Temperature regulation of Eskimos, Indians, and Caucasians in a bath calorimeter

¹ Physiology Department, Arctic Aeromedical Laboratory, Fort Wainwright, Alaska

Eighteen men: six Alaskan Eskimos, six Arctic Athapascan Indians, and six Caucasian U. S. soldiers were immersed serially in a bath calorimeter where the rates of heat production and loss were measured during whole-body exposure to water temperatures of 35, 33, and 30.5 C. At each of these temperatures the Eskimos exhibited the highest rates of heat production and loss, followed by the Indians and Caucasians in decreasing order. Duplicate basal metabolic rate measurements averaged 46 kcal/hr m² in the Eskimos, 42.5 kcal/hr m² in the Indians, and about 37 kcal/hr m² in the Caucasians. Body fat percentages calculated by the skin-fold method were: Eskimos, 6.6%; Indians, 12.3%; and Caucasians, 15.6%. Calculations showed the Eskimos had the lowest tissue insulation followed, respectively, by the Indians and Caucasians. Calculations showed the lower insulation in the Eskimos was independent of their lack of body fat and probably reflected a greater peripheral blood flow. Since the rectal temperature decrements during immersion were the same in all three groups, it was concluded that the surface temperature gradients extended more deeply in the Eskimos than in the other two groups. Hence, they could be described as having smaller "cores" and larger "shells" than either the Indians or the Caucasians.