Life History Traits in Humans: Theory and Empirical Studies

Life history theory offers evolutionary explanations for the timing of life events, with a particular focus on age-schedules of fertility and mortality and growth. Traditional models examine trade-offs between current and future reproduction and quality versus quantity of offspring. These models can be used to understand questions concerning time of gestation, age of weaning, juvenile mortality profiles, age at maturation, adult body size, fertility rates, senescence, menopause, and the length of the life span. The trajectory of energy acquisition and its allocations is also an important part of life history theory. Modifications of these models have been developed to examine the period of learning, postweaning parental investment, and patterns of development. In this article, we combine energetic and demographic approaches in order to examine the human life course from an optimality perspective. The evolved life history solves related problems across two generations. The first set of decisions concerns how to maximize own lifetime net energy production that can be used for reproduction. The second set of decisions concerns how to maximize total offspring energy production (summed over all offspring).