A gastroenterologist from the University of Iowa, Joel Weinstock, has been conducting human studies that involve feeding worms to people . The people have Crohn's disease, a bowel disorder, and the worms are Trichuris suis eggs, a parasite found in pigs. Of 29 Crohn's patients, 23 felt relief, and 21 went into complete remission. A second study showed that eating the parasite eggs also improved ulcerative colitis. Weinstock's reasoning here was that human beings evolved in tandem with parasites (also bacteria and viruses) and when modern hygiene eliminates them, we get sick. He formulated his theory after noticing a sharp upturn in inflammatory bowel disease about ten years after modern hygiene arrives at some new corner of the Third World.
All this was reported in an article in yesterday's New York Times, but it's not the first time I've read something similar. Too much cleanliness has been implicated in upswings in asthma, for instance. Our immune systems apparently need something familiar to work on -- parasites, dust, allergens -- and if you eliminate too many of these, the immune system gets cranky and misbehaves. We need a certain amount of filth.
I'm tempted to make a metaphor here. We also evolved with bloody competition and violence. I would say that the evolutionary advantages of violence would make a good novel, except that I already wrote that book (An Alien Light) twenty years ago. Too bad -- I need a novel topic now and I don't have one.
Maybe beneficial parasites...