Group Social Structure Research Articles

The Human Sleep Paradox: The Unexpected Sleeping Habits ofHomo sapiens

The human sleep pattern is paradoxical. Sleep is vital for optimal physical and cognitive performance, yet humans sleep the least of all primates. In addition, consolidated and continuous monophasic sleep is evidently advantageous, yet emerging comparative data sets from small-scale societies show that the phasing of the human pattern of sleep–wake activity is highly variable and characterized by significant nighttime activity. To reconcile these phenomena, the social sleep hypothesis proposes that extant traits of human sleep emerged because of social and technological niche construction. Specifically, sleep sites function as a type of social shelter by way of an extended structure of social groups that increases fitness. Short, high-quality, and flexibly timed sleep likely originated as a response to predation risks while sleeping terrestrially. This practice may have been a necessary preadaptation for migration out of Africa and for survival in ecological niches that penetrate latitudes with the greatest seasonal variation in light and temperature on the planet.

Selection on heritable social network positions is context-dependent in Drosophila melanogaster

Social group structure is highly variable and can be important for nearly every aspect of behavior and its fitness consequences. Group structure can be modeled using social network analysis, but we know little about the evolutionary factors shaping and maintaining variation in how individuals are embedded within their networks (i.e., network position). While network position is a pervasive target of selection, it remains unclear whether network position is heritable and can respond to selection. Furthermore, it is unclear how environmental factors interact with genotypic effects on network positions, or how environmental factors shape selection on heritable network structure. Here we show multiple measures of social network position are heritable, using replicate genotypes and replicate social groups of Drosophila melanogaster flies. Our results indicate genotypic differences in network position are largely robust to changes in the environment flies experience, though some measures of network position do vary across environments. We also show selection on multiple network position metrics depends on the environmental context they are expressed in, laying the groundwork for better understanding how spatio-temporal variation in selection contributes to the evolution of variable social group structure.

Kinship does not predict the structure of a shark social network

AbstractGenetic relatedness in animal societies is often a factor that drives the structure of social groups. In the marine world, most studies which have investigated this question have focused on marine mammals such as whales and dolphins. For sharks, recent studies have demonstrated preferential associations among individuals from which social communities emerge. Assortment patterns have been found according to phenotypic or behavioral traits, but the role of genetic relatedness in shaping the social structure of adult shark populations has, to the best of our knowledge, never been investigated. Here, we used a social network analysis crossed with DNA microsatellite genotyping to investigate the role of the genetic relatedness in the social structure of a blacktip reef shark (Carcharhinus melanopterus) population. Based on the data from 156 groups of sharks, we used generalized affiliation indices to isolate social preferences from nonsocial associations, controlling for the contribution of sex, size, gregariousness, spatial, and temporal overlap on social associations, to test for the influence of genetic relatedness on social structure. A double-permutation procedure was employed to confirm our results and account for issues arising from potentially elevated type I and type II error rates. Kinship was not a predictor of associations and affiliations among sharks at the dyad or community levels as individuals tended to associate independently of the genetic relatedness among them. The lack of parental care in this species may contribute to the breakdown of family links in the population early in life, thereby preventing the formation of kin-based social networks.

Strandings provide insight into social group structure of Atlantic white‐sided dolphins

AbstractAtlantic white‐sided dolphins (Lagenorhynchus acutus) are highly social odontocetes with a poorly understood tendency to mass strand. With limited capacity to study social ecology in the open ocean, mass strandings provide an opportunity to improve our understanding of group structure. Our study of 32 mass stranding events that occurred on Cape Cod, Massachusetts, between 1999 and 2009 identifies aspects of social ecology that vary across the year. A greater number of mass stranding events occurred outside of the breeding season and there was evidence of age‐structuring during the breeding season. We find generally low average intragroup pairwise relatedness assessed across eight microsatellite loci in a subset of 16 mass stranding events. Mass stranded groups do not show higher than expected relatedness when compared to a baseline estimate derived from single‐stranded individuals. Overall, our integration of genetic estimates of relatedness with data on sex and maturity‐class from stranded specimens suggests that Atlantic white‐sided dolphins fall near the more fluid end of the continuum from short‐term, highly fluid social associations to long‐term, stable groups represented among the odontocetes. Despite their tendency to mass strand, stable, kin‐based associations are not a defining feature of social group structure in this species.

