Kin-based Groups Research Articles

Vocal recognition of former group members, but not unknown kin, in the cooperatively breeding southern pied babbler

Studies of vocal kin recognition in avian species have typically tested responses to vocal signals based upon either familiarity (recognition via ‘learned associations’) or relatedness (recognition of genetic kin) but have rarely simultaneously tested for the effects of both. Here we examined vocal kin recognition in the cooperatively breeding southern pied babbler, Turdoides bicolor, using vocalizations from familiar kin, unfamiliar kin, familiar nonkin and unfamiliar nonkin in a playback experiment. We found limited support for recognition based upon familiarity: individuals appeared to be recognized from a period of prior association and associative learning. Focal birds (dominant females) discriminated familiar birds from unfamiliar birds, but discrimination was evident in only one of three behavioural response measures. Focal birds did not discriminate familiar kin from familiar nonkin, nor did they discriminate unfamiliar kin from unfamiliar nonkin, indicating no support for vocal recognition based on relatedness. The context of the experiment also affected discrimination, with focal birds reacting more strongly to calls from females (potential rivals) than to calls from males. Because familiarity in this species arises from the association of individuals in groups, and most groups comprise close kin, familiarity with group members offers a close proxy for kin recognition. While kin recognition systems based upon familiarity do not allow the identification of unfamiliar kin, the benefits of such recognition may be negligible in cooperatively breeding species that live in kin-based groups.

Staging to join non-kin groups in a classical cooperative breeder, the Florida scrub-jay.

Why unrelated members form groups in animal societies remains a pertinent topic in evolutionary biology because benefits for group members often are not obvious. We studied subordinates that disperse to join unrelated social groups in the Florida scrub-jay Aphelocoma coerulescens, a cooperative breeding species mainly composed of kin-based groups. We evaluated potential adaptive benefits of dispersing to become an unrelated helper (staging) versus remaining home and dispersing only to pair and breed (direct dispersal) to understand why non-kin-based groups form. Using 35years of demographic data, we quantified life-history aspects of staging individuals and tested associations between social and ecological factors on the natal and staging territories. We compared fitness outcomes between dispersal strategies by analysing survival, breeding recruitment and direct reproductive output. We tested for sexual asymmetry potentially driven by differences in territory acquisition patterns and female-biased dispersal for this species. Of birds that reached 1year, 28% staged at a non-natal territory before breeding or disappearing. Staging dispersers departed at younger ages and moved greater distances than direct dispersers. When looking at proximate factors on the natal territory associated with staging, males left groups with many same-sex helpers, while females often left when their father disappeared. For both sexes, staging individuals more likely came from high-quality territories and joined groups with fewer same-sex helpers than in their natal group. While staging and direct dispersers did not differ in survival or likelihood of becoming a breeder, staging males became breeders later and had lower lifetime reproductive success than direct dispersers. In Florida scrub-jays, staging appears to be an alternative strategy for female helpers, but a best-of-a-bad-situation for males. This sexual asymmetry is consistent with males having more options than females to achieve higher reproductive success by breeding near home. Trade-offs in cost-benefits of departing the natal territory and joining unrelated groups as a helper seem to best explain alternative dispersal patterns, with optimal social queues primarily driving the benefits. This research highlights plasticity in dispersal behaviour in response to social and environmental conditions and offers a new perspective in our understanding of non-kin-based social groups.

Why do great and little traditions coexist in the world’s doctrinal religions?

ABSTRACT Anthropologists and historians of religion have commonly contrasted “great” (literate, authoritative, and centrally regulated) traditions with “little” (popular, unauthorized, and locally variable) traditions. These two dimensions of doctrinal religion are thought to be a product of divergent patterns of learning and cultural transmission. It is common for the official representatives of doctrinal religions to portray the unauthorized practices of little traditions pejoratively as amoral superstitions. Here, we consider an alternative theory, that great and little traditions are a product of distinct forms of cooperation: the one focused on loyalty to large-scale categories evolving via cultural group selection, the other focused on advancing the interests of kin-based relational ties evolving via intra-group selection. To investigate this theory further, we carried out a series of studies with followers of great and little traditions within Burmese Theravada Buddhism, showing overall that great tradition affiliation involves stronger alignment with categorical large-scale groups, while little tradition affiliation involves stronger alignments with relational kin-based groups. We propose an empirically-grounded general theory of the evolutionary processes and psychological mechanisms underlying the bifurcation between great and little traditions in the world’s doctrinal religions.

