Life history trade-offs in human growth: adaptation or pathology?

Abstract

Human beings growing-up in adverse biocultural environments, including undernutrition, exposure to infection, economic oppression/poverty, heavy workloads, high altitude, war, racism, and religious/ethnic oppression, may be stunted, have asymmetric body proportions, be wasted, be overweight, and be at greater risk for disease. One group of researchers explains this as a consequence of "developmental programming" (DP). Another group uses the phrase "predictive adaptive response" (PAR). The DP group tends to view the alterations as having permanent maladaptive effects that place people at risk for disease. The PAR group considers the alterations at two levels of adaptation: (1) "short-term adaptive responses for immediate survival" and (2) "predictive responses required to ensure postnatal survival to reproductive age." The differences between the DP and PAR hypotheses are evaluated in this article. A life history theory analysis rephrases the DP versus PAR debate from disease or adaptation to the concept of "trade-offs." Even under good conditions, the stages of human life history are replete with trade-offs for survival, productivity, and reproduction. Under adverse conditions, trade-offs result in reduced survival, poor growth, constraints on physical activity, and poor reproductive outcomes. Models of human development may need to be refined to accommodate a greater range of the biological and cultural sources of adversity as well as their independent and interactive influences.