The effects of extremely cold and hot environments on body proportions of rats were studied. These effects included changes in the length of the tail, trunk, extremities, cranio-facial and nasal dimensions, in bone robusticity and bone shape, in the size of the ear and in some characteristics of the skin and hair. Since animals in both extreme temperatures fail to gain normal body weight, all changes were also studied in a group of starving rats. Because of the lower body weight and its concomitant reduction of body measurements, absolute values were avoided for analysis and all parameters were related to neurocranial length and trunk length. Such a triple experimental approach (response to cold, heat, and starvation) combined with a two-fold frame of reference (neurocranial length and trunk length), as well as statistical corrections for body weight loss, made it possible to differentiate between nutrition-specific and temperaturespecific responses under conditions of extreme temperature exposure. Moreover, some attention was given to endocrine pathways involved in some morphological changes. The methodological advantages of a multi-experimental approach over a single-experimen tal technique were demonstrated.A considerable body of information has accumulated in the field of experimental biology on the effects of extreme cold and heat exposure on physiological and biochemical conditions of various body tissues. Experimental work on humans exposed temporarily to extreme temperatures has concentrated on such reactions as shivering and non-shivering thermogenesis, oral, rectal, and skin temperature, pulse, sweat and metabolic rates, insulation as related to skin fold thickness, and peripheral circulation in fingers, hands, and feet.However, the important anthropological problem of body proportions in human populations and their relationship to temperature differences has so far been treated mainly on a comparative and distributional basis with interpretations usually following the nineteenth century ecological "rules" of Bergmann and Allen. In fact, not even constitutional anthropology has ever made an attempt to analyze the problem of body constitution in a lower mammal, its sexud dimorphism, dependence AM. J. PnYs. ANTHROP., 39: 427460.on endocrine activity, nutrition and temperature exposure. The only exception is found in the study by Steegmann and Platner ('68) on experimental cold modification of cranio-facial morphology in the rat, attempting to "clarify the process by which the 'Arctic Mongoloid Face' has come to look as it does."The only problem pertaining to body proportions in a lower mammal that has been studied extensively is the problem of relative tail-length in cold and heat-exposed mice and rats (Sumner, '09; Przibram, '22, '25; Ogle, '34; Ashoub, '58; Harrison, '58, '59, '60, '62, '63; Harrison et al., '59; '64; Knoppers, '42; Barnett, '65; Thorington, '66, '70; Sundstroem, '27; etc.). The authors of these studies found that absolute trunk length is shorter in heat-exposed animals, tha...
