Toxoplasma gondii, the protozoan that causes toxoplasmosis, is as disturbing as it is exciting. This parasite is capable of turning its hosts into true puppets that it manipulates as it pleases in order to find new individuals to parasitize and guarantee its survival. His favorite hosts are felines, which is why he manipulates mice so that they go crazy for cat urine and chimpanzees so that they are not afraid to approach leopards. In humans it causes impulsive behaviors and is even related to psychotic outbreaks. But that's not all, because now it has also been discovered that it could make infected patients more attractive . This seems to occur in rats, but also in humans.
The causes are unclear. In fact, the authors of the study that was just published in PeerJ acknowledge that they should repeat it with a larger number of participants. However, they have some hypotheses. It is clear that the parasite that causes toxoplasmosis needs its hosts to be attractive to other individuals. Therefore, it could manipulate both their metabolic rate and the release of certain hormones that would make them healthier and more attractive.
This is especially seen with testosterone levels, which are generally higher in people infected with the parasite. However, we cannot forget that high levels of testosterone also give more impulsivity, so they could be more prone to infection. It is difficult to know what came before, the chicken or the egg. In any case, knowing everything that Toxoplasma gondii can do, that it is responsible for the attractiveness of its hosts, sounds surprising, but not implausible.
This is the parasite that causes the toxoplasmosis
Toxoplasma gondii is the protozoan that causes toxoplasmosis, a generally mild disease, which can be fatal in cats and human foetuses. Precisely for this reason, the possible routes of contagion of this parasite in pregnant women are closely controlled, to avoid abortions.
It is estimated that 50% of humans have this parasite in their body
In adults they are often not even aware that they are infected. In fact, it is estimated that up to 50% of humans have this parasite in their body. However, worrying symptoms can occur in some cases. Toxoplasma gondii manipulates the behavior of its hosts, making them more impulsive. The causes are very clear with mice and chimpanzees, but not so much with humans. However, if we look back at our ancestors, their impulsiveness could expose them to big cats and that would be wonderful for the parasite that causes toxoplasmosis.
Currently this is not a problem, but this behavior manipulation can trigger psychotic breaks or hasten the onset of schizophrenia. It is not usual, but there are several documented cases in the scientific literature. Now, what does all this have to do with the attractiveness of hosts?
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The attractive host is the best host
The authors of the just published study, from the University of Turku, in Finland, have detected the increased attractiveness of Toxoplasma gondii hosts at various levels.
To begin with, they started from the conclusions of a study published in 2011. It was found that male rats infected with the toxoplasmosis parasite were more attractive to females. Therefore, these gave them preference to mate.
People who had the parasite perceived themselves as more attractive, but other observers also evaluated them as such
They wanted to see if something similar happened in humans. Therefore, they carried out three types of experiments with 35 infected people and 178 without the parasite. On the one hand, focusing on male individuals, as was done with the rats, they measured their testosterone levels. Thus, they saw that this hormone is higher in patients with toxoplasmosis. But this could have other explanations and left women out.
For this reason, they also analyzed a parameter known as fluctuating asymmetry, which measures small variations in a person's traits that move them away from perfect bilateral symmetry. Supposedly, more asymmetry is associated with more attractiveness. And it turns out that people who had the parasite in their body had lower levels of asymmetry . They were more symmetrical and, in a way, more attractive. But this is still a relatively objective measure for something that tends to be very subjective. Therefore, they went on to conduct a series of interviews.
On the one hand, they asked the study participants about their perception of their own physique. They observed that those who had the toxoplasmosis parasite tended to self-perceive themselves as more attractive. This, in reality, does not necessarily mean that they are objectively more attractive. But it is true that sometimes self-confidence is the best beauty treatment. And it seems that that was what they were used for.
On the other hand, another 205 volunteers were recruited, who dedicated themselves to evaluating images of all the participants. The results continued in the same direction, since those who had the parasite were qualified as significantly more attractive.
It therefore appears that the parasite also manipulates the attractiveness of its hosts. By affecting the levels of certain hormones, these people can appear healthier and attract the attention of other individuals. It has even been seen that affected women have a lower body mass index. To know exactly what is happening, the study would have to be repeated with more participants. But it seems that the reasons why Toxoplasma gondii is exciting do not stop appearing. What will be next?
