Social network shrinking is explained by active and passive effects but not increasing selectivity with age in wild macaques

Sadoughi, Baptiste; Mundry, Roger; Schülke, Oliver; Ostner, Julia

doi:10.1098/rspb.2023.2736

Cited by 3 publications

References 73 publications

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Linking energy availability, movement and sociality in a wild primate ( Papio ursinus )

Fürtbauer,

Shergold,

Christensen

et al. 2024

Phil. Trans. R. Soc. B

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Proximate mechanisms of ‘social ageing’, i.e. shifts in social activity and narrowing of social networks, are understudied. It is proposed that energetic deficiencies (which are often seen in older individuals) may restrict movement and, in turn, sociality, but empirical tests of these intermediary mechanisms are lacking. Here, we study wild chacma baboons ( Papio ursinus ), combining measures of faecal triiodothyronine (fT3), a non-invasive proxy for energy availability, high-resolution GPS data (movement and social proximity) and accelerometry (social grooming durations). Higher (individual mean-centred) fT3 was associated with increased residency time (i.e. remaining in the same area longer), which, in turn, was positively related to social opportunities (i.e. close physical proximity). Individuals with more frequent social opportunities received more grooming, whereas for grooming given, fT3 moderated this effect, suggesting an energetic cost of giving grooming. While our results support the spirit of the energetic deficiencies hypothesis, the directionality of the relationship between energy availability and movement is unexpected and suggests that lower-energy individuals may use strategies to reduce the costs of intermittent locomotion. Thus, future work should consider whether age-related declines in sociality may be a by-product of a strategy to conserve energy. This article is part of the discussion meeting issue ‘Understanding age and society using natural populations’.

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Linking energy availability, movement and sociality in a wild primate ( Papio ursinus )

Fürtbauer,

Shergold,

Christensen

et al. 2024

Phil. Trans. R. Soc. B

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A causal framework for the drivers of animal social network structure

Kawam,

Ostner,

McElreath

et al. 2024

Preprint

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A major goal of behavioural ecology is to explain how phenotypic and ecological factors shape the social relationships that animals form with one another. This inferential task is notoriously challenging. The social networks of interest are generally not observed, but must be approximated from behavioural samples. Moreover, these data are highly dependent: the observed network edges correlate with one another, due to biological and sampling processes. Failing to account for the resulting uncertainty and biases can lead to dysfunctional statistical procedures, and thus to incorrect results. Here, we argue that these problems should be understood— and addressed—as problems of causal inference. For this purpose, we introduce a Bayesian causal modelling framework that explicitly defines the links between the target interaction network, its causes, and the data. We illustrate the mechanics of our framework with simulation studies and an empirical example. First, we encode causal effects of individual-, dyad-, and group-level features on social interactions using Directed Acyclic Graphs and Structural Causal Models. These quantities are the objects of inquiry, ourestimands. Second, we developestimatorsfor these effects— namely, Bayesian multilevel extensions of the Social Relations Model. Third, we recover the structural parameters of interest, map statistical estimates to the underlying causal structures, and compute causalestimatesfrom the joint posterior distribution. Throughout the manuscript, we develop models layer by layer, thereby illustrating an iterative workflow for causal inference in social networks. We conclude by summarising this workflow as a set of seven steps, and provide practical recommendations.

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