An older article on the effects of Toxoplasma gondii in Schizophrenia Bulletin:
Consistent and significant differences in Cattell’s personality factors were found between Toxoplasma-infected and -uninfected subjects in 9 of 11 studies, and these differences were not the same for men and women. After using the Bonferroni correction for multiple tests, the personality of infected men showed lower superego strength (rule consciousness) and higher vigilance (factors G and L on Cattell’s 16PF). Thus, the men were more likely to disregard rules and were more expedient, suspicious, jealous, and dogmatic. The personality of infected women, by contrast, showed higher warmth and higher superego strength (factors A and G on Cattell’s 16PF), suggesting that they were more warm hearted, outgoing, conscientious, persistent, and moralistic. Both men and women had significantly higher apprehension (factor O) compared with the uninfected controls.
I was thinking about this because I was trying to convince a friend who hadn’t had cats that he should really think about getting some. It reminded me a bit of the old Garfield episode, “King Cat,” where the Egyptians worshiped and pampered their cats. The feline dominated society was overthrown thanks to the influence of dogs upon human beings. There has been plenty of stuff on the differences of Toxoplasma gondii between nations, but I wonder about the effect over time. I haven’t been able to find the data, but I recall that widespread pet ownership was a practice which emerged with the rise of the middle class.