It turns out that cultures with a history of dairy farming and milk drinking have a much higher frequency of lactose tolerance – and its associated gene – than those who don’t. Drinking milk is just one of example of the way that traditions and cultural practices can influence the path of our evolution. Culture and genetics are traditionally thought of as two separate processes, but researchers are increasingly realizing that they are intimately connected, each influencing the natural progression of the other. Scientists call it “gene-culture co-evolution.” Why does it matter? If we can pin down how culture influences our genetic makeup – and how the same processes apply to other creatures too – then we can be better understand how the way we act as a society today could influence our future.