Evolution of Laterality and Language in Primates

Abstract

One salient feature of the human brain is lateralization, or the predominant localization of function to one hemisphere as compared to the other. Two uniquely human behavioral characteristics—handedness and language—show considerable lateralization in the human brain. Therefore, it has been suggested that these two characteristics may have coevolved in a recent hominid ancestor and provided that backbone for the phylogenetic origin of full-blown human language. In this chapter, we review the literature on nonhuman primate behavioral, neuroanatomical, and neurofunctional lateralization with a special emphasis on the great apes. We discuss this lateralization in the context of great ape cognitive and communicative behavior and discuss the relevance of this for the evolution of human spoken language. The data reviewed herein indicate that, rather than a recent and uniquely human adaptation, behavioral and neuroanatomical lateralization likely were present in an ape-human common ancestor and provided the foundation for the evolutionary origins of human language.