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Policing stabilizes construction of social niches in primates
Abstract
All organisms interact with their environment, and in doing so shape it, modifying resource availability. Termed niche construction, this process has been studied primarily at the ecological level with an emphasis on the consequences of construction across generations. We focus on the behavioural process of construction within a single generation, identifying the role a robustness mechanism--conflict management--has in promoting interactions that build social resource networks or social niches. Using 'knockout' experiments on a large, captive group of pigtailed macaques (Macaca nemestrina), we show that a policing function, performed infrequently by a small subset of individuals, significantly contributes to maintaining stable resource networks in the face of chronic perturbations that arise through conflict. When policing is absent, social niches destabilize, with group members building smaller, less diverse, and less integrated grooming, play, proximity and contact-sitting networks. Instability is quantified in terms of reduced mean degree, increased clustering, reduced reach, and increased assortativity. Policing not only controls conflict, we find it significantly influences the structure of networks that constitute essential social resources in gregarious primate societies. The structure of such networks plays a critical role in infant survivorship, emergence and spread of cooperative behaviour, social learning and cultural traditions.
... Conflict is dissipative. Organisms, aggregates, and societies must overcome the destabilizing consequences of conflict in order to persist [1][2][3][4][5]. Conflict consequently plays a central role in the evolution of social organization. ...
... Particularly problematic for social stability is ontogenetic conflict -conflict that finds expression in fights between individuals over the course of their lifetimes. Much is understood about control mechanisms [4][5][6][7][8][9][10][11], factors driving escalation of pair-wise contests [12][13][14][15], the influence of third parties on conflict outcome through coalition formation [16,17], audience [18,19] and reputation effects [20], and redirected aggression [21]. Somewhat paradoxically, less is understood about the causes of conflict, and almost nothing is known about the dynamics of multiparty conflict -conflicts that spread to involve more than two individuals to encompass a sizable fraction of a group. ...
... Macaque societies are characterized by social learning at the individual level, social structures that arise from nonlinear processes and feedback to influence individual behavior, frequent non-kin interactions and multiplayer conflict interactions, the cost and benefits of which can be quantified at the individual and social network levels [4,5,9,28,29,44,49,55]. These properties coupled to highly resolved data make this system an excellent one for drawing inferences about critical processes in social evolution as well as for developing new modeling approaches that are intended to apply more broadly. ...
Conflict destabilizes social interactions and impedes cooperation at multiple scales of biological organization. Of fundamental interest are the causes of turbulent periods of conflict. We analyze conflict dynamics in a monkey society model system. We develop a technique, Inductive Game Theory, to extract directly from time-series data the decision-making strategies used by individuals and groups. This technique uses Monte Carlo simulation to test alternative causal models of conflict dynamics. We find individuals base their decision to fight on memory of social factors, not on short timescale ecological resource competition. Furthermore, the social assessments on which these decisions are based are triadic (self in relation to another pair of individuals), not pairwise. We show that this triadic decision making causes long conflict cascades and that there is a high population cost of the large fights associated with these cascades. These results suggest that individual agency has been over-emphasized in the social evolution of complex aggregates, and that pair-wise formalisms are inadequate. An appreciation of the empirical foundations of the collective dynamics of conflict is a crucial step towards its effective management.
... Traditionally, the focus of investigations on such third-party interactions has been on interventions in agonistic encounters of others. Mostly, but not exclusively (Flack et al., 2006; for impartial interventions aka policing), in this situation, the third party supports one of the former opponents and they thereby form a coalition against the other former opponent (Harcourt & de Waal, 1992). Such within-group coalitions have now been described for a range of mammalian species (reviewed in Smith et al., 2010) and in several bird species (Bewick's swans, Cygnus bewickii: Scott, 1980; jackdaws, Corvus monedula : Wechsler, 1988; greylag geese, Anser anser: Scheiber et al., 2005; rooks, Corvus frugilegus: Emery et al., 2007;ravens, Fraser & Bugnyar, 2012). ...
... Specifically with regard to interventions in negative interactions, we can thereby distinguish coalitions from 'policing' (i.e. impartial interventions: Flack et al., 2006;von Rohr et al., 2012), and if these are partial, we can distinguish whether there is victim support or support for the aggressor. Second, we studied which individual characteristics (sex, age, affiliative status or dominance rank) may predict whether birds initiate such an intervention or become the target of an intervention. ...
... These results support the hypothesis that raven groups are very flexible and thus do not benefit from increased stability due to policing (cf. Flack et al., 2006;von Rohr et al., 2012). ...
The social intelligence hypothesis suggests that cognitive capacities evolved because of selection pressures related to increasing social complexity. For instance, social animals may need to monitor the relationships of others and intervene in them if that is ultimately beneficial to themselves. Traditionally, such third-party interactions are studied by examining coalitionary support during conflicts. However, growing evidence shows that some animals also intervene in others' positive social interactions. To aid our understanding of the patterns of such interventions in the wild, we examined third-party interventions in both positive and negative interactions in a population of individually marked wild ravens. Although we found that interventions in negative interactions were more frequently observed than those in positive interactions in this wild population, both were relatively common and, in fact, occurred in almost exact proportions relative to the number of such interactions (~10% of ad libitum interactions in both cases). Interventions were mostly active (compared to mere approaches) and aggressive. However, the mode of intervention varied across interactions. In positive interactions, interventions were mostly impartial, whereas in negative interactions, interventions were not, targeting one of the two partners. Neutral or policing interventions in negative interactions were rare. More than half of negative interventions reflected coalitionary support for the aggressor and a quarter for the victim. Furthermore, the likelihood of initiating an intervention and being the target of an intervention varied according to age, sex, rank, residency status and affiliation index. Taken together, our results provide a complete overview of third-party interventions in wild ravens and suggest that ravens use these interventions selectively and potentially even strategically. Future comparative studies may allow investigations into whether the necessity of such social strategies may have been a selection pressure regarding intelligence in animals.
... We propose two potential functions of this intervention: policing the agonistic behaviour between the younger elephants or joining the agonistic interactions towards Elephant B. In this case, policing serves to mark the bounds of appropriate social behaviour and discourages agonistic interactions between members of an allmale elephant group. This is similar to policing in social primates: when physically impartial intervention by a third party into conflicts between two other parties leads to decreased aggression and increased social stability in the face of chronic perturbations due to conflict [19,20]. Policing is inherently difficult to evolve, as it requires a cost to the individual intervening but results in a benefit that is diffuse across the entire social group and, therefore, is almost exclusively observed in highly social animals with complex societies [19][20][21]. ...
... This is similar to policing in social primates: when physically impartial intervention by a third party into conflicts between two other parties leads to decreased aggression and increased social stability in the face of chronic perturbations due to conflict [19,20]. Policing is inherently difficult to evolve, as it requires a cost to the individual intervening but results in a benefit that is diffuse across the entire social group and, therefore, is almost exclusively observed in highly social animals with complex societies [19][20][21]. Importantly, policing by dominant individuals requires the lowest cost, as even the threat of aggression is often sufficient for altering the behaviours of subordinate individuals [19,20]; therefore, we posit that the intervention of Elephant A, the dominant male, is aligned with these broader definitions of policing behaviours. ...
... Policing is inherently difficult to evolve, as it requires a cost to the individual intervening but results in a benefit that is diffuse across the entire social group and, therefore, is almost exclusively observed in highly social animals with complex societies [19][20][21]. Importantly, policing by dominant individuals requires the lowest cost, as even the threat of aggression is often sufficient for altering the behaviours of subordinate individuals [19,20]; therefore, we posit that the intervention of Elephant A, the dominant male, is aligned with these broader definitions of policing behaviours. ...
Male Asian elephant (Elephas maximus) sociality is complex and understudied. Increasingly, researchers recognize the role of mature bull elephants in shaping adolescent males’ appropriate social and reproductive behaviours that enable them to have normal intra-species relationships after the adolescents leave their natal herds. We describe a specific intervention event by a mature, dominant male in a novel social group with adolescent male elephants at Denver Zoo, Colorado, USA. The mature male intervened in an agonistic interaction between three adolescent males, which allowed an adolescent to escape from two other adolescents who were repeatedly chasing him. Such interventions by mature animals may serve to mark the boundaries of appropriate behaviour for adolescent male elephants, and/or may serve to reduce group conflict and improve group stability. This behavioural observation provides an example of the type of social intervention by mature conspecifics from which adolescent male elephants might learn appropriate social behavior and suggests that mature males may play an active role in this relationship. Overall, this intervention behaviour supports the inclusion of mature males in social groupings of male elephants in managed care.
... Similarly, in rhesus macaques (Macaca mulatta), individuals that signal subordination benefit from increased grooming and experience less severe aggression [18]. In both pig-tailed and rhesus macaques, submission signalling is associated with greater dominance relationship certainty, and individuals receiving subordination signals from many different signallers experience more social power by more frequently policing the fights of others [18,[20][21][22]. Hence, the ability to communicate long-term behaviour has been suggested to reduce uncertainty in social relationships, allowing for higher-quality relationships and leading to more robust dominance relationships [9]. ...
... Since kin, sex and age may influence affiliation and aggression, we also considered these effects in our analyses. In macaques, individuals receiving subordination signals more frequently enjoyed greater social power by also more frequently policing the fights of others, thereby stabilizing the social network [18,[20][21][22]. Although neither lemur species polices the fights of others [7,29], signalling subordination may nevertheless have a stabilizing effect at the group level. ...
... In macaques, individuals that received subordination signals more frequently enjoyed greater social power, allowing them to police others and, thus, to stabilize the social network [18,[20][21][22]. Although lemurs do not police the fights of others [29], we investigated whether signalling subordination might nevertheless be associated with more balanced and, thus, more stable social relationships at the group level. ...
Many animals use formalized signals to communicate dominance relationships. In some primates, such as macaques, the function of such signals varies with dominance style. Despotic species produce unidirectional submission signals that have a dual function: in conflict contexts, they signal a willingness to withdraw, whereas in peaceful contexts, they indicate the agreement to subordination. More despotic species produce these calls to a lesser extent than less despotic species. Here, we investigated whether the use of unidirectional submission signals is also related to dominance style in two lemur species and whether signalling subordination stabilizes social relationships at the group level. Ring-tailed lemurs (Lemur catta) exhibit a more despotic dominance hierarchy than Verreaux’s sifakas (Propithecus verreauxi). We observed social interactions in 75 dyads of Verreaux’s sifakas and 118 dyads of ring-tailed lemurs. Both species used unidirectional submissive calls that have a dual function, potentially suggesting convergent evolution of the function of these signals in independent primate lineages. However, signalling subordination did not stabilize social relationships at the group level in both species. Additionally, subordination occurred more frequently in dyads of the more despotic ring-tailed lemurs than in Verreaux’s sifakas, indicating opposite patterns to macaques in the coevolution of social traits with dominance style.
This article is part of the theme issue ‘The power of sound: unravelling how acoustic communication shapes group dynamics’.
... We propose two potential functions of this intervention: policing the agonistic behaviour between the younger elephants or joining the agonistic interactions towards Elephant B. In this case, policing serves to mark the bounds of appropriate social behaviour and discourages agonistic interactions between members of an allmale elephant group. This is similar to policing in social primates: when physically impartial intervention by a third party into conflicts between two other parties leads to decreased aggression and increased social stability in the face of chronic perturbations due to conflict [19,20]. Policing is inherently difficult to evolve, as it requires a cost to the individual intervening but results in a benefit that is diffuse across the entire social group and, therefore, is almost exclusively observed in highly social animals with complex societies [19][20][21]. ...
