Are toxoplasma-infected subjects more attractive than non-infected ones?
peerj.com
peerj.com
T. Gondii reproduces in felines, and is transmitted initially through their feces to other hosts. Humans catch it most often through infected food (meat, vegetables) or liquids (water, milk). Humans cannot transmit T. Gondii to other humans, unless pregnancies, organ transplants or cannibalism are involved.
So, regardless of how attractive an host is, he won't have more or less opportunities to be infected with T. Gondii than anyone else. This is not a STD.
Unless there is some sort of correlation between attractiveness and eating poorly corked meat.
Even then you'd have to infect yourself with the cat while getting together, as humans don't transfer to each other.
Personally I don't think there's any causation here at all with attractiveness directly.
It may be correlated with more outdoorsy people, those people are probably more attractive on average.
Hooking up was simply an example of why the person would be at the other person's environment.
Replace it with getting together if you're getting hung up on it. Whether or not the humans met up to have sex, talk, stand on their head, or whatever is irrelevant.
The point was house cats generally don't eat infected mice, if you're hanging out in barns or on the patio with outside cats, sure maybe.
I painted a scenario where your environment would occur, and dispute it by saying those cats in that environment generally aren't infected
Unless those attractive people are hanging out in barns or patios with outside cats.
Now that could be the case if you go at it from an outdoors perspective, outdoorsy people may be more attractive on average, and they may encounter infected cats more on average.
Your characterization of cat ownership is unrealistic.
I guess anecdotes from you or I isn't really telling if an indoor or outdoor majority of cat ownership is "unrealistic". Maybe we need a study :p
Do outside cat owners generally let their cats inside their home?
The ratio of cat owners with outdoor cats is irrelevant. They exist and they are common. That’s enough to sink your assertions.
> The ratio of cat owners with outdoor cats is irrelevant.
It's extremely relevant when talking about a large enough scale of infection to support the attractiveness causation hypothesis posed by GP.
> I have seen these cats for multiple years so unless they have an outdoor cat house (something I have never seen in my life)
Outdoor cats generally stay underneath the house / porches, cars, etc. during cold or especially hot weather.
> That’s enough to sink your assertions.
I'm disputing the above proposed hypothesis on the grounds I don't think it's common enough occurrence and we're lacking information.
> Since reports that T. gondii can be a sexually transmitted parasite in humans are relatively recent (e.g., Flegr, Klapilová & Kaňková, 2014; Hlaváčová et al., 2020; Kaňková, Hlaváčová & Flegr, 2020; Tong et al., 2021), many questions and hypotheses still need to be properly formulated and tested in further studies.
The basis for this theory is that T. gondii cysts have been found in human ejaculate, which means it could for example be transmitted through oral sex. There does not appear to be any conclusive proof that this has happened, but apparently these are viable cysts which, if swallowed in any other context, would result in infection, so it's plausible.
This non-"pregnancies, organ transplants or cannibalism" route is the basis for a lot of this article's theorising about T. gondii benefiting from raising its host's likelihood of having sex.
Our results suggest that 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. Taken together, these results lay the foundation for future research on the manipulation of the human host by sexually transmitted pathogens and parasites.
From the background paragraph:
> 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 (T. gondii) manipulates phenotypic characteristics of its intermediate hosts to increase its spread.
And the conclusions paragraph:
> Our results suggest that 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. Taken together, these results lay the foundation for future research on the manipulation of the human host by sexually transmitted pathogens and parasites.
It's hard to read that as anything other than the authors classifiying T. gondii as a "sexually transmitted parasite".
I don't know how to reconcile that with what you're saying. Am I missing something?
(phew.. I'm male)
> organ transplants
(none needed yet)
> or cannibalism are involved.
(oh, NO!!!!!)
https://academic.oup.com/aje/article/190/3/386/5905708 https://pubmed.ncbi.nlm.nih.gov/24986706/
That is expressing caution.
How else would you like them to state that without being overly verbose?
"Our results suggest that some sexually transmitted parasites, such as T. gondii, may be correlated with appearance and behavior of the human host."
