How a ‘Mind‑Altering’ Parasite Makes People Seem More Sexually Appealing


May 19, 2022


Image Credit: Wikimedia Commons

Scientists have found the newest “beauty secret” — in a discovery that sounds like an April Fools’ Day joke at best, and proof that we’re hurtling toward a dystopian and likely apocalyptic future at worst. A new study, published in PeerJ, suggests that people infected by a specific parasite can appear more “attractive” and “healthier-looking” than their non-infected counterparts.

Toxoplasma gondii, the microscopic invader behind this, is already deemed the “most successful parasite in the world.” Although its existence was just discovered a little over 100 years ago, it is known to infect up to 50% of the human population — although many remain asymptomatic of its presence in their bodies. But among children or immunocompromised adults, the parasite can cause flu-like symptoms and blurred vision.

The “brain-dwelling” parasite is often carried by cats and has also been linked to neurological disorders like schizophrenia, in the past — but no causation was established. The scientists conducted the study to gain a better understanding and deeper insights into the unexplored effects of the parasite.

In 2011, a similar experiment was performed with rats too; the findings were the same as those of the present study. Non-infected female rats found infected male ones more sexually attractive than their non-infected counterparts. The female rats were more likely to pick infected males for sexual engagements too.

As bizarre as the phenomenon sounds, evolutionary biology might be able to help us make sense of it.

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“Some sexually transmitted parasites, such as T. 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 authors noted. In other words, the parasite might boost their hosts’ metabolic processes and alter their hormone levels so they attract more sexual partners — allowing the parasite to spread further and infect more people.

To some extent, this explanation makes sense. Infected women were found to have a lower BMI; considered conventionally attractive, a lower BMI could indicate better metabolism. Added to that, infected men are known to have higher testosterone levels, which could suggest a hormonal alteration. It’s also possible, though, that “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,” wrote Peter Dockrill, a science and technology journalist.

But at the end of the day, these are merely hypotheses to explain what purpose it might serve a parasite to make its hosts look more attractive. Further research would be the next step to not just verify the hypotheses, but also understand the underlying biological processes involved in the execution of this “beauty makeover.”

For all we know, though, the findings of future studies on T. gondii might yield even more curious results. As Dockrill notes, perhaps, we’ll even find out the parasite isn’t our enemy at all — marking the realization of a symbiotic, inter-species relationship between us.

The researchers appear to be keeping their minds open too. “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,” they noted.


Written By Devrupa Rakshit

Devrupa Rakshit is an Associate Editor at The Swaddle. She is a lawyer by education, a poet by accident, a painter by shaukh, and autistic by birth. You can find her on Instagram @devruparakshit.


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