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Policing stabilizes construction of social niches in primates

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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.

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... Animal social networks have also been studied by complex systems researchers (and researchers working in both the animal behaviour and complex systems fields), and studies of the networks have been published outside of biological journals (e.g. [12][13][14][15][16]). However, the research on animal social networks going on in the field of animal behaviour is overall less extensively connected to the field of complex systems than might be expected, despite strong connections between the animal behaviour field and the complex systems field [17][18][19][20][21][22]. ...
... Knowledge about this is important for the conservation of animal populations (e.g. in the face of poaching or habitat destruction, which can lead to network fragmentation and reduction in network size), as well as for understanding social evolution and the role natural demographic changes play for social dynamics [129]. Robustness of animal social networks has been investigated by simulated [12,[130][131][132] and actual (experimental and natural) removal of individuals from the populations [12,[133][134][135][136][137]. Thus, we now have knowledge about the effects of node loss in multiple species, including real-world system reactions to such loss. ...
... Knowledge about this is important for the conservation of animal populations (e.g. in the face of poaching or habitat destruction, which can lead to network fragmentation and reduction in network size), as well as for understanding social evolution and the role natural demographic changes play for social dynamics [129]. Robustness of animal social networks has been investigated by simulated [12,[130][131][132] and actual (experimental and natural) removal of individuals from the populations [12,[133][134][135][136][137]. Thus, we now have knowledge about the effects of node loss in multiple species, including real-world system reactions to such loss. ...
Article
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Many animals live in societies where individuals frequently interact socially with each other. The social structures of these systems can be studied in depth by means of network analysis. A large number of studies on animal social networks in many species have in recent years been carried out in the biological research field of animal behaviour and have provided new insights into behaviour, ecology and social evolution. This line of research is currently not so well connected to the field of complex systems as could be expected. The purpose of this article is to provide an introduction to animal social networks for complex systems scientists and highlight areas of synergy. We believe that an increased integration of animal social networks with the interdisciplinary field of complex systems, and networks would be beneficial for various reasons. Increased collaboration between researchers in this field and biologists studying animal social systems could be valuable in solving challenges that are of importance to animal social network research. Furthermore, animal social networks provide the opportunity to investigate hypotheses about complex systems across a range of natural real-world social systems. In this article, we describe what animal social networks are and main research themes where they are studied; we give an overview of the methods commonly used to study animal social networks; we highlight challenges in the study of animal social networks where complex systems expertise may be particularly valuable; and we consider aspects of animal social networks that may be of particular interest to complex systems researchers. We hope that this will help to facilitate further interdisciplinary collaborations involving animal social networks and further integration of these networks into the field of complex systems.
... Whether observations are based on association or interaction, social network analysis (SNA) provides a framework for quantifying sociality and offers new approaches to explore the underlying mechanisms of complex social relationships (see Webber and Vander Wal, 2019, for a review). The analysis of animal social networks has advanced our understanding in key areas of behavioral ecology, including behavioral correlates of fitness (Stanton and Mann, 2012;Cheney et al., 2016;Silk et al., 2018;Thompson, 2019;Feldblum et al., 2021;Gerber et al., 2022), ontogenetic development (Turner et al., 2018), dominance (Bierbach et al., 2014;Bray et al., 2021), personality (Wilson et al., 2013;Kulahci et al., 2018), reproduction (Edenbrow et al., 2011;Solomon-Lane et al., 2015;Menz et al., 2020), information or behavior transfer (Flack et al., 2006;Ramos-Fernandez et al., 2009), and predation (Kelley et al., 2011;Heathcote et al., 2017). Conclusions drawn from SNA may also be used to recommend new conservation strategies (Anthony and Blumstein, 2000;McCowan et al., 2008;Snijders et al., 2017). ...
... The clustering coefficient of a node describes the density of its neighborhood; it measures the extent to which an individual's associates are themselves associated (Flack et al., 2006;Whitehead, 2008). Clustering coefficient, which can be interpreted as a measure of individual sociality (Croft et al., 2004), ranges from 0, signifying that none of an individual's associates are themselves linked, to 1, indicating that all are linked (Whitehead, 2008). ...
... Clustering coefficient, which can be interpreted as a measure of individual sociality (Croft et al., 2004), ranges from 0, signifying that none of an individual's associates are themselves linked, to 1, indicating that all are linked (Whitehead, 2008). Reach measures the indirect connectedness of a node to other nodes in a graph, defined here as the number of nodes one or two edges away, and is a valuable measure to study social effects such as behavioral contagion (Flack et al., 2006). The betweenness of a node, A, is the number of shortest paths between pairs of nodes besides A that pass through A (Croft et al., 2008). ...
Article
Social network analysis (SNA) can be used to explore a population’s social structure and how individuals contribute to social cohesion. Quantifying relationships between individuals in a network can vary depending on the data available or the relationship of interest. Studies of readily visible species can use direct interaction measures in SNA, while studies of cryptic species usually rely on the ‘gambit of the group’; individuals observed in a group are considered associates. This study compared the association and pectoral fin contact (PFC) networks of Atlantic spotted dolphins around Bimini to test the ‘gambit of the group’ hypothesis. The association network had nearly three times as many edges than the PFC network. Still, the two networks were correlated; individuals with a relationship in one network had a comparable relationship in the other. Many network measures were also correlated across networks, suggesting association is an acceptable substitute for physical interaction in certain cases. The current study supports the ‘gambit of the group’, but also highlights the importance of considering what types of relationships are used in the analysis of the social system of the focal species.
... For instance, the extent to which individuals form local clusters of partners with whom they preferentially interact within their network may also indicate a groups' social cohesivity. In other words, high clustering coefficient may indicate lower group-wide connectedness and (thereby) group cohesivity (Flack et al., 2006;Beisner et al., 2011;Sueur et al., 2011a). ...
... Clustering coefficient is an estimate of the extent to which individuals (or nodes) connected to a specific individual are also connected to each other (i.e., of the tendency for an individual to form a cluster with others: Newman, 2003). Clustering coefficient therefore indicates the overall cohesivity or connectedness of a network, with many individuals of high clustering coefficient indicating a network that may be less cohesive than a network in which clustering coefficients are predominantly low, by way of being more prone to fragmentation if/once these animals are absent or removed (Newman, 2003;Flack et al., 2006;Sueur et al., 2011). ...
... Our findings are of considerable practical value to colony managers. We add to a growing body of literature that reveals a number of potential benefits from successful introductions of males (1) moderating aggression and/or wounding through behaviours like conflict policing (Beisner et al., 2012;Bailey et al., 2020Bailey et al., , 2021Crast et al., data not shown; our results here), (2) increasing female reproductive success and infant births that are critical for biomedical research (Crast et al., data not shown) and (3) greater social tolerance and group cohesion (Flack et al., 2006;Rox et al., 2019; our results here). ...
Article
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Animal social structure is influenced by multiple socioecological factors. Of these, the links between changes to group demography through the arrival of new individuals and residents’ social structure remain unclear. Across seven groups of captive rhesus macaques ( Macaca mulatta ), we examine how male introductions may be influenced by, and in-turn influence, aspects of female social structure. GLMMs revealed that males integrated more successfully into groups in which females showed more ‘despotic’ social structures, i.e., higher aggression rates, steeper dominance hierarchies, and greater rank-skew in allogrooming network connectedness. Yet during periods that followed males’ social integration, females increased their social tolerance (decreased aggression and shallower hierarchies) and group cohesivity (less clustered allogrooming networks), but retained their tendencies to groom dominants. Our findings, independent of group size and matrilineal relatedness, help better understand how dispersal/immigration may influence social structure, and how assessing changes to social structure may inform macaque welfare and management.
... So-called "knockout experiments" or disturbance experiments have been applied with the withdrawal of specific individuals or interactions (Pinter-Wollman et al. 2014). These studies are mostly simulated removal (Williams and Lusseau 2006;Manno 2008;Kanngiesser et al. 2011;Puga-Gonzalez et al. 2018;Wiśniewska et al. 2020), while true experiments in removing (Flack et al. 2006;Naug 2009;Firth et al. 2017;Rueger et al. 2021) or observing natural suppression of individuals (Goldenberg et al. 2016) are scarcer. In general, all of them cause instability and show how networks can be restructured and how resilient they are (Kurvers et al. 2014;Pinter-Wollman et al. 2014), that is, whether they manage to maintain cohesion in the face of the loss of individuals (Puga-Gonzalez et al. 2018). ...
... Due to the absence of females in the study group, which could also encourage increased confrontations during reproduction, the post left by the alpha male reinforces that this is the main explanation for the observed instability. Similar episodes were observed in groups of pigtailed macaques (Macaca nemestrina; Flack et al. 2005Flack et al. , 2006, house sparrows (Passer domesticus; Franz et al. 2015a), and cichlids (Astatotilapia burtoni; Piefke et al. 2021), where the absence of individuals with high hierarchical positions increased agonism and a reduction in affiliate interactions among individuals in the groups. ...