... This is similar to policing in social primates: when physically impartial intervention by a third party into conflicts between two other parties leads to decreased aggression and increased social stability in the face of chronic perturbations due to conflict [19,20]. Policing is inherently difficult to evolve, as it requires a cost to the individual intervening but results in a benefit that is diffuse across the entire social group and, therefore, is almost exclusively observed in highly social animals with complex societies [19][20][21]. Importantly, policing by dominant individuals requires the lowest cost, as even the threat of aggression is often sufficient for altering the behaviours of subordinate individuals [19,20]; therefore, we posit that the intervention of Elephant A, the dominant male, is aligned with these broader definitions of policing behaviours. ...
... Policing is inherently difficult to evolve, as it requires a cost to the individual intervening but results in a benefit that is diffuse across the entire social group and, therefore, is almost exclusively observed in highly social animals with complex societies [19][20][21]. Importantly, policing by dominant individuals requires the lowest cost, as even the threat of aggression is often sufficient for altering the behaviours of subordinate individuals [19,20]; therefore, we posit that the intervention of Elephant A, the dominant male, is aligned with these broader definitions of policing behaviours. ...
Bull Asian elephant (Elephas maximus) sociality is complex and understudied. Increasingly, researchers recognize the role of mature bull elephants in teaching adolescent bulls appropriate social and reproductive behaviours that enable them to have normal intra-species relationships after the adolescents leave their natal herds. We describe a specific intervention event by a mature, dominant bull in a novel social group with adolescent bull elephants at Denver Zoo, Colorado, USA. The mature bull intervened on behalf of an adolescent elephant, allowing this adolescent to escape from two other adolescents who were repeatedly chasing him, marking boundaries of appropriate behaviour for the adolescent bulls. This example provides evidence for adolescent bull elephants learning appropriate social behaviours from mature conspecifics and suggests that mature bulls play an active role in this relationship. Overall, this intervention behaviour supports the inclusion of mature bulls in social groupings of bull elephants in managed care.
... Topological knockouts elucidate direct effects of removing an individual and its social connections from a network. Thus, they also provide information about the structural contribution to and systemic role of a knocked-out individual in their network (Flack et al., 2006;Lusseau, 2003). In contrast, natural knockout experiments often do not control for direct effects of removing an individual from the group but reflect the outcome of their interplay with indirect effects of individuals responding to perturbations by readjusting their social behaviour with the remaining group members (Flack et al., 2006). ...
... Thus, they also provide information about the structural contribution to and systemic role of a knocked-out individual in their network (Flack et al., 2006;Lusseau, 2003). In contrast, natural knockout experiments often do not control for direct effects of removing an individual from the group but reflect the outcome of their interplay with indirect effects of individuals responding to perturbations by readjusting their social behaviour with the remaining group members (Flack et al., 2006). From a practical viewpoint, topological knockouts are usually more feasible, particularly when working with wild populations (but see Firth et al., 2017). ...
... In chacma baboons, Papio ursinus, surviving females became more 'cliquish' in their spatial associations after the death of a high-ranking female (Barrett et al., 2012). In captive pigtailed macaques, Macaca nemestrina, experimental and topological knockouts of individuals that participated in third-party policing resulted in less integrated societies and increased the likelihood of group destabilization, indicating that 'policers' help maintain a stable social network (Flack et al., 2006). In contrast, in African elephants, targeted poaching of older females, despite their key role in the society, did not impair hierarchical social structure, because daughters took over their mothers' positions (Goldenberg et al., 2016). ...
... Such strategies are predicted in societies that display high fission-fusion dynamics where association patterns are flexible and highly variable (Aureli et al. 2008;Strier Twenty-five years of primate research in the Ndoki Forest 2017; Thierry 2008). As an extension of ecological niche theory, the Extended Evolutionary Synthesis accounts for the social niche as the set of social conditions required for species-typical social organization and structure as shaped by associations and interactions with conspecifics across multiple, overlapping social networks (Bergmuller and Taborsky 2010;Flack et al. 2006;Laland et al. 2000Laland et al. , 2015Odling-Smee et al. 1996). Therefore, the collection of social choices by which individuals influence their social environment or select a different set of conspecifics to associate with-i.e., social niche construction-sets forth a new series of hypotheses and predictions that are applicable to the study of fission-fusion social systems (Kaiser et al. 2024;Saltz et al. 2016;Trappes 2021;Trappes et al. 2022). ...
... From an individual's choices, their social niche is constructed, thereby influencing their fitness via an interaction with the bidirectional forces that are shared with ecological, cognitive, and other selective pressures (for a complete review, see Kaiser et al. 2024;Trappes 2021;Trappes et al. 2022). In animal societies with cohesive social structures and inflexible or highly consistent social environments, where social niche construction has been predominantly studied, individuals exert choice and agency via patterns of social interactions (e.g., primate conflict interventions: Flack et al. 2006;grooming: Mielke et al. 2021). However, social niche construction has not yet been extended to fission-fusion societies, where individuals are afforded an additional layer of choice in constructing their social environment via patterns of party co-attendance (e.g., associations: Boesch and Boesch-Achermann 2000;McCarthy et al. 2019). ...
Fission–fusion social systems allow individuals to make flexible choices about where, with whom, and in what contexts to spend their time in response to competing social and ecological pressures. The ability for fission–fusion societies to support individual behavioral strategies that vary across contexts has been suggested, but the potential function of such context-specific social choices remains largely understudied. We adopted the concept of social niche construction to explore possible differences in social complexity at the individual and group level across feeding contexts. Specifically, we examined patterns of co-attendance across two common ecological contexts in wild Central African chimpanzees ( Pan troglodytes troglodytes ) in the Goualougo Triangle, Republic of Congo. From data compiled over 6 years, we used multidimensional social network analysis to study the patterns of co-attendance generated from 436 group scans at Ficus and 4527 visits to termite mounds. These two contexts were chosen, because they are both fixed spatial features across the landscape that serve as well-defined points to compare association patterns. We identified context-specific social niche construction in a fission–fusion chimpanzee society that produce different patterns of relationships and social complexity that are consistent in their expression over many years, and offer functional benefits. While enhancing our understanding of chimpanzee behavioral strategies, culture, and conservation, our investigation also indicates that the social niche construction framework aids in elucidating the evolutionary advantages of fission–fusion sociality by accounting for intra- and interindividual variability, cognition, and choice in newfound ways.
... In many social primate groups, the behaviour of the highest-ranking individual in the dominance hierarchy often has the greatest influence on the organization of the group [22,23]. The influence of the dominant males on the overall structure of the network has been highlighted experimentally in captive groups of pig-tailed macaques (Macaca nemestrina), where their removal significantly increased aggression rate, group instability and disrupted social cohesion [24]. This is in part owing to their key role in policing and regulating third-party social interaction-in which effective communication plays a crucial role [25]. ...
... This suggests that facial behaviour is not only related to the structure of the network, but groups with expressive males also had comparatively stronger social bonds. The actions and behaviours of top-ranking males is known to directly impact the structure of macaque social networks, owing to the key role these individuals have in moderating third-party interactions [24]. Although these data at present are unable to directly assess the impact of policing and other third-party behaviours, it could be that greater expressivity is linked with a more successful moderation of these interactions. ...
Social living affords primates (including humans) many benefits. Communication has been proposed to be the key mechanism used to bond social connections, which could explain why primates have evolved such expressive faces. We assessed whether the facial expressivity of the dominant male (quantified from the coding of anatomically based facial movement) was related to social network properties (based on social proximity and grooming) in nine groups of captive rhesus macaques (Macaca mulatta) housed in uniform physical and social environments. More facially expressive dominant male macaques were more socially connected and had more cohesive social groups. These findings show that inter-individual differences in facial expressivity are related to differential social outcomes at both an individual and group level. More expressive individuals occupy more beneficial social positions, which could help explain the selection for complex facial communication in primates.
... Social niche is sometimes used in opposition to ecological niche (e.g., Flack et al. 2006 ) in order to stress that studies of ecological niches are focused on abiotic and heterospecific biotic environ-mental conditions (i.e., biotic conditions shaped by heterospecific interactions such as predator-prey and mutualistic interactions). Because environmental conditions, however, also include conspecific biotic conditions, strictly speaking, social niches are subtypes of ecological niches (on the species, population, and individual levels). ...
... Our approach is similar to theirs in that it focuses on individualized social niches and regards fitness as the essential qualifier of the social niche of an individual (in the present article, by fitness , we mean inclusive fitness without always making it explicit). However, we think that there is still theoretical work Kohn et al. 2011, Ryan 2011, Fisher et al. 2016, Mielke et al. 2021, Mutwill et al. 2020less prominently in Flack et al. 2006, Montiglio et al. 2013Social environment Formica and Tuttle 2009, Ryan 2011, Saltz et al. 2016, Fisher et al. 2016, Mielke et al. 2021less prominently in Bergmüller and Taborsky 2010, Bar Ziv et al. 2016, Stanley et al. 2018Social situations Montiglio et al. 2013, Mutwill et al. 2020 Social networks or patterns of social interactions Flack et al. 2006, Fisher et al. 2016 Lipatov et al. 2011 to be done on the concept. In particular, it must be clarified how the different terms involved in specifying the concept of a social niche, such as social interactions , social environment , and social role , relate to the social niche concept and to each other. ...
What are social niches, and how do they arise and change? Our first goal in the present article is to clarify the concept of an individualized social niche and to distinguish it from related concepts, such as a social environment and a social role. We argue that focal individuals are integral parts of individualized social niches and that social interactions with conspecifics are further core elements of social niches. Our second goal in the present article is to characterize three types of processes—social niche construction, conformance, and choice (social NC3 processes)—that explain how individualized social niches originate and change. Our approach brings together studies of behavior, ecology, and evolution and integrates social niches into the broader concept of an individualized ecological niche. We show how clarifying the concept of a social niche and recognizing the differences between the three social NC3 processes enhance and stimulate empirical research.
... Policing behaviors are adaptive when the inclusive fitness benefits the policer gets from their partners' increased cooperation outweighs the costs of the policing that generates this increase in cooperation (El Mouden et al., 2010;Frank, 1995Frank, , 1996Frank, , 2003Singh & Boomsma, 2015). Given these fitness benefits, policing behaviors evolve in many social species, including social bacteria (Manhes & Velicer, 2011), eusocial insects (Ratnieks & Wenseleers, 2005;Sun et al., 2020), mongooses (Cant et al., 2014), macaques (Beisner & McCowan, 2013;Flack et al., 2006), and vervet monkeys (Arseneau-Robar et al., 2016. A well-studied example is mutual policing among worker honeybees, which prevent each other from reproducing at the expense of the colony by destroying worker-laid eggs or aggressing reproducing workers (Ratnieks, 1988;Ratnieks & Visscher, 1989). ...
... This is the case when, by monitoring and punishing a recipient, you induce the recipient to increase her level of cooperation, not only towards you, but also toward other individuals ( Figure 2B). In pigtailed macaques, for example, dominant individuals directly benefit from policing within-group conflicts, yet thereby also benefit other individuals as a by-product, by decreasing conflict rates Flack et al., 2006;. In these cases, policing is cooperative behavior in the sense that it provides benefits to individuals other than the actor (West et al., 2007). ...
