Your brain. Your brain on toxoplasms. Eeeeek!
This month’s The Atlantic features a fascinating article – How Your Cat Is Making You Crazy. It highlights the work of a biologist at Charles University in Prague, Jaroslav Flegr, who has been studying parasites. What has sparked Flegr’s interest is a particular one-celled parasite called Toxoplasma gondii. It’s nickname is T.gondii and it’s an effective little bugger. People who host the parasite have toxoplasmosis. Other warm-blooded animals have it, too. It can be very damaging to fetuses, but its impact on adults is only starting to be understood.
T. Gondii has a fascinating life-cycle. It can only reproduce while in cats. It exists in cat feces, and is then picked up through a variety of means, by other animals. When in the host it moves to the brain, creates tiny cysts, and affects the host’s behavior in a variety of ways – many of which are being discovered by Flegr. The underlying assumption that the changes in the host’s behavior, from an evolutionary point of view, are all geared towards the T. gondii getting back into the cat where the parasite can reproduce. Infected rats move more slowly, for example, possibly so that they are easier to be eaten by a feline.
When a person is infected the usual signs are a slight flu and then, supposedly, the parasite sits dormant. Flegr has found, however, that infected people display statistically significant differences, especially when sex is taken into account. Men are more likely to be introverted, fearful and disinclined to follow rules while women present as more outgoing, trusting, and concerned about their appearance. Infected people have slower reaction times, are over-represented in schizophrenia, and are more likely to be in car accidents. Unbelievable weird, isn’t it?
Hard analysis of the science is beyond the article’s scope – we don’t really know if Flegr is correct or not. The early indicators are that he is on to something and it will be thrashed out in laboratories and journals for years to come. What resonates with me is that it highlights the extraordinarily complex interplay that make up evolution, evolutionary biology, and brain development.
Humans are, much more than we realize, open systems. Even more to the point, the interplay between what we conceptualize as the “self” and the “exterior” is extraordinarily fluid. Our internal systems do not simply react to external factors; they can change because of those factors. The systems themselves can transform as studies on neural plasticity reveal.
2500 years ago Heraclitus wrote that you cannot step into the same river twice. The observation holds true today – and it is not the river that is different. You, too, may also be different.