... This assistance shows that members can play different roles in networks, even those without a leadership position (Williams and Lusseau 2006), and exemplifies why structures lose stability when key nodes are removed, compared to removing random nodes (Manno 2008;Puga-Gonzalez et al. 2018;Wiśniewska et al. 2020). Central individuals can act in specific situations of tension and stress during social relationships, maintaining the cooperative structure of groups (Flack et al. 2005(Flack et al. , 2006Funkhouser et al. 2018). We found that the Social Dynamics hypothesis, which predicts that attributes may not be essential in maintaining a hierarchical organization, but rather a process of selforganization, is supported in this captive population. ...
Article
Dominance hierarchies are typically stable, with dominants occupying central positions in social interaction networks. However, system perturbations, such as the removal of individuals, may cause instability, which varies according to the group’s resilience. If the hierarchy undergoes a restructuring, this can occur through a dynamic process of self-organization (Social Dynamics hypothesis) or through the infuence of individuals’ attributes (Previous Attributes hypothesis). We analyzed the resilience of the white-lipped peccary hierarchy after the alpha’s death and observed how the rise of a new dominant occurred. Additionally, we evaluated the validity of these two hypotheses in the restructuring of the system. We observed the group of white-lipped peccary males of the Municipal Zoo of Curitiba, PR, Brazil, from May to October 2018. We recorded and analyzed the agonistic and afliative interactions, and we collected data from the attributes: weight, testicle size, testosterone serum and age, before and after the dominant’s death (August). Due to this perturbation, the hierarchy started to show instability, but proved to be resilient. There was an increase in agonism and more than one individual pleading for the new dominant position, which was occupied by a subordinate male. Afliative interactions were also important in the rise of the new alpha. The hierarchy was well ordered by the social dynamics among individuals, but weight and testicular volume were also correlated with the status of the individuals before, and with the serum testosterone after the alpha’s death. Thus, both hypotheses afected the restructuring of this system.
... First, with some exceptions (e.g., Phan & Airoldi, 2015;Stuart, 2017), observational analyses of how networked groups respond to exogenous shocks often do not have the pre-and post-network structure of the groups (e.g. Corbo et al., 2016;Jordan, 2014;Scatà et al., 2018;Milton & Price, 2020) or only analyze changes in a single social network (Flack et al., 2006;Azoulay et al., 2010). In turn, these studies lack causal inference leverage or may not generalize to other populations. ...
... Our research is driven by two hypotheses: (a) the loss of internal connectivity brought on by node knockouts will negatively impact the performances of teams and (b) teammates will adjust their behaviors to compensate for, but not fully offset, the lost contributions of the knocked out teammate, with the remaining central players becoming more central and the peripheral players becoming more peripheral within their team. The first hypothesis is based on a substantial literature that finds that the knockout of central and highly connected nodes can disrupt networked systems by reducing the system's overall connectivity (e.g., Barabási & Bonabeau, 2003;Flack et al., 2006;Azoulay et al., 2010). We expect node knockouts of central players to negatively influence team performance because it will reduce the remaining teammates' abilities to coordinate their behaviors and disseminate information. ...
... The importance of understanding how to design efficient and effective teams has led to an expansive literature on how network structures influence team and group dynamics, including scholarship on how social networks affect team and group performance (Bavelas, 1950;Guetzkow & Simon, 1955;Mulder, 1960;Landers & Lüschen, 1974;Carron & Chelladurai, 1981;Evans & Dion, 1991;Mullen & Copper, 1994;Beal et al., 2003;Kearns et al., 2006;Judd et al., 2010;Shore et al., 2015;Becker et al., 2017;Argote et al., 2018) and their resiliency to exogenous shocks (Najjar & Gaudiot, 1990;Flack et al., 2006;Azoulay et al., 2010;Sterbenz et al., 2011;Freeman, 2014;Phillips, 2015;Zhang et al., 2015;Dong et al., 2018;Liu et al., 2020;Wang & Edgerton, 2022). In this section, we briefly discuss the extant research on how social networks affect individuals and the performance of groups, but prioritize a discussion of the network resiliency literature, as the present study uses an experimental design to assess how social networks respond and adapt to node knockouts. ...
Article
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Researchers have found that although external attacks, exogenous shocks, and node knockouts can disrupt networked systems, they rarely lead to the system’s collapse. Although these processes are widely understood, most studies of how exogenous shocks affect networks rely on simulated or observational data. Thus, little is known about how groups of real individuals respond to external attacks. In this article, we employ an experimental design in which exogenous shocks, in the form of the unexpected removal of a teammate, are imposed on small teams of people who know each other. This allows us to causally identify the removed individual’s contribution to the team structure, the effect that an individual had on those they were connected, and the effect of the node knockout on the team. At the team level, we find that node knockouts decrease overall internal team communication. At the individual level, we find that node knockouts cause the remaining influential players to become more influential, while the remaining peripheral players become more isolated within their team. In addition, we also find that node knockouts may have a nominal influence on team performance. These findings shed light on how teams respond and adapt to node knockouts.
... Multilayer social networks could be especially important for studying the social niches of animals. Social niches are defined as a summary of an individual's social relationships in all social networks in which the individual participates (Flack et al., 2006). Social relationships and the position of individuals within their social networks depend on individuals' traits. ...
... Proximal foraging (Video S3) is non-contact interaction similar to proximity interactions recorded in primates (Flack et al., 2006;Smith-Aguilar et al., 2018). Arabian babblers mainly feed on arthropods, as well as fruits, seeds, and flowers (Kam et al., 2003;Keynan et al., 2015). ...
Article
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The social environment of individuals affects various evolutionary and ecological processes. Their social environment is affected by individual and environmental traits. We assessed the effects of these traits on nodes and dyads in six layers of networks of Arabian babblers, representing different interaction types. Additionally, we tested how traits affect social niches in the multilayer networks using the tSNE dimensionality reduction algorithm. The effect of group size and season was similar across network layers, but individual traits had different effects on different layers. Additionally, we documented assortativity with respect to individual traits in the dominance display and allopreening networks. The joint analysis of all six layers revealed that most traits did not affect individuals' social niches. However, older individuals occupied fewer social niches than younger ones. Our results suggest that multilayer social networks are an important tool for understanding the complex social systems of cooperative breeders and intragroup interactions.
... Grâce à des indices permettant de quantifier le temps ou la fréquence d'association entre deux individus, l'analyse des réseaux sociaux permet de déterminer comment le groupe est structuré, si des individus ont un rôle plus important dans le groupe ou si des sous-groupes apparaissent au sein du groupe. Malgré le développement de cette méthodologie en sociologie (Cummins, 2000;Freeman, 1992), l'analyse des réseaux sociaux a été très peu utilisée dans l'étude des sociétés animales (Croft et al., 2005;Krause et al., 2007;Lusseau et al., 2006;Wey et al., 2008;Whitehead, 1997;Wittemeyer et al., 2005) et encore moins en primatologie (Kappeler and Van Schaik, 2002;Mitani and Amsler, 2003;Flack et al., 2006). ...
... In this study we will assess how individuals choose one or another sub-group through four alternatives hypotheses: (1) an individual chooses a sub-group because it shares its motivations with the individuals of this sub-group, then social relationships will not influence group fission process (Conradt and Roper, 2000;Ramos-Fernandez et al., 2006); (2) an individual chooses the sub-group where there is the most of individuals because the group cohesiveness is high and/or more individuals is more advantageous in term of protection or knowledge about food (Lehmann and Boesch, 2004;Wittemyer at al., 2005;Kerth et al, 2006); in this context, the process will be an anonymous mimetism (Meunier et al., 2006;Gautrais et al., 2007); (3) These different hypotheses will be tested using a stochastic agent-based model in order to simulate interactions between group members and sub-grouping patterns (Meunier et al., 2006;Sellers et al., 2007;Bryson et al., 2007;Sueur et al., chapter IV, 1.2 in the thesis). Then, the observed sub-groups will be compared to the simulated sub-groups for each species using social networks analysis (Whitehead, 1997;Flack et al., 2006;Lusseau et al., 2006;Krause et al., 2007;Wey et al., 2008;. ...
... Leaders can be described as individuals who have a disproportionate level of influence and decision-making power within their communities, and can distort social relationships to their advantage (Conradt, Roper 2005;Bourjade, Sueur 2010;King 2010). Even in non-human animals, leaders shape social dynamics through policing (Flack et al. 2006) or by embodying culturally appropriate behaviour (Canteloup et al. 2020). In return, leaders are often rewarded with privileges (Flack et al. 2006;King et al. 2008). ...
... Even in non-human animals, leaders shape social dynamics through policing (Flack et al. 2006) or by embodying culturally appropriate behaviour (Canteloup et al. 2020). In return, leaders are often rewarded with privileges (Flack et al. 2006;King et al. 2008). Hence, leadership itself is a frequently contested resource that individuals compete to obtain and/or maintain. ...
Article
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Whilst fundamental to human societies, collective decision-making such as voting systems can lead to non-efficient decisions, as past climate policies demonstrate. Current systems are harshly criticised for the way they consider voters needs and knowledge. Collective decision-making is central in human societies but also occurs in animal groups mostly when animals need to choose when and where to move. In these societies, animals balance between the needs of the group members and their own needs and rely on each individuals (partial) knowledge. We argue that non-human animals and humans share similar collective decision processes, among which are agenda-setting, deliberation and voting. Recent works in artificial intelligence have sought to improve decision-making in human groups, sometimes inspired by animals decision-making systems. We discuss here how our societies could benefit from recent advances in ethology and artificial intelligence to improve our collective decision-making system.
