Low prevalence of lactase persistence in Neolithic South-West Europe

Abstract

The ability of humans to digest the milk component lactose after weaning requires persistent production of the lactoseconverting enzyme lactase. Genetic variation in the promoter of the lactase gene (LCT) is known to be associated with lactase production and is therefore a genetic determinant for either lactase deficiency or lactase persistence during adulthood. Large differences in this genetic trait exist between populations in Africa and the Middle-East on the one hand, and European populations on the other; this is thought to be due to evolutionary pressures exerted by consumption of dairy products in Neolithic populations in Europe. In this study, we have investigated lactase persistence of 26 out of 46 individuals from Late Neolithic through analysis of ancient South-West European DNA samples, obtained from two burials in the Basque Country originating from 5000 to 4500 YBP. This investigation revealed that these populations had an average frequency of lactase persistence of 27%, much lower than in the modern Basque population, which is compatible with the concept that Neolithic and post-Neolithic evolutionary pressures by cattle domestication and consumption of dairy products led to high lactase persistence in Southern European populations. Given the heterogeneity in the frequency of the lactase persistence allele in ancient Europe, we suggest that in Southern Europe the selective advantage of lactose assimilation in adulthood most likely took place from standing population variation, after cattle domestication, at a post-Neolithic time when fresh milk consumption was already fully adopted as a consequence of a cultural influence.

Regional asynchronicity in dairy production and processing in early farming communities of the northern Mediterranean

“…Archaeozoological studies have demonstrated that milk production in the Near East started early in the domestication process in "stock-herding hunter-cultivator" communities (PPN) (3,4), whereas dairy residues have been detected in early ceramic containers dating to the seventh millennium BC (9). Current evidence suggest dairying practices developed largely in lactase nonpersistent communities, providing the base for the selection of the European lactase persistence-associated (13,910*T) allele (10), with the allele first appearing in human ancient DNA during the Late Neolithic (11). The spread of farming practices westward along the northern Mediterranean seaboard is believed to have taken place by "punctuated maritime pioneer colonization," with subsequent adoption of agrarian practices by indigenous populations (12)(13)(14)(15)(16).…”

Going global by adapting local: A review of recent human adaptation

“…The European LP-associated variant is estimated to be ~9000 years old, whereas the most common East African LP variant is ~5000 years old, which is consistent with archeological evidence for cattle domestication in the Middle East and east Africa (5). Sequencing of aDNA indicates that the European LP-associated allele was absent in early Neolithic Central Europeans and was at low frequency in late Neolithic Europeans (10), suggesting that LP spread recently (within the past ~4000 years) across Europe (11). …”

Toward a new history and geography of human genes informed by ancient DNA

“…In fact, in the presence of admixture it is simple to create scenarios where the frequency trajectory of an allele over time allows one to identify selection despite there being no net change in allele frequency (Figure 4B). To date, studies of selection over time have been limited either to small sample sizes [53,112] or small numbers of sites [111,113–115]. However, whole-genome technologies should make it possible to interrogate many thousands of phenotypically-relevant variants simultaneously.…”