Re: Muscularity in males and self-perceived attractiveness in both sexes associate significantly negatively with egalitarianism (r around .36) (Price et al., 2011)
They provide an interesting evo-psych explanation:
In ancestral human environments, muscularity and height (in males) and physical attractiveness (in both sexes) would theoretically have correlated positively with one’s social status, and thus with one’s ability to benefit from social inequality. We therefore hypothesized that individuals who are more characterized by these traits would be less egalitarian (i.e., less likely to believe that resources should be distributed equally in social groups).
Though I think it's rather a matter of rational decisions: Males with weak physical dominance traits may use morality, prosociality, smiling, and possibly affection to cute animals etc. to avoid being regarded as creepy or anti-social. Their reputation is overall more vulnerable compared to physically dominant males. If males cannot compete they also may instead sneak up on females...
Edit: This pathway is possibly how some of the most persistent and loyal provider males are made, basically beta males driven towards a very high-investment strategy in order to get some physical affection at all.