In one such new study, researchers found that men and women infected by the parasite ended up being rated as more attractive and healthier-looking than non-infected individuals.

The evidence is far from clear, but some evidence suggests infected men have higher levels of testosterone than non-infected men.

Arguably, men with higher levels of testosterone could be more likely to become infected by the parasite in the first place, through greater levels of risk-taking behavior associated with the hormone.

To test this hypothesis, the researchers compared 35 people (22 men, 13 women) infected with T.

Following a number of different tests involving the participants – including surveys, physical measurements, and visual assessments, the researchers found Toxoplasma-infected subjects had significantly lower facial fluctuating asymmetry than the non-infected people.

In addition, women carrying the parasite were found to have lower body mass and lower BMI than non-infected women, and they reported both higher self-perceived attractiveness and a higher number of sexual partners.

gondii and some of its intermediate hosts, such as rats and humans, are the result of co-evolutionary strategies that benefit, or at least do not harm, the fitness of both the parasite and the host," the researchers write.