Protection from harvesting restores the natural social structure of eastern wolf packs

Legal and illegal killing of animals near park borders can significantly increase the threat of extirpation for populations living within ecological reserves, especially for wide-ranging large carnivores that regularly travel into unprotected areas. While the consequences of human-caused mortality near protected areas generally focus on numerical responses, little attention has been given to impacts on social dynamics. For wolves, pack structure typically constitutes an unrelated breeding pair, their offspring, and close relatives, but intense harvest may increase adoption of unrelated individuals into packs. Concerns that high human-caused mortality outside Algonquin Park, Canada threatened the persistence of eastern wolves, led to implementation of a harvest ban in surrounding townships. We combined ecological and genetic data to show that reducing anthropogenic causes of mortality can restore the natural social structure of kin-based groups despite the absence of a marked change in density. Since implementation of the harvest ban, human-caused mortality has decreased ( P = 0.000006) but been largely offset by natural mortality, such that wolf density has remained relatively constant at approximately three wolves/100 km 2. However, the number of wolf packs with unrelated adopted animals has decreased from 80% to 6% ( P = 0.00003). Despite the high kinship within packs, incestuous matings were rare. Our results indicate that even in a relatively large protected area, human harvesting outside park boundaries can affect evolutionarily important social patterns within protected areas. This research demonstrates the need for conservation policy to consider effects of harvesting beyond influences on population size.

The evolution of cooperative breeding in birds: kinship, dispersal and life history

The evolution of cooperation among animals has posed a major problem for evolutionary biologists, and despite decades of research into avian cooperative breeding systems, many questions about the evolution of their societies remain unresolved. A review of the kin structure of avian societies shows that a large majority live in kin-based groups. This is consistent with the proposed evolutionary routes to cooperative breeding via delayed dispersal leading to family formation, or limited dispersal leading to kin neighbourhoods. Hypotheses proposed to explain the evolution of cooperative breeding systems have focused on the role of population viscosity, induced by ecological/demographic constraints or benefits of philopatry, in generating this kin structure. However, comparative analyses have failed to generate robust predictions about the nature of those constraints, nor differentiated between the viscosity of social and non-social populations, except at a coarse level. I consider deficiencies in our understanding of how avian dispersal strategies differ between social and non-social species, and suggest that research has focused too narrowly on population viscosity and that a broader perspective that encompasses life history and demographic processes may provide fresh insights into the evolution of avian societies.

A Property Rights Approach to Understanding Human Displacement from Protected Areas: the Case of Marine Protected Areas

The physical, economic, and sociocultural displacement of local peoples from protected areas generates intense discussion among scholars and policy makers. To foster greater precision and clarity in these discussions, we used a conceptual framework from the political economy literature to examine different forms of human displacement from protected areas. Using marine protected areas (MPAs) to ground our analysis, we characterized the 5 types of property rights that are reallocated (lost, secured, and gained) through the establishment of protected areas. All forms of MPA "displacement" involve reallocation of property rights, but the specific types and bundles of rights lost, secured, and gained dramatically shape the magnitude, extent, and equity of MPA impacts--positive and negative--on governance, economic well-being, health, education, social capital, and culture. The impacts of reallocating rights to MPA resources vary within and among social groups, inducing changes in society, in patterns of resource use, and in the environment. To create more environmentally sustainable and socially just conservation practice, a critical next step in conservation social science research is to document and explain variation in the social impacts of protected areas.

A Model of Social Organization and the Evolution of Food Sharing in Vampire Bats

This article is aimed at exploring the role of groups in the evolution of a well-known form of altruism: blood sharing among vampire bats. In particular, we are interested in the formation and maintenance of new social structures (roosts) from initial populations as a consequence of both demographic growth and social organization. The example of vampire bats is especially interesting because of the flexible roost-switching behavior shown by these animals in nature. The main hypothesis made in this article concerns the role of grooming networks in roost formation, and was investigated by means of simula tion grounded on ethological evidence. The use of simulation allows the discussion of generative hypotheses on the origin of roosts, which are emergent from individual behavior. Besides confirming the main expectations, the results point to the need for a natural ordering in grooming partner selection. This ordering can be obtained not only through kin-based groups but also through the maintenance of a non kin-based precedence rule.