Larger workers outperform smaller workers across resource environments: An evaluation of demographic data using functional linear models.

Behavior and organization of social groups is thought to be vital to the functioning of societies, yet the contributions of various roles within social groups toward population growth and dynamics have been difficult to quantify. A common approach to quantifying these role‐based contributions is evaluating the number of individuals conducting certain roles, which ignores how behavior might scale up to effects at the population‐level. Manipulative experiments are another common approach to determine population‐level effects, but they often ignore potential feedbacks associated with these various roles.Here, we evaluate the effects of worker size distribution in bumblebee colonies on worker production in 24 observational colonies across three environments, using functional linear models. Functional linear models are an underused correlative technique that has been used to assess lag effects of environmental drivers on plant performance. We demonstrate potential applications of this technique for exploring high‐dimensional ecological systems, such as the contributions of individuals with different traits to colony dynamics.We found that more larger workers had mostly positive effects and more smaller workers had negative effects on worker production. Most of these effects were only detected under low or fluctuating resource environments suggesting that the advantage of colonies with larger‐bodied workers becomes more apparent under stressful conditions.We also demonstrate the wider ecological application of functional linear models. We highlight the advantages and limitations when considering these models, and how they are a valuable complement to many of these performance‐based and manipulative experiments.

Dominance and Leadership in the Equine Social Structure: A Preliminary Study About Mules and Sex Influence

Little is known about the dominance and leadership behaviors in the social structure of mules (Equus caballus × Equus asinus). Based on the frequency of threat and aggressive behaviors, we compared the social structure, dominance, and leadership of independent groups of mules and horses (n = 11 per group), and filmed the frequency of these behaviors over a period of four days. In both groups, aggressions were uncommon and, when based on threats, the social structure was linear and consistent with males ranking higher in dominance. When compared to horses, mules exhibited some agonistic social interactions without a recognized submissive individual and displayed more specific aggressive behaviors, whereas horses presented more specific threat behaviors. Comparing between groups, mares exhibited more leader behaviors than female mules, in contrast to male horses which showed fewer leader behaviors than male mules. Regarding behaviors within the mule group, males showed more leader and threat behaviors than females, while females showed more frequent aggression. While in horses, the females showed more leader behaviors than male horses and, although there were differences in specific agonistic behaviors, both sexes presented more often threat behaviors. In this preliminary study, we conclude that the social structure of mules, although similar to those of horses, showed to be less stable, since it involves more aggression and agonistic social interactions without a submissive. Moreover, although mules did not present a sex influence on leadership as horses did, they presented it on aggression: females showed more aggression than males.

THE FORMATION OF COLLECTIVE SUBJECTS’ SMALL SOCIAL GROUPS IN THE INFORMATION AGE (PROBLEM OF IDENTITY)social groups in the information age (problem of identity)

The article takes a new look at the impact of artificial intelligence (AI) technology on society, which leads to the formation of fundamentally new social groups. The greatest diversity and freedom of development will be allocated to small social groups that directly interact with AI. The model of the new social group should answer the following questions: what opportunities does AI offer? What role can AI play in a small social group? How will people identify with a similar group? The description of the structure of small social groups was used, the multisubject role of the organizer and intermediary of the AI was determined. The concept of «situational community» was used to reveal the equilibrium structure of such groups, where either individual or group identity dominates. In some situations, the AI will be able to replace the person who has left the group as a leader, or to ensure strict observance of the settings that are unchanged for the group, or to play the role of an implicit collective organizer, which, in order to preserve the integrity of the group, transforms its goals and objectives. Small social groups, thanks to AI, will gain access to professional skills and tools for organizing labor that previously had larger social structures. An increase in subjectivity can lead to significant transformations and a change in the role of these social groups. A threat has been identified: the individual may not be able to independently abandon his behavioral-cognitive and emotional identification with the group.