... However, most evidence on the effects of environmental disturbances on social structure comes from simulations, experimental manipulations, and opportunistic catastrophic events (Table 1). For example, captive studies have shown that the loss of a key individual can disrupt the policing behavior, thus destabilizing the social structure and the dominance hierarchy of the group (Flack et al., 2006), while experiments in wild populations of great tits (Parus major) have shown that flock members increase the strength of their social relationships (i.e., group cohesiveness) in response to the loss of their associates (Firth et al., 2017). Finally, changes in group membership can also affect parental care and cooperative interactions that may influence individual survival. ...
... First, we need to understand the direct and indirect effects of removing individuals from groups and identify the costs borne from disturbances caused by anthropogenic activities. We have stated that the removal of key individuals (e.g., high-ranking) can have negative cascading effects on the social dynamics of the group (Flack et al., 2006) and on the structure of populations (Archie et al., 2008), but up to date it is not clear to what extent these effects can be generalized to other species. Additionally, dominance rank is just one of the social-related traits characterizing individuals. ...
Article
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The internationally recognized levels of conservation, namely ecosystems, species , and genes, have thus far served as important guidelines to determine how national and international laws should protect nature. However, a far ignored aspect of a species' life history in the legislation is its tendency to form social groups. Group members greatly depend on each other for survival and reproduction , and when the persistence of groups is threatened, so may the population as a whole. Humans affect groups through indirect activities, such as tourism, or directly by removing individuals through poaching, for example. These activities disturb groups in both predictable and unpredictable ways: destabilizing dominance hierarchies, changing the strength of social relationships , modifying cooperative interactions, reducing alloparental care, and altering social skills, among others. We propose that greater efforts must be undertaken first, to more thoroughly understand how our actions are affecting group dynamics in as many species as possible, and second, to adapt policies to reduce the negative effects of direct and indirect anthropogenic activities on group and population persistence.
... Note, while a network may be resilient to change, this does not necessarily mean dyadic relationships remain the same. To maintain social network structure when group size changes, social interactions are likely to have to change as well (Flack et al. 2006; Barrett et al. 2012; see Shizuka and Johnson 2020 for overview). While overall network flexibility in response to external conditions has been previously documented (Godfrey et al. 2013;Goldenberg et al. 2016;Puehringer-Sturmayr et al. 2021) the response of individuals to the (permanent) loss of a large number of group members, remains poorly understood (Farine 2021). ...
... However, exactly what these impacts are is difficult to study, as it is very often either unethical or methodologically difficult to experimentally carry out such removals (Shizuka and Johnson 2020). Because of this, previous studies assessing the effects of individual loss on network structure tend to be based on either simulated removals (Raborn et al. 2002;Lusseau 2003;Williams and Lusseau 2006;Manno 2008;Kanngiesser et al. 2011;Levé et al. 2016;Fedurek and Lehmann 2017;Mourier et al. 2017;) or experimental short-term removal of individuals (Flack et al. 2006;Beisner et al. 2015;but see Cowl et al. 2020), with only a few studies investigating such effects in wild populations (Barrett et al. 2012;Franz et al. 2015). Studies using simulated removals usually compare the pre-removal structure of the network with that of the post-removal network (Shizuka and Johnson 2020). ...
Article
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In recent years, there has been considerable interest in investigating how animal social structure is affected by the loss of individuals. This is often achieved using simulations that generate predictions regarding how the removal of 'key' individuals from a group affects network structure. However, little is known about the effects of such removals in wild and free-ranging populations, particularly the extent to which naturally occurring mortality events and the loss of a large proportion of individuals from a social group affects the overall structure of a social network. Here, we used data from a population of wild Barbary macaques (Macaca sylvanus) that was exposed to an exceptionally harsh winter, culminating in the death of 64% of the adults from two groups. We analysed how social interaction patterns among surviving individuals were affected by the natural loss of group members using social networks based on affiliative (i.e., grooming) and aggressive social interactions. We show that only the structure of the pre-decline grooming networks was conserved in the post-decline networks, suggesting that grooming, but not aggression networks are resilient against the loss of group members. Surviving group members were not significantly different from the non-survivors in terms of their affiliative and agonistic relationships, and did not form assorted communities in the pre-decline networks. Overall, our results suggest that in primates, patterns of affiliative interactions are more resilient to changes in group composition than aggressive interaction patterns, which tend to be used more flexibly in new conditions.
... A skewed sex ratio with many more females than males can affect aggression through at least two mechanisms. First, adult males, particularly high-ranking ones, and/or those with certain personality traits (eg equable), are usually the group members that intervene in conflicts and prevent aggression from escalating ('policing' behaviour), which helps reduce severe wounding events (Flack et al 2005(Flack et al , 2006McCowan et al 2011;Beisner & McCowan 2013). Ha et al (2011) also demonstrated reduced contact aggression with male(s) present in groups of pigtail macaques (Macaca nemestrina). ...
... That is, the more balanced the ratios, the fewer traumas (see Figure 4 for the association between sex ratio and trauma frequency by group; overall r = 0.38). The likely mechanism for this effect is that these sex ratio differences are associated with differences in social group stability (McCowan et al 2018), likely driven by the presence of sufficient numbers of adult males that are willing and able to successfully intervene in conflicts (Flack et al 2006;Beisner et al 2012). Beisner and colleagues (2012) also found that the most successful males were not genetically related to the alpha and beta matrilines, nor socially familiar with them. ...
Article
Maintaining stable breeding groups of rhesus macaques ( Macaca mulatta ) can be challenging due to the complex social dynamics and despotic nature of the species. Trauma from aggression is a common problem in rhesus colonies and can cause social disruption, strain veterinary and animal management resources, and potentially affect reproduction. Previous research has shown that increasing the number of non-natal adult males in a breeding group can improve group stability, reduce trauma, and increase reproduction. Here, we used mixed-effects regression models to examine the effects of sex ratio and other factors on trauma and reproduction at the Yerkes National Primate Research Center using a historical dataset made up of four large rhesus groups over an eleven-year period (2003–2013). As expected, sex ratio was a significant predictor for both trauma and reproduction. However, group age since formation was a stronger predictor of trauma frequency and the amount of space available was a slightly better predictor of reproduction than sex ratio or trauma. These results indicate that improving sex ratios can be a viable management strategy to reduce trauma and improve reproduction, particularly when it is difficult to manipulate the group compositions and/or their housing situations. Reducing trauma is a primary goal for rhesus breeding colonies, as it directly impacts the monkeys' health and psychological well-being. Such improvements are necessary for the ethical treatment and care of the animals themselves, but also to reduce financial burdens and maintain a healthy colony for research purposes.
... Individuals that police do so at great physical risk, and they are only likely to do so if such risk is substantially minimized. This risk is best reflected by the metric known as social power: receipt of frequent subordination signals from a diversity of group members yields a high degree of consensus over the social power of the receiver, who then polices more frequently and successfully (figure 5) because their risk of retaliation is low [41,42,[44][45][46]. Networks of subordination signals, from which social power calculations are derived, exhibit important properties-the networks are acyclic (i.e. ...
Article
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The notion of dominance is ubiquitous across the animal kingdom, wherein some species/groups such relationships are strictly hierarchical and others are not. Modern approaches for measuring dominance have emerged in recent years taking advantage of increased computational power. One such technique, named Percolation and Conductance (Perc), uses both direct and indirect information about the flow of dominance relationships to generate hierarchical rank order that makes no assumptions about the linearity of these relationships. It also provides a new metric, known as ‘dominance certainty’, which is a complimentary measure to dominance rank that assesses the degree of ambiguity of rank relationships at the individual, dyadic and group levels. In this focused review, we will (i) describe how Perc measures dominance rank while accounting for both nonlinear hierarchical structure as well as sparsity in data—here we also provide a metric of dominance certainty estimated by Perc, which can be used to compliment the information dominance rank supplies; (ii) summarize a series of studies by our research team reflecting the importance of ‘dominance certainty’ on individual and societal health in large captive rhesus macaque breeding groups; and (iii) provide some concluding remarks and suggestions for future directions for dominance hierarchy research. This article is part of the theme issue ‘The centennial of the pecking order: current state and future prospects for the study of dominance hierarchies’.
... Distinguishing between behaviours exhibited by an individual because of personality variables versus social norms will be important. Social network analysis is increasingly used to analyse power structures in nonhuman societies [69], can highlight when individuals have leverage due to position in a network [67,70], and may facilitate comparisons between human and other animals. ...
Article
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Thorlief Schjelderup-Ebbe's seminal paper on the ‘pecking’ order of chickens inspired numerous ethologists to research and debate the phenomenon of dominance. The expansion of dominance to the broader concept of power facilitated disentangling aggression, strength, rank and power. Aggression is only one means of coercing other individuals, and can sometimes highlight a lack of power. The fitness advantages of aggression may only outweigh the costs during periods of uncertainty. Effective instruments of power also include incentives and refusals to act. Moreover, the stability of the power relationship might vary with the instruments used if different means of power vary in the number and types of outcomes achieved, as well as the speed of accomplishing those outcomes. In well-established relationships, actions or physiological responses in the subordinate individual may even be the only indicator of a power differential. A focus on strength, aggression and fighting provides an incomplete understanding of the power landscape that individuals actually experience. Multiple methods for constructing hierarchies exist but greater attention to the implications of the types of data used in these constructions is needed. Many shifts in our understanding of power were foreshadowed in Schjelderup-Ebbe's discussion about deviations from the linear hierarchy in chickens. This article is part of the theme issue ‘The centennial of the pecking order: current state and future prospects for the study of dominance hierarchies’.