Social Construction and the Concept of Race

There has been little serious work to integrate the constructionist approach and the cognitive/evolutionary approach in the domain of race, although many researchers have paid lip service to this project. We believe that any satisfactory account of human beings’ racialist cognition has to integrate both approaches. In this paper, we propose to move toward this integration. We present an evolutionary hypothesis that rests on a distinction between three kinds of groups—kin-based groups, small scale coalitions, and ethnies. Following Gil-White (1999, 2001a, 2001b), we propose that ethnies have raised specific evolutionary challenges that were solved by an evolved cognitive system. We suggest that the concept of race is a byproduct of this mechanism. We argue that recent theories of cultural transmission are our best hope for integrating social constructionists’ and cognitive/evolutionary theorists’ insights.

Top-down or bottom-up: rural settlement and raised field agriculture in the Lake Titicaca Basin, Bolivia

Differing interpretations regarding the organization of past intensive farming are often distinguished as “top-down” or “bottom-up” perspectives. The development of intensive farming and its social organization are attributed to either nascent states and centralized governments or the incremental work of local communities or kin-based groups. We address the social organization of raised field farming in one region of the Lake Titicaca Basin of the Andean altiplano, Bolivia. We evaluate past research in the Katari Valley, including our own, based on recent settlement survey, excavation, and a variety of analyses. Taking a long-term perspective covering 2500 years, we find that relations of production and rural organization changed greatly over time in relation to changing sociopolitical conditions. Local communities played dynamic roles in the development and organization of raised field farming, yet its intensification and ultimate recession were keyed to the consolidation and decline of the Tiwanaku state. We conclude that the top-down/bottom-up dichotomy is overdrawn. Local communities and their productive practices never operated in a political or economic vacuum but both shaped and were transfigured by regional processes of state formation, consolidation, and fragmentation.

Kinship and sociality in coastal river otters: are they related?

Previous studies of coastal river otters (Lontra canadensis) in Prince William Sound, Alaska, USA, documented atypical social organization for mammals. Social groups were composed largely of males, but some males remained solitary year-round and most females were asocial. Because, in carnivores, groups are usually composed of highly related individuals but group living also provides advantages unrelated to kinship, we concurrently evaluated the role of relatedness and ecological benefits in sociality among coastal river otters. By using DNA microsatellite analysis and radiotelemetry, we were able to reject the hypothesis that social groups of otters were kin based. In addition, we found no indication of kin avoidance, as would be expected from low dispersal and high local competition. Sociality conferred no reproductive benefits or costs to otters; number of offspring and number of relatives in the population did not differ between social and solitary animals. Solitary males were not older or larger than were social males, and there was no relation between male size and number of offspring, indicating that sexual selection did not mask a potential relation between sociality and reproductive success. Among coastal river otters in this region, sociality could be explained by the benefits obtained from cooperative foraging on high-quality schooling pelagic fishes. Such benefits did not require association with kin, resulting in no selection pressure for kin-based groups. The prediction that the degree of sociality in the population will fluctuate relative to the abundance of schooling pelagic fishes merits further investigation. Key words: Alaska, kin selection, Lontra canadensis, microsatellite DNA, reproductive success, schooling pelagic fishes, sexual selection. [Behav Ecol 15:705–714 (2004)]

Demography, life history, and social structure in Propithecus diadema edwardsi from 1986-2000 in Ranomafana National Park, Madagascar.

Prosimian lemurs differ fundamentally from anthropoid primates in many traits related to social structure. By exploring the demography of Milne-Edwards' sifakas (Propithecus diadema edwardsi), and comparing it to other well-studied primates, we explore the effect of demographic and life-history factors on social structure. Specifically, we compare lemur survivorship and fertility patterns to two published composite models: one created for New World and another created for Old World monkeys. Using longitudinal data collected on individual Propithecus diadema edwardsi from four study groups from 1986-2000 in Ranomafana National Park, Madagascar, we quantify 1) group composition, 2) birth seasonality, 3) interbirth interval, 4) life-table values, and 5) population growth estimates. The mortality, survivorship, and life-expectancy schedules indicate high infant and juvenile mortality. Fertility remains high until death. The intrinsic rate of increase and net reproductive rate indicate a shrinking population. We suggest that high mortality rather than low fertility causes the observed population decline. While sifaka survivorship closely resembles New World patterns, fertility resembles Old World patterns, i.e., like New World monkeys, few sifakas survive to reproductive age, and those that do, reproduce at a slow rate resembling the Old World pattern. This necessarily impacts social structure. An adult sifaka at the end of her lifespan will have one only daughter who survives to reproductive age, compared to 3.4 for New World or 2.7 for Old World monkeys. Demography limits the formation of large kin-based groups for sifakas, and survivorship and fertility patterns do not easily permit sifakas to form large same-sex family groups.

