Brains matter, bodies maybe not: the case for examining neuron numbers irrespective of body size
Abstract
It is usually considered a paradox that the human brain, although smaller than elephant and cetacean brains, is the most cognitively able. The concept that humans are more encephalized than all other mammals appeared in the 1970s as a solution to that paradox: humans have a brain that is much larger than expected from their body mass. Such an “excess brain mass” would provide increased cognitive abilities across species, thus explaining our cognitive superiority. However, behind the paradox lies the assumption that large mammalian brains are scaled‐up versions of smaller brains, always containing more neurons than smaller ones—an assumption that we have recently shown to be invalid. Here, it is proposed that the absolute number of neurons, irrespective of brain or body size, is a better predictor of cognitive ability—in which case, the cognitive superiority of humans would come as no paradox, surprise, or exception to evolutionary rules.
Integrity signals
Registry
Cites
Statistics
Claims the paper makes
Claims other papers make about this one
Each is checked against this paper’s own text: does it say what the citing paper says it does?
The cortical reorganization hypothesis suggests that selection for absolutely larger brains, and concomitant cortical reorganization, was the predominant mechanism supporting cognitive evolution.
“The cortical reorganization hypothesis suggests that selection for absolutely larger brains-and concomitant cortical reorganization-was the predominant mechanism supporting cognitive evolution (77, 91, 100-106, 120).”
From The evolution of self-control. (2014) · cites this paper as [104]
Cites
Azevedo, F. A. C., Carvalho, L. R. B., Grinberg, L. T., Farfel, J. M., Ferretti, R. E. L., Leite, R. E. P., Filho, W. J., Lent, R., & Herculano‐Houzel, S. (2009) · Journal of Comparative Neurology · doi:10.1002/cne.21974 · Cited by 2,337 · see citing works
Self-citationThe human brain in numbers: a linearly scaled-up primate brain
Herculano-Houzel, S. (2009) · Frontiers in Human Neuroscience · doi:10.3389/neuro.09.031.2009 · Cited by 1,778 · see citing works
Self-citationLinked Regularities in the Development and Evolution of Mammalian Brains
Finlay, B. L., & Darlington, R. B. (1995) · Science · doi:10.1126/science.7777856 · Cited by 1,217 · see citing works
Big brains, enhanced cognition, and response of birds to novel environments
Sol, D., Duncan, R. P., Blackburn, T. M., Cassey, P., & Lefebvre, L. (2005) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.0408145102 · Cited by 917 · see citing works
THE BASIC UNIFORMITY IN STRUCTURE OF THE NEOCORTEX
Röckel, A., Hiorns, R. W., & Powell, T. P. S. (1980) · Brain · doi:10.1093/brain/103.2.221 · Cited by 902 · see citing works
Evolution of the brain and intelligence
ROTH, G., & DICKE, U. (2005) · Trends in Cognitive Sciences · doi:10.1016/j.tics.2005.03.005 · Cited by 890 · see citing works
New and Revised Data on Volumes of Brain Structures in Insectivores and Primates
Stephan, H., Frahm, H. D., & Baron, G. (1981) · Folia Primatologica · doi:10.1159/000155963 · Cited by 877 · see citing works
A universal scaling law between gray matter and white matter of cerebral cortex
Zhang, K., & Sejnowski, T. J. (2000) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.090504197 · Cited by 723 · see citing works
Relative brain size and basal metabolic rate in terrestrial vertebrates
Martin, R. D. (1981) · Nature · doi:10.1038/293057a0 · Cited by 711 · see citing works
Evolution of the Brain and Intelligence
(1973) · Elsevier eBooks · doi:10.1016/b978-0-123-85250-2.x5001-9 · Cited by 667 · see citing works
Brains, Innovations and Evolution in Birds and Primates
Lefebvre, L., Reader, S. M., & Sol, D. (2004) · Brain, Behavior and Evolution · doi:10.1159/000076784 · Cited by 666 · see citing works
: Cellular scaling rules for rodent brains.
