Parasite hijacking the brain Toxoplasma It seems to be just about everywhere. The microscopic invader is thought to infect up to 50 percent of people, and a host of studies suggest it may alter human behavior, as well as that of many other animals.
The parasite has been linked to a wide range of neurological disorders, including schizophrenia and psychotic episodes, and scientists are still discovering more mysterious effects that may result from the infection.
In one of these new studies, researchers found that men and women infected with the parasite ended up rated as more attractive and healthier than uninfected individuals.
On the face of it, this may seem strange and unlikely. But in theory, the phenomenon could make sense from an evolutionary biology point of view, the scientists say.
Above: composite images of 10 men and women infected with toxoplasma (A), next to 10 composite images of 10 non-infected women and men (B).
In the midst of many neurological changes T. Gundy Infection appears to occur in its hosts, and the researchers hypothesize that some effects may sometimes benefit the affected animals — which may also benefit the parasite, by later helping to stimulate its own transmission possibilities.
In one study, ToxoplasmaInfected mice were perceived as more sexually attractive and preferred by uninfected females as sexual partners,” the researchers explain in a new paper led by first author and biologist Javier Poraz Leon of the University of Turku in Finland.
Much research has been devoted to investigating whether similar effects can be seen in human cases T. Gundy infection.
The evidence is far from clear, but some evidence suggests that affected men have higher levels of testosterone than unaffected men.
Arguably, men with higher levels of testosterone can be more likely to be infected with the parasite in the first place, through higher levels of risky behavior related to the hormone.
However, the alternative view is that the parasite may be able to alter its host’s phenotype, and manipulate chemicals in the animal’s body, such as neurotransmitters and hormones, for its later ends.
Boras Leon and his team suggest that these modifications could be far-reaching.
“Some parasites are sexually transmitted, such as T. Gundymay result in changes in the appearance and behavior of the human host, either as a byproduct of infection or as a result of manipulation of the parasite to increase its spread to new hosts,” the researchers wrote.
To test this hypothesis, researchers compared 35 people (22 men and 13 women) with T. Gundy Compared to 178 people (86 men and 92 women) who did not carry the parasite.
All participants (including those infected) were however healthy college students, who had previously had their blood tested in another investigation study. T. Gundy.
After a number of different tests involving participants — including surveys, physical measurements, and visual evaluations — the researchers found ToxoplasmaInfected persons have significantly fluctuating facial asymmetry compared to uninfected persons.
Volatile asymmetry is a measure of deviation from symmetric traits, with lower levels of asymmetry (ie, higher symmetry) associated with better physical health, good genes, and attractiveness, among other things.
In addition, women who carried the parasite were found to have lower body masses and a lower BMI than uninfected women, and they reported higher attractiveness in terms of self-perception and a greater number of sexual partners.
In a separate experiment, a group of 205 independent volunteers evaluated photographs of participants’ faces, and the evaluators found that the affected participants looked significantly more attractive and healthier than the unaffected participants.
When interpreting the results, the researchers say it’s possible T. Gundy Infections may produce changes in the facial symmetry of their hosts through changes in endocrine variables, such as testosterone levels.
Furthermore, the parasite can also affect the metabolic rate in hosts, alerting infected people in ways that may affect their perceptions of health and attractiveness.
However, this is all speculation at this point, and the team acknowledges that other explanations are also applicable, including the idea that highly asymmetric and attractive people might better bear the physiological costs related to the parasitism, which is a burden in other respects. By health.
As for any valid interpretation, it is impossible to say for sure based on this study alone, and the researchers acknowledge that the small sample size of their experiment is a limiting factor for their statistical analysis.
For this reason, future studies with larger numbers of participants will be required to confirm or refute their general hypothesis.
But maybe – just maybe, they say – this baffling parasite isn’t necessarily our enemy after all.
“It is possible that the apparently unsatisfactory and potentially beneficial interactions between T. Gundy And some of its intermediate hosts, such as rats and humans, are the result of shared evolutionary strategies that benefit, or at least do not harm, the fitness of both the parasite and the host,” the researchers wrote.
The results are reported in berg.