What explains the ubiquity and cultural success of prosocial religions? Leading accounts argue that prosocial religions evolved because they help societies grow and promote group cooperation. Yet recent evidence suggests that prosocial religious beliefs are not limited to large societies and might not have strong effects on cooperation. Here, we propose that prosocial religions, including beliefs in moralizing gods, develop because individuals shape supernatural beliefs to achieve their goals in within-group, strategic interactions. People have a fitness interest in controlling others' cooperation-either to extort benefits from others or to gain reputational benefits for protecting the public good. Moreover, they intuitively infer that other people could be deterred from cheating if they feared supernatural punishment. Thus, people endorse supernatural punishment beliefs to manipulate others into cooperating. Prosocial religions emerge from a dynamic of mutual monitoring, in which each individual, lacking confidence in the cooperativeness of conspecifics, attempts to incentivize their cooperation by endorsing beliefs in supernatural punishment. We show how variants of this incentive structure explain the variety of cultural attractors towards which supernatural punishment converges-including extractive religions that extort benefits from exploited individuals, prosocial religions geared toward mutual benefit, and moralized forms of prosocial religion where belief in moralizing gods is itself a moral duty. We review cross-disciplinary evidence for nine predictions of this account and use it to explain the decline of prosocial religions in modern societies. Prosocial religious beliefs seem endorsed as long as people believe them necessary to ensure other people's cooperation, regardless of their objective effectiveness in doing so.
... This finding suggests that social networks in these primates are primarily shaped by spatially close, related females and their interactions with other group members. Similarly, Flack et al. (2006) explored affiliation networks in captive pigtailed macaques (Macaca nemestrina), including networks based on spatial proximity. The temporary removal of individuals with high social centrality led to a reorganization of social networks, resulting in smaller, less morphotypically diverse groups. ...
Understanding the morphotypical masculinization gradient and its impact on social behavior in a natural animal model is essential for unraveling sexual differentiation dynamics and their ecological implications. In this study, we examined the presence of a morphotypical masculinization gradient in female wild cavies (Cavia aperea) and its association with social behavior. Experimental colonies in four enclosures with different initial population densities were established. Between October 2017 and June 2018, we collected two datasets. The first dataset included body mass and anogenital distance (AGD) from 48 females, collected every 15–30 days. Simultaneously, focal behavioral observations were carried out during the intervals between recaptures. The behavioral dataset encompassed 65 marked cavies (males and females); 50 in high-density and 15 low-density conditions. Behavioral data were utilized to construct a focal association index matrix. Social centrality by spatial proximity measures were calculated using eigenvector analysis. Using the AGDI as a proxy for masculinization, we categorized females into three groups based on their AGDI values: low, middle, and high. The AGDI demonstrated high repeatability, underscoring its stability as a metric. Morphotype analysis revealed distinct distributions of AGDI values across varying initial density conditions. No significant associations were found between AGDI values and social centrality. These findings enhance our understanding of social dynamics in C. aperea and emphasize the significance of accounting for morphotypical variability in ecological research.
... We expect to find structural leadership in relatively stable animal groups, often having complex social hierarchies, such as cetaceans, wolves, wild dogs, elephants and primates 15,[47][48][49][50] . The canonical example is the so-called 'alpha' individual in a primate society, who has some level of control over an entire group over a long period of time (assuming he society is stable) 51 . In our taxonomy, this dominant individual would be a persistent, centralized, structural leader with a large reach. ...
Understanding the mechanics behind the coordinated movement of mobile animal groups (collective motion) provides key insights into their biology and ecology, while also yielding algorithms for bio-inspired technologies and autonomous systems. It is becoming increasingly clear that many mobile animal groups are composed of heterogeneous individuals with differential levels and types of influence over group behaviors. The ability to infer this differential influence, or leadership, is critical to understanding group functioning in these collective animal systems. Due to the broad interpretation of leadership, many different measures and mathematical tools are used to describe and infer "leadership", e.g., position, causality, influence, information flow. But a key question remains: which, if any, of these concepts actually describes leadership? We argue that instead of asserting a single definition or notion of leadership, the complex interaction rules and dynamics typical of a group implies that leadership itself is not merely a binary classification (leader or follower), but rather, a complex combination of many different components. In this paper we develop an anatomy of leadership, identify several principle components and provide a general mathematical framework for discussing leadership. With the intricacies of this taxonomy in mind we present a set of leadership-oriented toy models that should be used as a proving ground for leadership inference methods going forward. We believe this multifaceted approach to leadership will enable a broader understanding of leadership and its inference from data in mobile animal groups and beyond.
... Rather than exclude conflict altogether, however, most societies attempt to manage the ways in which conflict and cooperation interact. The co-existence of conflict and cooperation is a basic theme of studies of intra-group conflict in the biological sciences [86,87]. Quarreling and fighting are not simply unstructured forms of letting off steam. ...
What is the boundary between a vigorous argument and a breakdown of relations? What drives a group of individuals across it? Taking Wikipedia as a test case, we use a hidden Markov model to approximate the computational structure and social grammar of more than a decade of cooperation and conflict among its editors. Across a wide range of pages, we discover a bursty war/peace structure where the systems can become trapped, sometimes for months, in a computational subspace associated with significantly higher levels of conflict-tracking "revert" actions. Distinct patterns of behavior characterize the lower-conflict subspace, including tit-for-tat reversion. While a fraction of the transitions between these subspaces are associated with top-down actions taken by administrators, the effects are weak. Surprisingly, we find no statistical signal that transitions are associated with the appearance of particularly anti-social users, and only weak association with significant news events outside the system. These findings are consistent with transitions being driven by decentralized processes with no clear locus of control. Models of belief revision in the presence of a common resource for information-sharing predict the existence of two distinct phases: a disordered high-conflict phase, and a frozen phase with spontaneously-broken symmetry. The bistability we observe empirically may be a consequence of editor turn-over, which drives the system to a critical point between them.
... Furthermore, we acknowledge that our data-collection windows encompass only a fraction of the lifespan of the apes, and that longitudinal data would be valuable to pinpoint determinants of sociality and possibly to identify regulating mechanisms for maintaining group stability (e.g. policing (Flack et al., 2006) and conformity (Tkaczynski et al., 2020;van Leeuwen, 2021)). Nonetheless, this crosssectional approach exposes variation between the ape groups that could affect their respective responses to all kinds of (experimental) conditions, like visitor effects (Davey, 2007), cooperation opportunities (Suchak et al., 2016;van Leeuwen et al., 2021) and unequal reward distributions (Brosnan et al., 2005). ...
Humans show remarkable differences in social behaviour between families, groups, communities and cultures, whereas such group-level within-species variation in socio-behavioural propensities is typically overlooked in other species. Studies on intraspecific variation in animal social structures are needed to inform an evolutionary account of human sociality. Here, we study multiple independent bonobo populations ( n = 6) in zoological settings to investigate if and how bonobos ( n = 70) show group-specific signatures in sociality. By applying tailored Bayesian statistical methods, we find that beyond individual and dyadic variation, the groups substantially differ from each other in core dimensions of great ape sociality: social proximity, grooming and play. Moreover, the groups’ network structures are distinct regarding cohesiveness and clustering, with some groups forming cohesive wholes, while others showcasing high levels of sub-grouping. Overall, while there is consistent evidence of differences in sociality between the groups, the patterns of cohesiveness and clustering are not consistent across the networks. This suggests that rather than groups having different levels of sociality, different patterns of sociality exist in each group. These findings warrant caution with characterising bonobos’ behavioural phenotype at the species level, and identify an essential source of variation that needs to be integrated in phylogenetic analyses.
... By reducing uncertainty and cognitive costs, the power distribution facilitates the emergence of novel forms of impartial conflict management. Conflict management, in turn, further reduces volatility, allowing individuals to build more diverse and cohesive local social niches and engage in a greater variety of socially positive interactions [65]. In other words, outsourcing memory to a stable social structure encoded in the power distribution allows for a significant increase in social complexity. ...
Organisms can learn in response to environmental inputs as well as actively modify their environments through niche construction on slower evolutionary time scales. How quickly should an organism respond to a changing environment, and when possible, should organisms adjust the time scale of environmental change? We formulate these questions using a model of learning costs that considers optimal time scales of both memory and environment. We derive a general, sublinear scaling law for optimal memory as a function of environmental persistence. This encapsulates a trade-off between remembering and forgetting. We place learning strategies within a niche construction dynamics in a game theoretic setting. Niche construction is found to reduce or stabilize environmental volatility when learned environmental resources can be monopolized. When learned resources are shared, niche destructors evolve to degrade the shared environment. We integrate these results into a metabolic scaling framework in order to derive learning strategies as a function of body size.
... Social network position is one way of describing variation in social behaviour. Metrics of social network position describe where an individual falls within the social structure of all interactions within a population, which modulates exposure to information, parasites, disease, grooming and other positive and negative fitness consequences of social interactions [37][38][39][40][41][42][43][44][45]. Many of these fitness consequences of interaction are due to traits associated with age, and so the net fitness effect of sociality will depend on the age of possible partners. ...
Social traits are expected to experience highly context-dependent selection, but we know little about the contextual factors that shape selection on social behaviours. We hypothesized that the fitness consequences of social interactions will depend on the age of social partners, and therefore that population age structure will shape evolutionary pressures on sociality. Here, we investigate the consequences of age variation at multiple levels of social organization for both individual fitness and sexual selection on social network traits. We experimentally manipulated the age composition of populations of the forked fungus beetle Bolitotherus cornutus, creating 12 replicate populations with either young or old age structures. We found that fitness is associated with variance in age at three different levels of organization: the individual, interacting social partners, and the population. Older individuals have higher reproductive success, males pay a fitness cost when they interact with old males and females achieve lower fitness in older populations. In addition to influencing fitness, population age structure also altered the selection acting on social network position in females. Female sociality is under positive selection only in old populations. Our results highlight age structure as an understudied demographic variable shaping the landscape of selection on social behaviour.
This article is part of the discussion meeting issue ‘Understanding age and society using natural populations’.
... (c) Sociality data I classified sociality following my proposed sociality continuum. In the development of this classification, my goal was to explicitly acknowledge how sociality is not a binary category, and that it indeed has a multi-faceted nature because animals can vary in their social interactions according to temporal and spatial dimensions [77], as well as according to group size [78], group hierarchy [79] and type of interactions [80]. My continuum of sociality takes five ordered levels, from less to more social, as follows: (i) Solitary: individuals spend most of their life cycles alone, except to breed; (ii) Gregarious: individuals spend some time in groups, but their social interactions are loose and these interactions can frequently disaggregate; (iii) Communal: individuals live in close proximity, often sharing a common nesting or dwelling area, but do not engage in cooperative breeding; (iv) Colonial: individuals live in close proximity and always share a common nesting or living area; and (v) Social: individuals live in close proximity and form stable, organized groups, engaging in social behaviours such as cooperative breeding and hierarchical structures. ...
