Contrary to what one might expect, facial masculinity was negatively associated with semen quality in a recent Journal of Evolutionary Biology study. As increased levels of testosterone have been demonstrated to impair sperm production, this finding may indicate a trade-off between investments in secondary sexual signaling (i.e. facial masculinity) and fertility.
Interestingly, males estimated facial images generally more attractive than females did, suggesting that males may generally overestimate the attractiveness of other men to females.
Study finds microplastics in semen and urine, linking PTFE exposure to lower sperm count