Facial masculinity does not appear to be a condition-dependent male ornament and does not reflect MHC heterozygosity in humans

Significance Facial masculinity has been considered a sexual ornament in humans, akin to peacock trains and stag antlers. Recently, studies have questioned the once-popular view that facial masculinity is a condition-dependent male ornament signaling immunocompetence (the immunocompetence handicap hypothesis). We sought to rigorously test these ideas using high-resolution phenotypic (3D facial images) and genetic data in the largest sample to date. We found no support for the immunocompetence handicap hypothesis of facial masculinity in humans. Our findings add to a growing body of evidence challenging a popular viewpoint in the field and highlight the need for a deeper understanding of the genetic and environmental factors underlying variation in facial masculinity and human sexual dimorphism more broadly.