1
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Speechley EM, Ashton BJ, Foo YZ, Simmons LW, Ridley AR. Meta-analyses reveal support for the Social Intelligence Hypothesis. Biol Rev Camb Philos Soc 2024. [PMID: 38855980 DOI: 10.1111/brv.13103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 05/13/2024] [Accepted: 05/15/2024] [Indexed: 06/11/2024]
Abstract
The Social Intelligence Hypothesis (SIH) is one of the leading explanations for the evolution of cognition. Since its inception a vast body of literature investigating the predictions of the SIH has accumulated, using a variety of methodologies and species. However, the generalisability of the hypothesis remains unclear. To gain an understanding of the robustness of the SIH as an explanation for the evolution of cognition, we systematically searched the literature for studies investigating the predictions of the SIH. Accordingly, we compiled 103 studies with 584 effect sizes from 17 taxonomic orders. We present the results of four meta-analyses which reveal support for the SIH across interspecific, intraspecific and developmental studies. However, effect sizes did not differ significantly between the cognitive or sociality metrics used, taxonomy or testing conditions. Thus, support for the SIH is similar across studies using neuroanatomy and cognitive performance, those using broad categories of sociality, group size and social interactions, across taxonomic groups, and for tests conducted in captivity or the wild. Overall, our meta-analyses support the SIH as an evolutionary and developmental explanation for cognitive variation.
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Affiliation(s)
- Elizabeth M Speechley
- Centre for Evolutionary Biology, University of Western Australia, 35 Stirling Highway, Perth, WA, 6009, Australia
| | - Benjamin J Ashton
- Centre for Evolutionary Biology, University of Western Australia, 35 Stirling Highway, Perth, WA, 6009, Australia
- School of Natural Sciences, Macquarie University, 205b Culloden Road, Sydney, NSW, 2109, Australia
| | - Yong Zhi Foo
- Centre for Evolutionary Biology, University of Western Australia, 35 Stirling Highway, Perth, WA, 6009, Australia
| | - Leigh W Simmons
- Centre for Evolutionary Biology, University of Western Australia, 35 Stirling Highway, Perth, WA, 6009, Australia
| | - Amanda R Ridley
- Centre for Evolutionary Biology, University of Western Australia, 35 Stirling Highway, Perth, WA, 6009, Australia
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2
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Dunbar RIM, Shultz S. Four errors and a fallacy: pitfalls for the unwary in comparative brain analyses. Biol Rev Camb Philos Soc 2023; 98:1278-1309. [PMID: 37001905 DOI: 10.1111/brv.12953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 03/17/2023] [Accepted: 03/17/2023] [Indexed: 04/03/2023]
Abstract
Comparative analyses are the backbone of evolutionary analysis. However, their record in producing a consensus has not always been good. This is especially true of attempts to understand the factors responsible for the evolution of large brains, which have been embroiled in an increasingly polarised debate over the past three decades. We argue that most of these disputes arise from a number of conceptual errors and associated logical fallacies that are the result of a failure to adopt a biological systems-based approach to hypothesis-testing. We identify four principal classes of error: a failure to heed Tinbergen's Four Questions when testing biological hypotheses, misapplying Dobzhansky's Dictum when testing hypotheses of evolutionary adaptation, poorly chosen behavioural proxies for underlying hypotheses, and the use of inappropriate statistical methods. In the interests of progress, we urge a more careful and considered approach to comparative analyses, and the adoption of a broader, rather than a narrower, taxonomic perspective.
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Affiliation(s)
- Robin I M Dunbar
- Department of Experimental Psychology, Anna Watts Building, University of Oxford, Oxford, OX2 6GG, UK
| | - Susanne Shultz
- Department of Earth and Environmental Sciences, Michael Smith Building, University of Manchester, Manchester, M13 9PT, UK
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3
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Mulholland MM, Meguerditchian A, Hopkins WD. Age- and sex-related differences in baboon (Papio anubis) gray matter covariation. Neurobiol Aging 2023; 125:41-48. [PMID: 36827943 PMCID: PMC10308318 DOI: 10.1016/j.neurobiolaging.2023.01.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 01/05/2023] [Accepted: 01/09/2023] [Indexed: 01/30/2023]
Abstract
Age-related changes in cognition, brain morphology, and behavior are exhibited in several primate species. Baboons, like humans, naturally develop Alzheimer's disease-like pathology and cognitive declines with age and are an underutilized model for studies of aging. To determine age-related differences in gray matter covariation of 89 olive baboons (Papio anubis), we used source-based morphometry (SBM) to analyze data from magnetic resonance images. We hypothesized that we would find significant age effects in one or more SBM components, particularly those which include regions influenced by age in humans and other nonhuman primates (NHPs). A multivariate analysis of variance revealed that individual weighted gray matter covariation scores differed across the age classes. Elderly baboons contributed significantly less to gray matter covariation components including the brainstem, superior parietal cortex, thalamus, and pallidum compared to juveniles, and middle and superior frontal cortex compared to juveniles and young adults (p < 0.05). Future studies should examine the relationship between the changes in gray matter covariation reported here and age-related cognitive decline.