The role of sociality in the demography of animals has become an intense focus of research in recent decades. However, efforts to understand the sociality–demography nexus have hitherto focused on single species or isolated taxonomic groups. Consequently, we lack generality regarding how sociality associates with demographic traits within the Animal Kingdom. Here, I propose a continuum of sociality, from solitary to tightly social, and test whether this continuum correlates with the key demographic properties of 152 species, from jellyfish to humans. After correction for body mass and phylogenetic relationships, I show that the sociality continuum is associated with key life history traits: more social species live longer, postpone maturity, have longer generation time and greater probability of achieving reproduction than solitary, gregarious, communal or colonial species. Contrary to the social buffering hypothesis, sociality does not result in more buffered populations. While more social species have a lower ability to benefit from disturbances, they display greater resistance than more solitary species. Finally, I also show that sociality does not shape reproductive or actuarial senescence rates. This cross-taxonomic examination of sociality across the demography of 13 taxonomic classes highlights key ways in which individual interactions shape most aspects of animal demography.
This article is part of the discussion meeting issue ‘Understanding age and society using natural populations’.
... Betweenness therefore reflects the importance of the focal individual as a point of social connection and transfer between different sections of the network [11,20]. Furthermore, individuals with high betweenness centrality are thought to be important for group stability as their removal may lead to a fragmentation of the network into smaller subunits [23][24][25]. ...
Data in behavioral research is often quantified with event-logging software, generating large data sets containing detailed information about subjects, recipients, and the duration of behaviors. Exploring and analyzing such large data sets can be challenging without tools to visualize behavioral interactions between individuals or transitions between behavioral states, yet software that can adequately visualize complex behavioral data sets is rare. TIBA (The Interactive Behavior Analyzer) is a web application for behavioral data visualization, which provides a series of interactive visualizations, including the temporal occurrences of behavioral events, the number and direction of interactions between individuals, the behavioral transitions and their respective transitional frequencies, as well as the visual and algorithmic comparison of the latter across data sets. It can therefore be applied to visualize behavior across individuals, species, or contexts. Several filtering options (selection of behaviors and individuals) together with options to set node and edge properties (in the network drawings) allow for interactive customization of the output drawings, which can also be downloaded afterwards. TIBA accepts data outputs from popular logging software and is implemented in Python and JavaScript, with all current browsers supported. The web application and usage instructions are available at tiba.inf.uni-konstanz.de. The source code is publicly available on GitHub: github.com/LSI-UniKonstanz/tiba.
... It is important to note that in social animals, not only are behavioural decisions influenced by the environment an individual uses, but that these decisions can also alter the environment itself, a concept now known as social niche construction 44,45 . Based on the relationship between individuals and their social environment, decisions made by parents about site selection and social association with conspecifics throughout their reproductive cycle can also influence the wider population and therefore the behaviour of conspecifics. ...
In many temperate animals, reproductive cycles coincide with seasonal weather changes resulting in behaviour changes such as movement and habitat selection. In social species, these physiological and environmental changes can alter the costs and benefits of social interactions, impacting the structure of animal groups. In little brown myotis (Myotis lucifugus), a gregarious bat occupying much of North America, the pregnancy and lactation phases present different challenges to energy balance and maternal movement, and reduced forage distance has been observed during the lactation period. As such, we hypothesized that differences between reproductive phases alter the roost switching decisions of individual bats and therefore the overall group structure of little brown myotis maternity colonies. We observed that adult females were less likely to switch roosts during the lactation period even when accounting for changing weather conditions. This shift in roost switching behaviour may be the source of observed differences in group structure between reproductive periods. We reported a decline in network cohesiveness, but no meaningful variation in individual roost fidelity and association strengths of dyads between reproductive phases. These results support the contention that reproductive processes in female little brown myotis influence sociality and overall roosting patterns within maternity groups.
... However, when one chimpanzee watches another stealing a victim's food, it does not try to punish the wrongdoer, indicating that chimpanzees do not punish others as third parties. However, some papers argue that primates show TPP-like behaviors, although these behaviors may not be TPP itself [15][16][17] . Similarly, dogs, fish, and other animals have been shown to display third-party evaluations or TPP-like interventions, although these actions are unlikely to be true TPP 6,[18][19][20] . ...
Third-party punishment (TPP) is an altruistic behavior or sense willing to punish transgressors as a third party not directly involved in the transgression. TPP is observed worldwide, regardless of tradition and culture, and is essential for morality in human society. Moreover, even preverbal infants display TPP-like judgement, suggesting that TPP is evolutionarily conserved and innate. Thus, it is possible that non-human animals display TPP-like behavior, although TPP has been said to be human-specific. We investigated whether or not male mature Wistar rats displayed TPP-like behaviors when they witnessed deadly aggression by an unknown aggressive mouse toward another unknown victim mouse. Normally reared rats did not display TPP-like behaviors, but rats reared with extensive affectionate handling by human caretakers as beloved pets contacted the unknown aggressive mice in a gentle manner leading to reduced aggression toward the unknown victim mice, even when the aggressive mice fought back. Furthermore, the handled rats touched unknown rat pups that were drowning in water and anesthesia-induced comatose rats more frequently than control rats. These findings suggest a possibility that TPP is not in fact human-specific and innate but rather an acquired behavior that flourishes in affectionate circumstances.
... RD = random, SF = scale-free, MD = modular. removal experiments may also be carried out on observed animal social networks (Flack et al. 2006, Williams & Lusseau 2006, and combining robustness simulations on real and simulated networks may be rewarding for future studies. It should be kept in mind that in real populations, individuals may react to the loss of individuals by adjusting their social linking. ...
Social networks constitute an important approach in the study of animal social behaviour. So far, focus has been on statistical analysis of animal social network structures. However, social networks can also be studied by generative network models - procedures that create simulated network structures. These models play a key role in wider network science, but despite occasional use, have not yet been as well integrated in the animal behaviour field. We believe that generative network models have considerable unexploited potential as a tool for understanding animal social systems. Here: 1) we provide a general introduction to generative network models, including a description of questions they are used for investigating in wider network science, explanation of key model features, and an overview of common models; 2) we consider generative network models in relation to the study of animal social behaviour, including description of questions about animal systems they can be used to investigate (demonstrated by case studies), an overview of animal behaviour studies that have used generative network modelling, the relevance of the key model features for animal behaviour studies, and consideration of how to choose a suitable generative network model for studies of animal social systems. We hope that this can help to further integrate generative network models into the study of animal sociality.
... Another (perhaps challenging) direction is to couple the rank dynamics with the entities' choices to interact with each other. For instance, one can imagine a model in which animals tend to challenge those immediately above them in the dominance hierarchy, or where new arrivals to a community test themselves against current members to find their place, or even three-way interactions where an animal who attacks another is punished by a third [31]. Testing these models would require rich data from biological and social systems. ...
We present a physics-inspired method for inferring dynamic rankings in directed temporal networks—networks in which each directed and timestamped edge reflects the outcome and timing of a pairwise interaction. The inferred ranking of each node is real-valued and varies in time as each new edge, encoding an outcome like a win or loss, raises or lowers the node's estimated strength or prestige, as is often observed in real scenarios including sequences of games, tournaments, or interactions in animal hierarchies. Our method works by solving a linear system of equations and requires only one parameter to be tuned. As a result, the corresponding algorithm is scalable and efficient. We test our method by evaluating its ability to predict interactions (edges' existence) and their outcomes (edges' directions) in a variety of applications, including both synthetic and real data. Our analysis shows that in many cases our method's performance is better than existing methods for predicting dynamic rankings and interaction outcomes.
Published by the American Physical Society 2024
... They can act as information clearinghouses, providing a central hub for information to be collected and distributed in an organized manner [25]. They can wield authority to bring unruly group members' behavior in line with the rest of the group [26,27]. And they can speed up difficult decisions by executive action, reducing the need for lengthy deliberation and discussion with decisive fiat [28]. ...
Consensus formation is a complex process, particularly in networked groups. When individuals are incentivized to dig in and refuse to compromise, leaders may be essential to guiding the group to consensus. Specifically, the relative geodesic position of leaders (which we use as a proxy for ease of communication between leaders) could be important for reaching consensus. Additionally, groups searching for consensus can be confounded by noisy signals in which individuals are given false information about the actions of their fellow group members. We tested the effects of the geodesic distance between leaders (geodesic distance ranging from 1-4) and of noise (noise levels at 0%, 5%, and 10%) by recruiting participants (N=3,456) for a set of experiments (n=216 groups). We find that noise makes groups less likely to reach consensus, and the groups that do reach consensus take longer to find it. We find that leadership changes the behavior of both leaders and followers in important ways (for instance, being labeled a leader makes people more likely to 'go with the flow'). However, we find no evidence that the distance between leaders is a significant factor in the probability of reaching consensus. While other network properties of leaders undoubtedly impact consensus formation, the distance between leaders in network sub-groups appears not to matter.
... This type of emergent pattern can be termed resilience, reflecting a system's ability to maintain (or regain) core functions and structures despite perturbations. For example, animal social systems may have high resilience to changes in lower-level structural or organizational components, such as demographic turnover events, but only up to a critical threshold and not to changes to key components, such as agents that act as 'hubs' that connect across the entire network or agents that play key social roles [81,82]. ...
In this article, we argue that social systems with fission–fusion (FF) dynamics are best characterized within a complex adaptive systems (CAS) framework. We discuss how different endogenous and exogenous factors drive scale-dependent network properties across temporal, spatial and social domains. Importantly, this view treats the dynamics themselves as objects of study, rather than variously defined notions of static ‘social groups’ that have hitherto dominated thinking in behavioural ecology. CAS approaches allow us to interrogate FF dynamics in taxa that do not conform to more traditional conceptualizations of sociality and encourage us to pose new types of questions regarding the sources of stability and change in social systems, distinguishing regular variations from those that would lead to system-level reorganization.
This article is part of the theme issue ‘Connected interactions: enriching food web research by spatial and social interactions’.
... Yet, there are several potential indirect benefits of the capacity for, and existence of, antagonism. For instance, dominance hierarchy plays a crucial role in reducing aggressive encounters and promoting group stability (14,15). Competition can drive individuals to pursue personal success (16). ...
Negative or antagonistic relationships are common in human social networks, but they are less often studied than positive or friendly relationships. The existence of a capacity to have and to track antagonistic ties raises the possibility that they may serve a useful function in human groups. Here, we analyze empirical data gathered from 24,770 and 22,513 individuals in 176 rural villages in Honduras in two survey waves 2.5 y apart in order to evaluate the possible relevance of antagonistic relationships for broader network phenomena. We find that the small-world effect is more significant in a positive world with negative ties compared to an otherwise similar hypothetical positive world without them. Additionally, we observe that nodes with more negative ties tend to be located near network bridges, with lower clustering coefficients, higher betweenness centralities, and shorter average distances to other nodes in the network. Positive connections tend to have a more localized distribution, while negative connections are more globally dispersed within the networks. Analysis of the possible impact of such negative ties on dynamic processes reveals that, remarkably, negative connections can facilitate the dissemination of information (including novel information experimentally introduced into these villages) to the same degree as positive connections, and that they can also play a role in mitigating idea polarization within village networks. Antagonistic ties hold considerable importance in shaping the structure and function of social networks.
... We selected these measures because of their established relationship to fitness in past studies both within this system (Wey and Blumstein 2012;Yang et al. 2017;Blumstein et al. 2018) and others (Hamede et al. 2009;Barocas et al. 2011;Formica et al. 2012;Ellis et al. 2019). Degree quantifies the number of social partners an individual has (Flack et al. 2006;Blumstein et al. 2009). Strength quantifies the number of social interactions an individual engages in (Wasserman and Faust 1994;Montero et al. 2020). ...
