scholarly journals Long-term repeatability in social behaviour suggests stable social phenotypes in wild chimpanzees

2020 ◽  
Vol 7 (8) ◽  
pp. 200454 ◽  
Author(s):  
Patrick J. Tkaczynski ◽  
Alexander Mielke ◽  
Liran Samuni ◽  
Anna Preis ◽  
Roman M. Wittig ◽  
...  
Keyword(s):  
Life History ◽  
Individual Differences ◽  
Social Behaviour ◽  
Group Living ◽  
Ecological Factors ◽  
Life History Stage ◽  
Dominance Hierarchies ◽  
Decision Making Processes ◽  
Fitness Benefits

Consistent individual differences in social phenotypes have been observed in many animal species. Changes in demographics, dominance hierarchies or ecological factors, such as food availability or disease prevalence, are expected to influence decision-making processes regarding social interactions. Therefore, it should be expected that individuals show flexibility rather than stability in social behaviour over time to maximize the fitness benefits of social living. Understanding the processes that create and maintain social phenotypes requires data encompassing a range of socioecological settings and variation in intrinsic state or life-history stage or strategy. Using observational data spanning up to 19 years for some individuals, we demonstrate that multiple types of social behaviour are repeatable over the long term in wild chimpanzees, a long-lived species with complex fission–fusion societies. We controlled for temporal, ecological and demographic changes, limiting pseudo-repeatability. We conclude that chimpanzees living in natural ecological settings have relatively stable long-term social phenotypes over years that may be independent of life-history or reproductive strategies. Our results add to the growing body of the literature suggesting consistent individual differences in social tendencies are more likely the rule rather than the exception in group-living animals.

scholarly journals Long-term repeatability in social behaviours suggests stable social phenotypes in wild chimpanzees

2020 ◽  
Author(s):  
Patrick J. Tkaczynski ◽  
Alexander Mielke ◽  
Liran Samuni ◽  
Anna Preis ◽  
Roman Wittig ◽  
...  
Keyword(s):  
Individual Differences ◽  
Social Behaviour ◽  
Group Living ◽  
Ecological Factors ◽  
Life History Stage ◽  
Decision Making Processes ◽  
Group Members ◽  
Using Data ◽  
Social Behaviours

AbstractAnimals living in social groups navigate challenges when competing and cooperating with other group members. Changes in demographics, dominance hierarchies or ecological factors, such as food availability or disease prevalence, are expected to influence decision-making processes regarding social interactions. Therefore, it could be expected individuals show flexibility in social behaviour over time to maximise the fitness benefits of social living. To date, research across species has shown that stable inter-individual differences in social behaviour exist, but mostly over relatively short data collection time periods. Using data spanning over 20 years, we demonstrate that multiple social behaviours are repeatable over the long-term in wild chimpanzees, a long-lived species occupying a complex fission-fusion society. We controlled for temporal, ecological and demographic changes, limiting pseudo-repeatability. We conclude that chimpanzees living in natural ecological settings have relatively stable long-term social phenotypes over years that may be independent of life history stage or strategies. Our results add to the growing body of literature suggesting consistent individual differences in social tendencies are more likely the rule rather than the exception in group-living animals.

scholarly journals Live Fast, Die Young, and Sleep Later: Life History Strategy and Human Sleep Behavior

2020 ◽  
Author(s):  
Vahe Dishakjian ◽  
Daniel M T Fessler ◽  
Adam Maxwell Sparks
Keyword(s):  
Life History ◽  
Individual Differences ◽  
Sleep Duration ◽  
Sleep Onset ◽  
Life History Strategy ◽  
The Body ◽  
Equation Modeling ◽  
Sleep Onset Latency ◽  
Sleep Behaviors

