Developmental energetics, sibling death, and parental instability as predictors of maturational tempo and life history scheduling in males from Cebu, Philippines.

Abstract

Cross-species comparisons show that high extrinsic mortality favors the evolution of "faster" life histories. There is interest in applying this principle to human life history plasticity, based on the idea that psychosocial stressors that correlate with extrinsic mortality accelerate reproductive pace. Most prior studies have been conducted in settings in which psychosocial stressors co-occur with the maturation-accelerating influence of nutritional abundance. We evaluate cues of local mortality (sibling death) or low parental investment (paternal instability; maternal absence) and energetic measures during development as predictors of life history scheduling among males (n = 754) in a Philippine population with marginal developmental nutritional. Males who had more favorable nutritional status during childhood, as reflected in linear growth, skinfold thickness, and caloric intake, were more maturationally advanced in adolescence (all P < 0.05). Taller stature and higher caloric intake during childhood also predicted earlier ages at first sex (both P < 0.01), which persisted after controlling for the effect of nutrition on pubertal maturation. While psychosocial stressors did not predict accelerated maturation, males who as children grew up with an unstable paternal presence had sex earlier (P < 0.05) and tended to become fathers sooner than those with a stable fatherly presence. Those who had a sibling die became fathers sooner than those who did not (P < 0.05). Our findings point to important energetic constraints on the onset of reproductive maturity, while psychosocial stressors accelerate entry to parenthood, which may be comparatively more socially, rather than biologically, constrained. Am J Phys Anthropol 158:175-184, 2015. © 2015 Wiley Periodicals, Inc.