Thursday, August 03, 2006

Time for a parasite story. As some of you may or may not know, there is a very common protozoan parasite infecting humans going by the name of Toxoplasma gondii. It has a pretty complicated life cycle, but here are the basics. To reproduce, the parasite needs to get into the gut of cats. After reproducing in the intestine of cats, oocysts are shed into the environment. These oocysts can infect a staggering number of species, including humans. In this host, which is sometimes people, the parasite develops into a dormant stage and essentially just waits for transmission to cats (i.e. you being eaten by a cat). Many of these dormant stages reside in the brain, but they aren’t really harmful in people, so the parasite isn’t a large health concern. Like many other parasites, T. gondii isn’t as passive as you’d expect…the parasites seem to alter host behaviour in a variety of different ways (increased neurosis and risk-taking among others). Given that this parasite occurs all around the world but at different levels of abundance, one might ask if this parasite can explain cultural differences. Well, Kevin Lafferty has done just that in a paper published in Proceedings of the Royal Soceity (a really good journal). To make a long story short, his conclusions were suggestive of a relationship between cultural traits (again neurosis) and Toxoplasma prevalence. This is a very cute idea, though I have to say the study doesn’t really show that much. Even in the abstract, he says that “non-causal correlations” may explain these patterns. Furthermore, we all have to remember that correlation doesn’t mean causation. In other words, neurotic cultures may be more prone to infection with Toxoplasma, not the other way around! Basically, a whole hell of a lot more work would be needed to make the connection between culture and brain parasites more conclusive. But imagine if he’s right...wouldn’t that change your world view a bit? Well, it wouldn’t be too mind-boggling for me because I already recognize the power of parasites. Though, I doubt that parasitology courses will ever be a required part of cultural studies.

Now I really want to know if I’ve got Toxoplasma in my brain…

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