Abstract Background and objectives Life History Theory (LHT) describes trade-offs that organisms make with regard to three investment pathways: growth, maintenance, and reproduction. In light of the reparative functions of sleep, we examine sleep behaviors and corresponding attitudes as proximate manifestations of an individual’s underlying relative prioritization of short-term reproduction versus long-term maintenance. Methodology We collected survey data from 568 participants across two online studies having different participant pools. We use a mixture of segmented and hierarchical regression models, structural equation modeling, and machine learning to infer relationships between sleep duration/quality, attitudes about sleep, and biodemographic/psychometric measures of life history strategy (LHS). Results An age-mediated U- or V-shaped relationship appears when LHS is plotted against habitual sleep duration, with the fastest strategies occupying the sections of the curve with the highest mortality risk: < 6.5 hours (short sleep) and > 8.5 hours (long sleep). LH “fastness” is associated with increased sleepiness and worse overall sleep quality: delayed sleep onset latency, more wakefulness after sleep onset, higher sleep-wake instability, and greater sleep duration variability. Hedonic valuations of sleep may mediate the effects of LHS on certain sleep parameters. Conclusions and implications The costs of deprioritizing maintenance can be parameterized in the domain of sleep, where “life history fastness” corresponds with sleep patterns associated with greater senescence and mortality. Individual differences in sleep having significant health implications can thus be understood as components of lifelong trajectories likely stemming from calibration to developmental circumstances. Relatedly, hedonic valuations of sleep may constitute useful avenues for non-pharmacological management of chronic sleep disorders. LAY Summary Sleep is essential because it allows the body to repair and maintain itself. But time spent sleeping is time that cannot be spent doing other things. People differ in how much they prioritize immediate rewards, including sociosexual opportunities, versus long-term goals. In this research, we show that individual differences in sleep behaviors, and attitudes toward sleep, correspond with psychological and behavioral differences reflecting such differing priorities. Orientation toward sleep can thus be understood as part of the overall lifetime strategies that people pursue.

scholarly journals Are elder siblings helpers or competitors? Antagonistic fitness effects of sibling interactions in humans

2013 ◽  
Vol 280 (1750) ◽  
pp. 20122313 ◽  
Author(s):  
Aïda Nitsch ◽  
Charlotte Faurie ◽  
Virpi Lummaa
Keyword(s):  
Life History ◽  
Sexual Maturity ◽  
Life History Stage ◽  
Same Sex ◽  
Fitness Effects ◽  
Sibling Interactions ◽  
Fitness Consequences ◽  
Opposite Sex ◽  
Fitness Measures

Determining the fitness consequences of sibling interactions is pivotal for understanding the evolution of family living, but studies investigating them across lifetime are lacking. We used a large demographic dataset on preindustrial humans from Finland to study the effect of elder siblings on key life-history traits. The presence of elder siblings improved the chances of younger siblings surviving to sexual maturity, suggesting that despite a competition for parental resources, they may help rearing their younger siblings. After reaching sexual maturity however, same-sex elder siblings' presence was associated with reduced reproductive success in the focal individual, indicating the existence of competition among same-sex siblings. Overall, lifetime fitness was reduced by same-sex elder siblings' presence and increased by opposite-sex elder siblings' presence. Our study shows opposite effects of sibling interactions depending on the life-history stage, and highlights the need for using long-term fitness measures to understand the selection pressures acting on sibling interactions.

scholarly journals How social behaviour and life-history traits change with age and in the year prior to death in female yellow-bellied marmots

2021 ◽  
Vol 376 (1823) ◽  
pp. 20190745
Author(s):  
Svenja B. Kroeger ◽  
Daniel T. Blumstein ◽  
Julien G. A. Martin
Keyword(s):  
Life History ◽  
Social Behaviour ◽  
Life History Traits ◽  
Evolutionary Ecology ◽  
Natural Populations ◽  
Late Life ◽  
Integrative Approach ◽  
Trade Offs ◽  
Social Behaviours

Studies in natural populations are essential to understand the evolutionary ecology of senescence and terminal allocation. While there are an increasing number of studies investigating late-life variation in different life-history traits of wild populations, little is known about these patterns in social behaviour. We used long-term individual based data on yellow-bellied marmots (Marmota flaviventer) to quantify how affiliative social behaviours and different life-history traits vary with age and in the last year of life, and how patterns compare between the two. We found that some social behaviours and all life-history traits varied with age, whereas terminal last year of life effects were only observed in life-history traits. Our results imply that affiliative social behaviours do not act as a mechanism to adjust allocation among traits when close to death, and highlight the importance of adopting an integrative approach, studying late-life variation and senescence across multiple different traits, to allow the identification of potential trade-offs.This article is part of the theme issue ‘Ageing and sociality: why, when and how does sociality change ageing patterns?’

scholarly journals Deconstructing sociality: the types of social connections that predict longevity in a group-living primate

