Within‐species brain‐body weight variability: A reexamination of the Danish data and other primate species

Abstract

A restudy of the Danish brain weight data published by Pakkenberg and Voigt (1964), using partial correlation techniques, confirms and extends their earlier conclusions regarding a much stronger allometric relationship between height and brain weight than between body weight and brain weight. The relationship is particularly strong in males and not in females, which may be related to higher fat components in the latter. Comparative data for smaller samples of Pan, Gorilla, Pongo, Macaca, Papio and Saimiri using body weights suggest that such relationships hold more strongly in males than females, although more reliable data are needed. In addition to providing within-species ranges of variability for variously derived neural statistics (e.g., encephalization quotients, extra neurons, etc.), for normal primates, it is suggested that while allometric trends do exist within species and particularly males, evolutionary pressures leading to larger brain size were probably very diverse, and any 1 homogenistic theory is unlikely.