Best known example of gene-culture coevolution - co-evolution of pastoralism and lactose intolerance - the adoption of dairying set up a modified niche - in which the ability to digest lactose into adulthood was an advantage. - ancestors who were lactose tolerant could take advantage of a new source of calories. - Hence it is the learned acquisition of dairying which explains the natural selection of genes favoring lactase persistence, - the continued production of the enzyme lactase beyond weaning - Dual inheritance theory (Gene-culture coevolution) typically uses this example to explain - Dairying is inherited via a cultural channel - lactase persistence is inherited via a genetic channel - Recent supporters of this also make recent claims that it is not possible to distinguish between - what is biological from what is cultural