There's two parts to their hypothesis, which shouldn't be conflated. They're not saying that because martial arts exist women are attracted to violence.
1. Arm length is sexually dimorphic, i.e. if you take men and women of the same height, men will tend to have longer arms than women. This seems simple enough to confirm with measurements that I assume it's uncontroversial.
2. Longer arms are useful in a fight. This is where the sports comes in - martial arts provides a convenient sample of people who consent to being in fights. The authors correlate their arm length with their success.
They find a weak but positive relationship between arm length and success, which supports the second part of the hypothesis. Obviously martial artists aren't a random sample of the population, but there are probably ethical issues with getting random people to fight each other. I'd expect that longer arms are actually more useful outside of martial arts, where technique is less of a factor than sheer size.
I don't think it's particularly controversial to suggest that men sometimes use violence to get stuff they want. They provide several references in the first paragraph of the article:
Growing evidence suggests that human males have been intrasexually selected for violent contest competition (Hill, Bailey, & Puts, 2017; Puts, 2010), and may possess adaptations specifically for fighting (Carrier, 2011; Carrier & Morgan, 2015; Třebický, Stirrat, & Havlíček, 2019).
If longer arms help males to win at violence they'd probably be selected for if there are no great costs.
As for what it says about women's preferences, selection doesn't require that 100% of copulations derive from a particular trait, only that the trait gives an incremental advantage in evolutionary time. For example, even if non-consensual copulation was rare, being successful at it might provide an evolutionary advantage - again if there are no great costs, like social opprobrium, but at least in modern times men who control a lot of resources seem to be able to get away with treating women terribly.
From what I remember of behavioural ecology lectures as an undergrad there is quite a bit of evidence that, all things being equal, men who control a lot of resources have more kids, in both modern and traditional societies.
Fishnut wrote: ↑
Wed Nov 04, 2020 1:20 pm
I think the biggest problem is that it's taking natural human variation and claiming there's a selection for it, rather than recognising that there's natural human variation and some sports are better suited to subsets of that variation. There's a reason you don't see many dumpy, big-breasted women on the professional marathon circuit but that doesn't mean that we've all been sexually selected for not running far. Oh, I can see it now - women who are dumpy and big-breasted are sexually selected because their big boobs mean they can produce more milk, therefore raising healthier kids, and their dumpiness means they're less likely to run away from bad partners or be at risk of cuckolding due to their unattractiveness. Give me a chance to slap in a couple of references and I'm sure I can come up with something publishable.
I know you're joking, but in the interest of taking-the-joke-too-seriously here are some critiques *dons Reviewer #2 hat*.
- Evolutionary theory generally suggests that the selection on females is to select good partners. In that context, running away from bad partners should be selected for, not against.
- I don't think breast size is correlated with milk production, but it is correlated with fertility (within individuals at least).