Brain Size and Its Relation to the Rate of Metabolism in Mammals

In mammals, brain size corrected for the influence of body mass appears to be independent of the basal rate of metabolism corrected for the influence of body mass. Brain size depends on the habits of a mammal: it is larger in arboreal species and in species that feed on vertebrates, seeds, or fruit, and it is smaller in terrestrial species that feed on grass or the leaves of woody plants. Some factors that are associated with a relatively high rate of metabolism, such as a small mass, a large surface-to-volume ratio, and life in a cold environment, have no direct effect on brain size. Caution should be used when using a similarity of scaling in two organic characters as sole evidence of their functional interrelatedness.