Thursday, May 16, 2013

Does the Size of Your Arms Affect Your Politics?

It does if you're male, apparently. At least, so says a paper by Petersen et al1 titled "The ancestral logic of politics: Upper body strength regulates men’s assertion of self-interest over economic redistribution," in press in Psychological Science (you can read the full manuscript here). Their methodology was pretty simple: for male and female participants in Argentina, Denmark, and the U.S., they measured the "circumference of the flexed bicep of the dominant arm," a strong indicator of upper body strength, and then correlated those measurements with their answers to several questions that measured support for economic redistribution policies.

For women, there was no relationship between arm size and support for redistribution. For men, however, there was a statistically significant relationship, even controlling for political ideology. In other words, regardless of whether you considered yourself liberal or conservative, your arm size was a good predictor of your support for economic redistribution. The relationship wasn't linear, though. For men of (self-reported) below average socioeconomic status (SES), support for redistribution increased with upper body strength, while for men of above average SES, it decreased that support. You can see that in the charts below (from Petersen et al's Figure 1, representing marginal effects from their Ordinary Least Squares model).


What does this mean? Here's how Petersen et al put it:


The asymmetric war of attrition model of animal conflict predicts that animals use advantages in fighting ability to bargain for increased access to resources. Equally, it predicts that attempts to self-interestedly increase resource share should not be initiated when at a competitive disadvantage. The findings reported here show that this model generalizes to humans, successfully predicting the distribution of support for, and opposition to, redistribution in three different nations.
I have to admit that the "asymmetric war of attrition model" sounds pretty cool, but also somewhat vague, particularly when it comes to mechanisms, a fact that Petersen et al. admit when they write, "the findings of this study are silent with regards to the precise proximate variables that mediate between upper body strength and psychological traits." Whatever gets males from "asymmetric war of attrition" to arm size mediating political views, though, this provides yet another piece of evidence that our politics are less well thought out than we like to think. I mean, it's not like our arms predict better or worse political reasoning, right? Particularly since the effect of arm size on support for redistribution is dependent on one's SES (suggesting that the key here is self-interest) and gender, and is independent of political ideology.
1 Petersen, M. B, Sznycer, D., Sell, A., Cosmides, L., & Tooby, J. (in press). The ancestral logic of politics: Upper body strength regulates men’s assertion of self-interest over economic redistribution. Psychological Science.

1 comment:

  1. Hey Chris, Glyph here.

    I saw this reported elsewhere, with some slants that I thought was not necessarily justified from what I was reading. To wit:

    "predicts that animals use advantages in fighting ability to bargain for increased access to resources. Equally, it predicts that attempts to self-interestedly increase resource share should not be initiated when at a competitive disadvantage."

    Now, I think there's a slant built right into this language - instead of saying "self-interestedly bargain for increase", it seems to me you could equally say "self-interestedly bargain AGAINST DEcrease".


    One way says I am trying to get more pie at the expense of others; the other way says I am trying to keep from having my pie taken from me. So right there it seems we have a slant, since one action seems aggressive/bad, and one defensive/normal.

    Second (and this is not the fault of the study authors, but this is how I am seeing the results painted elsewhere), the causal inference many people seem to be drawing is paraphrased as something like "of course strong bullies want to take weak people's stuff (or, more mildly, not to share their own stuff with weaker people)".

    The first issue I have here, is that arm circumference is genetic to a degree, but is obviously also influenced by lifestyle, like working out. But people seem to be only looking at this as though it's an innate, biological tendency/association (the innately strong genetic lottery-winners against the "weak").

    But in keeping with my "offense/defense" distinction above, it could be equally true that people choose to bulk up (ARM themselves, heh) whenever they think there is a threat of other people (people THEY may see as bullies) coming to get their stuff.

    Another interpretation might be, "people who are driven enough to go to the gym and work hard there so they look good and stay healthy, also tend to believe that others should also be driven enough to work hard, and not be handed things easily".

    I don't go to the gym, but I have no doubt those that do go, are largely more driven than I. It stands to reason this is more likely the true association to their beliefs on redistribution; large arm circumference may largely just be a side effect of being driven to excel in their personal lives.

    Anyway, if I am missing something obvious, pls LMK. Cool blog BTW!

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