A microscopic parasite from cat faeces has invaded the brains of billions of people on Earth, but could it be making you more attractive?
A new study led by Javier Borráz-León, of the University of Turku in Finland, has suggested that men and women infected by toxoplasmosis gondii are rated as more attractive by the uninfected.
The finding sounds bizarre, but could make sense from an evolutionary standpoint, ScienceAlert reports.
Toxoplasmosis gondii infects billions of people – at least a third of the world’s population – and is often transmitted from pet cats by spreading through contact with faeces.
The parasite is found in the brain, as well as the muscles, and mouse and rat studies have shown that infection triggers changes in personality.
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In rats, the parasite alters their behavior so they become sexually attracted to the smell of cat urine — so they transmit the parasite to other cats (often dying in the process).
Previous studies on humans have found that infection with the parasite makes people more prone to ‘daring’ behavior such as forming their own companies.
The researchers write: “Parasites are among the main factors that negatively impact the health and reproductive success of organisms.
“However, if parasites diminish a host’s health and attractiveness to such an extent that finding a mate becomes almost impossible, the parasite would decrease its odds of reproducing and passing to the next generation.
“There is evidence that Toxoplasma gondii manipulates phenotypic characteristics of its intermediate hosts to increase its spread.”
The researchers compared 35 people infected with T. gondii against 178 people who were uninfected.
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The researchers found that infected people had more symmetrical features — and women had lower body mass and BMI.
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Both sexes reported higher self-perceived attractiveness in a survey.
A group of 205 volunteers rated photos of the participants for attractiveness and researchers found that the infected people looked more attractive and healthier than the uninfected.
The researchers write: “It is possible that the apparently non-pathological and potentially beneficial interactions between T. 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 say that further research is needed due to the relatively small sample size in the study.
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