Across animal systems, abiotic environmental features, including timing of seasonal events and weather patterns, affect fitness. An individual’s degree of social integration also has fitness consequences, but we lack an understanding of how abiotic features relate to patterns of individual sociality. A deeper understanding of this relationship could be developed from studying systems where these two links with fitness have already been identified. We explored the relationship between individual social behavior and seasonal timing, seasonal length, and weather patterns. We used social network analysis on a sixteen-year dataset of a wild population of hibernating yellow-bellied marmots (Marmota flaviventer). We fit a series of generalized linear mixed models and found that longer growing seasons before winter hibernation and longer winters were associated with increased individual sociality in the following spring. However, later snowmelt was associated with decreased sociality that spring. We found no relationship between individual sociality and various measures of precipitation and temperature. This suggests that seasonal timing and length may be a more important driver of sociality than weather patterns in this system, both as a lag and contemporary effect. Seasonal timing and length may mediate the opportunity or intensity of social interactions. The entwined relationships between the seasonal schedule and weather, and the seemingly contradictory role of winter length and snowmelt, suggests the timing of seasons and its relationship with sociality is complex and further exploration of environment-sociality relationships is required across taxa.
Significance statement
While the adaptive benefits of social behavior are well studied, less is known about how features of the abiotic environment drive variation in individual social behavior. Given increasing stochasticity in the timing of seasonal events and weather patterns, mapping the environment-sociality relationship will provide important insights to the drivers of sociality in the wild. This is particularly salient for species most vulnerable to climate and environmental change, such as seasonal hibernators, like yellow-bellied marmots (Marmota flaviventer). We found that features of seasonal duration were positively associated with increased sociality, whereas the timing of seasonal onset was negatively associated. This work provides empirical evidence towards an important gap in the behavioral ecology literature.
... In hierarchical groups, high-ranking individuals may bully subordinates and usurp a disproportionate share of resources, social influence, and reproductive opportunities [8,9], which may amplify intragroup inequality and competitions [10], undermine the authority and legitimacy of group leaders [7]. Small groups overcome these problems through in-group social bonding [11,12], an adaptive means of forming, strengthening, and maintaining interpersonal connections with in-group members [13][14][15]. Social bonding exercises, such as grooming behaviors in nonhuman primate, collective rituals, traditions, and team-building activities in human society [16][17][18][19], have been widely adopted to facilitate leader influence [20], increase group cohesion [21], and reinforce the hierarchical structure [22]. ...
Social groups in various social species are organized with hierarchical structures that shape group dynamics and the nature of within-group interactions. In-group social bonding, exemplified by grooming behaviors among animals and collective rituals and team-building activities in human societies, is recognized as a practical adaptive strategy to foster group harmony and stabilize hierarchical structures in both human and nonhuman animal groups. However, the neurocognitive mechanisms underlying the effects of social bonding on hierarchical groups remain largely unexplored. Here, we conducted simultaneous neural recordings on human participants engaged in-group communications within small hierarchical groups (n = 528, organized into 176 three-person groups) to investigate how social bonding influenced hierarchical interactions and neural synchronizations. We differentiated interpersonal interactions between individuals of different (inter-status) or same (intra-status) social status and observed distinct effects of social bonding on inter-status and intra-status interactions. Specifically, social bonding selectively increased frequent and rapid information exchange and prefrontal neural synchronization for inter-status dyads but not intra-status dyads. Furthermore, social bonding facilitated unidirectional neural alignment from group leader to followers, enabling group leaders to predictively align their prefrontal activity with that of followers. These findings provide insights into how social bonding influences hierarchical dynamics and neural synchronization while highlighting the role of social status in shaping the strength and nature of social bonding experiences in human groups.
... In addition, SNA provided valuable information on integrating the two males in the host group, suggesting the formation of a one-male unit forerunner of harem social structure. Although SNA is an important tool for monitoring the dynamics of social life following an introduction into an existing group, it has only been applied to a limited number of zoo-housed groups and these are mainly restricted to primates (Beisner et al., 2015Flack et al., 2006Flack et al., , 2005Hansen et al., 2009;Less et al., 2010;McCowan et al., 2011;Ryan and Hauber, 2016;Schel et al., 2013). ...
... For instance, in pigtailed macaques (Macaca nemestrina), a small subset of well-connected individuals significantly contributes to maintaining stable social environments during periods of chronic perturbations. Without these individuals, group members build smaller, less diverse, and less integrated networks(Flack et al., 2006). In such situations where some individuals are responsible for maintaining links between groups that are otherwise less connected, weak ties emerge which can serve as transmission points(Vanderwaal et al., 2016).As mentioned above this could be beneficial for the population if information is transmitted or costly if parasites or pathogens are transmitted. ...
Extreme weather conditions, like heatwave events, are becoming more frequent with climate change. Animals often modify their behaviour to cope with environmental changes and extremes. During heat stress conditions, individuals change their spatial behaviour and increase the use of shaded areas to assist with thermoregulation. Here, we suggest that for social species, these behavioural changes and ambient conditions have the potential to influence an individual's position in its social network, and the social network structure as a whole. We investigated whether heat stress conditions (quantified through the temperature humidity index) and the resulting use of shaded areas, influence the social network structure and an individual's connectivity in it. We studied this in free‐ranging sheep in the arid zone of Australia, GPS‐tracking all 48 individuals in a flock. When heat stress conditions worsened, individuals spent more time in the shade and the network was more connected (higher density) and less structured (lower modularity). Furthermore, we then identified the behavioural change that drove the altered network structure and showed that an individual's shade use behaviour affected its social connectivity. Interestingly, individuals with intermediate shade use were most strongly connected (degree, strength, betweenness), indicating their importance for the connectivity of the social network during heat stress conditions. Heat stress conditions, which are predicted to increase in severity and frequency due to climate change, influence resource use within the ecological environment. Importantly, our study shows that these heat stress conditions also affect the animal's social environment through the changed social network structure. Ultimately, this could have further flow on effects for social foraging and individual health since social structure drives information and disease transmission.
... [We note that there are reports of third-party punishment in chimpanzees (reviewed in Rudolf von Rohr et al., 2011Rohr et al., , 2012 and vervet monkeys (Arseneau-Robar et al., 2016. Third-party 'policing' has also been identified in chimpanzees (Rudolf von Rohr et al., 2012) and pigtailed macaques (Macaca nemestrina) (Flack et al., 2006). Outside of the primate order, there is evidence of third-party punishment in cleaner fish (Labroides dimidiatus) (Deutchman et al., 2023;Raihani, Grutter & Bshary, 2010) and in eusocial insects (Singh & Boomsma, 2015). ...
Social norms – rules governing which behaviours are deemed appropriate or inappropriate within a given community – are typically taken to be uniquely human. Recently, this position has been challenged by a number of philosophers, cognitive scientists, and ethologists, who have suggested that social norms may also be found in certain non-human animal communities. Such claims have elicited considerable scepticism from norm cognition researchers, who doubt that any non-human animals possess the psychological capacities necessary for normative cognition. However, there is little agreement among these researchers about what these psychological prerequisites are. This makes empirical study of animal social norms difficult, since it is not clear what we are looking for and thus what should count as behavioural evidence for the presence (or absence) of social norms in animals. To break this impasse, we offer an approach that moves beyond contested psychological criteria for social norms. This approach is inspired by the animal culture research program, which has made a similar shift away from heavily psychological definitions of ‘culture’ and to become organized around a cluster of more empirically tractable concepts of culture. Here, we propose an analogous set of constructs built around the core notion of a normative regularity, which we define as a socially maintained pattern of behavioural conformity within a community. We suggest methods for studying potential normative regularities in wild and captive primates. We also discuss the broader scientific and philosophical implications of this research program with respect to questions of human uniqueness, animal welfare and conservation.
... In the laboratory, researchers have been unable to elicit third-party punishment in chimpanzees, operationalized as collapsing a food tray to prevent a thief from accessing stolen food [113]. There are reports of 'policing' in chimpanzees [5] and pigtailed macaques [126], understood as 'impartial interventions by third parties in ongoing conflicts' (typically, the interveners are dominant individuals). When the definition of punishment is broadened to include partner choice behaviours, we also find evidence for punishment of chimpanzees who freeload in a cooperative task [127]. ...
Human communities teem with a variety of social norms. In order to change unjust and harmful social norms, it is crucial to identify the psychological processes that give rise to them. Most researchers take it for granted that social norms are uniquely human. By contrast, we approach this matter from a comparative perspective, leveraging recent research on animal social behaviour. While there is currently only suggestive evidence for norms in nonhuman communities, we argue that human social norms are likely produced by a wide range of mechanisms, many of which we share with nonhuman animals. Approaching this variability from a comparative perspective can help norm researchers expand and reframe the range of hypotheses they test when attempting to understand the causes of socially normative behaviours in humans. First, we diagnose some of the theoretical obstacles to developing a comparative science of social norms, and offer a few basic constructs and distinctions to help norm researchers overcome these obstacles. Then we develop a six-dimensional model of the psychological and social factors that contribute to variability in both human and potential nonhuman norms.
This article is part of the theme issue ‘Social norm change: drivers and consequences’.
... Marginal and conditional R 2 values for Table 2. Descriptions of the six social network measures used to quantify social behaviour and network position. A higher value of each measure corresponds to higher sociality/connectivity. social measure description references degree number of social partners an individual has [64,81] strength number of social interactions an individual partakes in, including repeated interactions [41] closeness how centralized an individual is in a network calculated by the reciprocal of the sum of the shortest path lengths between a focal individual and all other individuals in its network [82,83] eigenvector centrality a measure of how connected an individual's social mates are [41] clustering coefficient a measure of an individual's clustering within their network [84] embeddedness quantifies how connected to the group an individual is based on the number of independent links to others in the group [41,45,64] royalsocietypublishing.org/journal/rsos R. Soc. Open Sci. ...
The gut microbiome has a well-documented relationship with host fitness. Greater microbial diversity and abundance of specific microbes have been associated with improved fitness outcomes. Intestinal microbes also may be associated with patterns of social behaviour. However, these associations have been largely studied in captive animal models; we know less about microbiome composition as a potential driver of individual social behaviour and position in the wild. We used linear mixed models to quantify the relationship between fecal microbial composition, diversity and social network traits in a wild population of yellow-bellied marmots (Marmota flaviventer). We focused our analyses on microbes previously linked to sociability and neurobehavioural alterations in captive rodents, primates and humans. Using 5 years of data, we found microbial diversity (Shannon–Wiener and Faith's phylogenetic diversity) has a modest yet statistically significant negative relationship with the number of social interactions an individual engaged in. We also found a negative relationship between Streptococcus spp. relative abundance and two social network measures (clustering coefficient and embeddedness) that quantify an individual's position relative to others in their social group. These findings highlight a potentially consequential relationship between microbial composition and social behaviour in a wild social mammal.
... At a group level, third-party intervention may also be an example of prosocial "policing", having evolved as an effective mechanism to stem the negative effects of a fight by helping terminate the aggression. It may therefore promote cohesion among group members, which in many species is necessary for the individual's survival and fitness ("group stability hypothesis") [31,59]. Policing is an expression of impartial interventions, as the interferer does not take sides with either one of the opponents but targets them both in order to stop the conflict [59,92]. ...
