Where's the Evidence for Selection? Climate Change and Human Colonization of the Northern Tibetan Plateau

Few dispute that the Tibetan Plateau represents one of the harshest environments on the planet. It is reasonable to expect that early human colonization of the Plateau entailed exposure to strong selective pressures. Successful colonization of the Plateau therefore implies the development of adaptations in response to these selective pressures. Genetic, physiological and morphological data from Plateau populations are consistent with a general model for biological adaptation under strong selective pressures. By contrast, archaeological data collected over the last two decades is remarkable for the paucity of evidence for major shifts in behavior and technology accompanied the colonization of the Plateau.  With few exceptions, Plateau behavioral adaptations appear to be close variants of those common in low-elevation settings. Why is there so little evidence for cultural selection? Here I examine several alternative hypotheses explaining this perplexing problem.