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Affiliation(s)
- M M Mulholland
- The University of Texas MD Anderson Cancer Center, Bastrop, TX.
| | - A Meguerditchian
- Laboratoire de Psychologie Cognitive UMR7290, LPC, CNRS, Aix-Marseille University, Institute of Language, Communication and the Brain, Marseille, France; Station de Primatologie-Celphedia, UAR846, Rousset, France
| | - W D Hopkins
- The University of Texas MD Anderson Cancer Center, Bastrop, TX
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4
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Zhang P, Yan J, Liu Z, Zhou Q. Impeded frontal-occipital communications during Go/Nogo tasks in humans owing to mental workload. Behav Brain Res 2023; 438:114182. [PMID: 36309243 DOI: 10.1016/j.bbr.2022.114182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Revised: 10/24/2022] [Accepted: 10/25/2022] [Indexed: 12/05/2022]
Abstract
Human brains rely on oscillatory coupling mechanisms for regulating access to prefrontal cognitive resources, dynamically communicating between the frontal and remote cortex. We worry that communications across cortical regions will be impeded when humans in extreme space environments travel with mental load work, affecting the successful completion of missions. Here, we monitored crews of workers performing a Go/Nogo task in space travel, accompanied by acquisitions of electroencephalography (EEG) signals. These data demonstrated that when the target stimulus suddenly changed to the non-target stimulus, an instantaneous communication mechanism between the frontal and occipital cortex was established by theta-gamma phase-amplitude coupling (PAC). However, this frontal-occipital communication was impeded because of the mental workload of space travel. 86 healthy volunteers who participated in the ground imitation further indicated that mental workload caused decoupled theta-gamma PAC during the Go/Nogo task, impeding frontal-occipital communications and behavioral performance. We also found that the degree of theta-gamma PAC coupling in space was significantly lower than on the ground, indicating that mental workload and other hazards worsen the impeded frontal-occipital communications of humans. These results could guide countermeasures for the inadaptability of humans working in spaceflight.
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Affiliation(s)
- Peng Zhang
- School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China; Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing 100191, China
| | - Juan Yan
- China CDC Key Laboratory of Radiological Protection and Nuclear Emergency, National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Beijing 100088, China
| | - Zhongqi Liu
- School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China; Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing 100191, China
| | - Qianxiang Zhou
- School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China; Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University, Beijing 100191, China.
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5
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Gräßle T, Crockford C, Eichner C, Girard‐Buttoz C, Jäger C, Kirilina E, Lipp I, Düx A, Edwards L, Jauch A, Kopp KS, Paquette M, Pine K, Haun DBM, McElreath R, Anwander A, Gunz P, Morawski M, Friederici AD, Weiskopf N, Leendertz FH, Wittig RM, Albig K, Amarasekaran B, Angedakin S, Anwander A, Aschoff D, Asiimwe C, Bailanda L, Beehner JC, Belais R, Bergman TJ, Blazey B, Bernhard A, Bock C, Carlier P, Chantrey J, Crockford C, Deschner T, Düx A, Edwards L, Eichner C, Escoubas G, Ettaj M, Fedurek P, Flores K, Francke R, Friederici AD, Girard‐Buttoz C, Fortun JG, GoneBi ZB, Gräßle T, Gruber‐Dujardin E, Gunz P, Hartel J, Haun DBM, Henshall M, Hobaiter C, Hofman N, Jaffe JE, Jäger C, Jauch A, Kahemere S, Kirilina E, Klopfleisch R, Knauf‐Witzens T, Kopp KS, Kouima GLM, Lange B, Langergraber K, Lawrenz A, Leendertz FH, Lipp I, Liptovszky M, Theron TL, Lumbu CP, Nzassi PM, Mätz‐Rensing K, McElreath R, McLennan M, Mezö Z, Moittie S, Møller T, Morawski M, Morgan D, Mugabe T, Muller M, Müller M, Njumboket I, Olofsson‐Sannö K, Ondzie A, Otali E, Paquette M, Pika S, Pine K, Pizarro A, Pléh K, Rendel J, Reichler‐Danielowski S, Robbins MM, Forero AR, Ruske K, Samuni L, Sanz C, Schüle A, Schwabe I, Schwalm K, Speede S, Southern L, Steiner J, Stidworthy M, Surbeck M, Szentiks C, Tanga T, Ulrich R, Unwin S, van de Waal E, Walker S, Weiskopf N, Wibbelt G, Wittig RM, Wood K, Zuberbühler K. Sourcing high tissue quality brains from deceased wild primates with known socio‐ecology. Methods Ecol Evol 2023. [DOI: 10.1111/2041-210x.14039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Tobias Gräßle
