Ever wish you could determine how healthy a guy's sperm is just by looking at him? Well, if you judge mates based on their reproductive potential, you should know that more masculine faces may indicate weaker sperm, according to a new study in the Journal of Evolutionary Biology.
A team of researchers at the University of Valencia used a sample of 50 Caucasian men from the university, testing their sperm quality and taking pictures of their faces. They performed an anthropometric analysis of the men's facial characteristics by measuring various parts of the face to determine how masculine or feminine each was. After, the researchers had 149 heterosexual women rate the facial attractiveness of the men as long term partners, and asked 77 heterosexual men to rate the facial attractiveness of the male test subjects the way that they thought a woman would.
In the end, the researchers found that male facial attractiveness did predict male semen quality. A more masculine face (ie wider, strong jaw) was found to correlate with poorer semen quality than more feminine-faced men. Therefore, male facial cues could signal male fertility. A wider and more masculine face tends to be associated with higher testosterone levels, which could explain the findings of the study, because higher testosterone levels are thought to have negative effects on sperm.
However, this isn’t to say that your future dream beau will have fertility problems. The women who were asked to rate the attractiveness of the photos actually preferred the men with healthier sperm, because women who are looking for long term mates tend to select men with more feminine faces.
Still, more studies with larger subject groups need to be done before we learn anything concrete about the correlation between masculine faces and semen. Until then, I suggest sticking to your usual methods of picking men.