摘要：Early humans coevolved with an array of microbes and parasites that modern city dwellers no longer encounter. A growing body of evidence suggests that reduced contact with these ancient microbial partners may be helping to fuel an epidemic of inflamma-tory diseases such as asthma, allergies, mul-tiple sclerosis, type 1 diabetes, and ulcerative colitis—all of which are on the rise in urban populations.1, 2Now ecology and evolution-ary biology professor Ilkka Hanski and his colleagues at the University of Helsinki have observed a link between the environments people inhabit, the diversity of microbes resid-ing on their skin, and their susceptibility to allergic reactions
