The balance between burden carrying, variable terrain, and thermoregulatory pressures in assessing morphological variation

Abstract

A series of studies have lately shown specific morphological correlations with energetic savings during locomotor tasks, including burden carrying and walking up inclines. These energetic savings appear significant and make sense given the interactions between morphological variation and behavior in many populations. For example, a wider pelvis for one's mass has been shown to save people energy while carrying both front and back burdens. Ethnographic reports suggest that females, who maintain a wider pelvis for their mass in any given group, carry a much higher proportion of burdens than males-some have even suggested that carrying is women's work. Simultaneously, a shorter tibia has been correlated with energy efficiency while walking up inclines, while a longer tibia has been shown to increase speed along flat terrain. All of these traits have also been shown to be correlated with climatic variables, particularly temperature, such that morphology may result from some interaction between selection pressures for thermoregulatory and mobility adaptations. Here I review work on the mobility effects of pelvic width and limb proportions in the context of carrying burdens across variable terrain and while balancing thermoregulatory pressures.