- Epidemiology of highly pathogenic microorganisms Robert Koch‐Institute Berlin Germany
- Helmholtz Institute for One Health Greifswald Germany
| | - Catherine Crockford
- Ape Social Mind Lab Institute of Cognitive Science Marc Jeannerod, UMR 5229, CNRS Lyon France
- Department of Human Behavior, Ecology and Culture Max Planck Institute for Evolutionary Anthropology Leipzig Germany
- Taï Chimpanzee Project Centre Suisse de Recherches Scientifiques en Côte d'Ivoire Abidjan Ivory Coast
| | - Cornelius Eichner
- Department of Neuropsychology Max Planck Institute for Human Cognitive and Brain Sciences Leipzig Germany
| | - Cédric Girard‐Buttoz
- Ape Social Mind Lab Institute of Cognitive Science Marc Jeannerod, UMR 5229, CNRS Lyon France
- Department of Human Behavior, Ecology and Culture Max Planck Institute for Evolutionary Anthropology Leipzig Germany
- Taï Chimpanzee Project Centre Suisse de Recherches Scientifiques en Côte d'Ivoire Abidjan Ivory Coast
| | - Carsten Jäger
- Department of Neurophysics Max Planck Institute for Human Cognitive and Brain Sciences Leipzig Germany
- Paul Flechsig Institute ‐ Center of Neuropathology and Brain Research, Faculty of Medicine Universität Leipzig Germany
| | - Evgeniya Kirilina
- Department of Neurophysics Max Planck Institute for Human Cognitive and Brain Sciences Leipzig Germany
- Center for Cognitive Neuroscience Berlin Freie Universität Berlin Berlin Germany
| | - Ilona Lipp
- Department of Neurophysics Max Planck Institute for Human Cognitive and Brain Sciences Leipzig Germany
| | - Ariane Düx
- Epidemiology of highly pathogenic microorganisms Robert Koch‐Institute Berlin Germany
- Helmholtz Institute for One Health Greifswald Germany
| | - Luke Edwards
- Department of Neurophysics Max Planck Institute for Human Cognitive and Brain Sciences Leipzig Germany
| | - Anna Jauch
- Department of Neurophysics Max Planck Institute for Human Cognitive and Brain Sciences Leipzig Germany
| | - Kathrin S. Kopp
- Department of Comparative Cultural Psychology Max Planck Institute for Evolutionary Anthropology Leipzig Germany
| | - Michael Paquette
- Department of Neurophysics Max Planck Institute for Human Cognitive and Brain Sciences Leipzig Germany
| | - Kerrin Pine
- Department of Neurophysics Max Planck Institute for Human Cognitive and Brain Sciences Leipzig Germany
| | - Daniel B. M. Haun
- Department of Comparative Cultural Psychology Max Planck Institute for Evolutionary Anthropology Leipzig Germany
| | - Richard McElreath
- Department of Human Behavior, Ecology and Culture Max Planck Institute for Evolutionary Anthropology Leipzig Germany
| | - Alfred Anwander
- Department of Neuropsychology Max Planck Institute for Human Cognitive and Brain Sciences Leipzig Germany
| | - Philipp Gunz
- Department of Human Evolution Max Planck Institute for Evolutionary Anthropology Leipzig Germany
| | - Markus Morawski
- Department of Neurophysics Max Planck Institute for Human Cognitive and Brain Sciences Leipzig Germany
- Paul Flechsig Institute ‐ Center of Neuropathology and Brain Research, Faculty of Medicine Universität Leipzig Germany
| | - Angela D. Friederici
- Department of Neuropsychology Max Planck Institute for Human Cognitive and Brain Sciences Leipzig Germany
| | - Nikolaus Weiskopf
- Department of Neurophysics Max Planck Institute for Human Cognitive and Brain Sciences Leipzig Germany
- Felix Bloch Institute for Solid State Physics, Faculty of Physics and Earth Sciences Leipzig University Leipzig Germany
| | - Fabian H. Leendertz
- Epidemiology of highly pathogenic microorganisms Robert Koch‐Institute Berlin Germany
- Helmholtz Institute for One Health Greifswald Germany
| | - Roman M. Wittig
- Ape Social Mind Lab Institute of Cognitive Science Marc Jeannerod, UMR 5229, CNRS Lyon France