Background
Third-party interference in agonistic contests entails a deliberate intervention in an ongoing fight by a bystanding individual (third party) and may be followed by post-conflict social behaviour to provide support to a specific individual. The mechanisms behind third-party intervention are, however, still largely understudied. The aim of this study was to investigate third-party interference, with the predictions that (1) the interferer derives benefits from its action by winning a fight, (2) that patterns of intervention depend on familiarity, (3) that dyadic fights last longer than triadic fights, and (4) that interferers engage in non-agonistic social behaviours afterwards. Pre-pubertal pigs (Sus scrofa) (n = 384) were grouped with one familiar and four unfamiliar conspecifics (all non-kin) to elicit contests for dominance rank. Third-party interference was analysed for the first 30 min after grouping, along with the behaviour (nosing or aggression), contest duration, contest outcome, and interferer behaviour after the fight (post-conflict social behaviour).
Results
Three types of interference were observed: non-agonistic involvement (nose contact) by the interferer in a dyadic fight; a triadic fight with each of three contestants fighting one opponent at a time; and triadic fights with two opponents jointly attacking the third one (two-against-one fights). The likelihood of a third-party intervention to occur did not depend on the presence of a familiar animal in the fight. However, once intervention was triggered, interferers attacked unfamiliar fight initiators more than familiar ones. Two-against-one fights lasted longer than other triadic fights and occurred more often when both initial contestants were females. Results of 110 triadic fights (out of 585 fights in total) revealed that interferers were more likely to win compared to the initial opponents at equal body weight. The most common post-conflict behaviour displayed by the interferer was agonistic behaviour towards another group member, independently of familiarity.
Conclusions
The general lack of discrimination for familiarity suggests interference is not driven by support to familiar individuals in pigs. The results show that intervening in an ongoing fight gives the interferer a high chance of contest success and may be a strategy that is beneficial to the interferer to increase its dominance status.
... Group stability and associated dominance structures may be maintained or disrupted over time. For example, to compensate for rank instability owing to the loss of a keystone individual, baboons and macaques sometimes compensate through their proximity network [173] or policing [174], respectively. Among birds, ravens (Corvus corax) also maintain group stability through social interventions that prevent others from forming competitive alliances [175]. ...
The extent of (in)equality is highly diverse across species of social mammals, but we have a poor understanding of the factors that produce or inhibit equitable social organizations. Here, we adopt a comparative evolutionary perspective to test whether the evolution of social dominance hierarchies, a measure of social inequality in animals, exhibits phylogenetic conservatism and whether interspecific variation in these traits can be explained by sex, age or captivity. We find that hierarchy steepness and directional consistency evolve rapidly without any apparent constraint from evolutionary history. Given this extraordinary variability, we next consider multiple factors that have evolved to mitigate social inequality. Social networks, coalitionary support and knowledge transfer advantage to privilege some individuals over others. Nutritional access and prenatal stressors can impact the development of offspring, generating health disparities with intergenerational consequences. Intergenerational transfer of material resources (e.g. stone tools, food stashes, territories) advantage those who receive. Nonetheless, many of the same social species that experience unequal access to food (survival) and mates (reproduction) engage in levelling mechanisms such as food sharing, adoption, revolutionary coalitions, forgiveness and inequity aversion. Taken together, mammals rely upon a suite of mechanisms of (in)equality to balance the costs and benefits of group living.
This article is part of the theme issue ‘Evolutionary ecology of inequality’.
... In addition, previous simulation studies have suggested that shrinking groups lead to reduced adherence to Kawamura's rules of maternal rank inheritance with youngest ascendency [73], which would in turn alter the structural effects of social inheritance of hierarchy position (figure 3). The work presented here focused primarily on the reproductive side of demographic turnover, but future work could productively explore how variation in the distribution of mortality can also have structural effects [35,[86][87][88]. However, work in hyenas and other species with nepotistic societies show either rank-independent mortality or a tendency for greater longevity among individuals at the top of the hierarchy [89][90][91][92][93]. ...
Individuals and societies are linked through a feedback loop of mutual influence. Demographic turnover shapes group composition and structure by adding and removing individuals, and social inheritance shapes social structure through the transmission of social traits from parents to offspring. Here I examine how these drivers of social structure feedback to influence individual outcomes. I explore these society-to-individual effects in systems with social inheritance of hierarchy position, as occur in many primates and spotted hyenas. Applying Markov chain models to empirical and simulated data reveals how demography and social inheritance interact to strongly shape individual hierarchy positions. In hyena societies, demographic processes—not status seeking—account for the majority of hierarchy dynamics and cause an on-average lifetime decline in social hierarchy position. Simulated societies clarify how social inheritance alters demographic effects—demographic processes cause hierarchy position to regress to the mean, but the addition of social inheritance modifies this pattern. Notably, the combination of social inheritance and rank-related reproductive success causes individuals to decline in rank over their lifespans, as seen in the hyena data. Further analyses explore how ‘queens’ escape this pattern of decline, and how variation in social inheritance generates variability in reproductive inequality.
This article is part of the theme issue ‘Evolutionary ecology of inequality’.
Over the last decade new technologies for making large numbers of fine-grained measurements have led to the surprising discovery that many biological systems sit near a critical point. These systems are potentially more adaptive in that small changes to component behavior can induce large-scale changes in aggregate structure and function. Accounting for criticality remains a challenge as sensitivity to perturbation suggests a lack of robustness. Furthermore, change induced by perturbation may not be adaptive. Complicating matters further critical phenomena can result from history-dependent stochastic processes. A question central to distinguishing among these conflicting views of criticality is to what degree criticality can be controlled by the components of the system. We address the control of criticality using data on conflict dynamics and fight sizes from an animal society model system (Macaca nemestrina, n=48). The system is fundamentally finite so we operationalize criticality in information theoretic terms using Fisher information and a measure of instability. We analyze criticality using empirically-grounded equilibrium (maximum entropy) and dynamic (branching process) models of the monkeys' fight-joining behavior. We find that (1) this heterogeneous, socially organized system, like homogeneous, spatial systems (flocks and schools), sits near a critical point, (2) the contributions individuals make to how critical the system is can be quantified and vary, and (3) the distance from the critical point (DFC) can be controlled through biologically plausible mechanisms operating on this heterogeneity. These mechanisms include third-party policing, which dampens fight participation of the individuals with the largest effect on DFC. Control of DFC allows biological systems to balance the tradeoff between robustness and need for rapid change.
Consensus formation is a complex process, particularly in networked groups. When individuals are incentivized to dig in and refuse to compromise, leaders may be essential to guiding the group to consensus. Specifically, the relative geodesic position of leaders could be important for reaching consensus. Separately, groups searching for consensus can be confounded by noisy signals in which individuals are given false information about the actions of their fellow group members. We tested the effects of the geodesic distance between leaders (geodesic distance ranging from 1 to 4) and of noise (noise levels at 0%, 5%, and 10%) by recruiting participants (N = 3,456) for a set of experiments (n = 216 groups). We find that noise makes groups less likely to reach consensus, and the groups that do reach consensus take longer to find it. We find that leadership changes the behavior of both leaders and followers in important ways (for instance, being labeled a leader makes people more likely to ‘go with the flow’). However, we find no evidence that the geodesic distance between leaders is a significant factor in the probability of reaching consensus. While other network properties of leaders undoubtedly affect consensus formation, the distance between leaders in network subgroups appears not to matter.
RESUMEN: Para una extensa tradición filosófica, la normatividad es un rasgo exclusivo de la especie humana. Recientemente, sin embargo , algunos filósofos y científicos comenzaron a explorar la posibilidad de atribuir algún tipo de normatividad a otras especies. Frans de Waal se destaca, en este contexto, por haber proporcionado un amplio repertorio de evidencia empírica sobre comportamientos de primates no humanos que parecen ajustarse a distintos tipos de normas. Los escépticos sobre la normatividad animal suelen, sin embargo, cuestionar este tipo de evi-dencia, brindando explicaciones alternativas, no normativas, de ella. Un modo en que los escépticos podrían justificar esta estrategia es apelando al llamado Canon de Morgan y aduciendo que las explicaciones no norma-tivas introducen procesos psicológicos más simples que las normativas. Ahora bien, cuán atractiva resulte esta línea argumentativa dependerá de cómo se entienda la sensibilidad normativa. Si en lugar de centrarnos en las caracterizaciones más demandantes de tal sensibilidad adoptamos la hipótesis de que algunos primates no humanos cuentan con una suerte de "normatividad primitiva" (Ginsborg, 2011; 2018), podremos elaborar expli-caciones de (al menos parte de) la evidencia empírica proporcionada por
Social network position in non-human primates has far-reaching fitness consequences. Critically, social networks are both heterogeneous and dynamic, meaning an individual's current network position is likely to change due to both intrinsic and extrinsic factors. However, our understanding of the drivers of changes in social network position is largely confined to opportunistic studies. Experimental research on the consequences of in situ, controlled network perturbations is limited. Here we conducted a food-based experiment in rhesus macaques to assess whether allowing an individual the ability to provide high-quality food to her group changed her social behavioural relationships. We considered both her social network position across five behavioural networks, as well as her dominance and kin interactions. We found that gaining control over a preferential food resource had far-reaching social consequences. There was an increase in both submission and aggression centrality and changes in the socio-demographic characteristics of her agonistic interaction partners. Further, we found that her grooming balance shifted in her favour as she received more grooming than she gave. Together, these results provide a novel, preliminary insight into how in situ, experimental manipulations can modify social network position and point to broader network-level shifts in both social capital and social power.
Human behavior is influenced by the presence of others, which scientists also call ‘the audience effect’. The use of social control to produce more cooperative behaviors may positively influence road use and safety. This study uses an online questionnaire to test how eyes images affect the behavior of pedestrians when crossing a road. Different eyes images of men, women and a child with different facial expressions -neutral, friendly and angry- were presented to participants who were asked what they would feel by looking at these images before crossing a signalized road. Participants completed a questionnaire of 20 questions about pedestrian behaviors (PBQ). The questionnaire was received by 1,447 French participants, 610 of whom answered the entire questionnaire. Seventy-one percent of participants were women, and the mean age was 35 ± 14 years. Eye images give individuals the feeling they are being observed at 33%, feared at 5% and surprised at 26%, and thus seem to indicate mixed results about avoiding crossing at the red light. The expressions shown in the eyes are also an important factor: feelings of being observed increased by about 10-15% whilst feelings of being scared or inhibited increased by about 5% as the expression changed from neutral to friendly to angry. No link was found between the results of our questionnaire and those of the Pedestrian Behavior Questionnaire (PBQ). This study shows that the use of eye images could reduce illegal crossings by pedestrians, and is thus of key interest as a practical road safety tool. However, the effect is limited and how to increase this nudge effect needs further consideration.
Influential theories of the evolution of cognition and cooperation posit that tracking information about others allows individuals to adjust their social associations strategically, re-shaping social networks to favour connections between compatible partners. Crucially, to our knowledge, this has yet to be tested experimentally in natural populations, where the need to maintain long-term, fitness-enhancing relationships may limit social plasticity. Using a social-network-manipulation experiment, we show that wild jackdaws (Corvus monedula) learned to favour social associations with compatible group members (individuals that provided greater returns from social foraging interactions), but resultant change in network structure was constrained by the preservation of valuable pre-existing relationships. Our findings provide insights into the cognitive basis of social plasticity and the interplay between individual decision-making and social-network structure.