... Prior research has already suggested a relationship between the social group and individual fitness correlates. For example, individuals residing in groups with regular intragroup conflict experience reduced reproductive opportunity and success and increased chronic stress in a variety of primates (de Waal 2000;Flack et al. 2006), as well as water striders (Aquarius remigis; Sih and Watters 2005) and meerkats (Suricata suricatta; Young et al. 2006). Although suggesting the social group may influence an individual's success, these studies did not identify specific attributes of the social group. ...
Article
The frequency and type of dyadic social interactions individuals partake in has important fitness consequences. Social network analysis is an effective tool to quantify the complexity and consequences of these behaviors on the individual level. Less work has used social networks to quantify the social structure-specific attributes of the pattern of all social interactions in a network-of animal social groups, and its fitness consequences for those individuals who comprise the group. We studied the association between social structure, quantified via five network measures, and annual reproductive success in wild, free-living female yellow-bellied marmots (Marmota flaviventer). We quantified reproductive success in two ways: (1) if an individual successfully weaned a litter and (2) how many pups were weaned. Networks were constructed from 38 968 interactions between 726 unique individuals in 137 social groups across 19 years. Using generalized linear mixed models, we found largely no relationship between either measure of reproductive success and social structure. We found a modest relationship that females residing in more fragmentable social groups (i.e., groups breakable into two or more separate groups of two or more individuals) weaned larger litters. Prior work showed that yellow-bellied marmots residing in more fragmentable groups gained body mass faster-another important fitness correlate. Interestingly, we found no strong relationships between other attributes of social group structure, suggesting that in this facultatively social mammal, the position of individuals within their group, the individual social phenotype, may be more important for fitness than the emergent group social phenotype.
... Such behaviour might therefore be considered male 'policing' (Singh & Boomsma, 2015), although experiments are needed to verify this hypothesis. The policing of subordinates by dominants can serve an important stabilizing function in animal social groups, reducing interindividual conflicts that threaten to fragment a cohesive social network into smaller, less-connected subgroups potentially impairing social information sharing, collective decision making (Flack et al., 2006) and other adaptive group level responses. ...
Article
Parental care can be associated with novel or altered social relationships with conspecifics, yet little is known about how the broader structure of the social environment is modulated by individuals caring for dependent offspring. Here, we compared the social environments of breeding groups in which dependent offspring were either present or absent. We conducted a field study with Neolamprologus multifasciatus, a group-living cichlid fish endemic to Lake Tanganyika, in which females provide direct care for their offspring within a group's territory. We used two methods to characterize the social environments in each group: (1) behavioural scoring to quantify the interactions among all group members and (2) automated, computer-assisted, visual detection to track the movements of fish on their territories. We found that relative to groups without offspring, groups with dependent offspring showed heightened conflict among females, as well as appreciable contests between dominant males and noncaregiving females. Patterns of space use revealed that territories comprise distinct, female-held subterritories, and although caregiving females used wider spaces than noncaregiving females, their subterritory areas remained largely nonoverlapping. By combining two complementary approaches for characterizing the social environment we were able to show how periods of parental care can be associated with marked differences in the makeup of breeding groups' social environments.
... Violating these social norms can unbalance the public good insofar that law-breakers will gain more benefits than their honest counterparts, or other individuals will be put at risk. In order to balance costs and benefits, punishment or police behaviors have evolved in humans societies Gächter, 2000, 2002), and in other primate societies (Boyd and Richerson, 1992;Flack et al., 2006;Mendes et al., 2018;Riedl et al., 2012). Like other primate species, humans have developed emotional bases for prosocial behaviors allowing cooperation. ...
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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.
... It is known that vervet monkeys can distinguish other individuals' ranks, matrilines and relationships accurately Cheney, 2011), and our results indicate the applied value of having such knowledge. Also, the increase in the grooming network suggests that animals living in complex societies can behave tactically, and consequently restructure their networks (Farine, 2021;Flack, Girvan, de Waal, & Krakauer, 2006). Such tactical displays could enable the fulfilment of personal gains by promoting integration in the social network, perhaps by enhancing the bonding (the emotional closeness) with their grooming partners, which requires substantial time and effort (Chang et al., 2013;Roberts et al., 2009;Sutcliffe et al., 2012). ...
Article
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Social animals face daily challenges to fulfil feeding, resting and social needs. In vervet monkeys, Chlorocebus pygerythrus, females are the core of the social group, in which relationships are mainly established and maintained through grooming. However, social relationships are not necessarily mutual or driven by the same interests. In a complex and diverse social environment, individuals may benefit from the ability to adapt their manoeuvring to different pressures. We experimentally manipulated the activity budget of two adult females (fed subjects) per group in four wild groups to investigate activity budgets, grooming behaviour variation and the implications for possible changes in social interactions. Specifically, we provisioned food to one fed subject at a time for 2 weeks (treatment), evaluated changes in their grooming behaviour before, during and after being fed, and compared their behaviour with that of the remaining adult females in the group (nonfed subjects) over the same period. In the provisioning phase, the fed subjects decreased feeding time, but increased resting and social time. Using null models, we found that the fed subjects increased their grooming strength and ratio of grooming given to received. They also showed preferences to groom existing partners, kin and adult females. Moreover, we found no carryover effect of provisioning on grooming strength after the treatment terminated. Our results demonstrate rapid social behaviour plasticity following manipulation of ecological conditions for specific female individuals, allowing for flexible shifts in grooming patterns that hint at Machiavellian-like adjustments that may help achieve social benefits through, at least partially, restructuring their social network when experimentally released from daily feeding obligations.
... These studies reveal that, under time constraints (e.g., lactation in the case of females) and increased competition over resources, it becomes important to focus on the most valuable partners to ensure their continued support. However, published analyses of grooming patterns are mostly based on correlational data, and only a few studies experimentally manipulated aspects of social patterns (Flack et al., 2006;Fruteau et al., 2009;Madden & Clutton-Brock, 2009). In primate species with a strict hierarchy, the rate of conflicts is usually influenced by seasonality, group size and food scarcity (reviewed in Isbell, 1991). ...
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In species that live in stable groups, successful management of time budget (i.e., the proportion of time involved in different behaviours) and social relationships has been proposed to be a key variable affecting individual fitness. Such management is limited by time constraints, which are group size and season dependancy. However, the link between time budget constraints and grooming patterns as a means to service social relationships has never been studied experimentally. Here, we reduced the time constraints of three wild vervet monkey (Chlorocebus aethiops pygerythrus) groups by offering them high quality food for 60 min in the morning. We conducted 10 trials in summer and 10 trials in winter. We found that vervet monkeys indeed reduced the proportion of time spent foraging during the rest of those days compared to control days and increased the proportion of grooming time spread over more bouts. Individuals that did not get access to the food still participated as much in grooming as those that did eat. In accordance with our expectations, social network analysis revealed a larger grooming network on supplementation days: vervet monkeys used their extra time to socialize with more different group members. Furthermore, following our predictions, the effect of provisioning was usually stronger during the winter season (when food was scarce and days shorter) than during the summer, and the number of conflicts decreased during supplementation days. Finally, despite the fact that adults and juveniles of all three groups increased their proportion of time spent grooming during supplementation days, few group and age differences emerged in the way vervet monkeys manage their time budget. Interestingly, some of these differences seem to be independent of group size. In conclusion, vervet monkeys seize the opportunity to increase the proportion of time spent in social behaviours if time budget constraints are reduced.
... Policing, which is defined broadly as the intervention by a third party in ongoing contests, has potentially costly risks to the intervening party . Studies of policing have found that that powerful dominant male policers are essential for maintaining social order and stability (Beisner & McCowan, 2013;Beisner et al., 2016;Flack et al., 2006). Therefore, while the presence of multiple males necessitates a biological system which selects for attributes necessary for attaining high rank, the dominant individual must also be able to fulfill a particular social role as well. ...
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The assumed evolutionary advantage of dominance is increased reproductive success. However, the efficacy of dominance as a mating strategy may be interrupted by any number of variables including female choice, estrous synchrony, and mating by non-troop males. In Japanese macaques (Macaca fuscata), there is evidence both for and against dominance as conferring reproductive success for adult males, with many discussions pointing to the importance of female choice in governing reproductive success in certain populations. In this study, we aimed to evaluate dominance-based versus female choice-based male behavioral strategies and their impact on reproductive success. This study was conducted on a group of Japanese macaques at the Oregon National Primate Research Center. We collected a total of 512 h of behavioral data across two summer study periods in 2018 and 2019. We conducted 15-min focal follows with 1-min instantaneous scans on 17 adult males. Reproductive data were available from genetic records. Using principal components analysis (PCA), we identified males that cluster according to similar behavioral strategies. We then used analysis of variance (ANOVA) and non-parametric ANOVA on ranks to ascertain significant variation in rank and reproductive success between clusters. We found that males that clustered based on high directed aggression held higher rank than less-aggressive male clusters (F = 27.21, df = 4, p < .0001). However, less aggressive male clusters had higher reproductive success (F = 3.50, df = 4, p = .04). There was no variation between affiliative clusters in reproductive success (F = 1.77, df = 3, p = .15). The highly aggressive strategy is effective for attaining high rank, but only resulted in high reproductive success for a single male which likely necessitates alternative strategies. We suggest the operation of female choice within this population, with females preferentially mating with males who are not only affiliative but also less aggressive. Highlights • Male Japanese macaques (Macaca fuscata) engaging in more dominance or aggression-centered behavioral strategies hold higher social rank than less-aggressive males. • There is no variation in reproductive success between males of differing affiliative strategies. • Less aggressive and lower-ranked males have higher reproductive success than more aggressive high-ranked males despite similar affiliative strategies.
