Human Evolutionary Studies Program and Department of Archaeology, Simon Fraser University
Saturday All day, Plaza Level
Thermoregulation is widely thought to have influenced the size and shape of the bodies of the two best-known fossil members of the genus Homo, Homo erectus and Homo neanderthalensis. The narrow-bodied, long-limbed H. erectus KNM-WT 15000 has been interpreted as tropically adapted, while the stocky, short-limbed Neanderthals have been interpreted as polar adapted. However, there is reason to think that current methods of estimating thermoregulation are problematic. Most significantly, they are incapable of taking into account body segment differences in surface areas, skin temperature, and kinematics.
With the foregoing in mind, we carried out a study to determine whether the current consensus regarding thermoregulation in H. erectus and H. neanderthalensis is supported when segment-specific variables are used. The ratio of heat production to heat loss was estimated for two H. erectus, three Neanderthals, and eleven modern human skeletal samples. Individuals were modeled as walking, unclothed, in four ambient temperatures.
Our results generally support the current consensus regarding the thermoregulatory adaptations of H. erectus and H. neanderthalensis, but there were some unexpected findings. The whole-body heat production to heat loss ratios were consistent with the tropical and polar adaptation hypotheses for H. erectus and Neanderthals, respectively. However, the segment-specific ratios of heat production to heat loss were inconsistent with the idea that lower limb segments are more evolutionarily labile in response to thermal stress than upper limb segments.
Research funded by SSHRC-CGS 767-2006-1902, Canada Research Chairs Program, Canada Foundation for Innovation, and Simon Fraser University.