Highly read on www.plosgenetics.org in November

Pathogens have driven genetic adaptation in humans more than climate or diet has.

Matteo Fumagalli, now at the University of California, Berkeley, and his colleagues calculated the frequency of different genetic variants in more than 1,500 people across 55 populations. They then developed a statistical model to predict the distribution of these variants across the populations. The model incorporates three potential selective pressures on the human genome: climate, diet regimes and pathogen load. Genetic variation correlated most strongly with local pathogen diversity.

Nearly one-quarter of the 103 genes most closely linked to pathogen diversity are involved in immunity. Many also seem to increase susceptibility to autoimmune diseases such as multiple sclerosis and type 1 diabetes. The authors suggest that adapting to cope with pathogens has made humans susceptible to autoimmune diseases when those pathogens are absent.

PLoS Genet. 7, e1002355 (2011)