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Amici F, Liebal K, Ersson-Lembeck M, Holodynski M. A longitudinal comparison of maternal behaviour in German urban humans (Homo sapiens) and captive chimpanzees (Pan troglodytes). Sci Rep 2024; 14:1517. [PMID: 38233560 PMCID: PMC10794219 DOI: 10.1038/s41598-024-51999-4] [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: 08/29/2023] [Accepted: 01/12/2024] [Indexed: 01/19/2024] Open
Abstract
Comparative perspectives are crucial in the study of human development, yet longitudinal comparisons of humans and other primates are still relatively uncommon. Here, we combined theoretical frameworks from cross-cultural and comparative psychology, to study maternal style in 10 mother-infant pairs of German urban humans (Homo sapiens) and 10 mother-infant pairs of captive chimpanzees (Pan troglodytes), during the first year of infants' development. We conducted focal observations of different behaviours (i.e. nursing, carrying, body contact, touching, grooming, restraining, approaching, leaving, rejection, aggression, mutual gaze, object stimulation), during natural interactions. Analyses revealed a more distal maternal style in WEIRD humans than in captive chimpanzees, with different behaviours being generally more common in one of the two species throughout development. For other behaviours (i.e. nursing), developmental trajectories differed between WEIRD humans and captive chimpanzees, although differences generally decreased through infants' development. Overall, our study confirms functional approaches as a valid tool for comparative longitudinal studies.
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Affiliation(s)
- Federica Amici
- Faculty of Life Sciences, Institute of Biology, Human Biology & Primate Cognition, Leipzig University, Talstrasse 33, 04103, Leipzig, Germany.
- Department of Comparative Cultural Psychology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
| | - Katja Liebal
- Faculty of Life Sciences, Institute of Biology, Human Biology & Primate Cognition, Leipzig University, Talstrasse 33, 04103, Leipzig, Germany
- Department of Comparative Cultural Psychology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Department of Education and Psychology, Comparative Developmental Psychology, Freie Universität Berlin, Habelschwerdter Allee 45, 14195, Berlin, Germany
| | - Manuela Ersson-Lembeck
- Department of Education and Psychology, Comparative Developmental Psychology, Freie Universität Berlin, Habelschwerdter Allee 45, 14195, Berlin, Germany
| | - Manfred Holodynski
- Faculty of Psychology/Sport and Exercise Studies, Institute for Psychology in Education, University of Münster, Fliednerstrasse 21, 48149, Münster, Germany
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2
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Bordes CNM, Beukeboom R, Goll Y, Koren L, Ilany A. High-resolution tracking of hyrax social interactions highlights nighttime drivers of animal sociality. Commun Biol 2022; 5:1378. [PMID: 36522486 PMCID: PMC9755157 DOI: 10.1038/s42003-022-04317-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 11/29/2022] [Indexed: 12/23/2022] Open
Abstract
Network structure is a key driver of animal fitness, pathogen transmission, information spread, and population demographics in the wild. Although a considerable body of research applied network analysis to animal societies, only little effort has been devoted to separate daytime and nighttime sociality and explicitly test working hypotheses on social structures emerging at night. Here, we investigated the nighttime sociality of a wild population of rock hyraxes (Procavia capensis) and its relation to daytime social structure. We recorded nearly 15,000 encounters over 27 consecutive days and nights using proximity loggers. Overall, we show that hyraxes are more selective of their social affiliates at night compared to daytime. We also show that hyraxes maintain their overall network topology while reallocating the weights of social relationships at the daily and monthly scales, which could help hyraxes maintain their social structure over long periods while adapting to local constraints and generate complex social dynamics. These results suggest that complex network dynamics can be a by-product of simple daily social tactics and do not require high cognitive abilities. Our work sheds light on the function of nighttime social interactions in diurnal social species.