I appreciate your viewpoint. I would counter it by saying that there are two sources of uncertainty here: choice of model & sampling variance. It's my opinion that in scientific writing, one should be precise with which source of uncertainty they are guarding. If I'm allowed to group these together, why can't I make a similar statement of causation of any old spurious correlation - when obviously my model is bad?
Considering this example again - isn't it arbitrary that the authors get to choose which hypothesis (among many, like attractive people being predisposed to own cats) they get to claim "may" be demonstrated?
Similar line of discussion: https://statmodeling.stat.columbia.edu/2015/04/04/thinking-p...
But that is a different statement. They say that they found correlation and there may be causation. You say there may be correlation, a much weaker claim.
> Considering this example again - isn't it arbitrary that the authors get to choose which hypothesis (among many, like attractive people being predisposed to own cats) they get to claim "may" be demonstrated?
Of course it is arbitrary. But that was their hypothesis and you have to start with some hypothesis, no? They gathered data to establish correlation between the infection and attractiveness. They didn't gather data for anything else, so I think it's pretty reasonable to say we found correlation and further research might be interesting to see if there is causation.
Literally the next sentence says "Taken together, these results lay the foundation for future research".
If you go beyond the abstract and into the actual article, they are pretty careful to just list possibilities for the observed correlation. They certainly could have stated that it might just be spurious correlation there, but I don't blame them too much. These articles are supposed to be concise and not verbose and especially the abstract is supposed to be as concise and short as possible.
I agree with your general premise and the linked article though. It should be a given to consider that and ideally also state it in the article.
Another one I have thought about is HPV virus(or other sexualy transmitted illnesses) and your desire to have sex. There should be a strong evolutionary pressure for the virus to increase your sex drive. If it does, I don't know.
Edit: Downvotes, again? Added a reference. A scientific claim about evolutionary psychology can have merit even if it doesn't fit your personal hopes for the human race. Furthermore, in what world do the downvoters live where women are more likely to causally sleep with the cautious inconspicuous male vs the reckless bad-boy.
[0] https://www.thetimes.co.uk/article/reckless-men-are-more-lik...
Smoking and drinking women young women (<30) would intuitively find smoking and drinking men more attractive for a short term thing, and find that behavior less acceptable for the long term as they probably find it less acceptable for themselves in the long term. Somebody else did this analysis with smokers, but didn't treat the women as fungible[1]. They found the heightened attraction to smokers was limited to smokers.
IMO, we don't really need explanation for why reckless (i.e. brave, risky decisionmaking) people have more short-term relationships. They're more willing to proposition people (brave), and more willing to sleep with people who they will ultimately decide they actually don't like (risky decisionmaking.) This is by definition, as valid if not more than the use smoking and drinking as a definitive sign or recklessness.
I'm not saying that people who smoke and drink are more likely to make brave and risky decisions when it comes to interactions with potential sexual partners, but both sets of behaviors can be called "reckless."
> in what world [are] women are more likely to causally sleep with the cautious inconspicuous male vs the reckless bad-boy.
The world in which the cautious inconspicuous male approached her, and the reckless bad boy didn't. Reckless behavior in women is also attractive, but it isn't due to conforming to some chad stereotype; it's due to the fact that if a woman makes bad decisions, sleeping with you might be one of them.
[0] https://journals.sagepub.com/doi/full/10.1177/14747049166316...
[1] https://www.researchgate.net/publication/263849372_Can_cigar...
For something to be of its very nature it has to be part of that thing.
No reference in the world can make one thing in to another.
Interesting idea, I am not convinced right now - but let's see if it reproduces.
What plausible mechanism is there for the body to even detect asymmetry and then change it? Your brain can't make your ear move lower.
This parasite alters sexual behavior in rats, could this be altering people's behavior not just their appearance as well?!
More sexual mates is riskier, living athletic/outdoorsy/"active" lives is also more risky than being a couch potato...
I don't think we're breaking new ground in saying the risk-averse tend to be less sexually attractive.
New sexual strategies are need I suppose.
"Our results suggest [...] these results lay the foundation for future research"
Its the classic do an easy little study, and suggest that the potential for results might point to further studies. Now you have something to tell your research coordinator next time they get in your hair.
There's no space after the comma and the commenter is putting two values in a single variable which normal holds an integer