Humans might not be exempt from the mind control of parasites, either. Half of us, scientists say, carry the parasitic protozoa Toxoplasma gondii. And once we have toxoplasma in our bodies, we carry it for life.
The rate of infection can vary wildly from country to country—only three percent of South Koreans have are infected by toxoplasma, while as many as 80 percent of French people are carriers. The Centers for Disease Control says that areas where people prefer undercooked meat, like France, or have stray cats running around, like Central America, are rife for infection.
Though the parasite's main host is the cat, it can live in thousands of warm-blooded species (and we're on the list). Toxoplasmosis, researchers have found, might make people more likely to be schizophrenic, and can change personality in subtle ways. One researcher found that infected men were more aggressive and jealous, women were more outgoing, and perhaps most seriously, both had slower reaction times and were in more traffic accidents.
