Evolutionary origins of great ape intelligence: an integrated view

Abstract

Among the great apes that once ranged the forests of the Old World, only four species survive. Their evolutionary history reveals a huge range of morphological and behavioral diversity, all of which must be considered successful adaptations in their own time. Some of these attributes (large brains, sclerocarp and hard-object feeding, frugivory, folivory, gigantism, terrestriality, and suspensory positional behavior) survive in modern great apes. Our questions are: what combination of behaviors and attributes characterized the ancestor of living great apes? what was the significance of this suite of features for cognition? and how did it arise in evolution? To that end, we offer our model of a distinct great ape cognition along with its biological underpinnings and environmental challenges, then attempt to trace the evolutionary origins of this ensemble of features.