Community structure of domesticated pigs in livestock facilities

The social structure of animal groups is considered to have an impact on their health and welfare. This could also be true for animals under commercial conditions, but research in this area has been limited. Pigs for example are known to be very social animals, but information about their grouping behavior is mostly derived from wild boars and a limited number of studies in seminatural and commercial conditions. Specifically under commercial conditions it is still unclear to what extent pig herds organize themselves in subgroups and how such group patterns emerge. To answer these questions, we tracked the positions of about 200 sows inside a barn during ongoing production over a period of five weeks and used these data to construct and analyze the animal contact networks. Our analysis showed a very high contact density and only little variation in the number of other animals that a specific animal is in contact with. Nevertheless, in each week we consistently detected three subgroups inside the barn, which also showed a clear spatial separation. Our results show that even in the high density environment of a commercial pig farm, the behavior of pigs to form differentiated groups is consistent with their behavior under seminatural conditions. Furthermore, our findings also imply that the barn layout could play an important role in the formation of the grouping pattern. These insights could be used to monitor and understand the spread of infectious diseases inside the barn better. In addition, our insights could potentially be used to improve the welfare of pigs.

Relatedness within and between Agta residential groups.

Theoretical models relating to the evolution of human behaviour usually make assumptions about the kinship structure of social groups. Since humans were hunter-gatherers for most of our evolutionary history, data on the composition of contemporary hunter-gatherer groups has long been used to inform these models. Although several papers have taken a broad view of hunter-gatherer social organisation, it is also useful to explore data from single populations in more depth. Here, we describe patterns of relatedness among the Palanan Agta, hunter-gatherers from the northern Philippines. Across 271 adults, mean relatedness to adults across the population is r = 0.01 and to adult campmates is r = 0.074, estimates that are similar to those seen in other hunter-gatherers. We also report the distribution of kin across camps, relatedness and age differences between spouses, and the degree of shared reproductive interest between camp mates, a measure that incorporates affinal kinship. For both this this measure (s) and standard relatedness (r), we see no major age or sex differences in the relatedness of adults to their campmates, conditions that may reduce the potential for conflicts of interest within social groups.

The Structure of Religion, Ethnicity, and Insurgent Mobilization

ABSTRACTThis article problematizes the social structure of ethnic groups to account for variation in insurgent mobilization within and across ethnic groups. Relying on network-based approaches to social structure, it argues that insurgent mobilization is constrained by the structural connectivity of the ethnic group, a measure of the extent to which subethnic communities—neighborhoods, villages, clans, and tribes—are socially connected internally and with each other. In agrarian societies, structural connectivity is traced to religion. On the basis of unique data on rebel recruitment from the Mizo insurgency in India and microlevel variations in changes associated with the spread of Christianity among Mizos, the author demonstrates that enhanced structural connectivity resulting from a network of highly centralized churches and institutions under the Welsh Presbyterian Mission significantly bolstered insurgent recruitment. Semistructured interviews of Mizo insurgents and ethnographic evidence from the neighboring Meitei and Naga ethnic insurgencies further support the argument and the casual mechanism.

