Being Clean Might Make You Allergic

Recently, Scientific American‘s “Science Talk” podcast featured a valuable interview with Johns Hopkins School of Medicine researcher Kathleen Barnes called “Can It Be Bad to Be Too Clean?: The Hygiene Hypothesis“. In the interview, Dr. Barnes explained the state of contemporary research into the “Hygiene Hypothesis”, which suggests that the reason we are seeing an increase in the number of allergies and other immune-system-related diseases is that we have removed key interactions with microbes, interaction which we have evolved to use in calibrating our immune system. There’s a lot of really informative content here, but I particularly was interested in the discussion of how our local genetic heritage might impact our propensity for allergies. If each local human population coevolved with local pathogens, it stands to reason that our immune systems would be tuned to respond differently to different pathogens. As Dr. Barnes pointed out nicely, the window for understanding these unique local adaptations is slowly closing as people migrate, ethnic distinctiveness decreases, and industrialized environments encroach on the few remaining areas resembling the environments of our ancestors.