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Affiliation(s)
- Camille N. M. Bordes
- grid.22098.310000 0004 1937 0503Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Rosanne Beukeboom
- grid.22098.310000 0004 1937 0503Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Yael Goll
- grid.12136.370000 0004 1937 0546School of Zoology, Tel Aviv University, Tel Aviv, Israel
| | - Lee Koren
- grid.22098.310000 0004 1937 0503Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Amiyaal Ilany
- grid.22098.310000 0004 1937 0503Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
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3
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Bzdok D, Dunbar RIM. Social isolation and the brain in the pandemic era. Nat Hum Behav 2022; 6:1333-1343. [PMID: 36258130 DOI: 10.1038/s41562-022-01453-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 08/24/2022] [Indexed: 11/08/2022]
Abstract
Intense sociality has been a catalyst for human culture and civilization, and our social relationships at a personal level play a pivotal role in our health and well-being. These relationships are, however, sensitive to the time we invest in them. To understand how and why this should be, we first outline the evolutionary background in primate sociality from which our human social world has emerged. We then review defining features of that human sociality, putting forward a framework within which one can understand the consequences of mass social isolation during the COVID-19 pandemic, including mental health deterioration, stress, sleep disturbance and substance misuse. We outline recent research on the neural basis of prolonged social isolation, highlighting especially higher-order neural circuits such as the default mode network. Our survey of studies covers the negative effects of prolonged social deprivation and the multifaceted drivers of day-to-day pandemic experiences.
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Affiliation(s)
- Danilo Bzdok
- The Neuro-Montreal Neurological Institute (MNI), McConnell Brain-Imaging Centre (BIC), Department of Biomedical Engineering, Faculty of Medicine, McGill University, Montreal, Quebec, Canada.
| | - Robin I M Dunbar
- Department of Experimental Psychology, University of Oxford, Oxford, UK.
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4
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Dunbar RIM. Managing the stresses of group-living in the transition to village life. EVOLUTIONARY HUMAN SCIENCES 2022; 4:e40. [PMID: 37588930 PMCID: PMC10426039 DOI: 10.1017/ehs.2022.39] [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: 03/22/2022] [Revised: 07/16/2022] [Accepted: 08/16/2022] [Indexed: 11/07/2022] Open
Abstract
Group living is stressful for all mammals, and these stresses limit the size of their social groups. Humans live in very large groups by mammal standards, so how have they solved this problem? I use homicide rates as an index of within-community stress for humans living in small-scale ethnographic societies, and show that the frequency of homicide increases linearly with living-group size in hunter-gatherers. This is not, however, the case for cultivators living in permanent settlements, where there appears to be a 'glass ceiling' below which homicide rates oscillate. This glass ceiling correlates with the adoption of social institutions that allow tensions to be managed. The results suggest (a) that the transition to a settled lifestyle in the Neolithic may have been more challenging than is usually assumed and (b) that the increases in settlement size that followed the first villages necessitated the introduction of a series of social institutions designed to manage within-community discord.
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Affiliation(s)
- R. I. M. Dunbar
- Department of Experimental Psychology, University of Oxford, Radcliffe Observatory Quarter, Oxford OX2 6GG, UK
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5
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Dunbar RIM. Female Dispersion Is Necessary, but Not Sufficient, for Pairbonded Monogamy in Mammals. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.905298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Explanations for the evolution of social monogamy in mammals typically emphasise one of two possibilities: females are overdispersed (such that males cannot defend access to more than one female at a time) or males provide a service to the female. However, the first claim has never been formally tested. I test it directly at three levels using population-level data from primates and ungulates. First, I show that the females of monogamous genera do not have territories that are significantly larger, either absolutely or relatively, than those of polygynous genera. Second, using two indices of territorial defendability, I show that, given their typical day journey lengths, males of most monogamous species could easily defend an area large enough to allow them to monopolise as many as 5–10 females if they ranged solitarily. Finally, I use a model of male mate searching strategies to show that the opportunity cost incurred by pairbonded males is typically 5–10 times the reproductive success they actually obtain by being obligately monogamous. This suggests that the selection pressure dissuading them from pursuing a roving male strategy must be very considerable. At present, the evidence is undecided as to whether mitigating predation or infanticide risk is the primary function, but estimates of their impacts suggest that both are in fact plausible.
