A study published in the European Journal of Personality suggests that humans infected with toxoplasmosis gondii are more extroverted compared to non-infected individuals. According to the CDC, roughly 22.5% of Americans over 12 are infected. The effects of the parasite are attributed to increased levels of dopamine in the brains of infected individuals. People can become infected with the parasite through exposure to undercooked contaminated meat, unwashed fruits and vegetables from contaminated soil as well as infected cat litter.
Lindová J, Příplatová L, Flegr J. Higher Extraversion and Lower Conscientiousness in Humans Infected with Toxoplasma. European Journal of Personality. 25(3): 285-291, 2012.
I would've thought it would be to get out of the house to get away from the treacherous beasts.
So that's why I've become more extraverted after all these years. I had cats for years, until I met my wife, who is allergic to cats and a flaming introvert. I used to call myself an introvert, but compared to her - forget it. But then, according to C Jung, where you are on the Introversion/extraversion scale is something you are born. Unless.... you have a cat. Maybe Jung didn't like cats. Thankyou for my laugh of the day.
'... suggests that humans infected with toxoplasmosis gondii are more extroverted compared to non-infected individuals...'
...Probably not too different from rodents infected with T. gondii, exhibiting 'more extroverted' behavior including diminished anxiety/avoidance behavior in the presence of felines. T. gondii can only complete reproduction in feline digestive track so the selective pressure that motivated this clever adaptation is easy to understand...but I still find it fascinating anyway..
Aside from the risk to young children infected with T Gondii of later diagnosis of schizophrenia, i wonder if there are significant observable reduced-risk avoidance behaviors to be found among those people infected with T Gondii (but not clinically schizophrenic)?
All my life I was incredibly reserved and shy, always wishing I could just talk freely to strangers and even to people I knew. Five years ago I got a cat. It was a year or two later when I noticed I was beginning to change. I started talking to whoever I wanted to talk to, no fear at all. Also, my normally dour and clinically depressed mood lifted, and I was able to stop taking antidepressants. This was after 25 years of barely being able to keep myself from trying to drown myself in the bathtub. It was not until this year that I first heard about this entire cat parasite thing, and it took half a year until I started wondering if maybe that had been part of what had changed in my life. Maybe it was that, but I prefer to think it was just because of all the love and attention that I get from my cat.
Or maybe my cat went out and got infected on purpose just so she could help me out. She is a very smart cat, after all.