Anatomical Factors of Body-Heat Regulation

Abstract

AS has already been shown, the body-weight/body-surface ratio decreases more or less regularly from north to south, and the lowest averages are found in hot climates^1,2. Manifestly the decrease of the weight/surface ratio in human beings is an anthropological—and strictly biometrical—equivalent of the two well-known zoological ‘laws’: Bergmann's rule (body-size of related homeotherms decreases in the warmer parts of their geographical range), and Allen's rule (relative increase of protruding organs in warmer districts). I think that a biometrically correct rule may be generalized in the following way: in closely related homeotherms, the body-mass/body-surface ratio tends to decrease in climates which, at least during a part of the year, put a stress on heat-eliminating mechanisms.