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6
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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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Ebensperger LA, Quirici V, Bunster V, León C, Ramírez‐Estrada J, Hayes LD. Effects of Radio‐Collars are not Contingent on Socioecological Conditions in Degus. J Wildl Manage 2021. [DOI: 10.1002/jwmg.22098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Luis A. Ebensperger
- Departamento de Ecología, Facultad de Ciencias Biológicas Pontificia Universidad Católica de Chile Santiago Chile
| | - Verónica Quirici
- Centro de Investigación para la Sustentabilidad Facultad de Ciencias de la Vida, Universidad Andrés Bello, República 440 Santiago Chile
| | - Valentina Bunster
- Departamento de Ecología, Facultad de Ciencias Biológicas Pontificia Universidad Católica de Chile Santiago Chile
| | - Cecilia León
- Departamento de Ecología, Facultad de Ciencias Biológicas Pontificia Universidad Católica de Chile Santiago Chile
| | - Juan Ramírez‐Estrada
- Departamento de Ecología, Facultad de Ciencias Biológicas Pontificia Universidad Católica de Chile Santiago Chile
| | - Loren D. Hayes
- Department of Biology, Geology, and Environmental Sciences University of Tennessee at Chattanooga Chattanooga 37403 TN USA
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8
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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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Emotional bookkeeping and differentiated affiliative relationships: Exploring the role of dynamics and speed in updating relationship quality in the EMO-model. PLoS One 2021; 16:e0249519. [PMID: 33798222 PMCID: PMC8018660 DOI: 10.1371/journal.pone.0249519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 03/19/2021] [Indexed: 11/28/2022] Open
Abstract
Emotional bookkeeping is the process by which primates integrate the emotional effects of social interactions to form internal representations of their affiliative relationships. The dynamics and speed of this process, which comprises the formation, maintenance and fading out of affiliative relationships, are not clear. Empirical data suggest that affiliative relationships are slowly formed and do not easily fade out. The EMO-model, an agent-based model designed to simulate the social life of primates capable of emotional bookkeeping, was used to explore the effects of different types of internal relationship dynamics and speeds of increase and decrease of relationship strength. In the original EMO-model the internal dynamics involves a fast built-up of a relationship independent of its current quality, alongside a relatively fast fading out of relationship quality. Here we explore the effect of this original dynamics and an alternative dynamics more in line with empirical data, in combination with different speeds of internal relationship quality increase and decrease, on the differentiation and stability of affiliative relationships. The alternative dynamics leads to more differentiated and stable affiliative relationships than the original dynamics, especially when the speed with which internal relationship quality increases is low and the speed with which it decreases is intermediate. Consequently, individuals can groom different group members with varying frequency and support a rich social life with stable preferred partners and attention to several others. In conclusion, differentiated and stable affiliative relationships are especially formed when friends are not made too quickly and not forgotten too easily.
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10
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Burleson MH, Quigley KS. Social interoception and social allostasis through touch: Legacy of the Somatovisceral Afference Model of Emotion. Soc Neurosci 2021; 16:92-102. [PMID: 31810428 PMCID: PMC7299836 DOI: 10.1080/17470919.2019.1702095] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 11/21/2019] [Indexed: 10/25/2022]
Abstract
John Cacioppo and colleagues' Somatovisceral Afference Model of Emotion (SAME) highlighted the importance of interoception in emotional experience. Here we compare how the SAME and the more recent theory of constructed emotion (TCE) view the role of interoceptive signals in creating emotional experiences. We describe the characteristics of touch sensations that are carried by thin, unmyelinated fibers called C-tactile afferents (CTs) to the posterior insula, and are thus deemed interoceptive despite their typically social (external) origin. We explore how this social interoceptive input might contribute to the emotion-related effects of social touch more generally, and speculate that all social touch, with or without CT afferent stimulation, can directly influence allostasis, or the predictive regulation of short- and long-term energy resources required by the body. Finally, we describe several features of CT-optimal touch that make it a potentially useful tool to help illuminate basic interoceptive mechanisms, emotion-related phenomena, and disorders involving atypical affect or somatosensation. These proposed ideas demonstrate the long intellectual reach of John Cacioppo and Gary Berntson's highly productive scientific collaboration, which was formative for the fields of social neuroscience, social psychophysiology, and affective neuroscience.