... In line with this argument, it was the most dominant male in our population-the individual that is likely to be most threatened by any winner effectswho instigated most of the observed interventions. Other possible reasons for third-party intervention have been proposed, mostly in primates, and typically involve either coalitionary support or putative group benefits of intervention, such as by stabilising group structure (Beisner & McCowan, 2013;Flack et al., 2006;Kulik et al., 2012). The relevance of such mechanisms in giraffes are currently unclear but are perhaps less likely than in primates where other forms of relationally complex behaviour have been well described (e.g. ...
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Sparring by male giraffes has been commonly reported since its first description in 1958 and is believed to play a role in establishing male dominance hierarchies. However, despite being often documented, quantitative investigations of sparring behaviour are currently lacking. Here, we investigate the factors affecting the frequency, duration and intensity of sparring bouts in a population of giraffes Giraffa camelopardalis giraffa living on a private fenced reserve in Limpopo, South Africa. We show that sparring bouts were most frequently observed in young adults, and between males that were more evenly matched in size. Sparring bouts between males of similar body size were also characterised by being of high intensity and of short duration. Taken together, these results support the suggestion that sparring functions principally to provide maturing males a means of testing their competitive ability without escalating to full‐scale fights. Additionally, mature bulls intervened on young adults possibly to disable any winner effect achieved by the latter, with the most dominant bull being responsible for the majority of interventions. For the first time, we also show that individuals displayed strong laterality when engaged in sparring: individuals consistently preferred delivering blows from either their left or right side, and these preferences dictated the orientation of sparring bouts (whether head‐to‐head or head‐to‐tail). Lastly, we show that sparring displayed a seasonal peak which coincided with the onset of the wet season and possibly reflected the increased aggregation of males at this time. A more nuanced understanding of how social and environmental factors shape interactions among individuals, such as sparring, will improve our understanding and management of this charismatic animal.
... For instance, during the mandrill (Mandrillus sphinx) mating season, an increased influx of males leads to increased intra-sexual competition, more active mobility among males and consequently higher rank instability, and higher levels of oxidative damage in high ranking males [111]. The loss of certain key individuals can also lead to rank instability [119,120] and aggression network instability [121], or even group collapse [122]. Membership instability, rank instability or aggression network instability may be more impactful if it occurs in the upper portion of the hierarchy [47,120]. ...
Article
Although social hierarchies are recognized as dynamic systems, they are typically treated as static entities for practical reasons. Here, we ask what we can learn from a dynamical view of dominance, and provide a research agenda for the next decades. We identify five broad questions at the individual, dyadic and group levels, exploring the causes and consequences of individual changes in rank, the dynamics underlying dyadic dominance relationships, and the origins and impacts of social instability. Although challenges remain, we propose avenues for overcoming them. We suggest distinguishing between different types of social mobility to provide conceptual clarity about hierarchy dynamics at the individual level, and emphasize the need to explore how these dynamic processes produce dominance trajectories over individual lifespans and impact selection on status-seeking behaviour. At the dyadic level, there is scope for deeper exploration of decision-making processes leading to observed interactions, and how stable but malleable relationships emerge from these interactions. Across scales, model systems where rank is manipulable will be extremely useful for testing hypotheses about dominance dynamics. Long-term individual-based studies will also be critical for understanding the impact of rare events, and for interrogating dynamics that unfold over lifetimes and generations. This article is part of the theme issue ‘The centennial of the pecking order: current state and future prospects for the study of dominance hierarchies’.
... It is further possible that excluding particular individuals -super-spreaders, keystone individuals, policing individuals, alpha individuals -would have a much larger effect on the processes that occur on social networks than would excluding individuals with a less influential role. For instance, knocking out policers in a social group of pigtailed macaques greatly destabilised the structure of several social networks, setting the stage for reduced group cohesion (Flack et al., 2006). This is also reminiscent on the one hand of work investigating the effect of targeting specific individuals for heath interventions or information transmission: depending on which individual is targeted, information has a greater likelihood to spread in the community (e.g. ...
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Group living is beneficial for individuals, but also comes with costs. One such cost is the increased possibility of pathogen transmission, because increased numbers or frequencies of social contacts is often associated with increased parasite abundance or diversity. The social structure of a group or population has been shown to be paramount to patterns of infection and transmission. Yet, for various reasons, studies investigating the social transmission of parasites in animals, and especially in primates, have only taken into account parts of the group (e.g., only adults or even only adult females), which is likely to impact the interpretation of any results linking sociality and parasitism. Here, we investigated the relationship between social network centrality and an estimate of gastrointestinal helminth infection intensity in a complete group of Japanese macaques (Macaca fuscata). We then tested the impact of missing parts of the group on this relationship. We aimed to test: (1) whether social network centrality - the number of partners (degree), frequency of interactions (strength) and level of social integration (eigenvector) - was linked to parasite infection intensity; and, (2) to what extent excluding all or portions of individuals within the group from the analyses might influence the observed relationship. We conducted social network analysis on data collected from one complete group of Japanese macaques over two months on Koshima Island, Japan, to relate metrics of network centrality to an index of parasite infection intensity (eggs per gram of feces: EPG). We then ran a series of knock-out simulations to test the effect(s) of accounting only for certain age-sex classes on the observed relationship. General linear mixed models showed that, in the complete network, centrality was positively associated with infection by the examined geohelminths (Oesophagostomum aculeatum, Trichuris trichiura and Strongyloides fuelleborni), but in partial networks with only adult females, only juveniles, or random subsets of the group, the strength of this relationship - albeit still positive - lost statistical significance. Our study indicates that sampling bias can impact the relationship that is observed between social interaction and parasitism. In addition to supporting earlier results linking geohelminths to Japanese macaque social networks, this work introduces important methodological considerations for research into the dynamics of social transmission, with applications to infectious disease epidemiology, population management, and health interventions.
... Policing, which is defined broadly as the intervention by a third party in ongoing contests, has potentially costly risks to the intervening party . Studies of policing have found that it is an effective means of reducing the intensity of conflict (or terminating it entirely) when the most dominant individual is the intervening third party and, furthermore, that powerful policers are essential for maintaining social order and stability (Beisner et al., 2016;Beisner & McCowan, 2013;Flack et al., 2006;. Very broadly, it has been said that "a well-recognized hierarchy promotes social bonds and reduces violence" (De Waal, 1986). ...
Thesis
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Evolutionarily, individuals should pursue social strategies which confer advantages such as coalitionary support, mating opportunities, or access to limited resources. How an individual forms and maintains social bonds may be influenced by a large number of factors including sex, age, dominance rank, group structure, group demographics, relatedness, or seasonality. Individuals may employ differential social strategies both in terms of the type and quantity of interactions they engage in as well as their chosen social partners. The objective of this dissertation is to examine sociality in adult male Japanese macaques (Macaca fuscata) and the varying strategies that individuals may employ depending on their relative position within a social group. The first study examines dominance from multiple contextual measures and compares rank against social network centrality. Results from this study indicate that approaches based exclusively in aggressive interactions may not capture nuances of rank relationships and also that rank does not necessarily predict network centrality. The second study compared individual dominance rank and reproductive success based on their aggressive and affiliative behavioral strategies. Results from this study suggest that while increased aggression may enable individuals to attain high rank, males with lower rates of aggression achieve higher reproductive success. An individual’s aggressive strategy did not predict their affiliative strategy. We also see evidence for the operation of alternative mating strategies within this population. The third study used a biological markets approach to examine the relationship between male demography, social trends (directionality and chosen partner), and social centrality. Results from this study show that older individuals of higher rank are able to maintain fewer high-value social bonds as demonstrated by decreases in directed affiliation and negative correlations between rank and measures of network centrality. Conversely, younger lower-ranking males exhibit higher rates of directed affiliation and more network centrality likely as a means of maintaining multiple lower-value social bonds. This dissertation includes co-authored material currently in review for publication with peer-reviewed journals
... Fission-fusion dynamics are predicted to be most frequent in environments with spatial variability and to increase with temporal uncertainty and unpredictability of the environment (Sueur et al., 2011). Other factors known to influence the structure and cohesion of groups are demographic processes such as deaths, births, dispersal and immigration (Ilany & Akçay, 2016) that may influence social structure through the loss of some social connections and the formation of new ones (Shizuka & Johnson, 2020) as well as by driving changes in patterns of association between remaining individuals (e.g., Flack et al., 2006). ...
