Darwin Day 2009: Worm Therapy

By Will James

Stephen Stearns began his lecture with a little aphorism. If the greatness of a theory is in proportion to the time it takes for people to catch on to it, the Yale professor said, at this point Darwin's must be pretty great.

At the celebration of the 200th anniversary of the famed biologist's birth, and on the 150th anniversary of his revolutionary theory, Stearns spoke of the ways Darwin's ideas are beginning to creep into medical treatments – for instance, the use of pig parasites to treat multiple sclerosis.

His Friday evening lecture at the Student Activities Center topped off Darwin Day at Stony Brook, an annual celebration of the biologist and his ideas. This year, the holiday was not bereft of its usual politics – a movie called "What about God?" played early in the afternoon – but Stearns' lecture was strictly clinical. In medicine, unlike other disciplines, said Stearns, we can see evolution applied before our eyes, when viruses grow resistant to antibiotics, when insight into humanity's past translates into remedies for today.

The bit about the pig worms is part of something called the "Old Friends" hypothesis, which Stearns, a professor of ecology and evolution, spent a good deal of his lecture explaining. The Old Friends hypothesis starts with the idea that humans, and our immune responses, co-evolved with worms and other parasites that lived inside us for most of our history. Over time, as we became a cleaner and more parasite-conscious species, our immune systems are sometimes thrown off by an acute lack of worms and bacteria.

The “Old Friends” hypothesis adds to the existing Hygiene Hypothesis, which takes note of the fact that the “cleanest” and most modern countries (like the U.S.) have the highest incidence of autoimmune disease – multiple sclerosis, type-1 diabetes, asthma and Crohn’s disease, to name a few.

In Stearns’ own words: "The human immune system evolved on the assumption that we are reliably infected with worms…" By some measure, when our immune systems freak, they’re just missing some old friends.

This revelation has resulted in the experimental use of therapeutic worms. In Stearns’ lecture, he brought up a case in Argentina, in which multiple sclerosis patients were infested with the ova of pig whipworms. The result: their disease slowed dramatically. A happy reunion. One of Stearns’ points was that evolutionary medicine is the place where we can feel Darwin’s 150-year-old pageant play out in our own guts.