Dairying, diseases and the evolution of lactase persistence in Europe.

In European and many African, Middle Eastern and southern Asian populations, lactase persistence (LP) is the most strongly selected monogenic trait to have evolved over the past 10,000 years1. Although the selection of LP and the consumption of prehistoric milk must be linked, considerable uncertainty remains concerning their spatiotemporal configuration and specific interactions2,3. Here we provide detailed distributions of milk exploitation across Europe over the past 9,000 years using around 7,000 pottery fat residues from more than 550 archaeological sites. European milk use was widespread from the Neolithic period onwards but varied spatially and temporally in intensity. Notably, LP selection varying with levels of prehistoric milk exploitation is no better at explaining LP allele frequency trajectories than uniform selection since the Neolithic period. In the UK Biobank4,5 cohort of 500,000 contemporary Europeans, LP genotype was only weakly associated with milk consumption and did not show consistent associations with improved fitness or health indicators. This suggests that other reasons for the beneficial effects of LP should be considered for its rapid frequency increase. We propose that lactase non-persistent individuals consumed milk when it became available but, under conditions of famine and/or increased pathogen exposure, this was disadvantageous, driving LP selection in prehistoric Europe. Comparison of model likelihoods indicates that population fluctuations, settlement density and wild animal exploitation-proxies for these drivers-provide better explanations of LP selection than the extent of milk exploitation. These findings offer new perspectives on prehistoric milk exploitation and LP evolution.

Cytochrome P4501A induction in brown trout exposed to small streams of an urbanised area: results of a five-year-study.

This case study examines the ability of the cytochrome P4501A (CYP1A) biomarker to distinguish the pollution status of two small streams, Krähenbach and Körsch, receiving different levels of urban and agricultural impact, with low to moderate contamination by arylhydrocarbon receptor (AhR)-binding PAHs and PCBs. Brown trout, Salmo trutta, exposed in enclosure restrictions, showed significant between-stream differences of hepatic CYP1A levels. EROD activities were the better discriminator than CYP1A protein levels. The CYP1A response was consistent and repeatable over the 5-year observation period from 1995 to 1999. In contrast to brown trout, hepatic CYP1A of stone loach, Barbatula barbatula, did not clearly distinguish the streams. The findings of this long-term study lend support to the use of CYP1A as a biomarker of degraded environmental conditions, provided that sufficiently long observation periods are used to average out confounding factors, that sufficiently sensitive detection methods are used, and that a responsive monitoring species is chosen.