By Jane Bunce

A common parasite, Toxoplasma gondii, has been found to influence human behavior in surprising ways. While it can increase a woman’s attractiveness to men, it may also reduce men’s cognitive abilities, according to Australian researcher Nicky Boulter.

Approximately 40% of the global population is infected with Toxoplasma gondii, including around eight million Australians. Humans typically become infected by consuming raw or undercooked meat containing cysts of the parasite or accidentally ingesting eggs excreted by infected cats.

This parasite poses significant risks to pregnant women, as it can lead to disabilities or miscarriages. It can also be life-threatening for individuals with weakened immune systems. Historically, the infection was considered harmless in healthy individuals, but recent studies have uncovered its mind-altering effects.

“Interestingly, the impact of the infection differs between men and women,” writes Dr. Boulter in the Australasian Science magazine.

Infected men tend to display lower IQ levels, shorter attention spans, and a reduced likelihood of achieving higher education. They are also more prone to breaking rules, taking risks, and displaying anti-social, suspicious, and jealous behaviors. Additionally, men infected with the parasite are often perceived as less attractive to women.

Conversely, infected women exhibit increased friendliness, sociability, and outgoing behavior. They are also deemed more attractive to men and display more promiscuous tendencies than their uninfected counterparts.

“In essence, the parasite seems to make men behave more recklessly while making women appear more alluring,” Dr. Boulter notes.

Research from the Czech Republic, though not conclusive, aligns with findings from animal studies. Infected mice, for instance, exhibit riskier behaviors, increasing their chances of being preyed upon by cats, thereby enabling the parasite to continue its life cycle. However, when treated with drugs that eliminate the parasite, the mice’s behavior returns to normal.

One study revealed that individuals infected with Toxoplasma gondii were 2.7 times more likely to be involved in car accidents, whether as drivers or pedestrians. Other research has linked the parasite to a higher prevalence of schizophrenia.