Slow it down: evolution of human metabolism over two million years

Abstract

Previous estimates of the total energy expenditure (TEE) of fossil hominins have assumed vigorous to very vigorous physical activity levels (PALs) when reconstructing their daily energy budgets. However, these PALs are not common for current hunter-gatherers and other subsistence economy populations. The purpose of this study is to reassess the evolution of TEE in the Homo genus by applying predictive equations recently evaluated based on body mass (BM). These equations were applied to 112 individuals of Homo erectus sensu lato, Homo antecessor, Mid-Pleistocene Homo, Homo neanderthalensis and fossil Homo sapiens. Our results suggest that the use of vigorous PALs for past hominins would overestimate their daily energy budgets by approximately 8.4 MJ/day compared to current populations. Furthermore, metabolic acceleration and deceleration linked to changes in BM have likely occurred over the past 2 Mya. These shifts could have been related to the ability of certain species to use exosomatic energy. The use of the predictive models presented here can be an asset to modelling past energetic dynamics and populations’ ecology.