Evo-devo of child growth II: human life history and transition between its phases.

UNLABELLED This review attempts to use evolutionary life-history theory in understanding child growth in a broad evolutionary perspective. It uses the data and theory of evolutionary predictive adaptive strategies for transition from one life-history phase to the next, and the inherent adaptive plasticity in the timing of such transitions. Humans evolved to withstand energy crises by decreasing their body size, and evolutionary short-term adaptations to energy crises utilize a plasticity that modifies the timing of transition from infancy into childhood, culminating in short stature at the time of an energy crisis. Transition to juvenility is part of a strategy of conversion from a period of total dependence on the family and tribe for provision and security to self-supply, and a degree of adaptive plasticity is provided and determines body composition. Transition to adolescence entails plasticity in adapting to energy resources, other environmental cues, and the social needs of the maturing adolescent to determine lifespan and the period of fecundity and fertility. CONCLUSION Life-history transitions are the times when the child adaptively responds to environmental cues in order to enhance growth-body composition-lifespan-fecundity schedules and behavioral strategies that yield the highest fitness in a given environment.