All human societies are permeated by collectively shared entities that govern daily social interactions and promote coordination and cooperation: norms. While the study of norm development is not new to developmental psychology, it has only recently been the target of an interdisciplinary wave of research using new methodologies and (often) complementary theoretical accounts to describe and explain the origins and potentially species-unique aspects of human norm psychology. Here we review recent developmental research showing that young children swiftly acquire and infer norms in a variety of social contexts. Moreover, children actively enforce these norms, even as unaffected bystanders, when third parties do things the wrong way. This research suggests that the foundations of human norm psychology can be found in early childhood. Deeper insights into the ontogenetic roots of norm psychology may contribute to understanding the evolutionary emergence of human cooperation and its maintenance in the contemporary world.
Expected final online publication date for the Annual Review of Developmental Psychology, Volume 5 is December 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
The paper presents a novel view of social norms that reflects the importance of different agent types, their specific motivations and roles. How one identifies with a role and behavioral options available to the agent is crucial for the sustainability of the social norms. The analysis of a simple case of social norm is suggested as a default model for analysis, and then the classification of subjects, enforcers, and audience is introduced. This triangular typology of agents is extended by introducing a network of interlocking patterns underlying social behavior. Lastly, the paper describes two categories of transgressions based on misidentification.
A model is presented to account for the natural selection of what is termed reciprocally altruistic behavior. The model shows how selection can operate against the cheater (non-reciprocator) in the system. Three instances of altruistic behavior are discussed, the evolution of which the model can explain: (1) behavior involved in cleaning symbioses; (2) warning cries in birds; and (3) human reciprocal altruism. Regarding human reciprocal altruism, it is shown that the details of the psychological system that regulates this altruism can be explained by the model. Specifically, friendship, dislike, moralistic aggression, gratitude, sympathy, trust, suspicion, trustworthiness, aspects of guilt, and some forms of dishonesty and hypocrisy can be explained as important adaptations to regulate the altruistic system. Each individual human is seen as possessing altruistic and cheating tendencies, the expression of which is sensitive to developmental variables that were selected to set the tendencies at a balance ap...
A Family of new measures of point and graph centrality based on early intuitions of Bavelas (1948) is introduced. These measures define centrality in terms of the degree to which a point falls on the shortest path between others and therefore has a potential for control of communication. They may be used to index centrality in any large or small network of symmetrical relations, whether connected or unconnected.
In biological markets, two classes of traders exchange commodities to their mutual benefit. Characteristics of markets are: competition within trader classes by contest or outbidding; preference for partners offering the highest value; and conflicts over the exchange value of commodities. Biological markets are currently studied under at least three different headings: sexual selection, intraspecific cooperation and interspecific mutualism. The time is ripe for the development of game theoretic models that describe the common core of biological markets and integrate existing knowledge from the separate fields.
In this paper we present the first mathematical analysis of the protein interaction network found in the yeast, S. cerevisiae. We show that, (a) the identified protein network display a characteristic scale-free topology that demonstrate striking similarity to the inherent organization of metabolic networks in particular, and to that of robust and error-tolerant networks in general. (b) the likelihood that deletion of an individual gene product will prove lethal for the yeast cell clearly correlates with the number of interactions the protein has, meaning that highly-connected proteins are more likely to prove essential than proteins with low number of links to other proteins. These results suggest that a scale-free architecture is a generic property of cellular networks attributable to universal self-organizing principles of robust and error-tolerant networks and that will likely to represent a generic topology for protein-protein interactions. Comment: See also http:/www.nd.edu/~networks and http:/www.nd.edu/~networks/cell
Techniques recently developed for the analysis of human social networks are applied to the social network of bottlenose dolphins living in Doubtful Sound, New Zealand. We identify communities and subcommunities within the dolphin population and present evidence that sex- and age-related homophily play a role in the formation of clusters of preferred companionship. We also identify brokers who act as links between sub-communities and who appear to be crucial to the social cohesion of the population as a whole. The network is found to be similar to human social networks in some respects but different in some others, such as the level of assortative mixing by degree within the population. This difference elucidates some of the means by which the network forms and evolves.
Conflict management mechanisms have a direct, critical effect on system robustness because they mitigate conflict intensity and help repair damaged relationships. However, robustness mechanisms can also have indirect effects on system integrity by facilitating interactions among components. We explore the indirect role that conflict management mechanisms play in the maintenance of social system robustness, using a perturbation technique to 'knockout' components responsible for effective conflict management. We explore the effects of knockout on pigtailed macaque (Macaca nemestrina) social organization, using a captive group of 84 individuals. This system is ideal in addressing this question because there is heterogeneity in performance of conflict management. Consequently, conflict managers can be easily removed without disrupting other control structures. We find that powerful conflict managers are essential in maintaining social order for the benefit of all members of society. We show that knockout of components responsible for conflict management results in system destabilization by significantly increasing mean levels of conflict and aggression, decreasing socio-positive interaction and decreasing the operation of repair mechanisms.
Many complex systems, such as communication networks, display a surprising degree of robustness: while key components regularly malfunction, local failures rarely lead to the loss of the global information-carrying ability of the network. The stability of these complex systems is often attributed to the redundant wiring of the functional web defined by the systems' components. In this paper we demonstrate that error tolerance is not shared by all redundant systems, but it is displayed only by a class of inhomogeneously wired networks, called scale-free networks. We find that scale-free networks, describing a number of systems, such as the World Wide Web, Internet, social networks or a cell, display an unexpected degree of robustness, the ability of their nodes to communicate being unaffected by even unrealistically high failure rates. However, error tolerance comes at a high price: these networks are extremely vulnerable to attacks, i.e. to the selection and removal of a few nodes that play the most important role in assuring the network's connectivity. Comment: 14 pages, 4 figures, Latex
Macaques, like baboons, regularly exhibit third party interference in dyadic conflicts. These most hierarchical primates are well known for forming alliances and coalitions, so presence of interference is not surprising. But as a risky helping behavior which prevents damage to other individuals and also reduces levels of agonism in a group, interference does present some special problems for explanation.
Teeth-baring in a large captive rhesus monkey group (Macaca mulatta) was observed over a 30-month period. Its directional consistency among adults was significantly higher than that of aggression. The unidirectionality was so extreme that the facial display must be seen as a formal status indicator; ie, a signal of which the direction is independent of short-term contextual variation. As such, it seems adapted for communication about the state of the relationship. Formal dominance relationships among adults could be arranged in a hierarchy which approached perfect linearity. Focal observations demonstrated that teeth-baring was associated with withdrawal. It was uncommon among foraging monkeys, perhaps because dominant animals paid less attention to their subordinates in this context. The speed of rank acquisition by young females, in terms of received teeth-baring, was highest among peers and lowest against the group's old matriarchs. The age at which dominance over unrelated adult females was achieved correlated negatively with the amount of affiliative contact with these females. This translates into a positive correlation between bonding and rank establishment, indicating that dominance processes may be indistinguishable from social integration.
Repression of competition within groups joins kin selection as the second major force in the history of life shaping the evolution of cooperation. When opportunities for competition against neighbors are limited within groups, individuals can increase their own success only by enhancing the efficiency and productivity of their group. Thus, characters that repress competition within groups promote cooperation and enhance group success. Leigh first expressed this idea in the context of fair meiosis, in which each chromosome has an equal chance of transmission via gametes. Randomized success means that each part of the genome can increase its own success only by enhancing the total number of progeny and thus increasing the success of the group. Alexander used this insight about repression of competition in fair meiosis to develop his theories for the evolution of human sociality. Alexander argued that human social structures spread when they repress competition within groups and promote successful group-against-group competition. Buss introduced a new example with his suggestion that metazoan success depended on repression of competition between cellular lineages. Maynard Smith synthesized different lines of thought on repression of competition. In this paper, I develop simple mathematical models to illustrate the main processes by which repression of competition evolves. With the concepts made clear, I then explain the history of the idea. I finish by summarizing many new developments in this subject and the most promising lines for future study.
Seven major types of sampling for observational studies of social behavior have been found in the literature. These methods differ considerably in their suitability for providing unbiased data of various kinds. Below is a summary of the major recommended uses of each technique: In this paper, I have tried to point out the major strengths and weaknesses of each sampling method. Some methods are intrinsically biased with respect to many variables, others to fewer. In choosing a sampling method the main question is whether the procedure results in a biased sample of the variables under study. A method can produce a biased sample directly, as a result of intrinsic bias with respect to a study variable, or secondarily due to some degree of dependence (correlation) between the study variable and a directly-biased variable. In order to choose a sampling technique, the observer needs to consider carefully the characteristics of behavior and social interactions that are relevant to the study population and the research questions at hand. In most studies one will not have adequate empirical knowledge of the dependencies between relevant variables. Under the circumstances, the observer should avoid intrinsic biases to whatever extent possible, in particular those that direcly affect the variables under study. Finally, it will often be possible to use more than one sampling method in a study. Such samples can be taken successively or, under favorable conditions, even concurrently. For example, we have found it possible to take Instantaneous Samples of the identities and distances of nearest neighbors of a focal individual at five or ten minute intervals during Focal-Animal (behavior) Samples on that individual. Often during Focal-Animal Sampling one can also record All Occurrences of Some Behaviors, for the whole social group, for categories of conspicuous behavior, such as predation, intergroup contact, drinking, and so on. The extent to which concurrent multiple sampling is feasible will depend very much on the behavior categories and rate of occurrence, the observational conditions, etc. Where feasible, such multiple sampling can greatly aid in the efficient use of research time.
Excerpt
This concluding survey1 of the problems considered in the Symposium naturally falls into three sections. In the first brief section certain of the areas in which there is considerable difference in outlook are discussed with a view to ascertaining the nature of the differences in the points of view of workers in different parts of the field; no aspect of the Symposium has been more important than the reduction of areas of dispute. In the second section a rather detailed analysis of one particular problem is given, partly because the question, namely, the nature of the ecological niche and the validity of the principle of niche specificity has raised and continues to raise difficulties, and partly because discussion of this problem gives an opportunity to refer to new work of potential importance not otherwise considered in the Symposium. The third section deals with possible directions for future research.
The Demographic
The seemingly innocent observation that the activities of organisms bring about changes in environments is so obvious that it seems an unlikely focus for a new line of thinking about evolution. Yet niche construction--as this process of organism-driven environmental modification is known--has hidden complexities. By transforming biotic and abiotic sources of natural selection in external environments, niche construction generates feedback in evolution on a scale hitherto underestimated--and in a manner that transforms the evolutionary dynamic. It also plays a critical role in ecology, supporting ecosystem engineering and influencing the flow of energy and nutrients through ecosystems. Despite this, niche construction has been given short shrift in theoretical biology, in part because it cannot be fully understood within the framework of standard evolutionary theory. Wedding evolution and ecology, this book extends evolutionary theory by formally including niche construction and ecological inheritance as additional evolutionary processes. The authors support their historic move with empirical data, theoretical population genetics, and conceptual models. They also describe new research methods capable of testing the theory. They demonstrate how their theory can resolve long-standing problems in ecology, particularly by advancing the sorely needed synthesis of ecology and evolution, and how it offers an evolutionary basis for the human sciences. Already hailed as a pioneering work by some of the world's most influential biologists, this is a rare, potentially field-changing contribution to the biological sciences.
