A study of Neanderthal physiology, engetics and behaviour

Abstract

The general context of Neanderthal existence in Europe and Southwest Asia is assessed from a physiological perspective, based on studies of living populations experiencing certain roughly analogous circumstances. Various aspects of the fossil, archaeological, and paleoenvironmental records relevant to the discussion of energy balance among the Neanderthals were investigated. Within living populations exposed to cold climate, subsisting on energy deficient diets, or participating in strenuous exercise regimes, various metabolic and physiological responses are evident. These relate to an attempt to maintain energy balance under such stresses, and are mediated by the action of thyroid hormones. It is proposed that the Neanderthals, who endured similar conditions, must have adapted to a low level of circulating active thyroid hormones in the face of an energy imbalance (negative) and sacrificed linear growth (of the legs/limbs primarily) as an energy sparing mechanism, so that other more essential body functions could be maintained to enable survival. Given that the Neanderthal physique was skeletally robust and highly muscled (and that a significant degree and frequency of trauma is evident) it logical that they were engaging in very specific and stressful activity patterns. The Neanderthal physique would have prohibited certain activities but facilitated others. It is clear that modem athletes who share these attributes take part in power and speed events, involving intermittent bursts of high intensity exercise, rather than more stamina orientated ones. This information is used, in conjunction with archaeological and paleoenvironmental evidence, to develop a theory of the daily subsistence practices of the Neanderthals, involving the ambushing of game in a closed environment. Such start-stop activities in a cold environment would have had a bearing on metabolism and energy balance, but also exerted pressure on thermoregulatory mechanisms. In light of this a new theory is developed to explain the evolution of the Neanderthals' exceptional cranial capacity and morphology. The elongated and unflexed basicranium is proposed to have arisen in order to accommodate an expanded cavernous sinus at the base of the brain. This would have provided a mechanism for regulating brain temperature under oscillating periods of heavy physical exertion and rest in a cold environment. The points outlined here are made with reference to previously suggested notions of ecogeographic patterning of body morphology and differential mobility at the time of the 'transition'. Finally, the aspects of Neanderthal existence discussed are placed in a broad ecological and evolutionary context alongside the contemporaneous Early Anatomically Modem Humans (EAMH).