive over time, probably without major adaptive episodes

John Hawks draws a different conclusion:

[I]n fact, we have abundant signs of recent positive selection in the genome, but those signs are nearly all very recent partial sweeps in different human populations. Complete sweeps and near-complete sweeps are indeed few, suggesting that there was relatively little directional adaptive evolution associated with the “origin of modern humans.” Measuring by genetic change, agriculture was many times more important than the appearance of modern humans throughout the world.

It is obvious in some ways, but if we wish to link economic growth with genetic changes since the appearance of agriculture, those genetic changes may look very different across populations, even comparing two populations that have similar long histories of agricultural life.