Fatal Attraction

Just in case I haven’t offended enough people, I thought this bit of scientific marginalia about my least favorite domesticate might help, especially as it has some referents to the wonders of nature to soften the blow.

Begin with the amazing instance of brain control exhibited by a parasite called Toxoplasma gondii. This tiny protozoan invests its all in the relationship between cats and their rodent prey. To begin with, the mouse (or other rodent) ingests the Toxoplasma, which then forms cysts within the mouse, notably in its brain. When a cat in turn eats the rodent, it also imbibes the Toxoplasma, which thereupon reproduces in the cat gut, and is eventually released in the cat feces. The cat feces are in turn nibbled at by other rodents, which ingest the Toxoplasma, and the cycle continues. Of course, the cat feces can be ingested by beetles or other creatures, just as the rodent can be eaten by a hawk, but this would interrupt the cycle—the Toxoplasma can only reproduce inside a cat, and in biology, reproduction is everything.

Now comes the amazing part. Rodents of all kinds are hard-wired to be wary of cats, to avoid them like the plague. If it wants to land inside a cat, which it must, Toxoplasma has to "do" something about this. And what it does (as described in neurologist Robert Sapolsky’s fascinating new book, Monkeyluv), is astonishing. Toxoplasma gondii has evolved the ability to control the brain of its rodent hosts in such a way as to inhibit their inborn aversion to the smell of cats. Instead, rodents infected with Toxoplasma not only lose their aversion to cat pheromones, they become positively attracted to them. This is like someone being drugged with a potion whose only effect is to generate a fatal attraction to its mortal enemy.

The point for you and me in all this lies in the aforementioned potential of Toxoplasma to infect other species besides rodents—humans for example. Remembering that cat feces carry the parasite, it becomes clear why pregnant women in particular have long been advised to be wary of cats. It’s not that cats can "take the baby’s breath away" as my mother used to insist. It has to do with those parasites in their feces. For if Toxoplasma from a cat’s feces finds its way into a pregnant woman (either via her garden, or via the litter box), it can migrate to her fetus’s brain, and cause neurological damage.

All of which makes one wonder: does the Toxoplasma in cat feces have something to do with the cat allergy exhibited by many humans, including myself? And, contrarily, is the inordinate, even obsessive appeal of cats for countless pet owners at least partly attributable to the action of some variant Toxoplasma which has, in an evolutionary accident of species-hopping, somehow managed to imbue millions of humans with a fatal attraction to feline pheromones?

Which leads to my final speculation. Can the day be far off when deviant geneticists, fiddling with Toxoplasma in the bowels of the DOD, find a way to fabricate a parasite that causes the human brain to lose its suspicion of political humbug, and become fatally attracted to idiot Texans and musclebound Teutonics instead? Or, more omninously, is such a cerebral deviation no longer necessary?
Lawrence DiStasi