Human Evolution: Pathogen Influence on Human Genetic Variation

RESEARCH HIGHLIGHTS

Nature Reviews Genetics | AOP, published online 22 November 2011; doi:10.1038/nrg3134

HUMAN EVOLUTION Pathogen influence on human genetic variation

Human population genetic variation study, the statistical framework that by pathogens were heavily enriched in is known to be influenced by envi- was developed by Fumagalli et al. genes that are associated with autoim- ronmental pressures. By developing a enabled them to correlate allele mune diseases, such as coeliac disease novel statistical framework, Fumagalli frequencies for 500,000 SNPs in 55 and type 1 diabetes. and colleagues have been able to distinct human populations with local The finding that pathogens have discern the relative contributions of environmental factors, such as diet, left such a strong mark on human environmental factors to evolution climate conditions and pathogen load. genomes is perhaps not surprising of genomes, and they found that local Consistent with previous studies, given the influence that pathogens pathogen diversity had the strongest the authors found a greater correla- have on the human lifespan. However, role in the selective process. tion of these environmental factors the trace left by these pathogens Recent genome-wide human with the frequencies of genic SNPs at autoimmune disease gene loci population genetic analyses have and nonsynonymous SNPs than with suggests an intriguing relationship revealed that genes involved in traits non-genic SNPs. After correcting between achieving protection against such as immune function, skin pig- for demography, they showed that infection and maintaining disease- mentation and metabolism are non- pathogen diversity has the strongest causing mutations neutrally evolving sequences and have influence on local genetic variance, Hannah Stower therefore been under the influence of and they detected about 100 human environmental pressures. However, genes for which the allele frequency ORIGINAL RESEARCH PAPER Fumagalli, M. et al. Signatures of environmental genetic adaptation although it has been possible to iden- significantly correlated with pathogen pinpoint pathogens as the main selective tify genes that have been influenced load. Interestingly, helminths seemed pressure through human evolution. PLoS Genet. 7, by selection, it has not been possible to have a stronger influence than e1002355 (2011) FURTHER READING Barreiro, L. B. & to pinpoint the pressures that have viruses, protozoa or bacteria. Climate Quintana-Murci, L. From evolutionary genetics to shaped these sections of the genome was shown to have a limited role. human immunology: how selection shapes host or their relative contributions. In this Furthermore, genes that were shaped defence genes. Nature Rev. Genet. 11, 17–30 (2010)