Personhood, Agency, and Mortuary Ritual: A Case Study from the Ancient Maya

The archaeological identification of individuals has been an important component of both processual attempts to characterize social organization by the treatment of individuals in mortuary ritual and more recent agency theory applications to studies of political economy and social change. Both approaches have been critiqued for failing to adequately define the individual, instead applying the Western concept of the individual to other societies. These shortcomings are shown to be part of a larger problem in social theory: the continuing polarization between individualism and holism. They point to the need for renewed interest in the anthropological analysis of the “person”—a socially shaped construct—in order to better understand social relationships and recognize the collective aspects of agency. A case study from the Classic Maya civilization illustrates how emphasis on the individual, as represented in mortuary events, artistic depictions, and texts, has resulted in interpretive difficulties that can be avoided by viewing these data from the perspective of the social collectivity from which personhood was derived. Maya corporate kin-based groups, known as “houses,” were a major source of the social identities expressed in political action and represented in mortuary ritual and monumental imagery.

Complex social organization reflects genetic structure and relatedness in the cooperatively breeding bell miner, Manorina melanophrys.

The cooperatively breeding bell miner, Manorina melanophrys, differs from most other cooperative breeding species in the complexity of its social system, where discrete social organization occurs on at least three levels. Microsatellite markers were used to investigate the degree of genetic structure underlying the social organization of M. melanophrys by comparing colonies, coteries and nest contingents. The genetic data confirmed behavioural observations of M. melanophrys living in male kin-based groups between which females disperse short distances to breed. Estimates of FST revealed restricted gene flow between eight colonies located within 30 km that was significantly associated with geographical distance when the two most distant colonies were included. Within a high density colony significant differences were found between coteries; analysis of the degree of relatedness between coterie members showed that this is due to related individuals associating preferentially with each other. Similarly, the contingent of individuals attending a nest were generally close relatives of the young they were aiding, supporting models invoking kin selection as the selective agency mediating helping.

Craft and Local Power: Embedded Specialization in Tiwanaku Cities

Proponents of many comparative models of craft specialization explain variability in the organization of production according to the nature of elite interest and economic demand. To this end, many propose a basic dichotomy between independent and attached specialization, whereby valued goods are produced for elites in controlled, nondomestic workshops. I examine new evidence for craft production in the prehispanic Andean polity of Tiwanaku (A. D. 500-1150). I outline expectations for these two forms of specialization and, based on ethnohistorical research in the Tiwanaku region, propose a third form, termed embedded specialization. I appraise primary evidence for the production of ceramic vessels at the site of Tiwanaku and the production of musical instruments at the nearby regional site of Lukurmata. Weighing expectations against evidence, I argue that in Tiwanaku centers many goods were produced by kin-based groups residing in large residential compounds. Skilled production served the overarching political economy and the demands of nonspecialists, but it was neither strictly independent of nor directly attached to elite interests. Craft was rooted in segmentary principles of sociopolitical order, and so was local but not wholly autonomous. On a comparative scale, I suggest that embedded production characterized some states emphasizing corporate strategies of political integration.

Kin recognition in a social spider

Social spiders accept immigrant spiders into their kin-based groups, suggesting that spiders cannot recognise kin and may lose inclusive fitness benefits. A field and two laboratory experiments on Diaea ergandros , a social crab spider, demonstrated that younger and older instar D. ergandros do discriminate siblings, but potential benefits were variable and not equally distributed. First, proportional survival was greater in large groups regardless of the within-group relatedness, so accepting immigrants increases probability of group survival (although relatedness was more important among smaller groups). Second, juvenile D. ergandros ate unrelated spiders instead of siblings when starved, so immigrants might represent a food reserve in times of food shortage. Third, subadult resident, sibling females cannibalised unrelated, immigrant females and their brothers instead of immigrant males when starved, suggesting that subadult female spiders may maximise outbreeding opportunities. These benefits provide selective pressure for groups to accept immigrants, but as benefits are realised differentially, conflict and cooperation will exist within spider groups similar to that shown in other group–living taxa.