Ancient DNA Analysis Reveals High Frequency of European Lactase Persistence Allele (T-13910) in Medieval Central Europe

Abstract

Ruminant milk and dairy products are important food resources in many European, African, and Middle Eastern societies. These regions are also associated with derived genetic variants for lactase persistence. In mammals, lactase, the enzyme that hydrolyzes the milk sugar lactose, is normally down-regulated after weaning, but at least five human populations around the world have independently evolved mutations regulating the expression of the lactase-phlorizin-hydrolase gene. These mutations result in a dominant lactase persistence phenotype and continued lactase tolerance in adulthood. A single nucleotide polymorphism (SNP) at C/T-13910 is responsible for most lactase persistence in European populations, but when and where the T-13910 polymorphism originated and the evolutionary processes by which it rose to high frequency in Europe have been the subject of strong debate. A history of dairying is presumed to be a prerequisite, but archaeological evidence is lacking. In this study, DNA was extracted from the dentine of 36 individuals excavated at a medieval cemetery in Dalheim, Germany. Eighteen individuals were successfully genotyped for the C/T-13910 SNP by molecular cloning and sequencing, of which 13 (72%) exhibited a European lactase persistence genotype: 44% CT, 28% TT. Previous ancient DNA-based studies found that lactase persistence genotypes fall below detection levels in most regions of Neolithic Europe. Our research shows that by AD 1200, lactase persistence frequency had risen to over 70% in this community in western Central Europe. Given that lactase persistence genotype frequency in present-day Germany and Austria is estimated at 71–80%, our results suggest that genetic lactase persistence likely reached modern levels before the historic population declines associated with the Black Death, thus excluding plague-associated evolutionary forces in the rise of lactase persistence in this region. This new evidence sheds light on the dynamic evolutionary history of the European lactase persistence trait and its global cultural implications.

Isotopic anthropology of rural German medieval diet: intra- and inter-population variability

“…While we consider the possibility of meat consumption in this community with caution, recent analyses of genetic material extracted from dental calculus indicate that meat protein (pig/boar, and sheep) was consumed by some Dalheim individuals (Warinner et al 2014a). Additionally, host ancient DNA investigation of 18 individuals in the Dalheim cemetery, on one hand, revealed a high level of genetic lactase persistence, indicative of milk consumption and genetic selection for the trait at some point in the population's past (Krüttli et al, 2014). On the other hand, protein analysis of the dental calculus of nine Dalheim individuals did not identify any milk proteins (Warinner et al 2014b).…”

Association of Lactase Persistence Genotypes with High Intake of Dairy Saturated Fat and High Prevalence of Lactase Non-Persistence among the Mexican Population

“…The LP trait has been described as a result of a gene-culture coevolution process related to pastoralist populations [3,27], since the highest frequencies of LP have been observed in Northern European populations and descendants [28,29]. In this study, the distribution of the LNP/LP-associated genotypes ( LCT -13910 C>T and -22018 G>A) were consistent with the ethnicity as tested by the genetic analyses (LD, Fst values and ancestry).…”

Lactancia: la firma de los mamíferos

“…Por otro lado, la hipótesis de causa reversa sostiene que el alelo pudo haber sido común en poblaciones humanas que adoptaron la práctica del cultivo de ganado lechero y el consumo de leche. Ambas teorías están sostenidas e influenciadas por el hecho de que las regiones donde aquellos hombres del Neolítico se establecieron presentaban climas áridos donde la leche era una fuente segura de agua; también, eran climas fríos que facilitaban el almacenamiento de los productos lácteos y, en latitudes más septentrionales, la concentración relativamente alta de vitamina D de la leche ayudó a evitar enfermedades como el raquitismo pues la presencia de lactosa facilita la absorción de nutrientes de la leche tan importantes como el calcio (26,33).…”

“…Luego de que la leche es ingerida, la enzima llamada lactasa rompe o hidroliza el disacárido y sus componentes son absorbidos por el intestino delgado. Cuando no hay lactasa, la lactosa no puede ser absorbida por la mucosa del intestino y llega al colon en donde es fermentada por las bacterias presentes allí, causando dolor abdominal, flatulencias y diarrea (33).…”