Relation of Lifespan to Brain and Body Weight 119 



The theory of extremes can be used to compensate for the 

 bias introduced by very great differences in cohort size. This 

 has not been attempted in the present study. 



The data on brain weight and body weight were taken from 

 the extensive compilations of these values by Count (1947), 



BODY WEIGHT -GRAMS 

 10301^3X10^ lo' 3XI0' 10* 3X10* lo' 3Xlo' 10* 3X10* 



2.0 - 



-. 1.0 



LOG|o BODY WEIGHT 



Fig, 2. Relation of lifespan to body weight for 63 species of 

 mammals. Data plotted on double logarithmic grid. The 

 symbols denote groups of species as follows : open circles — 

 primates and lemurs ; solid circles — rodents and insectivores; 

 crosses — carnivores; solid triangles — ungulates and ele- 

 phants ; star in circular field — man. 



von Bonin (1937), and Quiring (1950). The body weights and 

 brain weights are in some instances averages of values re- 

 ported by two or more investigators. Lifespans are the maxi- 

 mum records encountered in the sources examined, and were 

 obtained principally from the compilations by Bourliere 

 (1946), Comfort (1956), Flower (1931), Walker (1954), and 

 Yerkes and Yerkes (1929). 



