Evidence of intralocus sexual conflict: physically and hormonally masculine individuals have more attractive brothers relative to sisters

Publication year: 2011
Source: Evolution and Human Behavior, In Press, Corrected Proof, Available online 14 June 2011

Christine E., Garver-Apgar , Melissa A., Eaton , Joshua M., Tybur , Melissa, Emery Thompson

Intralocus sexual conflict (IASC) occurs when sex-specific selection favors genes that increase fitness in one sex and decrease fitness in the other sex. The current study was designed to explore whether IASC occurs in humans. In a sample of siblings, we identified and measured sexually dimorphic traits and hormones within each sex that are related to fitness and are likely coded for by antagonistic genes: waist-to-hip ratio (WHR) and breast size in women, WHR and bicep size (an index of muscularity) in men, and estradiol (E) and testosterone (T) in both sexes. If these traits and hormones are coded for…