Article
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Despite its recognized importance for understanding the evolution of animal sociality as well as for conservation, long term analysis of social networks of animal populations is still relatively uncommon. We investigated social network dynamics in males of a gregarious mountain ungulate (Alpine ibex, Capra ibex) over ten years focusing on groups, sub‐groups and individuals, exploring the dynamics of sociality over different scales. Despite the social structure changing between seasons, the Alpine ibex population was highly cohesive: fission–fusion dynamics lead almost every male in the population to associate with each other male at least once. Nevertheless, we found that male Alpine ibex showed preferential associations that were maintained across seasons and years. Age seemed to be the most important factor driving preferential associations while other characteristics, such as social status, appeared less crucial. We also found that centrality measures were influenced by age and were also related to individual physical condition. The multi‐scale and long‐term frame of our study helped us show that ecological constrains, such as resource availability, may play a role in shaping associations in a gregarious species, but they cannot solely explain sociality and preferential association that are likely also to be driven by life‐history linked physiological and social needs. Our results highlight the importance of long‐term studies based on individually recognizable subjects to help us build on our understanding of the evolution of animal sociality.
... In primitively eusocial insects, the mechanism of queen choice and the determination of the new queen is a major issue to solve (Bhadra and Gadagkar 2008) and the network position of individuals may play a role here (Bhadra and Jordán 2013). Some individuals may play an outstandingly important role in the group, for example, by policing (Flack et al., 2006), making a large impact on the structure of the social network. Research on the role individual organisms play in social groups is evolving from focusing almost exclusively on dominance hierarchies (pecking orders) to multi-networks of several interaction types. ...
Article
Life is organized into more or less well-defined organizational levels, connected both horizontally and vertically. Our knowledge is richer along the horizontal levels (e.g. inter-specific interactions in multispecies communities), while vertical thinking (e.g. individual-level variability of the prey in a predator-prey interaction) is more challenging, more often crossing disciplinary borders. This review overviews the major challenges, concepts and network analysis-related methods related to studying vertical processes, giving a number of examples. It is argued the network theory is essentially about linking parts to the whole, and this is equivalent to connecting units at one level to a larger unit at the next level. Mostly, but not only, social networks, food webs and landscape graphs are discussed. Methods and concepts in network research, both classical and recently emerged, for supporting this vertical thinking are discussed.
Chapter
Humans live in large and extensive societies and spend much of their time interacting socially. Likewise, most other animals also interact socially. Social behaviour is of constant fascination to biologists and psychologists of many disciplines, from behavioural ecology to comparative biology and sociobiology. The two major approaches used to study social behaviour involve either the mechanism of behaviour - where it has come from and how it has evolved, or the function of the behaviour studied. With guest articles from leaders in the field, theoretical foundations along with recent advances are presented to give a truly multidisciplinary overview of social behaviour, for advanced undergraduate and graduate students. Topics include aggression, communication, group living, sexual behaviour and co-operative breeding. With examples ranging from bacteria to social mammals and humans, a variety of research tools are used, including candidate gene approaches, quantitative genetics, neuro-endocrine studies, cost-benefit and phylogenetic analyses and evolutionary game theory.
Article
Understanding the development of social relationships, or the process of socialization, can provide insights into the processes by which social network structures emerge and vary across species. In this analysis, we investigated the process of network formation from a developmental perspective using data from three groups of wild vervet monkeys, Chlorocebus pygerythrus. We used a dynamic social network approach that allowed us to capture patterns of social change over time. Specifically, we considered the temporal dynamics of two separate interaction networks, spatial and grooming associations, and investigated these patterns between the sexes. We used these data to test predictions derived from a developmental framework on relationship formation put forward by Kohn (2019, Animal Behaviour, 154, 1–6). We found that females and males differed in their grooming patterns but were similar in their spatial associations. Furthermore, spatial proximity ego-networks showed seasonal patterns, whereas grooming ego-networks did not. When all relevant centrality measures were considered in concert, we found evidence to suggest that a distinctive network structure forms across the course of development, with ego-networks composed of few strong ties and many weak ties, regardless of behaviour and sex. However, these networks were not produced according to the processes described by Kohn (2019), perhaps because Kohn's framework is concerned mainly with network composition and not structure. Overall, our results provide evidence for social niche construction across development, with the formation of a core social ‘bubble’ of strong ties that can provide a consistent and predictable immediate social environment. More broadly, these patterns suggest that network formation is a process of ongoing adjustment to the social environment, and not an attempt to meet an optimal end goal.
Book
Evolution of Learning and Memory Mechanisms is an exploration of laboratory and field research on the many ways that evolution has influenced learning and memory processes, such as associative learning, social learning, and spatial, working, and episodic memory systems. This volume features research by both outstanding early-career scientists as well as familiar luminaries in the field. Learning and memory in a broad range of animals are explored, including numerous species of invertebrates (insects, worms, sea hares), as well as fish, amphibians, birds, rodents, bears, and human and nonhuman primates. Contributors discuss how the behavioral, cognitive, and neural mechanisms underlying learning and memory have been influenced by evolutionary pressures. They also draw connections between learning and memory and the specific selective factors that shaped their evolution. Evolution of Learning and Memory Mechanisms should be a valuable resource for those working in the areas of experimental and comparative psychology, comparative cognition, brain–behavior evolution, and animal behavior.
Article
The social behaviour of wild animals living in groups leads to social networks with structures that produce group-level effects and position individuals within them with differential consequences for an individual’s fitness. Social dynamics in captivity can differ greatly from those in wild conspecifics given the different constraints on social organization in wild populations, e.g. group size, predation pressure, distribution of resources (food, mates), which are all regulated by human carers in captive populations. The social networks of animals in zoos is expected to differ from those of free-living conspecifics. While many studies have described the social networks of a wide diversity of wild and captive animals, none has directly compared the networks of multiple groups of a single species both in the wild and in captivity. Meerkats, Suricata suricatta, are an excellent species to compare the social networks of wild and captive groups. We replicated the methods of Madden et al. (2009, 2011), who studied eight groups in the wild, in fifteen captive groups. We tested how network structures and individual positions in grooming, foraging competition and dominance networks differed between wild and captive groups. Groups of wild and captive meerkats differed in various aspects of their social network structure. Differences in the network may be due to individuals occupying different network positions and the difference in the number and strength of their connections to other individuals. This distinct way of interacting and associating could be a result of group specific attributes, such as group size, and/or the attributes of the donor and recipient, including sex, status or age. Critically, the differences may be explained by the dissimilar living environment that each encounters.
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Here, we present a protocol for collecting data on multiple interaction types in small, stable groups of Arabian babblers (Argya squamiceps). We describe the procedure of habituation, the recording of social interactions, and how to classify the interaction types. Additionally, we provide code for testing, comparing, and visualizing data. The high-resolution data collection is time demanding and requires several data tests before forming the final protocol. The collected data can then be used for multiplex social network analysis. For complete details on the use and execution of this protocol, please refer to Dragić et al. (2021).
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Reconciliation is an aspect of conflict resolution, with similar behavioural patterns documented in non-human primates, human children, and human adults of non-Western, non-industrialized cultures. Reconciliation amongst adults of industrialized societies has rarely been studied. We observed naturally occurring conflicts between adults, captured by public security cameras in England. Reconciliation was found in one-quarter of all conflicts and was more prevalent in milder conflicts. Reconciliation typically occurred spontaneously between opponents — and was found within friendship groups and across stranger groups. Reconciliation between opponents also appeared to be stimulated by peers, law enforcement, or shared objects. In some instances, reconciliation extended beyond the initial conflict dyad toward victimized third-party peacemakers. These findings add to growing cross-cultural and cross-species evidence demonstrating the presence and function of post-conflict reconciliation. We extend the repertoire of reconciliatory behaviour and introduce five common features of reconciliation that are central to the study of adult peacemaking.