2019 ◽  
Vol 286 (1917) ◽  
pp. 20191991 ◽  
Author(s):  
Samuel Ellis ◽  
Noah Snyder-Mackler ◽  
Angelina Ruiz-Lambides ◽  
Michael L. Platt ◽  
Lauren J. N. Brent
Keyword(s):  
Social Connectedness ◽  
Rhesus Macaques ◽  
Group Structure ◽  
Group Living ◽  
Relative Survival ◽  
High Rate ◽  
Survival Models ◽  
Fitness Benefits ◽  
Socially Isolated

Many species use social interactions to cope with challenges in their environment and a growing number of studies show that individuals which are well-connected to their group have higher fitness than socially isolated individuals. However, there are many ways to be ‘well-connected’ and it is unclear which aspects of sociality drive fitness benefits. Being well-connected can be conceptualized in four main ways: individuals can be socially integrated by engaging in a high rate of social behaviour or having many partners; they can have strong and stable connections to favoured partners; they can indirectly connect to the broader group structure; or directly engage in a high rate of beneficial behaviours, such as grooming. In this study, we use survival models and long-term data in adult female rhesus macaques ( Macaca mulatta ) to compare the fitness outcomes of multiple measures of social connectedness. Females that maintained strong connections to favoured partners had the highest relative survival probability, as did females well-integrated owing to forming many weak connections. We found no survival benefits to being structurally well-connected or engaging in high rates of grooming. Being well-connected to favoured partners could provide fitness benefits by, for example, increasing the efficacy of coordinated or mutualistic behaviours.

scholarly journals Hamilton's rule and the causes of social evolution

2014 ◽  
Vol 369 (1642) ◽  
pp. 20130362 ◽  
Author(s):  
Andrew F. G. Bourke
Keyword(s):  
Life History ◽  
Social Behaviour ◽  
Social Evolution ◽  
Inclusive Fitness ◽  
Phylogenetic Analyses ◽  
Natural Populations ◽  
Ecological Factors ◽  
Hamilton’S Rule ◽  
Direct Fitness ◽  
Hamilton's Rule

Hamilton's rule is a central theorem of inclusive fitness (kin selection) theory and predicts that social behaviour evolves under specific combinations of relatedness, benefit and cost. This review provides evidence for Hamilton's rule by presenting novel syntheses of results from two kinds of study in diverse taxa, including cooperatively breeding birds and mammals and eusocial insects. These are, first, studies that empirically parametrize Hamilton's rule in natural populations and, second, comparative phylogenetic analyses of the genetic, life-history and ecological correlates of sociality. Studies parametrizing Hamilton's rule are not rare and demonstrate quantitatively that (i) altruism (net loss of direct fitness) occurs even when sociality is facultative, (ii) in most cases, altruism is under positive selection via indirect fitness benefits that exceed direct fitness costs and (iii) social behaviour commonly generates indirect benefits by enhancing the productivity or survivorship of kin. Comparative phylogenetic analyses show that cooperative breeding and eusociality are promoted by (i) high relatedness and monogamy and, potentially, by (ii) life-history factors facilitating family structure and high benefits of helping and (iii) ecological factors generating low costs of social behaviour. Overall, the focal studies strongly confirm the predictions of Hamilton's rule regarding conditions for social evolution and their causes.

Chick Growth, Sibling Rivalry, and Chick Production in American Black Oystercatchers

The Auk ◽  
1984 ◽  
Vol 101 (3) ◽  
pp. 525-531 ◽  
Author(s):  
Sarah Groves
Keyword(s):  
British Columbia ◽  
Life History ◽  
Brood Size ◽  
Sibling Rivalry ◽  
Life History Stage ◽  
Chick Growth ◽  
Dominance Hierarchies ◽  
American Black

Abstract I studied chick growth, sibling rivalry, and chick production in a population of American Black Oystercatchers (Haematopus bachmani) on Cleland Island, British Columbia from 1975 to 1978. For these birds, survival from hatching until time of first flight is the critical life-history stage. Chick growth varied with brood size, and heavier chicks had higher survival to the time of first flight. Once chicks could fly, however, their survival to 1 and 2 yr of age was not related to brood size or weight at time of first flight. Dominance hierarchies based on weight existed in two-chick broods, and dominant sibs could control access to parental feedings through sibling rivalry. Sibling rivalry probably increases the likelihood of some chick production in years when food is difficult to obtain.

