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Woodman JP, Gokcekus S, Beck KB, Green JP, Nussey DH, Firth JA. The ecology of ageing in wild societies: linking age structure and social behaviour. Philos Trans R Soc Lond B Biol Sci 2024; 379:20220464. [PMID: 39463244 DOI: 10.1098/rstb.2022.0464] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 02/14/2024] [Accepted: 04/29/2024] [Indexed: 10/29/2024] Open
Abstract
The age of individuals has consequences not only for their fitness and behaviour but also for the functioning of the groups they form. Because social behaviour often changes with age, population age structure is expected to shape the social organization, the social environments individuals experience and the operation of social processes within populations. Although research has explored changes in individual social behaviour with age, particularly in controlled settings, there is limited understanding of how age structure governs sociality in wild populations. Here, we synthesize previous research into age-related effects on social processes in natural populations, and discuss the links between age structure, sociality and ecology, specifically focusing on how population age structure might influence social structure and functioning. We highlight the potential for using empirical data from natural populations in combination with social network approaches to uncover pathways linking individual social ageing, population age structure and societal functioning. We discuss the broader implications of these insights for understanding the social impacts of anthropogenic effects on animal population demography and for building a deeper understanding of societal ageing in general.This article is part of the discussion meeting issue 'Understanding age and society using natural populations'.
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Affiliation(s)
- Joe P Woodman
- Edward Grey Institute of Field Ornithology, Department of Biology, University of Oxford, Oxford OX1 3SZ, UK
| | - Samin Gokcekus
- Edward Grey Institute of Field Ornithology, Department of Biology, University of Oxford, Oxford OX1 3SZ, UK
| | - Kristina B Beck
- Edward Grey Institute of Field Ornithology, Department of Biology, University of Oxford, Oxford OX1 3SZ, UK
- Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main, Germany
| | - Jonathan P Green
- Edward Grey Institute of Field Ornithology, Department of Biology, University of Oxford, Oxford OX1 3SZ, UK
| | - Dan H Nussey
- Institute of Ecology & Evolution, The University of Edinburgh, Edinburgh EH9 3JT, UK
| | - Josh A Firth
- Edward Grey Institute of Field Ornithology, Department of Biology, University of Oxford, Oxford OX1 3SZ, UK
- School of Biology, University of Leeds, Leeds, UK
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Harrison LM, Churchill ER, Fairweather M, Smithson CH, Chapman T, Bretman A. Ageing effects of social environments in 'non-social' insects. Philos Trans R Soc Lond B Biol Sci 2024; 379:20220463. [PMID: 39463243 DOI: 10.1098/rstb.2022.0463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/29/2024] Open
Abstract
It is increasingly clear that social environments have profound impacts on the life histories of 'non-social' animals. However, it is not yet well known how species with varying degrees of sociality respond to different social contexts and whether such effects are sex-specific. To survey the extent to which social environments specifically affect lifespan and ageing in non-social species, we performed a systematic literature review, focusing on invertebrates but excluding eusocial insects. We found 80 studies in which lifespan or ageing parameters were measured in relation to changes in same-sex or opposite-sex exposure, group size or cues thereof. Most of the studies focused on manipulations of adults, often reporting sex differences in lifespan following exposure to the opposite sex. Some studies highlighted the impacts of developmental environments or social partner age on lifespan. Several studies explored potential underlying mechanisms, emphasizing that studies on insects could provide excellent opportunities to interrogate the basis of social effects on ageing. We discuss what these studies can tell us about the social environment as a stressor, or trade-offs in resources prompted by different social contexts. We suggest fruitful avenues for further research of social effects across a wider and more diverse range of taxa.This article is part of the discussion meeting issue 'Understanding age and society using natural populations'.
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Affiliation(s)
- Lauren M Harrison
- School of Biological Sciences, University of East Anglia, Norwich, Norfolk, NR4 7TJ, UK
| | - Emily R Churchill
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Megan Fairweather
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Claire H Smithson
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Tracey Chapman
- School of Biological Sciences, University of East Anglia, Norwich, Norfolk, NR4 7TJ, UK
| | - Amanda Bretman
- School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
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Cook PA, Costello RA, Formica VA, Brodie ED. Individual and Population Age Impact Social Behavior and Network Structure in a Long-Lived Insect. Am Nat 2023; 202:667-680. [PMID: 37963123 DOI: 10.1086/726063] [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] [Indexed: 11/16/2023]
Abstract
AbstractSocial behaviors vary among individuals, and social networks vary among groups. Understanding the causes of such variation is important for predicting or altering ecological processes such as infectious disease outbreaks. Here, we ask whether age contributes to variation in social behavior at multiple levels of organization: within individuals over time, among individuals of different ages, among local social environments, and among populations. We used experimental manipulations of captive populations and a longitudinal dataset to test whether social behavior is associated with age across these levels in a long-lived insect, the forked fungus beetle (Bolitotherus cornutus). In cross-sectional analyses, we found that older beetles were less connected in their social networks. Longitudinal data confirmed that this effect was due in part to changes in behavior over time; beetles became less social over 2 years, possibly because of increased social selectivity or reproductive investment. Beetles of different ages also occupied different local social neighborhoods. The effects of age on behavior scaled up: populations of older individuals had fewer interactions, fewer but more variable relationships, longer network path lengths, and lower clustering than populations of young individuals. Age therefore impacted not only individual sociality but also the network structures that mediate critical population processes.
