<資料・研究ノート>ヒトの熱帯馴化に関する生理学的研究

Abstract

1. Basic concepts of the human physiology of thermoregulation are described. 2. Studies on acclimatization to heat are reviewed on the basis of thermoregulatory functions, and changes in the pattern of physiological functions in acclimatization are discussed. It is clarified that the pattern of changes of physiological function differs according to the degree of acclimatization. For example, in the case of a man born and raised in a tropical region, the pattern of the sweating reflex to heat exposure and the number of active sweat glands are quite different as compared with those in the transitory acclimatization to hot summers of a man living in the temperate zone or in a cold climate. 3. Group means of the basal metabolism (B. M.) of peoples living in various regions, from the temperate zone to tropical areas where the monthly mean temperature is from 8℃ to 35℃ were plotted against the monthly mean temperature at the time of B. M. measurment. It was ascertained that the B. M. is well correlated with temperature, and its regression line is expressed by the following equation : Y=41.78-0.208X, where Y is the group mean of B. M. and X is the monthly mean temperature. 4. This correlation exists among peoples in Asia who eat rice and whose fat intake is below 25% of total caloric intake. In the case of Caucasians whose daily intake of fat is over 35% of total calories, the seasonal variation of B. M. which was found among Japanese disappears. 5. It was found that a reduction of B. M. occurs in heat acclimatization, and this reduction is accelerated in people having rice as their staple food. As the wet cultivation of rice is well developed in Asia, where the climate is hot and humid, the peoples there use rice as their main food and thus their lives are well adapted to their hot and humid habitat, and this forms a well-developed ecosystem. 6. Racial differences of physiological functions between tropical nations and those living in arctic or subarctic regions were compared, and an attempt was made to explain those differences as adaptative differentiation which may develop into an apparently gentic differentiation.