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Affiliation(s)
- Mary H Burleson
- School of Social and Behavioral Sciences, Arizona State University , Phoenix, AZ, USA
| | - Karen S Quigley
- Center for Healthcare Organization and Implementation Research (CHOIR) and Social and Community Reintegration Research (SoCRR) Program, Edith Nourse Rogers Memorial VA , Bedford, MA, USA
- Department of Psychology, Northeastern University , Boston, MA, USA
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11
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Jablonski NG. Social and affective touch in primates and its role in the evolution of social cohesion. Neuroscience 2020; 464:117-125. [PMID: 33246063 DOI: 10.1016/j.neuroscience.2020.11.024] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 10/26/2020] [Accepted: 11/13/2020] [Indexed: 12/21/2022]
Abstract
Primates are long-lived, highly social mammals who maintain long-term social bonds and cohesive social groups through many affiliative mechanisms, foremost among them social touch. From birth through adulthood, social touch - primarily mutual grooming - creates and maintains relationships of trust and reliance, which are the basis for individual physical and emotional well-being and reproductive success. Because social touch helps to establish, maintain, and repair social alliances in primates, it contributes to the emotional stability of individuals and the cohesion of social groups. In these fundamental ways, thus, social touch supports the slow life histories of primates. The reinforcing neurochemistry of social touch insures that it is a pleasurable activity and this, in turn, makes it a behavioral commodity that can be traded between primates for desirable rewards such as protection against future aggression or opportunities to handle infants. Social touch is essential to normal primate development, and individuals deprived of social touch exhibit high levels of anxiety and lower fertility compared to those receiving regular social touch. Understanding the centrality of social touch to primate health and well-being throughout the lifespan provides the foundation for appreciating the importance of social touch in human life.
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Affiliation(s)
- Nina G Jablonski
- Department of Anthropology, The Pennsylvania State University, University Park, PA 16802, USA.
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12
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Pearce E, Machin A, Dunbar RIM. Sex Differences in Intimacy Levels in Best Friendships and Romantic Partnerships. ADAPTIVE HUMAN BEHAVIOR AND PHYSIOLOGY 2020. [DOI: 10.1007/s40750-020-00155-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
AbstractObjectives Close romantic and friendship relationships are crucial for successful survival and reproduction. Both provide emotional support that can have significant effects on an individual’s health and wellbeing, and through this their longer term survival and fitness. Nonetheless, the factors that create and maintain intimacy in close relationships remain unclear. Nor is it entirely clear what differentiates romantic relationships from friendships in these terms. In this paper, we explore which factors most strongly predict intimacy in these two kinds of relationship, and how these differ between the two sexes. Results Aside from best friendships being highly gendered in both sexes, the dynamics of these two types of relationships differ between the sexes. The intimacy of female relationships was influenced by similarity (homophily) in many more factors (notably dependability, kindness, mutual support, sense of humour) than was the case for men. Some factors had opposite effects in the two sexes: gift-giving had a negative effect on women’s friendships and a positive effect on men’s, whereas shared histories had the opposite effect. Conclusion These results confirm and extend previous findings that the dynamics of male and female relationships are very different in ways that may reflect differences in their functions.
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13
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Bzdok D, Dunbar RIM. The Neurobiology of Social Distance. Trends Cogn Sci 2020; 24:717-733. [PMID: 32561254 PMCID: PMC7266757 DOI: 10.1016/j.tics.2020.05.016] [Citation(s) in RCA: 105] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 05/20/2020] [Accepted: 05/29/2020] [Indexed: 12/11/2022]
Abstract
Never before have we experienced social isolation on such a massive scale as we have in response to coronavirus disease 2019 (COVID-19). However, we know that the social environment has a dramatic impact on our sense of life satisfaction and well-being. In times of distress, crisis, or disaster, human resilience depends on the richness and strength of social connections, as well as on active engagement in groups and communities. Over recent years, evidence emerging from various disciplines has made it abundantly clear: perceived social isolation (i.e., loneliness) may be the most potent threat to survival and longevity. We highlight the benefits of social bonds, the choreographies of bond creation and maintenance, as well as the neurocognitive basis of social isolation and its deep consequences for mental and physical health.
