A Study of Human Adaptability in Antarctica

The metabolic and nutritional conditions in Antarctica were studied in 29 members of the 10th Japanese wintering party (1968-1970), 25-47 years of age. 1. Change in basal metabolism : It has long been known that there is an apparent seasonal variation in basal metabolism of Japanese people ; higher rate in the winter and lower late in the summer. There has hitherto been much argument, and many possible factors such as natural environment, composition of food, mode of living, racial disposition, have come up for discussion. However, little is known about the real mechanism causing this peculiar phenomenon. This report is the experiments carried out by author in hope that a comparative study in a special environmental condition might throw light on this problem. Generally, in Antarctica, the basal metabolism showed the highest value, 40-43 kcal/m^2/h in January-February, then it gradually decreased to 35-38 kcal in the Antarctic fall. Then it tended to rise again to 39.42 kcal in August and September. In the Antarctic winter, June and July, there is little daylight and little chance to go out, and basal metabolism drops to the lowest level of the year. As described above, the characteristic feature of basal metabolism in Japanese, the apparent seasonal variation, was not affected by the Antarctic environmental and living conditions. However, the values for basal metabolism in Antarctica are higher in every age than the standard values in Japan, as recorded by the Ministry of Health and Welfare. 2. As to the behavioral pattern and activity level of wintering members in Antarctica, several studies have been reported. The author tried to show physical activity level of the subjects by counting daily step using a stepmeter (pedometer). On the average, in the Antarctic summer, December and January, the step count is 15,000, the largest count of the year. It drops to the lowest level, 6,000 steps, in the antarctic midwinter, June and July. These changes seem to have a close relation to the changes in length of daylight. The correlation coefficient between step count and ambient temperature was 0.53, and that between step count and daylight length was 0.64. 3. Food intake: In general, the metabolic balance was always positive throughout the year in Antarctica, resulting in the weight-increase of most wintering members during their stay in Antarctica. Skinfold thickness in the upper arm and around the navel increased in parallel with body weight. 4. Comparing the sleeping pattern of the summer with that of the winter, there was no conspicuous feature in the former, but a symptom of intermittent sleep and a tendency of nocturnal habits were observed. 5. Considering monthly the change of physical rhythm per day, there was only narrow margin of variation and the night-and-day rhythm was absent in midwinter period