 A similar phenomenon can result from processes of niche construction, which affect the selective environment faced by organisms and their descendants (Odling-Smee et al. 2003). A particularly well known example of the possible effects of cultural niche construction on genetic evolution is the relationship between a history of dairy farming in a culture and the prevalence of adults with a genetic variant enabling them to continuously produce lactase, the enzyme needed to digest fresh milk (Durham 1991; Mace 2009). This example illustrates how cultural evolution can drive genetic evolution, a element of gene-culture coevolution.