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Affiliation(s)
- Danilo Bzdok
- Department of Biomedical Engineering, McConnell Brain Imaging Centre (BIC), Montreal Neurological Institute (MNI), Faculty of Medicine, McGill University, Montreal, Canada; Quebec Artificial Intelligence Institute (Mila), Montreal, Canada.
| | - Robin I M Dunbar
- Department of Experimental Psychology, University of Oxford, Oxford, UK.
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14
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Dunbar RIM. Structure and function in human and primate social networks: implications for diffusion, network stability and health. Proc Math Phys Eng Sci 2020; 476:20200446. [PMID: 32922160 PMCID: PMC7482201 DOI: 10.1098/rspa.2020.0446] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 07/10/2020] [Indexed: 12/12/2022] Open
Abstract
The human social world is orders of magnitude smaller than our highly urbanized world might lead us to suppose. In addition, human social networks have a very distinct fractal structure similar to that observed in other primates. In part, this reflects a cognitive constraint, and in part a time constraint, on the capacity for interaction. Structured networks of this kind have a significant effect on the rates of transmission of both disease and information. Because the cognitive mechanism underpinning network structure is based on trust, internal and external threats that undermine trust or constrain interaction inevitably result in the fragmentation and restructuring of networks. In contexts where network sizes are smaller, this is likely to have significant impacts on psychological and physical health risks.
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Affiliation(s)
- R. I. M. Dunbar
- Department of Experimental Psychology, University of Oxford, New Radcliffe Building, Radcliffe Observatory Quarter, Oxford OX1 6GG, UK
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15
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Suvilehto JT, Nummenmaa L, Harada T, Dunbar RIM, Hari R, Turner R, Sadato N, Kitada R. Cross-cultural similarity in relationship-specific social touching. Proc Biol Sci 2020; 286:20190467. [PMID: 31014213 PMCID: PMC6501924 DOI: 10.1098/rspb.2019.0467] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Many species use touching for reinforcing social structures, and particularly, non-human primates use social grooming for managing their social networks. However, it is still unclear how social touch contributes to the maintenance and reinforcement of human social networks. Human studies in Western cultures suggest that the body locations where touch is allowed are associated with the strength of the emotional bond between the person touched and the toucher. However, it is unknown to what extent this relationship is culturally universal and generalizes to non-Western cultures. Here, we compared relationship-specific, bodily touch allowance maps across one Western (N = 386, UK) and one East Asian (N = 255, Japan) country. In both cultures, the strength of the emotional bond was linearly associated with permissible touch area. However, Western participants experienced social touching as more pleasurable than Asian participants. These results indicate a similarity of emotional bonding via social touch between East Asian and Western cultures.
