Metabolic constraint imposes tradeoff between body size and number of brain neurons in human evolution
Open accessAbstract
Despite a general trend for larger mammals to have larger brains, humans are the primates with the largest brain and number of neurons, but not the largest body mass. Why are great apes, the largest primates, not also those endowed with the largest brains? Recently, we showed that the energetic cost of the brain is a linear function of its numbers of neurons. Here we show that metabolic limitations that result from the number of hours available for feeding and the low caloric yield of raw foods impose a tradeoff between body size and number of brain neurons, which explains the small brain size of great apes compared with their large body size. This limitation was probably overcome in Homo erectus with the shift to a cooked diet. Absent the requirement to spend most available hours of the day feeding, the combination of newly freed time and a large number of brain neurons affordable on a cooked diet may thus have been a major positive driving force to the rapid increased in brain size in human evolution.
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- Authors
- Fonseca-Azevedo, K., & Herculano-Houzel, S.
- Affiliations
- Universidade Federal do Rio de Janeiro (BR)
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, 21941-590, Rio de Janeiro, Brazil; and Instituto Nacional de Neurociência Translacional, 04023-900, São Paulo, Brazil
- Venue
- Proceedings of the National Academy of Sciences
- Publisher
- National Academy of Sciences
- Published
- 2012-10-03
- Volume
- 109
- Issue
- 45
- Pages
- 18571-18576
- ISSN
- 0027-8424 (ISSN-L)
- 1091-6490
- PMC
- PMC3494886
- OpenAlex
- W2098413526
- Cited by
- 196
- References
- 59
- Citations by year
- 2026: 4 · 2025: 17 · 2024: 11 · 2023: 7 · 2022: 12 · 2021: 15 · 2020: 15 · 2019: 16 · 2018: 15 · 2017: 11 · 2016: 29 · 2015: 18 · 2014: 14 · 2013: 12
- FWCI
- 65.72
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- Proceedings of the National Academy of Sciences (publishedVersion)
- Europe PMC (PubMed Central) (publishedVersion)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- Funders
- James S. McDonnell Foundation
- Conselho Nacional de Desenvolvimento Científico e Tecnológico
- Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro
- Instituto Nacional de Ciência e Tecnologia de Neurociência Translacional
- Topics
- Social Sciences › Anthropology › Pleistocene-Era Hominins and Archaeology
- Social Sciences › Psychology › Social Psychology › Primate Behavior and Ecology
- Social Sciences › Cultural Studies › Language and cultural evolution
- Keywords
- brain size, body size, metabolic constraints, meal timing, cooking, Homo erectus, human evolution, great apes, brain evolution, primate brain size
- MeSH terms
- Animals, Brain, Cell Count, Diet, Biological Evolution, Feeding Behavior, Humans, Neurons, Organ Size, Primates, Species Specificity, Time Factors, Body Size
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