Thesis
Social learning refers to the spread of novel behaviours between individuals and is important to survival. Visual attention is generally biased towards dominant individuals and/or affiliates in social animals. Therefore, social dynamics may represent patterns of social diffusion. Communication interactions, often depicting affiliative relations, may also represent social learning opportunities. This thesis aims to explore the role of communication networks in social learning in a nonhuman primate society. Specifically, the thesis answers three questions: (1) can communication acts predict affiliative relations, (2) can social learning be identified in Barbary macaques and (3) can communication interactions represent paths of social information diffusion. To address the first question I describe a series of networks based on affiliative behaviours (grooming, huddling, proximity) and communication interactions (aid-recruitment calls and vocal comments in affiliative and agonistic contexts) in a group of Barbary macaques housed in Blair Drummond Safari Park (BDG). All affiliative behaviours, except huddling, predicted the aid-recruitment network. Vocal comments in affiliative contexts were predicted by grooming and huddling. In agonistic contexts, vocal comments occurred when the aggressor was an ally and the victim was not an affiliate. For the second and third question, extractive foraging tasks were presented to two groups of Barbary macaques independently. Three tasks of increasing difficulty were presented to a group in Trentham Monkey Forest (TG) to investigate social learning. Evidence of social transmission was found only for the most difficult tasks. For BDG and TG, communication and/or affiliative networks were compared to observation networks during task introductions. Affiliative and observation networks predicted social learning. Communication networks predicted affiliative interactions. Only vocal comments in affiliative contexts predicted observation networks. Results suggest that communication networks, which mirror social bonds, may represent social learning opportunities. Integration of communication networks into studies of social learning is a fruitful avenue for further research. http://etheses.dur.ac.uk/14140/
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The transition of housing gestating sows from individual stalls to group pens allows for a greater freedom of movement and social interactions, but it comes with many challenges to ensure group cohesion and safety of all animals. Previous research on the behavior and welfare of group housed sows has predominately focused on aggression at mixing, feeding systems, and flooring type, with little information on association patterns within the pen. In order to examine the complex direct and indirect relationships among group housed sows, this study recorded dyadic associations (defined as resting in proximity, <1.5 m) among a subset of multiparous sows (n = 129) housed in the same dynamic group pen. Stochastic simulations were used to compare the association patterns observed to random permutations of association patterns given the pen logistics. For this study pen, 13.4 % of the dyads had significantly higher associations than we would expect under the null model of completely random lying patterns, while 43 % of dyads were never recorded to rest in proximity. Distinct subpopulations demonstrating clear preferences for different subareas of the gestation pen were also found. Younger sows demonstrated association preferences above and beyond what would be expected if there were only a mutual preference for a general area of the pen. The older sows, on the other hand, seldom formed strong associations, and their distribution within the pen appears to be driven by preferences for specific lying areas rather than for resting partners. Beyond this age dynamic, our results also indicated that sows that rested most often on the slatted floors, tended to be younger, smaller, had more severe lesions and had higher feed rank scores (i.e., ate last in the day) – all indicators of lower social rank – relative to the sows which were consistently recorded in the sow cubicles (i.e., concrete lying areas). While the results of this observational study have shed some light on the factors which influence positive-to-neutral social interactions amongst sows in group housed pens, we hope that they will ultimately serve as a jumping-off point for future experimental work capable of producing more comprehensive and conclusive insights into these important social dynamics.
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Niche construction is a concept that captures a wide array of biological phenomena, from the environmental effects of metabolism to the creation of complex structures such as termite mounds and beaver dams. A central point in niche construction theory is that organisms do not just passively undergo developmental, ecological, or evolutionary processes, but are also active participants in them (Lewontin RC, In: DS Bendall (ed) Evolution: From molecules to men, Cambridge University Press, Cambridge, 1983; Laland KN, Odling-Smee J, Feldman MW, In: KN Laland and T Uller (eds) Evolutionary causation: Biological and philosophical reflections, MIT Press, Cambridge, MA, 2019). In this paper, we distinguish between two fundamentally different ways in which organisms are active participants: as agents and as contributors. Roughly, organisms act as agents when niche constructing effects are a result of a goal-directed behavior over which the organisms have some degree of control. Organisms act as contributors when the niche constructing effects do not arise from a goal to perform the constructive activity. As illustrative examples we discuss plants altering leaf-morphology to optimize light exposure as reported by Sultan (Organism and environment: Ecological development, niche construction, and adaptation. Oxford University Press, Oxford, 2015) and bacteria creating novel niches through excreting energy-rich metabolites (San Roman and Wager in PLoS Comput Biol 14: e1006340, 2018). The difference between agential and contributional niche construction is important for understanding the different ways organisms can actively participate in development, ecology, and evolution. Additionally, this distinction can increase our understanding of how the capacity of agency is distributed across the tree of life and how agency influences developmental and evolutionary processes.
Article
Third-party interventions may regulate conflicts to reduce aggression and promote cohesion amongst group members, but are rarely documented in ungulates. The white-lipped peccary (Tayassu pecari) lives in mixed-sex herds of hundreds of individuals in Neotropical forests, which are likely to benefit from mechanisms that sustain social cohesiveness. We examined third-party conflict interventions between individuals in captive groups of white-lipped peccaries. During a period of 60 days, we recorded agonistic interactions and occurrences of third-party conflict interventions, and estimated the genetic relatedness between the individuals involved using multilocus microsatellite genotypes. Most third-party conflict interventions were by the dominant male of each group, resulting in conflict termination 100% of the time. Our results also revealed that white-lipped peccaries favour their closest relatives and that individuals showed lower levels of aggression towards kin than to non-kin, and interventions on behalf of kin were more frequent than on behalf of non-kin. Our findings support the idea that genetic relatedness is fundamental in both social structure and third-party conflict interventions in this species, allowing us to suggest that kin selection could have a key role in the evolution of social behaviour of white-lipped peccaries.
Chapter
This edited volume demonstrates the potential of mixed-methods designs for the research of social networks and the utilization of social networks for other research. Mixing methods applies to the combination and integration of qualitative and quantitative methods. In social network research, mixing methods also applies to the combination of structural and actor-oriented approaches. The volume provides readers with methodological concepts to guide mixed-methods network studies with precise research designs and methods to investigate social networks of various sorts. Each chapter describes the research design used and discusses the strengths of the methods for that particular field and for specific outcomes.
Chapter
This edited volume demonstrates the potential of mixed-methods designs for the research of social networks and the utilization of social networks for other research. Mixing methods applies to the combination and integration of qualitative and quantitative methods. In social network research, mixing methods also applies to the combination of structural and actor-oriented approaches. The volume provides readers with methodological concepts to guide mixed-methods network studies with precise research designs and methods to investigate social networks of various sorts. Each chapter describes the research design used and discusses the strengths of the methods for that particular field and for specific outcomes.
Article
Social network structure is a critical group character that mediates the flow of information, pathogens and resources among individuals in a population, yet little is known about what shapes social structures. In this study, we experimentally tested whether social network structure depends on the personalities of individual group members. Replicate groups of forked fungus beetles ( Bolitotherus cornutus ) were engineered to include only members previously assessed as either more social or less social. We found that individuals expressed consistent personalities across social contexts, exhibiting repeatable numbers of interactions and numbers of partners. Groups composed of more social individuals formed networks with higher interaction rates, higher tie density, higher global clustering and shorter average shortest paths than those composed of less social individuals. We highlight group composition of personalities as a source of variance in group traits and a potential mechanism by which networks could evolve.
Chapter
This edited volume demonstrates the potential of mixed-methods designs for the research of social networks and the utilization of social networks for other research. Mixing methods applies to the combination and integration of qualitative and quantitative methods. In social network research, mixing methods also applies to the combination of structural and actor-oriented approaches. The volume provides readers with methodological concepts to guide mixed-methods network studies with precise research designs and methods to investigate social networks of various sorts. Each chapter describes the research design used and discusses the strengths of the methods for that particular field and for specific outcomes.
Chapter
This edited volume demonstrates the potential of mixed-methods designs for the research of social networks and the utilization of social networks for other research. Mixing methods applies to the combination and integration of qualitative and quantitative methods. In social network research, mixing methods also applies to the combination of structural and actor-oriented approaches. The volume provides readers with methodological concepts to guide mixed-methods network studies with precise research designs and methods to investigate social networks of various sorts. Each chapter describes the research design used and discusses the strengths of the methods for that particular field and for specific outcomes.
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Free-roaming dogs have been identified as an important reservoir of rabies in many countries including Thailand. There is a need for novel insights to improve current rabies control strategies in these countries. Network analysis is commonly used to study the interactions between individuals or organizations and has been applied in preventive veterinary medicine. However, contact networks of domestic free-roaming dogs are mostly unexplored. The objective of this study was to explore the contact network of free-roaming dogs residing on a university campus. Three one-mode networks were created using co-appearances of dogs as edges. A two-mode network was created by associating the dog with the pre-defined area it was seen in. The average number of contacts a dog had was 6.74. The normalized degree for the weekend network was significantly higher compared to the weekday network. All one-mode networks displayed small-world network characteristics. Most dogs were observed in only one area. The average number of dogs which shared an area was 8.67. In this study, we demonstrated the potential of observational methods to create networks of contacts. The network information acquired can be further used in network modeling and designing targeted disease control programs.
Chapter
This edited volume demonstrates the potential of mixed-methods designs for the research of social networks and the utilization of social networks for other research. Mixing methods applies to the combination and integration of qualitative and quantitative methods. In social network research, mixing methods also applies to the combination of structural and actor-oriented approaches. The volume provides readers with methodological concepts to guide mixed-methods network studies with precise research designs and methods to investigate social networks of various sorts. Each chapter describes the research design used and discusses the strengths of the methods for that particular field and for specific outcomes.
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Despite its recognized importance for understanding the evolution of animal sociality as well as for conservation, long term analysis of social networks of animal populations is still relatively uncommon. We investigated social network dynamics in males of a gregarious mountain ungulate (Alpine ibex, Capra ibex) over ten years focusing on groups, sub-groups and individuals, exploring the dynamics of sociality over different scales. Despite the social structure changing between seasons, the Alpine ibex population was highly cohesive: fission-fusion dynamics lead almost every male in the population to associate with each other male at least once. Nevertheless, we found that male Alpine ibex showed preferential associations that were maintained across seasons and years. Age seemed to be the most important factor driving preferential associations while other characteristics, such as social status, appeared less crucial. We also found that centrality measures were influenced by age and were also related to individual physical condition. The multi-scale and long-term frame of our study helped us show that ecological constrains, such as resource availability, may play a role in shaping associations in a gregarious species, but they cannot solely explain sociality and preferential association that are likely also to be driven by life-history linked physiological and social needs. Our results highlight the importance of long-term studies based on individually recognizable subjects to help us build on our understanding of the evolution of animal sociality.
