Thursday, July 23, 2009

My body is a wonderland (and an ecosystem)

A friend just sent me this posting from Marginal Revolution on a very unique bug I had heard but not read too much on, called Toxoplasma. This parasite is pretty widespread in the vertebrate world, where it was first described to alter the interaction between rats and cats. Basically, the bug lives in the guts of cats, and then gets pooped out into the cat's feces, which are then eaten by rats, and the bug in turn infects the rat hosts. In order to complete the circle of life, though, the bug has to get back into the cat, and it achieves this not apparently very easy task by altering the rat's neurochemistry: it makes the rats less averse to risk, which in turn makes the rats more likely to be eaten by cats, thereby getting Toxoplasma back to its rightful place in the cat's gut. Pretty cool from a community ecology/evolution.

The kicker, though, is that Toxoplasma also lives in humans (lots of humans), and according to recent work, may have the same effect on us it does on rats: Individuals infected with Toxoplasma were six times more likely to get into a car accident than non-infected individuals. Just another reminder that the complex stuff we call a human may be a bit more like an entire ecosystem than just one organism.