This post at NextNature rounds up some of the latest reseach into my all-time favourite parasitic lifeform, Toxoplasma gondii. Toxoplasma, so the theories go, has an effect on the psychology of its hosts; as part of its original lifescycle, it makes rats less afraid of cats, thus increasing its chance of finding a new feline host to colonise. But it gets into us people-monkeys, too, where the effects appear to be a mild version of B-movie bodysnatching:
The effects are sex-dependent. Toxo makes men more distrustful of authority, more jealous, and more likely to engage in rule-bending and breaking. Male motorcyclists are disproportionately affected. In a perverse twist, motorists of either sex who have T. gondii are three to four times more likely to die in car accidents, either from their increased disregard of the speed limit, or because the parasite wears down reaction times. There’s even shaky evidence that T. gondii correlates with success on the football field, at least in predicting the winners of the World Cup.
Women get the sweeter half of the brain parasite. Women harboring T. Gondii are considered by others to be more cheerful, warmhearted, and sexually attractive. They are also outspend their uninfected sisters when it comes to clothing. In some ways Toxo is the microbial mascot of romantic comedies, turning women into spendy social butterflies, and their dates into over-masculine dolts. But take care: Before you go out to find some infectious cat feces to gussy up your social appeal, it’s important to point out that the personality changes are statistically significant but still only minor. Researchers still disagree as to how and even if Toxo alters behavior. It could be that the personality predisposes people to the infection, and not the other way around.
This is the more cautious end of Toxoplasma theory, especially when compared to the notion that it might be the root cause of schizophrenia (which has also been blamed on retroviral gene-jacking). I still find it to be a massive (if rather creepy subspecies of) sensawunda kick; unnoticed civilisational symbiosis FTW!
Bonus points to NextNature for including two amazing images in that post: the first is the well-known wall-of-death-motorcyclist-with-lion-in-sidecar shot, which is one of my all-time favourite images of all time; the second is of two scientists watching a woman with a towel tied across her face shoving her head into a well-used kitty litter-tray. SRSLY.