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Shell WA, Rehan SM. Social divergence: molecular pathways underlying castes and longevity in a facultatively eusocial small carpenter bee. Proc Biol Sci 2022; 289:20212663. [PMID: 35317677 PMCID: PMC8941392 DOI: 10.1098/rspb.2021.2663] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Unravelling the evolutionary origins of eusocial life is a longstanding endeavour in the field of evolutionary-developmental biology. Descended from solitary ancestors, eusocial insects such as honeybees have evolved ontogenetic division of labour in which short-lived workers perform age-associated tasks, while a long-lived queen produces brood. It is hypothesized that (i) eusocial caste systems evolved through the co-option of deeply conserved genes and (ii) longevity may be tied to oxidative damage mitigation capacity. To date, however, these hypotheses have been examined primarily among only obligately eusocial corbiculate bees. We present brain transcriptomic data from a Japanese small carpenter bee, Ceratina japonica (Apidae: Xylocopinae), which demonstrates both solitary and eusocial nesting in sympatry and lives 2 or more years in the wild. Our dataset captures gene expression patterns underlying first- and second-year solitary females, queens and workers, providing an unprecedented opportunity to explore the molecular mechanisms underlying caste-antecedent phenotypes in a long-lived and facultatively eusocial bee. We find that C. japonica's queens and workers are underpinned by divergent gene regulatory pathways, involving many differentially expressed genes well-conserved among other primitively eusocial bee lineages. We also find support for oxidative damage reduction as a proximate mechanism of longevity in C. japonica.
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Affiliation(s)
- Wyatt A. Shell
- Department of Biology, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3
| | - Sandra M. Rehan
- Department of Biology, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3
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Siracusa ER, Higham JP, Snyder-Mackler N, Brent LJN. Social ageing: exploring the drivers of late-life changes in social behaviour in mammals. Biol Lett 2022; 18:20210643. [PMID: 35232274 PMCID: PMC8889194 DOI: 10.1098/rsbl.2021.0643] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Social interactions help group-living organisms cope with socio-environmental challenges and are central to survival and reproductive success. Recent research has shown that social behaviour and relationships can change across the lifespan, a phenomenon referred to as 'social ageing'. Given the importance of social integration for health and well-being, age-dependent changes in social behaviour can modulate how fitness changes with age and may be an important source of unexplained variation in individual patterns of senescence. However, integrating social behaviour into ageing research requires a deeper understanding of the causes and consequences of age-based changes in social behaviour. Here, we provide an overview of the drivers of late-life changes in sociality. We suggest that explanations for social ageing can be categorized into three groups: changes in sociality that (a) occur as a result of senescence; (b) result from adaptations to ameliorate the negative effects of senescence; and/or (c) result from positive effects of age and demographic changes. Quantifying the relative contribution of these processes to late-life changes in sociality will allow us to move towards a more holistic understanding of how and why these patterns emerge and will provide important insights into the potential for social ageing to delay or accelerate other patterns of senescence.
