Brain Parasites

hat the parasite changes the rats in one subtle but vital way.

Normal rats stay away from anything that smells of cat, sensibly enough. But infected rats don’t.

Rats carrying the parasite are for the most part indistinguishable from healthy ones. They can compete for mates just as well and have no trouble feeding themselves. The only difference, the researchers found, is that they are more likely to get themselves killed. The scent of a cat in the enclosure didn’t make them anxious, and they went about their business as if nothing was bothering them. They would explore around the odor at least as often as they did anywhere else in the enclosure. In some cases, they even took a special interest in the spot and came back to it over and over again.

The scientists speculated that Toxoplasma was secreted some substance that was altering the patterns of brain activity in the rats. This manipulation likely evolved through natural selection, since parasites that were more likely to end up in cats would leave more offpsring.

It gets creepier: humans are not so different from rats (apart from the whiskers and long tails). It’s estimated that about half of all people on Earth are infected with Toxoplasma, and one study (admittedly controversial) claimed to find psychological differences between those infected and normals, in terms of an increased tendency to be more self-reproaching and insecure. Just the kind of traits that might make you want to surround yourself with….nice cuddly pussy cats.

Well I, for one, welcome our new cat parasite overlords.