Human Physiological Adaptations to the Arctic Climate

Abstract

This review deals with thermal, metabolic and hormonal responses of various human populations to natural or experimental acclimation. Modern people react to cold with shivering, increased metabolism and cutaneous vasoconstriction (metabolic response). Native people, such as Australian aborigines, Eskimos, arctic Indians and Lapps, who were regularly exposed to cold in their natural habitat, have been reported to exhibit less pronounced shivering during experimental cold exposure and experience a greater fall in body temperature (hypometabolic and hypothermic type of adaptation). Australian aborigines and traditional Korean divers have been shown to have low body heat conductivity (insulative type of adaptation). Modern Caucasians intensively exposed to prolonged cold may also develop hypothermic and insulative types of adaptation. Exposure to cold climate increases blood pressure, which may be a factor contributing to the greater mortality due to cardiovascular diseases and stroke observed in the winter. The secretion of the pineal hormone melatonin, which is believed to inhibit the secretion of a pituitary luteinizing hormone, is elevated during winter and decreased in summer. This leads to the higher conception rate observed during spring and summer.

Key words: acclimatization, birth rate, blood pressure, body temperature, cold exposure, conceptions, hormones, light, metabolic rate, mortality, native people, season