Jaroslav Flegr has a theory: Cat poop is rewiring the human brain, including his own. The Prague-based biologist has been pursuing the theory since the early '90s, but he's only recently beginning to garner scientific respect, with some of the biggest names in neurobiology backing him up, the Atlantic reports. The theory revolves around Toxoplasma Gondii, a parasite that lives in cats, and is excreted in their feces. From there it can infect humans, making them briefly sick, but then lying dormant forever more in their brains. Or so conventional wisdom holds.
But research has shown that rodents infected with T. Gondii become less wary of predators, and move more quickly, making them more attractive targets for cats. The hypothesis is that the parasite is trying to get back into a cat, where it can reproduce. Flegr thinks it alters behavior in humans, as well. He's done years of personality studies, and found some strange results. Infected men, he finds, tend to become more introverted, poorly dressed, and reckless; infected women become more outgoing, well-dressed, and rule-abiding. Infected people also have slower reaction times, and appear more prone to get into car accidents. "Toxoplasma might even kill as many people as malaria," Flegr posits, "or at least a million people a year." For much more, read the full article. (Read more cat stories.)