Neuroanatomical asymmetries and handedness in chimpanzees (Pan troglodytes): a case for continuity in the evolution of hemispheric specialization
Article first published online: 3 MAY 2013
© 2013 New York Academy of Sciences.
Annals of the New York Academy of Sciences
Volume 1288, The Evolution of Human Handedness pages 17–35, June 2013
How to Cite
Hopkins, W. D. (2013), Neuroanatomical asymmetries and handedness in chimpanzees (Pan troglodytes): a case for continuity in the evolution of hemispheric specialization. Annals of the New York Academy of Sciences, 1288: 17–35. doi: 10.1111/nyas.12109
- Issue published online: 6 JUN 2013
- Article first published online: 3 MAY 2013
- NIH. Grant Numbers: NS-42867, NS-73134, HD-60563, HD-56232
- brain asymmetry;
Many historical and contemporary theorists have proposed that population-level behavioral and brain asymmetries are unique to humans and evolved as a consequence of human-specific adaptations such as language, tool manufacture and use, and bipedalism. Recent studies in nonhuman animals, notably primates, have begun to challenge this view. Here, I summarize comparative data on neuroanatomical asymmetries in the planum temporale (PT) and inferior frontal gyrus (IFG) of humans and chimpanzees, regions considered the morphological equivalents to Broca's and Wernicke's areas. I also review evidence of population-level handedness in captive and wild chimpanzees. When similar methods and landmarks are used to define the PT and IFG, humans and chimpanzees show similar patterns of asymmetry in both cortical regions, though humans show more pronounced directional biases. Similarly, there is good evidence that chimpanzees show population-level handedness, though, again, the expression of handedness is less robust compared to humans. These results stand in contrast to reported claims of significant differences in the distribution of handedness in humans and chimpanzees, and I discuss some possible explanations for the discrepancies in the neuroanatomical and behavioral data.