- Department of Human Behavior, Ecology and Culture Max Planck Institute for Evolutionary Anthropology Leipzig Germany
- Taï Chimpanzee Project Centre Suisse de Recherches Scientifiques en Côte d'Ivoire Abidjan Ivory Coast
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6
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Traniello JF, Linksvayer TA, Coto ZN. Social complexity and brain evolution: insights from ant neuroarchitecture and genomics. CURRENT OPINION IN INSECT SCIENCE 2022; 53:100962. [PMID: 36028191 DOI: 10.1016/j.cois.2022.100962] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 08/02/2022] [Accepted: 08/09/2022] [Indexed: 06/15/2023]
Abstract
Brain evolution is hypothesized to be driven by requirements to adaptively respond to environmental cues and social signals. Diverse models describe how sociality may have influenced eusocial insect-brain evolution, but specific impacts of social organization and other selective forces on brain architecture have been difficult to distinguish. Here, we evaluate predictions derived from and/or inferences made by models of social organization concerning the effects of individual and collective behavior on brain size, structure, and function using results of neuroanatomical and genomic studies. In contrast to the predictions of some models, we find that worker brains in socially complex species have great behavioral and cognitive capacity. We also find that colony size, the evolution of worker physical castes, and task specialization affect brain size and mosaicism, supporting the idea that sensory, processing and motor requirements for behavioral performance select for adaptive allometries of functionally specialized brain centers. We review available transcriptomic and comparative genomic studies seeking to elucidate the molecular pathways functionally associated with social life and the genetic changes that occurred during the evolution of social complexity. We discuss ways forward, using comparative neuroanatomy, transcriptomics, and comparative genomics, to distinguish among multiple alternative explanations for the relationship between the evolution of neural systems and social complexity.
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Affiliation(s)
- James Fa Traniello
- Department of Biology, Boston University, Boston, MA, USA; Graduate Program in Neuroscience, Boston University, Boston, MA, USA.
| | | | - Zachary N Coto
- Department of Biology, Boston University, Boston, MA, USA
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Shultz S, Dunbar RIM. Socioecological complexity in primate groups and its cognitive correlates. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210296. [PMID: 35934968 PMCID: PMC9358314 DOI: 10.1098/rstb.2021.0296] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Characterizing non-human primate social complexity and its cognitive bases has proved challenging. Using principal component analyses, we show that primate social, ecological and reproductive behaviours condense into two components: socioecological complexity (including most social and ecological variables) and reproductive cooperation (comprising mainly a suite of behaviours associated with pairbonded monogamy). We contextualize these results using a meta-analysis of 44 published analyses of primate brain evolution. These studies yield two main consistent results: cognition, sociality and cooperative behaviours are associated with absolute brain volume, neocortex size and neocortex ratio, whereas diet composition and life history are consistently associated with relative brain size. We use a path analysis to evaluate the causal relationships among these variables, demonstrating that social group size is predicted by the neocortex, whereas ecological traits are predicted by the volume of brain structures other than the neocortex. That a range of social and technical behaviours covary, and are correlated with social group size and brain size, suggests that primate cognition has evolved along a continuum resulting in an increasingly flexible, domain-general capacity to solve a range of socioecological challenges culminating in a capacity for, and reliance on, innovation and social information use in the great apes and humans. This article is part of the theme issue 'Cognition, communication and social bonds in primates'.