재한조선족 집거지 내부의 사회단체조직설립 특징과 함의

한국은 다문화 사회로의 준비가 부족한 상황에서 진입하였지만, 다양한 대내외적인 요 인을 극복하면서 다문화 국가로서 발전하고 있다. 이 과정에서 같은 민족인 재한조선족들 의 사회단체조직설립은 2004년의 재외동포법 개정과 2007년의 방문취업제도 실시이후 더 욱 활성화되었고, 자신들만의 집거지를 중심으로 다양한 단체들이 설립되어 왔다. 재한조 선족들의 사회단체조직설립 특징은 다음과 같다. 첫째, 사회단체설립조직이 한국 사회와 의 공존보다는 자신들만의 이익과 문제 해결을 위함에 있다. 둘째, 사회단체조직설립을 통 해 중국소수민족으로서 정체성 형성을 강화하고 있다. 셋째, 사회단체조직설립에서 중국 정부를 대변하는 모양으로 단체가 설립되었고 이면에는 또 다른 정치적 목적이 있다. 이러 한 특징을 토대로 이들 사회단체조직설립의 함의는 다음과 같다. 첫째, 재한조선족들은 한 국 이주초기와는 달리 자신들에게 부여되었던 권한을 집단형태로 활용하면서 정치성 발언 까지 표현하는 적극적 참여주체로서 변화하였다. 둘째, 재한조선족들은 한국사회의 구성 원으로서 한국문화의 특수성에 대한 이해 및 한국사회로의 동화 시도를 통해 한국사회 구 성원으로서 인정을 합법적으로 요구하고 있다. 셋째, 재한조선족들은 한국사회와의 수평 적인 민족관계형성과 관련 법률 및 제도적 사회적 구조 개정에 대해 지속적으로 요구하고 있다.

Early Life Experience Shapes Male Behavior and Social Networks in Drosophila

Living in a group creates a complex and dynamic environment in which behavior of individuals is influenced by and affects the behavior of others. Although social interaction and group living are fundamental adaptations exhibited by many organisms, little is known about how prior social experience, internal states, and group composition shape behavior in groups. Here, we present an analytical framework for studying the interplay between social experience and group interaction in Drosophila melanogaster. We simplified the complexity of interactions in a group using a series of experiments in which we controlled the social experience and motivational states of individuals to compare behavioral patterns and social networks of groups under different conditions. We show that social enrichment promotes the formation of distinct group structure that is characterized by high network modularity, high inter-individual and inter-group variance, high inter-individual coordination, and stable social clusters. Using environmental and genetic manipulations, we show that visual cues and cVA-sensing neurons are necessary for the expression of social interaction and network structure in groups. Finally, we explored the formation of group behavior and structure in heterogenous groups composed of flies with distinct internal states and documented emergent structures that are beyond the sum of the individuals that constitute it. Our results demonstrate that fruit flies exhibit complex and dynamic social structures that are modulated by the experience and composition of different individuals within the group. This paves the path for using simple model organisms to dissect the neurobiology of behavior in complex social environments.

Social interaction, and not group size, predicts parasite burden in mammals

Although parasitism is often considered a cost of sociality, the evidence is mixed, possibly because sociality is multivariate. Here we contrast the dependence of parasitism costs on major social variables such as group size and social structure, as measured by network metrics. We conduct two robust phylogenetic meta-analyses, comprising 43 published results for studies with group size and 32 results with social structure metrics. This is the first meta-analytical test of this hypothesis for mammals as a whole. Contrarily to theoretical expectations and previous meta-analyses, there is no relationship between group size and parasitism, but we find conflicting results when analysing different aspects of sociality. Our analysis reveals that social structure is connected to parasite load, possibly because contact between group members, and not group size, is linked to parasite transmission. While more intensely interconnected groups facilitate parasite transmission, large groups are frequently fragmented into smaller, weakly connected subgroups. Strong social modularisation should thus be favoured by natural selection to hamper parasite overload. Future empirical studies should focus on specific parameters of social network structure and on parasite transmissibility. If social structure can evolve fast, even culturally, then host/parasites evolutionary games enter into a whole new fast dynamics, and animal conservation studies should take advantage of this possibility.

Szervezeti relációk a japán ipari vállalkozási kultúrában

The present article develops a practical operational view of Ruth Benedict’s shame and guilt culture concept as one of the attributes which might characterize the structure and operation of Japanese social groups. After giving a short overview of critical approaches to this concept, several norm-forming, normoperating and sanctioning practices are examined in relation to the aspect of shame and guilt reactions from the everyday lives of intercultural industrial organizations (companies) located in Hungary, featuring Japanese company cultural elements in their operation. The evaluation and analysis of several related phenomena are conducted on the basis of fieldwork, involving further sociological concepts such as relational subjectivism, kanjin 閑人, shikaku 資格 and ba 場, chū 忠 and kō 孝, giri 義理 and ninjō 人情, wa 和, amae 甘えand others.

