I’ve always been disturbed by parasites that can take over your body and alter your physiology and behavior in subtle ways. Wasps, for instance, lay eggs on the bodies of caterpillars, which then alter the caterpillar’s behavior so that instead of eventually turning into pupa, it continues eating until it bursts with the wasp’s young.
Now some people are theorizing that cats toxoplasma gondii, which lives in cats, alters not only the behavior of rats but of humans as well.
While the science of the experiement sounds speculative at this stage, it’s still an interesting reading for an example of the subtle, chaotic interactions between us and our environment.