The team says this strange connection could have its roots in evolution, theorizing that changes which benefit the host (an animal or human) also benefit the parasite.

This symbiotic relationship would help the parasite spread through carriers having more sex.

gondii suggest that the parasite leads to higher testosterone levels in men, others suspect that the parasite manipulates chemicals in a host’s body — including neurotransmitters and hormones.

gondii, may produce changes in the appearance and behavior of the human host, either as a by-product of the infection or as the result of the manipulation of the parasite to increase its spread to new hosts,” the researchers write in their study.

In an experiment including 35 college students (22 men, 13 women) infected with T.

gondii and 178 students not carrying the parasite, researchers looked at how symmetrical their facial features were.

Results show that Toxoplasma-infected participants had lower levels of fluctuating asymmetry than healthy college students.

Additionally, young women carrying the parasite had a lower body mass index than their peers.

These women also rated themselves as more attractive and reported that they had more 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,” study authors conclude.