Human caregivers are integrated social partners for captive chimpanzees.

In a captive environment, it is challenging to ensure the highest level of social and psychological well-being for species with naturally complex social organizations and structures. There is a growing need to meet the social requirements for individuals of these species, especially chimpanzees, housed in zoos, sanctuaries, rehabilitation centers, and laboratories. Complex social interactions and broader social structures can be aptly described via social network analysis. We expand on the literature regarding captive chimpanzee social networks, but uniquely consider their human caregivers as potential social partners. We observed the social interactions between one group of seven chimpanzees (Pan troglodytes) and their caregivers in six behavioral contexts (nearest neighbor, play, aggression, grooming, grooming solicitation, and social vigilance) at Chimpanzee Sanctuary Northwest (USA). By constructing multiple chimpanzee and chimpanzee-caregiver social networks, our results indicate that caregivers are integrated partners in this group's social structure. Additionally, we observed that the type and strength of chimpanzee-caregiver relationships varied between the chimpanzees. These results support the notion that caregivers offer additional opportunities (i.e., beyond those with conspecifics) for captive chimpanzees to construct and maintain meaningful social relationships. Our results show that considerations of captive primate social dynamics should include caregivers as potentially important social partners. Our results also highlight the importance of evaluating individual chimpanzee characteristics when developing philosophies of care and adopting husbandry practices that offer fulfilling social niches. Our findings bear influence oncontemporary discussions of interspecies social relationships, captive welfare, health, translocation, and husbandry protocols for captive chimpanzees and other nonhuman primates.

Modelling and inference for the movement of interacting animals

Abstract Statistical modelling of animal movement data is a rapidly growing area of research. Typically though, these models have been developed for analysing the tracks of individual animals and we lose sight of the impact animals have on each other with regards to their movement behaviours. We aim to develop a model with a flexible social framework that allows us to capture that information. Our approach is based on the concept of social hierarchies, and this is embedded in a multivariate diffusion process which models the movement of a group of animals. The possibility of switching between behavioural states facilitates dynamic social behaviours and we augment the observed data with sampled state switching times in order to model the animals' behaviour naturally in continuous time. In addition, this enables us to carry out exact inference in a Bayesian setting with the benefits of being able to handle regular, irregular and missing data. All movement and behaviour parameters are estimated with Markov chain Monte Carlo methods. We examine the capability of our model with simulated data before fitting it to GPS locations of five wild olive baboons Papio anubis. The results enable us to identify which animals are influencing the movement of others and when, which provides both a dynamic and long‐term static insight into the group's social behaviours. Our model offers a flexible method in continuous time with which to model the network of social interactions within animal movement. Doing so avoids the limitations caused by a discrete‐time approach and it allows us to capture rich information with regards to a group's social structure, leading to constructive applications in conservation and management decisions. However, currently it is a computationally expensive task to fit the model to data, which in turns limits extending the model to more fruitful but complex cases such as heterogeneity in space or individual characteristics. Furthermore, our social hierarchy approach assumes all relevant animals are tracked and that any interactions have some ordering, both of which narrow the scope within which this approach is appropriate.

Breeders are less active foragers than non-breeders in wild Damaraland mole-rats.

Eusocial societies are characterized by a clear division of labour between non-breeding workers and breeding queens, and queens often do not contribute to foraging, defence and other maintenance tasks. It has been suggested that the structure and organization of social mole-rat groups resembles that of eusocial insect societies. However, the division of labour has rarely been investigated in wild mole-rats, and it is unknown whether breeders show decreased foraging activity compared with non-breeding helpers in natural groups. Here, we show that, in wild Damaraland mole-rats (Fukomys damarensis), breeders show lower activity in foraging areas than non-breeding group members. Both breeders and non-breeders displayed variation in activity across the different seasons. Our results suggest that group living allows social mole-rat breeders to reduce their investment in energetically costly behaviour, or alternatively, that the high cost of reproduction in this species forces a behavioural trade-off against foraging investment.

