A little while ago, I wrote about our parasite overlords. One of these potential puppet masters in humans, so I scribbled, is Toxoplasma gondii. This little, manipulative parasite has previously been (tentatively) linked to personality changes in infected human beings (roughly a quarter of the adult population). A new article in the European Journal of Personality asserts this connection once more.
The authors screened a group of students with the help of a personality questionnaire. They found that infected students, both male and female, showed higher extraversion and lower conscientiousness. What is more, in men the length of infection was negatively correlated with conscientiousness, which means that the longer the infection had been present, the less conscientious they were.
So maybe our minds and/or personalities are not our own…
However, note my careful language in the first paragraph (potential, tentative). The reason for this is, fortunately, not ignored by the researchers (pay specific attention to the part between parentheses):
The existence of this correlation also supported (but of course not proved) the hypothesis that Toxoplasma infection influenced the personality, rather than the hypothesis that the personality influenced the probability of the infection.
One way to start looking for proof could be to purposefully infect previously uninfected people, and then compare the ‘before and after personality’. Good luck getting that research proposal through ethical commissions and funding committees.
(If you want some info on preventing and controlling T. gondii infection, check this CDC page.)
Sneaky little critters, those brain-infecting parasites…
Lindová, J., Příplatová, L., & Flegr, J. (2012). Higher Extraversion and Lower Conscientiousness in Humans Infected with Toxoplasma. European Journal of Personlity, 26 (3), 285-291 DOI: 10.1002/per.838