Brain Size Takes an Evolutionary Backseat to Body Size

Abstract

Safi describes as “thinking around three corners.” “You have to think about how differences in the rates of change can result in changes in relative brain size,” he says. An increase in relative brain size, for example, can result when brain size increases faster than body size or when it decreases slower than body size. For the human lineage, the analysis showed, relative brain size did increase at a rate faster than body size, in keep­ ing with the view that natural selection favored hominins with more processing capability. But for other primates, relative body size was more important, accord­ ing to the analysis. Gorillas, for example, experienced an increase in both brain and body size but more so in body size. The same pattern held for carnivorans.