4 ms·

From a quick skim, it looks like they don't present anything which would distinguish which way the causal arrow points. Do the parasites make their hosts more a

by abeppu 5y ago

From a quick skim, it looks like they don't present anything which would distinguish which way the causal arrow points. Do the parasites make their hosts more attractive so they are more likely to be passed on, or do more attractive people have more sex that gives them opportunities to be infected?

holub008 5y ago
Seriously, has the bar sunk this low? I was certain the authors would express caution in interpreting causality, but alas: "Our results suggest that some sexually transmitted parasites, such as T. gondii, may produce changes in the appearance and behavior of the human host".
- lupire 5y ago
  > may That is expressing caution.
  - holub008 5y ago
    Perhaps it's because I don't frequent the literature, but I interpret that as "T Gondii. may [provided by our level of statistical certainty in MANCOVA] produce changes". Otherwise, what's the point of performing a statistical analysis? Moreover what's the value of any assertion if it can be guarded by an unbounded-uncertainty keyword "may".
    - ascar 5y ago
      I think that's a classic case of reading between the lines and making implications where one shouldn't. If I'm using words that state uncertainty, it is because I am not certain, but only say it is a possibility. A research result that shows there is a correlation is already interesting without establishing or confirming causation. Their wording is exactly saying that. Without that paper we wouldn't even know there is a correlation! How else would you like them to state that without being overly verbose?
      - holub008 5y ago
        > 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-possibility-spurious-correlation-isnt-matter-liking-pretty-much-automatic/ https://statmodeling.stat.columbia.edu/2015/04/04/thinking-p...
        ascar 5y ago
        > "Our results suggest that some sexually transmitted parasites, such as T. gondii, may be correlated with appearance and behavior of the human host." 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.
- folli 5y ago
  T. gondii is not a sexually transmitted parasite. Or am I missing something?
  - holub008 5y ago
    I was directly quoting the article and am not a domain expert. It is interesting to see some commenters here state that it isn't an STD. It appears this is an open question. https://academic.oup.com/aje/article/190/3/386/5905708 https://academic.oup.com/aje/article/190/3/386/5905708 https://pubmed.ncbi.nlm.nih.gov/24986706/ https://pubmed.ncbi.nlm.nih.gov/24986706/
    - folli 5y ago
      TIL. Thank you, this is news to me.
axlee 5y ago
> Do the parasites make their hosts more attractive so they are more likely to be passed on, or do more attractive people have more sex that gives them opportunities to be infected? 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.
- holub008 5y ago
  How about correlation between attractiveness and owning cats? Attractiveness and having a larger number of partners, which increases odds of exposure to cats / T. Gondii? These hypotheses seem plausible enough that I believe the authors are wrong in claiming causality.
  - hunterb123 5y ago
    Unless people are hooking up in barns I don't think frequenting partners that own cats would be correlated. House cats generally eat kibble, not infected mice. 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.
    - jjj123 5y ago
      I don’t understand why you keep mentioning hooking up, that seems irrelevant since it’s been clarified this is not an STD. The parent comment was saying people who own cats could be more attractive on average, and people who own cats are more likely to get toxoplasmosis.
      - 5y ago
atty 5y ago
Agreed. I think it’s far more likely that the lifestyle differences between more and less attractive individuals is causing increased exposure. Not to mention they performed a LOT of tests without correcting for multiple comparisons (as far as I could tell by skimming). Overall pretty disappointing.
layer8 5y ago
Or maybe the more attractive people are just more attractive to T. Gondii.

by abeppu 5y ago

holub008 5y ago

Seriously, has the bar sunk this low? I was certain the authors would express caution in interpreting causality, but alas: "Our results suggest that some sexually transmitted parasites, such as T. gondii, may produce changes in the appearance and behavior of the human host".

lupire 5y ago
> may That is expressing caution.
- holub008 5y ago
  Perhaps it's because I don't frequent the literature, but I interpret that as "T Gondii. may [provided by our level of statistical certainty in MANCOVA] produce changes". Otherwise, what's the point of performing a statistical analysis? Moreover what's the value of any assertion if it can be guarded by an unbounded-uncertainty keyword "may".
  - ascar 5y ago
    I think that's a classic case of reading between the lines and making implications where one shouldn't. If I'm using words that state uncertainty, it is because I am not certain, but only say it is a possibility. A research result that shows there is a correlation is already interesting without establishing or confirming causation. Their wording is exactly saying that. Without that paper we wouldn't even know there is a correlation! How else would you like them to state that without being overly verbose?
    - holub008 5y ago
      > 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-possibility-spurious-correlation-isnt-matter-liking-pretty-much-automatic/ https://statmodeling.stat.columbia.edu/2015/04/04/thinking-p...
      - ascar 5y ago
        > "Our results suggest that some sexually transmitted parasites, such as T. gondii, may be correlated with appearance and behavior of the human host." 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.
folli 5y ago
T. gondii is not a sexually transmitted parasite. Or am I missing something?
- holub008 5y ago
  I was directly quoting the article and am not a domain expert. It is interesting to see some commenters here state that it isn't an STD. It appears this is an open question. https://academic.oup.com/aje/article/190/3/386/5905708 https://academic.oup.com/aje/article/190/3/386/5905708 https://pubmed.ncbi.nlm.nih.gov/24986706/ https://pubmed.ncbi.nlm.nih.gov/24986706/
  - folli 5y ago
    TIL. Thank you, this is news to me.

axlee 5y ago

> Do the parasites make their hosts more attractive so they are more likely to be passed on, or do more attractive people have more sex that gives them opportunities to be infected? 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.

holub008 5y ago
How about correlation between attractiveness and owning cats? Attractiveness and having a larger number of partners, which increases odds of exposure to cats / T. Gondii? These hypotheses seem plausible enough that I believe the authors are wrong in claiming causality.
- hunterb123 5y ago
  Unless people are hooking up in barns I don't think frequenting partners that own cats would be correlated. House cats generally eat kibble, not infected mice. 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.
  - jjj123 5y ago
    I don’t understand why you keep mentioning hooking up, that seems irrelevant since it’s been clarified this is not an STD. The parent comment was saying people who own cats could be more attractive on average, and people who own cats are more likely to get toxoplasmosis.
    - 5y ago

atty 5y ago

Agreed. I think it’s far more likely that the lifestyle differences between more and less attractive individuals is causing increased exposure. Not to mention they performed a LOT of tests without correcting for multiple comparisons (as far as I could tell by skimming). Overall pretty disappointing.

layer8 5y ago

Or maybe the more attractive people are just more attractive to T. Gondii.