Why big brains? A comparison of models for both primate and carnivore brain size evolution

Chambers, HR; Heldstab, SA; O'Hara, SJ

Abstract

Despite decades of research, much uncertainty remains regarding the selection pressures responsible for brain size variation. Whilst the influential social brain hypothesis once garnered extensive support, more recent studies have failed to find support for a link between brain size and sociality. Instead, it appears there is now substantial evidence suggesting ecology better predicts brain size in both primates and carnivores. Here, different models of brain evolution were tested, and the relative importance of social, ecological, and life-history traits were assessed on both overall encephalisation and specific brain regions. In primates, evidence is found for consistent associations between brain size and ecological factors, particularly diet; however, evidence was also found advocating sociality as a selection pressure driving brain size. In carnivores, evidence suggests ecological variables, most notably home range size, are influencing brain size; whereas, no support is found for the social brain hypothesis, perhaps reflecting the fact sociality appears to be limited to a select few taxa. Life-history associations reveal complex selection mechanisms to be counterbalancing the costs associated with expensive brain tissue through extended developmental periods, reduced fertility, and extended maximum lifespan. Future studies should give careful consideration of the methods chosen for measuring brain size, investigate both whole brain and specific brain regions where possible, and look to integrate multiple variables, thus fully capturing all of the potential factors influencing brain size.

Citation

Chambers, H., Heldstab, S., & O'Hara, S. (2021). Why big brains? A comparison of models for both primate and carnivore brain size evolution. PLoS ONE, 16(12), e0261185. https://doi.org/10.1371/journal.pone.0261185

• Journal Article Type: Article
• Acceptance Date: Nov 24, 2021
• Publication Date: Dec 21, 2021
• Deposit Date: Jan 12, 2022
• Publicly Available Date: Jan 12, 2022
• Journal: PLoS ONE
• Publisher: Public Library of Science
• Volume: 16
• Issue: 12
• Pages: e0261185
• DOI: https://doi.org/10.1371/journal.pone.0261185
• Publisher URL: https://doi.org/10.1371/journal.pone.0261185
• Related Public URLs: https://journals.plos.org/plosone/
• Additional Information: Access Information : This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.