Longitudinal evidence linking childhood energetics, maturation, skeletal muscle mass and adult human male sociosexuality.

Humans exhibit variation in their strategic expression of longer-term versus shorter-term mating strategies, including sociosexuality, which is defined as their interest and engagement in sexual activity outside of committed partnerships. There is substantial interest in the factors that drive variation in these strategies between individuals. Early life energetic conditions and psychosocial adversity may play key roles in shaping the expression of shorter-term mating strategies, particularly for males, given male-male mating competition. Drawing on a multi-decade study in the Philippines, we tested for links between males' early life growth/maturation, adult skeletal muscle mass and childhood experiences of adversity with age at sexual debut ( = 965) and adult sociosexuality ( = 1594 obs.). Males who experienced more favourable childhood energetics had sex earlier and had more unrestricted sociosexuality, but these patterns were explained by males' adult skeletal muscle mass. Males who were more maturationally advanced in adolescence also had younger ages at sexual debut and more unrestricted sociosexuality. We did not find evidence supporting the hypothesis that males exposed to early life adversity (family instability and sibling death) and favourable energetic conditions would show 'faster' life history strategies. Our findings point to the importance of developmental growth and maturation trajectories in energetically challenging ecologies to males' later-life mating strategies.