Extreme and variable environmental temperatures are linked to reduction of social network cohesiveness in a highly social passerine

Organisms living in hot, arid environments face important risks associated with hyperthermia and dehydration which are expected to become more severe with climate change. To mitigate these risks, individuals often modify behaviour, e.g. reducing activity and seeking shade. These behavioural modifications may affect interactions between individuals, with consequences for the social structure of groups. We tested whether the social structure of cooperative groups of sociable weavers Philetairus socius varied with environmental temperature. We recorded the nature and frequency of interactions at feeders positioned beneath three sociable weaver colonies (n = 49 identified birds) in the Kalahari Desert with respect to environmental temperatures over a 30‐day period. Using random forest models, we examined whether thermal conditions predicted variation in social network structure. We also conducted focal observations of individual weavers to assess functional links between temperature, intensity of heat dissipation behaviour (panting) and immediate effects on social behaviour. Our results suggest that the social structure of weaver colonies becomes less cohesive and more fragmented at extreme and variable environmental temperatures. These changes in network structure appear to be linked with individuals’ heat dissipation behaviour: extreme and variable temperatures were associated with increased panting, which was significantly correlated with an immediate reduction in the frequency of association. Collectively, our results indicate that interactions within groups could be disturbed by environmental temperature variation and extremes. Changing temperature regimes could therefore affect the functioning of animal societies by altering social networks.

The brain of the African wild dog. II. The olfactory system.

Employing a range of neuroanatomical stains, we detail the organization of the main and accessory olfactory systems of the African wild dog. The organization of both these systems follows that typically observed in mammals, but variations of interest were noted. Within the main olfactory bulb, the size of the glomeruli, at approximately 350 μm in diameter, are on the larger end of the range observed across mammals. In addition, we estimate that approximately 3,500 glomeruli are present in each main olfactory bulb. This larger main olfactory bulb glomerular size and number of glomeruli indicates that enhanced peripheral processing of a broad range of odorants is occurring in the main olfactory bulb of the African wild dog. Within the accessory olfactory bulb, the glomeruli did not appear distinct, rather forming a homogenous syncytia-like arrangement as seen in the domestic dog. In addition, the laminar organization of the deeper layers of the accessory olfactory bulb was indistinct, perhaps as a consequence of the altered architecture of the glomeruli. This arrangement of glomeruli indicates that rather than parcellating the processing of semiochemicals peripherally, these odorants may be processed in a more nuanced and combinatorial manner in the periphery, allowing for more rapid and precise behavioral responses as required in the highly social group structure observed in the African wild dog. While having a similar organization to that of other mammals, the olfactory system of the African wild dog has certain features that appear to correlate to their environmental niche.

Long-term overlap of social and genetic structure in free-ranging house mice reveals dynamic seasonal and group size effects.

Associating with relatives in social groups can bring benefits such as reduced risk of aggression and increased likelihood of cooperation. Competition among relatives over limited resources, on the other hand, can induce individuals to alter their patterns of association. Population density might further affect the costs and benefits of associating with relatives by altering resource competition or by changing the structure of social groups; preventing easy association with relatives. Consequently, the overlap between genetic and social structure is expected to decrease with increasing population size, as well as during times of increased breeding activity. Here, we use multi-layer network techniques to quantify the similarity between long-term, high resolution genetic, and behavioral data from a large population of free-ranging house mice (Mus musculus domesticus), studied over 10 years. We infer how the benefit of associating with genetically similar individuals might fluctuate in relation to breeding behavior and environmental conditions. We found a clear seasonal effect, with decreased overlap between social and genetic structure during summer months, characterized by high temperatures and high breeding activity. Though the effect of overall population size was relatively weak, we found a clear decrease in the overlap between genetic similarity and social associations within larger groups. As well as longer-term within-group changes, these results reveal population-wide short-term shifts in how individuals associate with relatives. Our study suggests that resource competition modifies the trade-off between the costs and benefits of interacting with relatives.