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Affiliation(s)
- Juulia T Suvilehto
- 1 Department of Neuroscience and Biomedical Engineering, Aalto University , Espoo , Finland.,4 Turku PET Centre, University of Turku , Turku , Finland
| | - Lauri Nummenmaa
- 4 Turku PET Centre, University of Turku , Turku , Finland.,5 Department of Psychology, University of Turku , Turku , Finland
| | - Tokiko Harada
- 6 Institute of Biomedical and Health Sciences, Hiroshima University , Hiroshima , Japan
| | - Robin I M Dunbar
- 2 Department of Computer Science, Aalto University , Espoo , Finland.,7 Department of Experimental Psychology, University of Oxford , Oxford , UK
| | - Riitta Hari
- 3 Department of Art, Aalto University , Espoo , Finland
| | - Robert Turner
- 8 Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences , Leipzig , Germany
| | - Norihiro Sadato
- 9 National Institute for Physiological Sciences , Okazaki , Japan
| | - Ryo Kitada
- 10 Division of Psychology, School of Social Sciences, Nanyang Technological University , 14 Nanyang Avenue, 637332 Singapore
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16
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Dunbar RIM. Fertility as a constraint on group size in African great Apes. Biol J Linn Soc Lond 2019. [DOI: 10.1093/biolinnean/blz172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Abstract
Gorillas and chimpanzees live in social groups of very different size and structure. Here I test the hypothesis that this difference might reflect the way fertility maps onto group demography as it does in other Catarrhines. For both genera, birth rates and the number of surviving offspring per female are quadratic (or ∩-shaped) functions of the number of adult females in the group, and this is independent of environmental effects. The rate at which fertility declines ultimately imposes a constraint on the size of social groups that can be maintained in both taxa. The differences in group size between the two genera seem to reflect a contrast in the way females buffer themselves against this cost. Gorillas do this by using males as bodyguards, whereas chimpanzees exploit fission–fusion sociality to do so. The latter allows chimpanzees to live in much larger groups without paying a fertility cost (albeit at a cognitive cost).
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Affiliation(s)
- R I M Dunbar
- Department of Experimental Psychology, University of Oxford, Radcliffe Observatory Quarter, Oxford, UK
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17
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Dunbar RIM, MacCarron P, Robertson C. Trade-off between fertility and predation risk drives a geometric sequence in the pattern of group sizes in baboons. Biol Lett 2019. [PMID: 29514992 PMCID: PMC5897608 DOI: 10.1098/rsbl.2017.0700] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Group-living offers both benefits (protection against predators, access to resources) and costs (increased ecological competition, the impact of group size on fertility). Here, we use cluster analysis to detect natural patternings in a comprehensive sample of baboon groups, and identify a geometric sequence with peaks at approximately 20, 40, 80 and 160. We suggest (i) that these form a set of demographic oscillators that set habitat-specific limits to group size and (ii) that the oscillator arises from a trade-off between female fertility and predation risk.
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Affiliation(s)
- R I M Dunbar
- Department of Experimental Psychology, University of Oxford, South Parks, Oxford OX1 3UD, UK .,Department of Computer Science, Aalto University, Espoo FI-00076, Finland
| | - Padraig MacCarron
- Department of Experimental Psychology, University of Oxford, South Parks, Oxford OX1 3UD, UK
| | - Cole Robertson
- Department of Experimental Psychology, University of Oxford, South Parks, Oxford OX1 3UD, UK
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Boucherie PH, Loretto MC, Massen JJM, Bugnyar T. What constitutes "social complexity" and "social intelligence" in birds? Lessons from ravens. Behav Ecol Sociobiol 2019; 73:12. [PMID: 30930524 PMCID: PMC6404394 DOI: 10.1007/s00265-018-2607-2] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 07/10/2018] [Accepted: 11/12/2018] [Indexed: 02/05/2023]
Abstract
In the last decades, the assumption that complex social life is cognitively challenging, and thus can drive mental evolution, has received much support from empirical studies in nonhuman primates. While extending the scope to other mammals and birds, different views have been adopted on what constitutes social complexity and which specific cognitive skills are selected for. Notably, many avian species form "open" groups as non-breeders (i.e., seasonally and before sexual maturity) that have been largely ignored as potential sources of social complexity. Reviewing 30 years of research on ravens, we illustrate the socio-ecological conditions faced by these birds as non-breeders and discuss how these relate to their socio-cognitive skills. We argue that the non-breeding period is key to understand raven social life and, to a larger extent, avian social life in general. We furthermore emphasize how the combination of the large-scale perspective (defining social system components: e.g., social organization, mating system) and the individual-scale perspective on social systems allows to better capture the complete set of social challenges experienced by individuals throughout their life, ultimately resulting on a more comprehensive understanding of species' social complexity.