Agonistic intervention behavior was observed in captive groups of chimpanzees (Pan troglodytes), rhesus monkeys (Macaca mulatta), and stumptail monkeys (M. arctoides). Reciprocity correlations of interventions were determined while removing from the data the effects of several symmetrical relationship characteristics, that is, matrillineal kinship, proximity relations, and same-sex combination. It was considered likely that if significant reciprocity persisted after controlling for these characteristics, the reciprocity was based on cognitive mechanisms. Statistical significance was tested by means of recently developed matrix permutation procedures. All three species exhibited significant reciprocity with regard to beneficial interventions, even after controlling for symmetrical traits. Harmful interventions were, however, reciprocal among chimpanzees only. This species showed a “revenge system”, that is, if A often intervened against B, B did the same to A. In contrast, both macaque species showed significantly inversed reciprocity in their harmful interventions: if A often intervened against B, B rarely intervened against A. Further analysis indicates that the strict hierarchy of macaques prevents them from achieving complete reciprocity. Compared to chimpanzees, macaques rarely intervene against higher ranking group members. The observed contrast can be partially explained on the basis of differences in available space, as indicated by a comparison of indoor and outdoor living conditions for the chimpanzee colony. Yet, even when such spatial factors are taken into account, substantial behavior differences between chimpanzees and macaques remain.
Ontologies in current computer science parlance are computer based resources that represent agreed domain semantics. Unlike data models, the fundamental asset of ontologies is their relative independence of particular applications, i.e. an ontology consists ...
The paper offers a detailed quantitative descripition of the distribution of agonistic activities over the members of two groups of Java-monkeys (Macaca fascicularis). These groups lived in captivity and were well-established: i.e. they had an extensive network of genealogical relationships. The study pays special attention to agonistic interactions with three or more participants. Its main purpose is an analysis of the way dyadic agonistic relations (e.g. dominance relations) are affected by third group members and the relations among these. The paper presents data on the ontogeny of 'dependent dominance', the 'control role' of the alpha-male, and the functions of different types of alliances.
Networks of coupled dynamical systems have been used to model biological oscillators, Josephson junction arrays, excitable media, neural networks, spatial games, genetic control networks and many other self-organizing systems. Ordinarily, the connection topology is assumed to be either completely regular or completely random. But many biological, technological and social networks lie somewhere between these two extremes. Here we explore simple models of networks that can be tuned through this middle ground: regular networks 'rewired' to introduce increasing amounts of disorder. We find that these systems can be highly clustered, like regular lattices, yet have small characteristic path lengths, like random graphs. We call them 'small-world' networks, by analogy with the small-world phenomenon (popularly known as six degrees of separation. The neural network of the worm Caenorhabditis elegans, the power grid of the western United States, and the collaboration graph of film actors are shown to be small-world networks. Models of dynamical systems with small-world coupling display enhanced signal-propagation speed, computational power, and synchronizability. In particular, infectious diseases spread more easily in small-world networks than in regular lattices.
The traditional notion of aggression as an antisocial instinct is being replaced by a framework that considers it a tool of
competition and negotiation. When survival depends on mutual assistance, the expression of aggression is constrained by the
need to maintain beneficial relationships. Moreover, evolution has produced ways of countering its disruptive consequences.
For example, chimpanzees kiss and embrace after fights, and other nonhuman primates engage in similar “reconciliations.” Theoretical
developments in this field carry implications for human aggression research. From families to high schools, aggressive conflict
is subject to the same constraints known of cooperative animal societies. It is only when social relationships are valued
that one can expect the full complement of natural checks and balances.
Capuchin monkeys (Cebus apella) share food even if separated by a mesh restraint. Pairs of capuchins were moved into a test chamber in which one of them received apple pieces for 20 min, and the other received carrot pieces for the next 20 min. Previous research had shown a correlation between the rate of food transfer in both directions across female-female dyads. The present study confirmed this result. Reciprocity across dyads can be explained, however, by symmetry in affiliative and tolerant tendencies between two individuals, provided these tendencies determine food sharing. The present study was designed to exclude this symmetry-based explanation by testing each pair (N=16) of adult females on six separate occasions. There existed a significant covariation across tests of sharing in both dyadic directions, a result unexplained by relationship symmetry. Moreover, control procedures (i.e. testing of a food possessor without a partner, or testing of two individuals with the same food or two different foods at the same time) indicated that behaviour during food trials is not fully explained by mutual attraction or aversion. The monkeys take the quality of their own and the partner's food into account, and possessors limit transfers of high-quality foods. Instead of a symmetry-based reciprocity explanation, a mediating role of memory is suggested, and a mirroring of social attitude between partners. Copyright 2000 The Association for the Study of Animal Behaviour.
We study assortative mixing in networks, the tendency for vertices in networks to be connected to other vertices that are like (or unlike) them in some way. We consider mixing according to discrete characteristics such as language or race in social networks and scalar characteristics such as age. As a special example of the latter we consider mixing according to vertex degree, i.e., according to the number of connections vertices have to other vertices: do gregarious people tend to associate with other gregarious people? We propose a number of measures of assortative mixing appropriate to the various mixing types, and apply them to a variety of real-world networks, showing that assortative mixing is a pervasive phenomenon found in many networks. We also propose several models of assortatively mixed networks, both analytic ones based on generating function methods, and numerical ones based on Monte Carlo graph generation techniques. We use these models to probe the properties of networks as their level of assortativity is varied. In the particular case of mixing by degree, we find strong variation with assortativity in the connectivity of the network and in the resilience of the network to the removal of vertices.
Repression of competition within groups joins kin selection as the second major force in the history of life shaping the evolution of cooperation. When opportunities for competition against neighbors are limited within groups, individuals can increase their own success only by enhancing the efficiency and productivity of their group. Thus, characters that repress competition within groups promote cooperation and enhance group success. Leigh first expressed this idea in the context of fair meiosis, in which each chromosome has an equal chance of transmission via gametes. Randomized success means that each part of the genome can increase its own success only by enhancing the total number of progeny and thus increasing the success of the group. Alexander used this insight about repression of competition in fair meiosis to develop his theories for the evolution of human sociality. Alexander argued that human social structures spread when they repress competition within groups and promote successful group-against-group competition. Buss introduced a new example with his suggestion that metazoan success depended on repression of competition between cellular lineages. Maynard Smith synthesized different lines of thought on repression of competition. In this paper, I develop simple mathematical models to illustrate the main processes by which repression of competition evolves. With the concepts made clear, I then explain the history of the idea. I finish by summarizing many new developments in this subject and the most promising lines for future study.
Among nonhuman primates, females often form strong bonds with kin and other group members. These relationships are thought to have adaptive value for females, but direct effects of sociality on fitness have never been demonstrated. We present 16 years of behavioral data from a well-studied population of wild baboons, which demonstrate that sociality of adult females is positively associated with infant survival, an important component of variation in female lifetime fitness. The effects of sociality on infant survival are independent of the effects of dominance rank, group membership, and environmental conditions. Our results are consistent with the evidence that social support has beneficial effects on human health and well-being across the life span. For humans and other primates, sociality has adaptive value.
Motion camouflage is a strategy whereby an aggressor moves towards a target while appearing stationary to the target except for the inevitable change in perceived size of the aggressor as it approaches. The strategy has been observed in insects, and mathematical models using discrete time or neural-network control have been used to simulate the behaviour. Here, the differential equations for motion camouflage are derived and some simple cases are analysed. These equations are easy to simulate numerically, and simulations indicate that motion camouflage is more efficient than the classical pursuit strategy ('move directly towards the target').
Conflict management is one of the primary requirements for social complexity. Of the many forms of conflict management, one of the rarest and most interesting is third-party policing, or intervening impartially to control conflict. Third-party policing should be hard to evolve because policers personally pay a cost for intervening, while the benefits are diffused over the whole group. In this study we investigate the incidence and costs of policing in a primate society. We report quantitative evidence of non-kin policing in the nonhuman primate, the pigtailed macaque. We find that policing is effective at reducing the intensity of or terminating conflict when performed by the most powerful individuals. We define a measure, social power consensus, that predicts effective low-cost interventions by powerful individuals and ineffective, relatively costly interventions by low-power individuals. Finally, we develop a simple probabilistic model to explore whether the degree to which policing can effectively reduce the societal cost of conflict is dependent on variance in the distribution of power. Our data and simple model suggest that third-party policing effectiveness and cost are dependent on power structure and might emerge only in societies with high variance in power.
Rich circumstantial evidence suggests that the extensive behavioural diversity recorded in wild great apes reflects a complexity of cultural variation unmatched by species other than our own. However, the capacity for cultural transmission assumed by this interpretation has remained difficult to test rigorously in the field, where the scope for controlled experimentation is limited. Here we show that experimentally introduced technologies will spread within different ape communities. Unobserved by group mates, we first trained a high-ranking female from each of two groups of captive chimpanzees to adopt one of two different tool-use techniques for obtaining food from the same 'Pan-pipe' apparatus, then re-introduced each female to her respective group. All but two of 32 chimpanzees mastered the new technique under the influence of their local expert, whereas none did so in a third population lacking an expert. Most chimpanzees adopted the method seeded in their group, and these traditions continued to diverge over time. A subset of chimpanzees that discovered the alternative method nevertheless went on to match the predominant approach of their companions, showing a conformity bias that is regarded as a hallmark of human culture.
Techniques recently developed for the analysis of human social networks are applied to the social network of bottlenose dolphins living in Doubtful Sound, New Zealand. We identify communities and subcommunities within the dolphin population and present evidence that sex- and age-related homophily play a role in the formation of clusters of preferred companionship. We also identify brokers who act as links between subcommunities and who appear to be crucial to the social cohesion of the population as a whole. The network is found to be similar to human social networks in some respects but different in some others such as the level of assortative mixing by degree within the population. This difference elucidates some of the means by which the network formed and evolves.
An Ecological and Behavioral Study of the Pigtailed Macaque (Contributions to Primatology
- J O Caldecott
Caldecott, J. O. An Ecological and Behavioral Study of the Pigtailed Macaque (Contributions to Primatology, S. Karger, Basel, 1986).
Seres for assistance with the data collection, and the animal care staff at YNPRC. YNPRC is fully accredited by the American Association for Accreditation of Laboratory Animal Care. This work was supported by
- Acknowledgements We
- Thank E Jen
- E Goldberg
- J Miller
- E Smith
- L Erwin
- H Marino
- C Gouzoules
- N Boehm
- Y Ay
- M Sato
- J Morris
- M J C F Padgett For Discussions
Acknowledgements We thank E. Jen, E. Goldberg, J. Miller, E. Smith, D. Erwin,
L. Marino, H. Gouzoules, C. Boehm, N. Ay, Y. Sato, M. Morris and J. Padgett for
discussions, M. Seres for assistance with the data collection, and the animal
care staff at YNPRC. YNPRC is fully accredited by the American Association for
Accreditation of Laboratory Animal Care. This work was supported by the
Packard Foundation (D.C.K.), the McDonnell Foundation (D.C.K., J.C.F., M.G.),
the Wenner-Gren Foundation (J.C.F.), the Proteus Foundation (D.C.K.), the NSF
(F.B.M.d.W.) and the NIH (F.B.M.d.W., J.C.F., D.C.K.).