Behavioral Ecology Blog

Did you know that rats have an innate aversion to cat urine?? Well, I certainly did not. Seems reasonable though, that this represents an adaptation- i.e. where there is cat urine- there are cats- rats are in danger of being eaten by cats…. Something that might block this aversion in rats might be really advantageous to the cat- and it just so happens that is the case.

Toxoplasma gondii is a micro-parasite that infects cats at high frequency. You may know about this little guy as they are the reason pregnant females are advised not to mess with cat litter box. Anyway- according to a recent paper by Vyas in PNAS, urine from infected cats does not produce aversion in rats… in fact, it is an attractant. See the Abstract:

“The protozoan parasite Toxoplasma gondii blocks the innate aversion of rats for cat urine, instead producing an attraction to the pheromone; this may increase the likelihood of a cat predating a rat. This is thought to reflect adaptive, behavioral manipulation by Toxoplasma in that the parasite, although capable of infecting rats, reproduces sexually only in the gut of the cat. The “behavioral manipulation” hypothesis postulates that a parasite will specifically manipulate host behaviors essential for enhancing its own transmission. In mice and rats, latent Toxoplasma infection converted the aversion to feline odors into attraction. Such loss of fear is remarkably specific, because infection did not diminish learned fear, anxiety-like behavior, olfaction, or nonaversive learning. These effects are associated with a tendency for parasite cysts to be more abundant in amygdalar structures than those found in other regions of the brain. By closely examining other types of behavioral patterns that were predicted to be altered we show that the behavioral effect of chronic Toxoplasma infection is highly specific. Overall, this study provides a strong argument in support of the behavioral manipulation hypothesis. Proximate mechanisms of such behavioral manipulations remain unknown, although a subtle tropism on part of the parasite remains a potent possibility.”

Toxoplasma is known to produce several other behavioral effects..Aside from it being cat perfume,it is also know to enhance promiscuity in infected females… While neither proximate mechanisms are really known- one can argue that both involve the attraction/repulsion axis. In one case- rats and cats; in the other, women and sexual partners…
OK- here is strategy for single men:

1. Get a cat
2. Ensure infection with T. gondii
3. Get a girlfriend- make her change the cat-litter box
4. Soon- she will be.. well… you know…
5. Extra bonus- all the rodents will be eaten by the cat- as per the aversion/attraction effects.

You might imagine this being a winning strategy in some place like a College dorm (but then again- it doesn’t seem like promiscuity needs much help in the average dorm), or other communal living situation..