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Affiliation(s)
- Erin R Siracusa
- School of Psychology, Centre for Research in Animal Behaviour, University of Exeter, Exeter, UK
| | - James P Higham
- Department of Anthropology, New York University, New York, NY, USA
| | - Noah Snyder-Mackler
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ, USA.,School of Life Sciences, Arizona State University, Tempe, AZ, USA.,School for Human Evolution and Social Change, Arizona State University, Tempe, AZ, USA
| | - Lauren J N Brent
- School of Psychology, Centre for Research in Animal Behaviour, University of Exeter, Exeter, UK
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Piolatto M, Bianchi F, Rota M, Marengoni A, Akbaritabar A, Squazzoni F. The effect of social relationships on cognitive decline in older adults: an updated systematic review and meta-analysis of longitudinal cohort studies. BMC Public Health 2022; 22:278. [PMID: 35148704 PMCID: PMC8831686 DOI: 10.1186/s12889-022-12567-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 01/12/2022] [Indexed: 04/11/2023] Open
Abstract
Background A previous meta-analysis (Kuiper et al., 2016) has shown that multiple aspects of social relationships are associated with cognitive decline in older adults. Yet, results indicated possible bias in estimations of statistical effects due to the heterogeneity of study design and measurements. We have updated this meta-analysis adding all relevant publications from 2012 to 2020 and performed a cumulative meta-analysis to map the evolution of this growing field of research (+80% of studies from 2012-2020 compared to the period considered in the previous meta-analysis). Methods Scopus and Web of Science were searched for longitudinal cohort studies examining structural, functional and combined effects of social relationships. We combined Odds Ratios (OR) with 95% confidence intervals (CI) using random effects meta-analysis and assessed sources of heterogeneity and the likelihood of publication bias. The risk of bias was evaluated with the Quality of Prognosis Studies in Systematic Reviews (QUIPS) tool. Results The review was prospectively registered on PROSPERO (ID: CRD42019130667). We identified 34 new articles published in 2012-2020. Poor social relationships were associated with cognitive decline with increasing precision of estimates compared to previously reviewed studies [(for structural, 17 articles, OR: 1.11; 95% CI: 1.08; 1.14) (for functional, 16 articles, OR: 1.12; 95% CI: 1.05; 1.20) (for combined, 5 articles, OR: 1.15; 95% CI: 1.06; 1.24)]. Meta-regression, risk and subgroup analyses showed that the precision of estimations improved in recent studies mostly due to increased sample sizes. Conclusions Our cumulative meta-analysis would confirm that multiple aspects of social relationships are associated with cognitive decline. Yet, there is still evidence of publication bias and relevant information on study design is often missing, which could lead to an over-estimation of their statistical effects. Supplementary Information The online version contains supplementary material available at (10.1186/s12889-022-12567-5).
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Affiliation(s)
- Matteo Piolatto
- Cluster of Excellence, Department of Sociology, University of Konstanz, Universität-Str. 10, Konstanz, Germany
| | - Federico Bianchi
- Department of Social and Political Sciences, University of Milan, Via Conservatorio 7 20122, Milan, Italy
| | - Matteo Rota
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, Brescia, Italy
| | - Alessandra Marengoni
- Department of Clinical and Experimental Sciences, University of Brescia, Viale Europa 11, Brescia, Italy
| | - Aliakbar Akbaritabar
- Laboratory of Digital and Computational Demography, Max Planck Institute for Demographic Research, Konrad-Zuse-Str. 1, Rostock, Germany
| | - Flaminio Squazzoni
- Department of Social and Political Sciences, University of Milan, Via Conservatorio 7 20122, Milan, Italy.
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Korb J, Heinze J. Ageing and sociality: why, when and how does sociality change ageing patterns? Philos Trans R Soc Lond B Biol Sci 2021; 376:20190727. [PMID: 33678019 PMCID: PMC7938171 DOI: 10.1098/rstb.2019.0727] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/04/2021] [Indexed: 02/07/2023] Open
Abstract
Individual lifespans vary tremendously between and also within species, but the proximate and ultimate causes of different ageing speeds are still not well understood. Sociality appears to be associated with the evolution of greater longevity and probably also with a larger plasticity of the shape and pace of ageing. For example, reproductives of several termites and ants reach lifespans that surpass those of their non-reproductive nestmates by one or two decades. In this issue, 15 papers explore the interrelations between sociality and individual longevity in both, group-living vertebrates and social insects. Here, we briefly give an overview of the contents of the various contributions, including theoretical and comparative studies, and we explore the similarities and dissimilarities in proximate mechanisms underlying ageing among taxa, with particular emphasis on nutrient-sensing pathways and, in insects, juvenile hormone. These studies point to an underestimated role of more downstream processes. We highlight the need for reliable transcriptomic markers of ageing and a comprehensive ageing theory of social animals, which includes the reproductive potential of workers, and considers the fact that social insect queens reach maturity only after a prolonged period of producing non-reproductive workers. This article is part of the theme issue 'Ageing and sociality: why, when and how does sociality change ageing patterns?'
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Affiliation(s)
- Judith Korb
- Department of Evolutionary Biology and Ecology, University of Freiburg, Hauptstrasse 1, 79104 Freiburg, Germany
| | - Jürgen Heinze
- Department of Zoology/Evolutionary Biology, University of Regensburg, Universitätsstraße, 93040 Regensburg, Germany
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