The Origins of Lactase Persistence in Europe

Abstract

Lactase persistence (LP) is common among people of European ancestry, but with the exception of some African, Middle Eastern and southern Asian groups, is rare or absent elsewhere in the world. Lactase gene haplotype conservation around a polymorphism strongly associated with LP in Europeans (−13,910 C/T) indicates that the derived allele is recent in origin and has been subject to strong positive selection. Furthermore, ancient DNA work has shown that the −13,910*T (derived) allele was very rare or absent in early Neolithic central Europeans. It is unlikely that LP would provide a selective advantage without a supply of fresh milk, and this has lead to a gene-culture coevolutionary model where lactase persistence is only favoured in cultures practicing dairying, and dairying is more favoured in lactase persistent populations. We have developed a flexible demic computer simulation model to explore the spread of lactase persistence, dairying, other subsistence practices and unlinked genetic markers in Europe and western Asia's geographic space. Using data on −13,910*T allele frequency and farming arrival dates across Europe, and approximate Bayesian computation to estimate parameters of interest, we infer that the −13,910*T allele first underwent selection among dairying farmers around 7,500 years ago in a region between the central Balkans and central Europe, possibly in association with the dissemination of the Neolithic Linearbandkeramik culture over Central Europe. Furthermore, our results suggest that natural selection favouring a lactase persistence allele was not higher in northern latitudes through an increased requirement for dietary vitamin D. Our results provide a coherent and spatially explicit picture of the coevolution of lactase persistence and dairying in Europe.

Low prevalence of lactase persistence in Neolithic South-West Europe

“…1 Although this distribution would suggest an origin of the mutation in the populations living in the North, a recent modelling of the evolutionary history of the mutation has rather surprisingly suggested its origin in a region located between the Central Balkans and Central Europe, which spread through the dissemination of Neolithic Linearbandkeramiek culture. 36 Although this may seem counterintuitive on the first sight, other simulations have also shown that the geographic origin of an allele can differ from the region of highest frequency, in particular when it occurs on the wave front of a demographic expansion. 37,38 On the basis of these data, one may speculate regarding the likely arrival of the lactase persistence genotype with Neolithic farmers arriving around 7000 YBP from Central Europe.…”

Separating the post-Glacial coancestry of European and Asian Y chromosomes within haplogroup R1a

“…51 However, computer simulations have shown that its increased frequency particularly in North Europe does not necessarily imply stronger effect of positive selection there than in other parts of Europe. 52 Ancient DNA evidence for the Y-chromosome M458G allele is still lacking and it is therefore possible only to speculate about its existence and prevalence in Neolithic Europe. Beyond its spread in the Central European river basins (Figure 2), the LBK extended around the northern Carpathians into the steppe zone of Ukraine and participated in the establishment of the Crisç ulture.…”

Archaeology: The milk revolution

“…Thomas and his colleagues estimated the timing by looking at genetic variations in modern populations and running computer simulations of how the related genetic mutation might have spread through ancient populations 4 . They proposed that the trait of lactase persistence, dubbed the LP allele, emerged about 7,500 years ago in the broad, fertile plains of Hungary.…”