By encouraging hosts to engage in more sex with more partners (and/or engage in more unprotected sex), organisms have the ability to survive and thrive by increasing their spread.
After writing that article, I was reminded of another study I read a few years ago that further supports the idea that certain pathogens can manipulate human sexuality -- and in this case, it might even make us more prone to distortion.
A 2016 study published in the journal Evolutionary Psychology looked at whether there was a link between toxoplasma infection and abnormal sexual interest. Toxoplasmosis is a parasitic disease that can be transmitted from cats to humans. So why, you ask, do you associate it with weird sex?
Previous studies -- nearly two dozen studies, in fact -- have shown that the parasite can change the behavior of infected mice and mice. Basically, when rodents are infected with Toxoplasma, their natural fear of cat smell goes away. Instead, they are attracted to the smell of cats. Researchers have dubbed this phenomenon "fatal attraction" because it can put cats' lives at risk, given that they are natural enemies of rodents.
In a way, toxoplasmosis also alters the fear circuits in the human brain. One can imagine a variety of ways in which it could potentially influence behaviour, both sexual and otherwise. Does it make "sharp" sex more sexually attractive, for example? This is what the authors of this study wanted to explore.
They surveyed more than 36,000 people, but only analyzed data from 5,828 people who had previously been tested for toxoplasmosis in the lab and knew they were positive or negative.
Participants completed a survey about their sexual desires, behaviors and preferences. The researchers found that people's attraction to deviant sex really does seem to depend on whether they are infected with the parasite.
In the words of the study's authors, "infected subjects showed increased attraction to nonroutine sexual behaviors, especially those related to BDSM." In addition, infected people are "more attracted to slavery, violence, animal fetishes and fetishes, and men are more likely to be abused, raped and raped."
They believe the results are consistent with the idea that the parasite alters people's perceptions of fear and danger, thereby increasing their acceptance of more deviant sexual behavior. However, they make it clear that this effect may only "slightly increase" the propensity for kink and BDSM. It is hardly entirely responsible for the human sexual excitement caused by BDSM."
I write a lot about kinks and BDSM interests on my blog - in fact, it's one of the most popular sexual fantasies. And people are attracted to people for all sorts of reasons (in previous studies, there were at least eight possible reasons).
Therefore, it is important to reiterate that even if toxoplasmosis plays some role in the development of allergic interest, it is likely to be very small. In other words, this is not to say that kink is the result of some disease process, or that it is necessarily unhealthy.
It's worth noting that this isn't the only study to find that toxoplasmosis may cause changes in sexual behavior. Recently I came across a different study that found higher testosterone levels in men infected with Toxoplasma than in uninfected men, suggesting that toxoplasmosis may cause changes in the neuroendocrine system. Increased testosterone levels and risk-taking tendencies could potentially lay the groundwork for finding more partners and engaging in more sexual activity -- and, given that Toxoplasma can be sexually transmitted between humans, it would provide a mechanism for the parasite to reproduce.
Taken together, these results are yet another piece of evidence that human behavior may be manipulated by microbes in ways that we are not aware of.
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