Article
Forming groups of captive rhesus macaques (Macaca mulatta) is a common management practice. New formations of unfamiliar macaques can be costly, with high levels of trauma, particularly as intense aggression is used to establish a dominance hierarchy. Combining previous subgroups into one new group may be beneficial, as some individuals already have established dominance relationships. We tested this hypothesis by forming a new mixed-sex group of rhesus macaques that combined an established group of females with an established group of males. Prior to the mixed-sex group formation, both the female and male hierarchies had been stable for 3 y; after mixed-sex group formation these hierarchies were maintained by the females and were initially maintained by the males for 3 wks. However, the temporary hospitalization (due to a laceration caused by aggression) of the alpha male destabilized the male hierarchy. Age and weight then predicted male rank. Temporary hospitalizations resulted in rank changes for the males, evidenced by reversals in subordination signals. Thisstudy indicates that using established groups of familiar individuals may maintain female hierarchical stability in a mixed-sex group formation, but further research is needed to understand how to maintain and predict male hierarchical stability to reduce trauma. Improved knowledge of hierarchical stability would be invaluable to managers of large rhesus macaque groups and would help improve the welfare of captive rhesus macaques.
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Tras más de 15 años de investigación observando a un grupo de gorilas fuera de su hábitat natural, presentamos una investigación interdisciplinar que engloba Biología, Antropología y Derecho, que se ha enfrentado a la ausencia de estudios específicos en esta materia. Partíamos de la hipótesis de que los comportamientos regulares que habíamos detectado en el grupo de gorilas de estudio eran susceptibles de ser sistematizados aplicando criterios propiamente jurídicos. Mediante la observación ad libitum de los comportamientos de los gorilas hemos tratado de demostrar que algunos comportamientos de los individuos de nuestro grupo de gorilas de estudio responden a normas que son equivalentes a las normas jurídicas. Estas normas y sanciones que hemos encontrado están integradas en un sistema funcionalmente equivalente a nuestro Ordenamiento Jurídico-Penal, lo que nos ha permitido abrir nuevas perspectivas y plantear un origen común y la continuidad de los sistemas normativos entre distintas especies de primates.
Article
Most ungulate mammals are social species that live in large groups where agonistic encounters with con‐specifics are common. Such interactions may be a source of distress and can pose a threat to group's cohesion. Group stability may be achieved by third‐party interventions, defined as the behavior of individuals (interveners) interrupting agonistic interactions between two con‐specifics through direct physical contact, interposition, or threats. This can be costly for the intervener but may lead to benefits like reciprocity, group cohesion, and enhance lifetime fitness. The study investigated whether sheep (Ovis aries) perform third‐party interventions. Adult rams (n = 13) reared under intensive farming were observed during three different periods (A, B, C). At period A, rams formed one stable group of eight individuals. Period B started when five familiar rams returned to the group simultaneously and period C, when rams formed one stable group of 13 individuals. Scan sampling was used to record close proximity. Social behaviours between individuals were collected ad libitum to increase the number of social interactions because of the low‐sample size. In total, 125 interventions occurred. Interventions were higher in period B (N = 69; frequency = 2.55) followed by period C (N = 45; frequency = 0.56) and period A (N = 12; frequency = 0.18). Only a few individuals played a crucial role in performing this behaviour. Interventions were positively correlated with agonistic interactions. Interveners were high or middle ranked, rose faster in the social hierarchy and spent more time in social proximity. The supported animals performed more frequent affiliative behaviors. The study presents preliminary evidence of third‐party interventions in agonistic encounters of sheep, suggesting that such behaviour may act as a preventive tool towards the disruption of group stability, by enhancing long‐term fitness of interveners and supported individuals and providing valuable information for sheep welfare. Rams perform third‐party interventions when two individuals (A and B) get involved in a fight and a third individual (C) intervenes by supporting one individual (B) and targeting the other (A). High frequency of fighting was correlated with high frequency of third‐party interventions, which were performed mainly by a few individuals. The interveners were high or middle ranked, rose faster in the social hierarchy and spent more time in social proximity while the supported animals performed more frequent affiliativebehaviors.
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Group living is beneficial for individuals, but also comes with costs. One such cost is the increased possibility of pathogen transmission because increased numbers or frequencies of social contacts are often associated with increased parasite abundance or diversity. The social structure of a group or population is paramount to patterns of infection and transmission. Yet, for various reasons, studies investigating the links between sociality and parasitism in animals, especially in primates, have only accounted for parts of the group ( e.g. , only adults), which is likely to impact the interpretation of results. Here, we investigated the relationship between social network centrality and an estimate of gastrointestinal helminth infection intensity in a whole group of Japanese macaques ( Macaca fuscata ). We then tested the impact of omitting parts of the group on this relationship. We aimed to test: (1) whether social network centrality –in terms of the number of partners (degree), frequency of interactions (strength), and level of social integration (eigenvector) –was linked to parasite infection intensity (estimated by eggs per gram of faeces, EPG); and, (2) to what extent excluding portions of individuals within the group might influence the observed relationship. We conducted social network analysis on data collected from one group of Japanese macaques over three months on Koshima Island, Japan. We then ran a series of knock-out simulations. General linear mixed models showed that, at the whole-group level, network centrality was positively associated with geohelminth infection intensity. However, in partial networks with only adult females, only juveniles, or random subsets of the group, the strength of this relationship - albeit still generally positive - lost statistical significance. Furthermore, knock-out simulations where individuals were removed but network metrics were retained from the original whole-group network showed that these changes are partly a power issue and partly an effect of sampling the incomplete network. Our study indicates that sampling bias can thus hamper our ability to detect real network effects involving social interaction and parasitism. In addition to supporting earlier results linking geohelminth infection to Japanese macaque social networks, this work introduces important methodological considerations for research into the dynamics of social transmission, with implications for infectious disease epidemiology, population management, and health interventions.
Chapter
Evolution of Learning and Memory Mechanisms is an exploration of laboratory and field research on the many ways that evolution has influenced learning and memory processes, such as associative learning, social learning, and spatial, working, and episodic memory systems. This volume features research by both outstanding early-career scientists as well as familiar luminaries in the field. Learning and memory in a broad range of animals are explored, including numerous species of invertebrates (insects, worms, sea hares), as well as fish, amphibians, birds, rodents, bears, and human and nonhuman primates. Contributors discuss how the behavioral, cognitive, and neural mechanisms underlying learning and memory have been influenced by evolutionary pressures. They also draw connections between learning and memory and the specific selective factors that shaped their evolution. Evolution of Learning and Memory Mechanisms should be a valuable resource for those working in the areas of experimental and comparative psychology, comparative cognition, brain–behavior evolution, and animal behavior.
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In many animal societies, individuals differ consistently in their ability to win agonistic interactions, resulting in dominance hierarchies. These differences arise due to a range of factors that can influence individuals’ abilities to win agonistic interactions, spanning from genetically driven traits through to individuals’ recent interaction history. Yet, despite a century of study since Schjelderup‐Ebbe's seminal paper on social dominance, we still lack a general understanding of how these different factors work together to determine individuals’ positions in hierarchies. Here, we first outline five widely studied factors that can influence interaction outcomes: intrinsic attributes, resource value asymmetry, winner–loser effects, dyadic interaction‐outcome history and third‐party support. A review of the evidence shows that a variety of factors are likely important to interaction outcomes, and thereby individuals’ positions in dominance hierarchies, in diverse species. We propose that such factors are unlikely to determine dominance outcomes independently, but rather form part of feedback loops whereby the outcomes of previous agonistic interactions (e.g. access to food) impact factors that might be important in subsequent interactions (e.g. body condition). We provide a conceptual framework that illustrates the multitude potential routes through which such feedbacks can occur, and how the factors that determine the outcomes of dominance interactions are highly intertwined and thus rarely act independently of one another. Further, we generalise our framework to include multi‐generational feed‐forward mechanisms: how interaction outcomes in one generation can influence the factors determining interaction outcomes in the next generation via a range of parental effects. This general framework describes how interaction outcomes and the factors determining them are linked within generations via feedback loops, and between generations via feed‐forward mechanisms. We then highlight methodological approaches that will facilitate the study of feedback loops and dominance dynamics. Lastly, we discuss how our framework could shape future research, including: how feedbacks generate variation in the factors discussed, and how this might be studied experimentally; how the relative importance of different feedback mechanisms varies across timescales; the role of social structure in modulating the effect of feedbacks on hierarchy structure and stability; and the routes of parental influence on the dominance status of offspring. Ultimately, by considering dominance interactions as part of a dynamic feedback system that also feeds forward into subsequent generations, we will understand better the factors that structure dominance hierarchies in animal groups.
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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...
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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.
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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.
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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
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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.
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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.
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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
Chapter
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.
Article
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.
Article
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.
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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.
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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
Book
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.
Article
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.
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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 ...
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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.
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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.
Article
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.
Article
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.
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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.
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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.
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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').
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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.
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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.
Article
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.
Article
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.).