Herculano-Houzel, S., Mota, B., & Lent, R. (2006) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.0604911103 · Cited by 579 · see citing works
Self-citationHerculano-Houzel, S., & Lent, R. (2005) · The Journal of Neuroscience · doi:10.1523/jneurosci.4526-04.2005 · Cited by 551 · see citing works
Self-citationDeaner, R. O., Isler, K., Burkart, J., & van Schaik, C. (2007) · Brain, Behavior and Evolution · doi:10.1159/000102973 · Cited by 549 · see citing works
Haug, H. (1987) · American Journal of Anatomy · doi:10.1002/aja.1001800203 · Cited by 481 · see citing works
Cellular scaling rules for primate brains.
Herculano-Houzel, S., Collins, C. E., Wong, P., & Kaas, J. H. (2007) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.0611396104 · Cited by 422 · see citing works
Self-citationThe primate neocortex in comparative perspective using magnetic resonance imaging
Rilling, J. K., & Insel, T. R. (1999) · Journal of Human Evolution · doi:10.1006/jhev.1999.0313 · Cited by 406 · see citing works
Density of neurons and synapses in the cerebral cortex of the mouse
Schüz, A., & Palm, G. (1989) · Journal of Comparative Neurology · doi:10.1002/cne.902860404 · Cited by 376 · see citing works
Coordinated scaling of cortical and cerebellar numbers of neurons
Herculano-Houzel (2010) · Frontiers in Neuroanatomy · doi:10.3389/fnana.2010.00012 · Cited by 288 · see citing works
Ramnani, N., Behrens, T. E. J., Johansen‐Berg, H., Richter, M. C., Pinsk, M. A., Andersson, J., Rudebeck, P. H., Ciccarelli, O., Richter, W., Thompson, A. J., et al. (2005) · Cerebral Cortex · doi:10.1093/cercor/bhj024 · Cited by 279 · see citing works
The density of synapses and neurones in the motor and visual areas of the cerebral cortex.
Cragg, B. G. (1967) · Europe PMC (PubMed Central) · Cited by 243 · see citing works
Balsters, J. H., Cussans, E., Diedrichsen, J., Phillips, K. A., Preuss, T. M., Rilling, J. K., & Ramnani, N. (2010) · NeuroImage · doi:10.1016/j.neuroimage.2009.10.045 · Cited by 241 · see citing works
Beaulieu, C., & Colonnier, M. (1985) · The Journal of Comparative Neurology · doi:10.1002/cne.902310206 · Cited by 239 · see citing works
Animal intelligence as encephalization
Jerison, H. J. (1985) · Philosophical Transactions of the Royal Society of London. B, Biological Sciences · doi:10.1098/rstb.1985.0007 · Cited by 234 · see citing works
A comparison of encephalization between odontocete cetaceans and anthropoid primates
Marino, L. (1998) · Brain, Behavior and Evolution · doi:10.1159/000006540 · Cited by 232 · see citing works
Size and Shape of the Cerebral Cortex in Mammals (Part 1 of 2)
Hofman, M. A. (2008) · Brain Behavior and Evolution · doi:10.1159/000118718 · Cited by 217 · see citing works
Tower, D. B. (1954) · Journal of Comparative Neurology · doi:10.1002/cne.901010103 · Cited by 203 · see citing works
Whiting, B. A., & Barton, R. A. (2003) · Journal of Human Evolution · doi:10.1016/s0047-2484(02)00162-8 · Cited by 137 · see citing works
Genetics of Growth Predict Patterns of Brain-Size Evolution
Riska, B., & Atchley, W. R. (1985) · Science · doi:10.1126/science.229.4714.668 · Cited by 137 · see citing works
Brain-Weight and Body-Weight of Mammals
von Bonin, G. (1937) · The Journal of General Psychology · doi:10.1080/00221309.1937.9917959 · Cited by 135 · see citing works
