The ability for adults to digest the milk sugar, lactose, is often referred to as lactase persistence (LP), describing the continued (persistent) production of lactase into adulthood. LP is an autosomal dominant trait that is most often associated with a T allele situated 13,910 base pairs (–13,910*T allele) upstream of the lactase gene, LCT. Archaeogenetic data indicates that pre- and early Neolithic populations were largely LP-negative, and that the frequency of the LP phenotype rose dramatically in Europe around 8,000 years ago, coinciding with the Neolithic transition from a hunter-gather to an agricultural-based lifestyle (1) and the appearance of domesticated dairying animals. Today roughly 35% of adults are lactose persistent. The frequency varies dramatically by geographic region, from a high prevalence in Europe (89–90%) and to a relatively low prevalence in the eastern Mediterranean (15%)(1). The spread of lactase persistence is an often cited example of gene-culture co-evolution. You can’t separate the history of domestic dairying and the evolution of lactase persistence, but scientists are still trying to understand how these two worked together. Continue reading “What Came First: LP or the Cow? Genetic and Cultural Co-evolution of Lactase Persistence and Dairying”