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Affiliation(s)
| | - Matthias-Claudio Loretto
- Department of Cognitive Biology, University of Vienna, Vienna, Austria
- Konrad Lorenz Forschungsstelle, Core Facility for Behaviour and Cognition, University of Vienna, Vienna, Austria
| | - Jorg J. M. Massen
- Department of Cognitive Biology, University of Vienna, Vienna, Austria
| | - Thomas Bugnyar
- Department of Cognitive Biology, University of Vienna, Vienna, Austria
- Konrad Lorenz Forschungsstelle, Core Facility for Behaviour and Cognition, University of Vienna, Vienna, Austria
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Dunbar RIM, Cheyne SM, Lan D, Korstjens A, Lehmann J, Cowlishaw G. Environment and time as constraints on the biogeographical distribution of gibbons. Am J Primatol 2019; 81:e22940. [DOI: 10.1002/ajp.22940] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 11/14/2018] [Accepted: 11/19/2018] [Indexed: 11/10/2022]
Affiliation(s)
| | - Susan M. Cheyne
- Borneo Nature Foundation; Palangka Raya; Indonesia & Oxford Brookes University; Oxford UK
| | - Daoying Lan
- Guangdong Institute of Applied Biological Resources; Guangzhou China
| | - Amanda Korstjens
- Department of Life and Environmental Sciences; Bournemouth University; Poole UK
| | - Julia Lehmann
- Department of Life Science; University of Roehampton; London UK
| | - Guy Cowlishaw
- Institute of Zoology; Zoological Society of London; London UK
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Dunbar RIM, Mac Carron P. Does a trade‐off between fertility and predation risk explain social evolution in baboons? J Zool (1987) 2018. [DOI: 10.1111/jzo.12644] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- R. I. M. Dunbar
- Department of Experimental Psychology University of Oxford Oxford UK
- Department of Computer Science Aalto University Espoo Finland
| | - P. Mac Carron
- Department of Experimental Psychology University of Oxford Oxford UK
- Maynooth University Maynooth Co. Kildare Ireland
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Abstract
We examine community longevity as a function of group size in three historical, small scale agricultural samples. Community sizes of 50, 150 and 500 are disproportionately more common than other sizes; they also have greater longevity. These values mirror the natural layerings in hunter-gatherer societies and contemporary personal networks. In addition, a religious ideology seems to play an important role in allowing larger communities to maintain greater cohesion for longer than a strictly secular ideology does. The differences in optimal community size may reflect the demands of different ecologies, economies and social contexts, but, as yet, we have no explanation as to why these numbers seem to function socially so much more effectively than other values.
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Affiliation(s)
- Robin I M Dunbar
- Department of Experimental Psychology, University of Oxford, Oxford, UK.,Department of Computer Sciences, Aalto University, Espoo, Finland
| | - Richard Sosis
- Department of Anthropology, University of Connecticut, Storrs, CT 06269-2176, USA
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Dunbar RIM, Mac Carron P, Shultz S. Primate social group sizes exhibit a regular scaling pattern with natural attractors. Biol Lett 2018; 14:20170490. [PMID: 29343560 PMCID: PMC5803586 DOI: 10.1098/rsbl.2017.0490] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 12/22/2017] [Indexed: 12/23/2022] Open
Abstract
Primate groups vary considerably in size across species. Nonetheless, the distribution of mean species group size has a regular scaling pattern with preferred sizes approximating 2.5, 5, 15, 30 and 50 individuals (although strepsirrhines lack the latter two), with a scaling ratio of approximately 2.5 similar to that observed in human social networks. These clusters appear to form distinct social grades that are associated with rapid evolutionary change, presumably in response to intense environmental selection pressures. These findings may have wider implications for other highly social mammal taxa.
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Affiliation(s)
- R I M Dunbar
- Department of Experimental Psychology, University of Oxford, New Richards Building, Old Road Campus, Oxford OX3 7LG, UK
- Department of Computer Sciences, Aalto University, Espoo, Finland
| | - Padraig Mac Carron
- Department of Experimental Psychology, University of Oxford, New Richards Building, Old Road Campus, Oxford OX3 7LG, UK
| | - Susanne Shultz
- School of Biological Sciences, University of Manchester, Oxford Road, Manchester M13 9PL, UK
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