Size and Diet in the Evolution of African Ape Craniodental Form
Shea, B. T. (1983) · Folia Primatologica · doi:10.1159/000156090 · Cited by 122 · see citing works
Jerison, H. J. (1977) · Annals of the New York Academy of Sciences · doi:10.1111/j.1749-6632.1977.tb41903.x · Cited by 110 · see citing works
Glia/Nerve Cell Index for Cortex of the Whale
Hawkins, A., & Olszewski, J. (1957) · Science · doi:10.1126/science.126.3263.76 · Cited by 104 · see citing works
Cellular Scaling Rules for the Brains of an Extended Number of Primate Species
Gabi, M., Collins, C. E., Wong, P., Torres, L. B., Kaas, J. H., & Herculano-Houzel, S. (2010) · Brain, Behavior and Evolution · doi:10.1159/000319872 · Cited by 102 · see citing works
Self-citationActivity of Acetylcholine System in Cerebral Cortex of Various Unanesthetized Mammals
Tower, D. B., & Elliott, K. A. C. (1952) · American Journal of Physiology-Legacy Content · doi:10.1152/ajplegacy.1952.168.3.747 · Cited by 100 · see citing works
Behavioral Flexibility Positively Correlated with Relative Brain Volume in Predatory Bats
Ratcliffe, J. M., Fenton, M. B., & Shettleworth, S. J. (2006) · Brain Behavior and Evolution · doi:10.1159/000090980 · Cited by 95 · see citing works
Herculano‐Houzel, S., & Kaas, J. H. (2011) · Brain Behavior and Evolution · doi:10.1159/000322729 · Cited by 93 · see citing works
Self-citationCellular scaling rules of insectivore brains.
Sarko, D. (2009) · Frontiers in Neuroanatomy · doi:10.3389/neuro.05.008.2009 · Cited by 92 · see citing works
DER QUANTITATIVE ANTEIL DER GLIA AN DER CORTEXENTWICKLUNG
Friede, R. L. (2008) · Acta Anatomica · doi:10.1159/000140905 · Cited by 91 · see citing works
INTERPRETING THE EVOLUTION OF THE BRAIN.
Jerison, H. J. (1963) · PubMed · Cited by 89 · see citing works
Garey, L. J., & Leuba, G. (1986) · The Journal of Comparative Neurology · doi:10.1002/cne.902470408 · Cited by 81 · see citing works
Stolzenburg, J., Reichenbach, A., & Neumann, M. (1989) · Glia · doi:10.1002/glia.440020203 · Cited by 66 · see citing works
Total neocortical cell number in the mysticete brain
Eriksen, N., & Pakkenberg, B. (2007) · The Anatomical Record · doi:10.1002/ar.20404 · Cited by 65 · see citing works
Cellular Scaling Rules for Primate Spinal Cords
Burish, M. J., Peebles, J. K., Baldwin, M. K. L., Tavares, L., Kaas, J. H., & Herculano‐Houzel, S. (2010) · Brain Behavior and Evolution · doi:10.1159/000319019 · Cited by 46 · see citing works
Self-citationThe scaling of gross dimensions of the spinal cord in primates and other species
MacLarnon, A. M. (1996) · Journal of Human Evolution · doi:10.1006/jhev.1996.0005 · Cited by 38 · see citing works
Encephalization, Neuronal Excess, and Neuronal Index in Rodents
Herculano‐Houzel, S. (2007) · The Anatomical Record · doi:10.1002/ar.20598 · Cited by 38 · see citing works
Self-citationA simple method for determining cerebralization. Brain weight and intelligence
Krompecher, S., & Lipák, J. (1966) · The Journal of Comparative Neurology · doi:10.1002/cne.901270108 · Cited by 28 · see citing works
Schüz, A., & Gp, D. (1995) · PubMed · Cited by 18 · see citing works
Flagged first, then by citations
Cited by
Sorted by citations
The evolution of self-control.
