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

Abstract

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.

Long-Term Response to GH Therapy in Short Children With a Delayed Infancy-Childhood Transition (DICT)

“…Retarded growth in early life should not be confused with constitutional delay of growth and puberty, with a normal growth rate during early life and childhood that slows down around juvenility, and lack signs of puberty at an age of 2 SD above the mean chronological age for puberty onset (3). In this study, analysis of the timing of puberty showed comparable ages both at onset of puberty and when FH was reached for DICT and non-DICT children.…”

“…We have recently defined a second and larger subgroup of short individuals who have experienced a delay in the onset of the infancy-childhood transition (ICT) so-called DICT (2,3).…”

Evo-Devo of Child Growth III: Premature Juvenility as an Evolutionary Trade-Off

“…The child, who up to this point has been provided with food and protection, is still under the social influence of his parents, but is now taking part in hunting, gathering and tribal/family affairs without showing signs of sexual maturation. The data and theory of evolutionary strategies for transition from one life history phase to the next was previously shown to inherently contain adaptive plasticity in the timing of such transitions, including the transition from childhood to juvenility, in order to match (mostly) energy supply, but also other environmental cues [1,3]. …”

Life Course Research Agenda (LCRA), Version 1.0

“…As the LCHD framework began to take shape, it helped support the growing recognition that (1) health development is a complex adaptive process that emerges out of the dynamic coactions between an organism and its environments, (2) this emergent process is mediated by different types and levels of plasticity that evolution has engineered into the human developmental process to optimize a range of adaptive responses to diverse environments, and (3) the synchronization and harmonization of different embedded time frames must be considered, assessed, and understood (Hochberg 2009). …”