The claim that culturally-determined selection pressures can act on human gene frequencies to create biological changes. Two examples offered are lactose tolerance and the ability to metabolise alcohol, both seemingly having arisen rapidly and recently to create divergent evolution in humans. Such downward causation has been challenged by those who prefer to interpret these examples in terms of the founder effect and random genetic drift (e.g., lactose tolerance may have occurred in those cultures where the relevant genes were already fortuitously present).
See Alcohol tolerance, Cultural evolution, Cultural evolution and biological evolution, Downward causation (or macrocausation), Founder effect (or principle), Genetic drift (or random walk), Lactose tolerance, Meme