Ecological factors affecting body size of Japanese adolescents.

Prefectural data of 17-year-old Japanese adolescents' body size were excerpted from the annual series of Reports on School Health Statistics (Ministry of Education) for the last 35 years, and were correlated with the mean annual temperature of prefectural capitals. A negative correlation was found for both height and weight. Thus, it can be stated that children in colder climates conform to Bergmann's rule that they are larger in their height and weight than children growing up in warmer climates. Partial correlation coefficients indicate that body weight is primarily related to the temperature. Further, the results of a multiple regression analysis, using temperature, daily energy intake (National Nutrition Surveys), and annual per capita income (Annual Reports of Prefectural Accounts) as the independent variables among the 12 districts (groups of prefectures) for the last 25 years, suggest that the observed Bergmann's phenomenon is related to geographical differences in nutrition; people in colder regions consume more calories than those in warmer regions.