MacLean, E. L., Hare, B., Nunn, C. L., Addessi, E., Amici, F., Anderson, R. C., Aureli, F., Baker, J. M., Bania, A. E., Barnard, A. M., et al. (2014) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.1323533111 · Cited by 819 · see citing works
Herculano-Houzel, S. (2012) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.1201895109 · Cited by 726 · see citing works
Self-citationBirds have primate-like numbers of neurons in the forebrain
Olkowicz, S., Kocourek, M., Lučan, R. K., Porteš, M., Fitch, W. T., Herculano-Houzel, S., & Němec, P. (2016) · Proceedings of the National Academy of Sciences · doi:10.1073/pnas.1517131113 · Cited by 564 · see citing works
Self-citationBODDY, A. M., McGOWEN, M. R., SHERWOOD, C. C., GROSSMAN, L. I., GOODMAN, M., & WILDMAN, D. E. (2012) · Journal of Evolutionary Biology · doi:10.1111/j.1420-9101.2012.02491.x · Cited by 207 · see citing works
THE EVOLUTIONARY HISTORY OF CETACEAN BRAIN AND BODY SIZE: CETACEAN BRAIN EVOLUTION
Montgomery, S. H., Geisler, J. H., McGowen, M. R., Fox, C., Marino, L., & Gatesy, J. (2013) · Evolution · doi:10.1111/evo.12197 · Cited by 106 · see citing works
Mikhalevich, I., Powell, R., & Logan, C. (2017) · Interface Focus · doi:10.1098/rsfs.2016.0121 · Cited by 76 · see citing works
Grabowski, M., Voje, K. L., & Hansen, T. F. (2016) · Journal of Human Evolution · doi:10.1016/j.jhevol.2016.03.001 · Cited by 55 · see citing works
Wartel, A., Lindenfors, P., & Lind, J. (2019) · PLOS ONE · doi:10.1371/journal.pone.0218655 · Cited by 40 · see citing works
- Authors
- Herculano‐Houzel, S.
- Affiliations
- Universidade Federal do Rio de Janeiro (BR)
- Corresponding author
- Herculano‐Houzel, Suzana
- Venue
- Annals of the New York Academy of Sciences
- Publisher
- Wiley
- Published
- 2011-04
- Volume
- 1225
- Issue
- 1
- Pages
- 191-199
- ISSN
- 0077-8923 (ISSN-L)
- 1749-6632
- OpenAlex
- W1660063171
- Semantic Scholar
- ea34224601c81828afeefc29522d98375233d355
- Cited by
- 137
- References
- 49
- Citations by year
- 2026: 1 · 2025: 3 · 2024: 6 · 2023: 4 · 2022: 3 · 2021: 19 · 2020: 35 · 2019: 5 · 2018: 6 · 2017: 5 · 2016: 15 · 2015: 6 · 2014: 10 · 2013: 11 · 2012: 7
- FWCI
- 1.16
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Annals of the New York Academy of Sciences (publishedVersion)
- PubMed (publishedVersion)
- Funders
- Conselho Nacional de Desenvolvimento Científico e Tecnológico
- Topics
- Social Sciences › Psychology › Social Psychology › Primate Behavior and Ecology
- Social Sciences › Psychology › Experimental and Cognitive Psychology › Cognitive Abilities and Testing
- Physical Sciences › Earth and Planetary Sciences › Paleontology › Evolution and Paleontology Studies
- Keywords
- neuron number, brain size, encephalization quotient, cognitive ability, comparative cognition, brain evolution
- MeSH terms
- Anatomy, Comparative, Animals, Brain, Cell Count, Cognition, Humans, Mammals, Neurons, Organ Size, Body Size
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
What counts as a claim ›How we measure confidence ›How we check this ›
Are you an author, or do you see a problem with this page? Request a review