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Affiliation(s)
- Susanne Shultz
- Department of Earth and Environmental Sciences, University of Manchester, Manchester, UK
| | - Robin I M Dunbar
- Department of Experimental Psychology, University of Oxford, Oxford, UK
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8
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DeSilva JM, Traniello JFA, Claxton AG, Fannin LD. When and Why Did Human Brains Decrease in Size? A New Change-Point Analysis and Insights From Brain Evolution in Ants. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.742639] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Human brain size nearly quadrupled in the six million years since Homo last shared a common ancestor with chimpanzees, but human brains are thought to have decreased in volume since the end of the last Ice Age. The timing and reason for this decrease is enigmatic. Here we use change-point analysis to estimate the timing of changes in the rate of hominin brain evolution. We find that hominin brains experienced positive rate changes at 2.1 and 1.5 million years ago, coincident with the early evolution of Homo and technological innovations evident in the archeological record. But we also find that human brain size reduction was surprisingly recent, occurring in the last 3,000 years. Our dating does not support hypotheses concerning brain size reduction as a by-product of body size reduction, a result of a shift to an agricultural diet, or a consequence of self-domestication. We suggest our analysis supports the hypothesis that the recent decrease in brain size may instead result from the externalization of knowledge and advantages of group-level decision-making due in part to the advent of social systems of distributed cognition and the storage and sharing of information. Humans live in social groups in which multiple brains contribute to the emergence of collective intelligence. Although difficult to study in the deep history of Homo, the impacts of group size, social organization, collective intelligence and other potential selective forces on brain evolution can be elucidated using ants as models. The remarkable ecological diversity of ants and their species richness encompasses forms convergent in aspects of human sociality, including large group size, agrarian life histories, division of labor, and collective cognition. Ants provide a wide range of social systems to generate and test hypotheses concerning brain size enlargement or reduction and aid in interpreting patterns of brain evolution identified in humans. Although humans and ants represent very different routes in social and cognitive evolution, the insights ants offer can broadly inform us of the selective forces that influence brain size.
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Dunbar RIM, Shultz S. The Infertility Trap: The Fertility Costs of Group-Living in Mammalian Social Evolution. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.634664] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mammal social groups vary considerably in size from single individuals to very large herds. In some taxa, these groups are extremely stable, with at least some individuals being members of the same group throughout their lives; in other taxa, groups are unstable, with membership changing by the day. We argue that this variability in grouping patterns reflects a tradeoff between group size as a solution to environmental demands and the costs created by stress-induced infertility (creating an infertility trap). These costs are so steep that, all else equal, they will limit group size in mammals to ∼15 individuals. A species will only be able to live in larger groups if it evolves strategies that mitigate these costs. We suggest that mammals have opted for one of two solutions. One option (fission-fusion herding) is low cost but high risk; the other (bonded social groups) is risk-averse, but costly in terms of cognitive requirements.
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Dunbar RIM, Shultz S. Social complexity and the fractal structure of group size in primate social evolution. Biol Rev Camb Philos Soc 2021; 96:1889-1906. [PMID: 33945202 DOI: 10.1111/brv.12730] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 04/17/2021] [Indexed: 12/25/2022]
Abstract
Compared to most other mammals and birds, anthropoid primates have unusually complex societies characterised by bonded social groups. Among primates, this effect is encapsulated in the social brain hypothesis: the robust correlation between various indices of social complexity (social group size, grooming clique size, tactical behaviour, coalition formation) and brain size. Hitherto, this has always been interpreted as a simple, unitary relationship. Using data for five different indices of brain volume from four independent brain databases, we show that the distribution of group size plotted against brain size is best described as a set of four distinct, very narrowly defined grades which are unrelated to phylogeny. The allocation of genera to these grades is highly consistent across the different data sets and brain indices. We show that these grades correspond to the progressive evolution of bonded social groups. In addition, we show, for those species that live in multilevel social systems, that the typical sizes of the different grouping levels in each case coincide with different grades. This suggests that the grades correspond to demographic attractors that are especially stable. Using five different cognitive indices, we show that the grades correlate with increasing social cognitive skills, suggesting that the cognitive demands of managing group cohesion increase progressively across grades. We argue that the grades themselves represent glass ceilings on animals' capacity to maintain social and spatial coherence during foraging and that, in order to evolve more highly bonded groups, species have to be able to invest in costly forms of cognition.
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Affiliation(s)
- Robin I M Dunbar
- Department of Experimental Psychology, Radcliffe Observatory Quarter, University of Oxford, Oxford, OX2 1GG, UK
| | - Susanne Shultz
- Department of Earth and Environmental Sciences, Michael Smith Building, University of Manchester, Manchester, M13 9PT, UK
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