The Capital Economy in Hominin Evolution

Abstract

The global distribution of our species indicates a biology capable of adapting to an extraordinary range of ecosystems, generating interest in how such a biology evolved. Whereas much attention has been directed to genetic adaptation and developmental plasticity as adaptive strategies, ecological stochasticity within the life course may be addressed by additional strategies such as bet hedging and phenotypic flexibility. Both social relationships and adipose tissue may be considered as “energy capital” conferring reversible phenotypic flexibility across the life course. Evidence from primates and contemporary humans demonstrates the value of such energy capital in accommodating ecological uncertainty. The fact that Homo sapiens is characterized by high levels of both cooperative sociality and adiposity compared with extant apes suggests that ecological stochasticity may have been a key ecological stress in the evolution of our genus. The benefits of phenotypic flexibility for ecological risk management may have preceded and enabled the emergence of traits such as carnivory, encephalization, colonizing, and the maintenance of a single breeding species across diverse environments.