Vivid Imagers Are Better at Detecting Salient Changes

2006 ◽  
Vol 27 (4) ◽  
pp. 218-228 ◽  
Author(s):  
Paul Rodway ◽  
Karen Gillies ◽  
Astrid Schepman
Keyword(s):  
Individual Differences ◽  
Change Detection ◽  
Visual Imagery ◽  
Detection Task ◽  
Level Of Detail ◽  
Detection Accuracy ◽  
Change Detection Task ◽  
Term Change ◽  
High Level

This study examined whether individual differences in the vividness of visual imagery influenced performance on a novel long-term change detection task. Participants were presented with a sequence of pictures, with each picture and its title displayed for 17  s, and then presented with changed or unchanged versions of those pictures and asked to detect whether the picture had been changed. Cuing the retrieval of the picture's image, by presenting the picture's title before the arrival of the changed picture, facilitated change detection accuracy. This suggests that the retrieval of the picture's representation immunizes it against overwriting by the arrival of the changed picture. The high and low vividness participants did not differ in overall levels of change detection accuracy. However, in replication of Gur and Hilgard (1975) , high vividness participants were significantly more accurate at detecting salient changes to pictures compared to low vividness participants. The results suggest that vivid images are not characterised by a high level of detail and that vivid imagery enhances memory for the salient aspects of a scene but not all of the details of a scene. Possible causes of this difference, and how they may lead to an understanding of individual differences in change detection, are considered.

Relationships between temperature and Pacific hake distribution vary across latitude and life-history stage

2020 ◽  
Vol 639 ◽  
pp. 185-197 ◽  
Author(s):  
MJ Malick ◽  
ME Hunsicker ◽  
MA Haltuch ◽  
SL Parker-Stetter ◽  
AM Berger ◽  
...  
Keyword(s):  
Life History ◽  
Environmental Effects ◽  
Environmental Conditions ◽  
Vancouver Island ◽  
Additive Models ◽  
Life History Stage ◽  
Fish Stocks ◽  
Merluccius Productus ◽  
Multiple Dimensions ◽  
Effects Of Temperature

Environmental conditions can have spatially complex effects on the dynamics of marine fish stocks that change across life-history stages. Yet the potential for non-stationary environmental effects across multiple dimensions, e.g. space and ontogeny, are rarely considered. In this study, we examined the evidence for spatial and ontogenetic non-stationary temperature effects on Pacific hake Merluccius productus biomass along the west coast of North America. Specifically, we used Bayesian additive models to estimate the effects of temperature on Pacific hake biomass distribution and whether the effects change across space or life-history stage. We found latitudinal differences in the effects of temperature on mature Pacific hake distribution (i.e. age 3 and older); warmer than average subsurface temperatures were associated with higher biomass north of Vancouver Island, but lower biomass offshore of Washington and southern Vancouver Island. In contrast, immature Pacific hake distribution (i.e. age 2) was better explained by a nonlinear temperature effect; cooler than average temperatures were associated with higher biomass coastwide. Together, our results suggest that Pacific hake distribution is driven by interactions between age composition and environmental conditions and highlight the importance of accounting for varying environmental effects across multiple dimensions.

Individual differences in white and grey matter structure associated with verbal habits of thought

2019 ◽  
Author(s):  
Justin C. Hayes ◽  
Katherine L Alfred ◽  
Rachel Pizzie ◽  
Joshua S. Cetron ◽  
David J. M. Kraemer
Keyword(s):  
Individual Differences ◽  
White Matter ◽  
Cognitive Processing ◽  
Grey Matter ◽  
Structural Changes ◽  
Structural Integrity ◽  
Diffusion Tensor ◽  
Self Report ◽  
White Matter Tracts

Modality specific encoding habits account for a significant portion of individual differences reflected in functional activation during cognitive processing. Yet, little is known about how these habits of thought influence long-term structural changes in the brain. Traditionally, habits of thought have been assessed using self-report questionnaires such as the visualizer-verbalizer questionnaire. Here, rather than relying on subjective reports, we measured habits of thought using a novel behavioral task assessing attentional biases toward picture and word stimuli. Hypothesizing that verbal habits of thought are reflected in the structural integrity of white matter tracts and cortical regions of interest, we used diffusion tensor imaging and volumetric analyses to assess this prediction. Using a whole-brain approach, we show that word bias is associated with increased volume in several bilateral language regions, in both white and grey matter parcels. Additionally, connectivity within white matter tracts within an a priori speech production network increased as a function of word bias. These results demonstrate long-term structural and morphological differences associated with verbal habits of thought.

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