Social complexity from within: how individuals experience the structure and organization of their groups

We argue that the study of social complexity can follow two different approaches, based on how it is seen from the outside or on how it is experienced from within. Recent focus has been on the former with social complexity emerging from the interactions of group members. Here, we take the view from within and deal with the social complexity that individual group members may experience, exploring complexity arising from aspects of the social structure and social organization. We review a variety of sources of social complexity in terms of variation between and within social relationships, variation in opportunities to interact with different group members, and the role of third parties. We then examine how individuals can cope with the social complexity they face. We conclude that a refined view of social relationships at different levels is needed to study the social complexity faced by individual group members and emphasize the potential contribution of the view from within to the study of social complexity and cognition. Animals may experience different degrees of complexity in their social groups. Instead of viewing social complexity as an emergent property of the interactions exchanged by group members, we focus on the social complexity individual group members may experience. We examine how aspects of social structure and social organization, such as the variation between and within social relationships, the variation in opportunities to interact with different group members, and the role of third parties, could create challenges and sources of complexity for individual group members. We then evaluate how emotions and cognitive abilities could be used by animals of different species to navigate the social complexity they experience and make appropriate decisions. We show that there are neglected sources of social complexity related to social relationships that derive from them changing over time and consisting of different components. We conclude by emphasizing that a change in perspective is needed to study how cognition is linked to the social complexity individual group members may experience

There is no Other Monkey in the Mirror for Spider Monkeys (Ateles geoffroyi)

©American Psychological Association, 2020. This paper is not the copy of record and may not exactly replicate the authoritative document published in the APA journal. Please do not copy or cite without author's permission. The final article is available, upon publication, at: https://doi.org/10.1037/com0000243Mirror self-recognition (MSR), usually considered a marker of self-awareness, occurs in several species and may reflect a capacity that has evolved in small incremental steps. In line with research on human development and building on previous research adopting a gradualist framework, we categorized the initial mirror responses of naïve spider monkeys (Ateles geoffroyi) according to four levels. We compared social, exploratory, contingent and self-exploratory responses to a mirror and faux mirror during three short trials. If spider monkeys respond as most monkey species, we predicted they would perform at level 0, mainly showing social behavior toward their mirror-image. However, because spider monkeys show enhancement of certain cognitive skills comparable to those of great ape species, we predicted that they would perform at level 1a (showing exploratory behavior) or 1b (showing contingent behavior). GLMMs revealed that monkeys looked behind and visually inspected the mirror significantly more in the mirror than the faux mirror condition. Although the monkeys engaged in contingent body movements at the mirror, this trend was not significant. Strikingly, they showed no social behaviors toward their mirror-image. We also measured self-scratching as an indicator of anxiety and found no differences in frequencies of self-scratching between conditions. Therefore, in contrast to most findings on other species, spider monkeys did not treat their image as another monkey during their initial exposure to the mirror. In fact, they reached at least level 1a within minutes of mirror exposure. These responses recommend spider monkeys as good candidates for further explorations into monkey self-recognition

Traditions in Spider Monkeys Are Biased towards the Social Domain

Cross-site comparison studies of behavioral variation can provide evidence for traditions in wild species once ecological and genetic factors are excluded as causes for cross-site differences. These studies ensure behavior variants are considered within the context of a species' ecology and evolutionary adaptations. We examined wide-scale geographic variation in the behavior of spider monkeys (Ateles geoffroyi) across five long-term field sites in Central America using a well established ethnographic cross-site survey method. Spider monkeys possess a relatively rare social system with a high degree of fission-fusion dynamics, also typical of chimpanzees (Pan troglodytes) and humans (Homo sapiens). From the initial 62 behaviors surveyed 65% failed to meet the necessary criteria for traditions. The remaining 22 behaviors showed cross-site variation in occurrence ranging from absent through to customary, representing to our knowledge, the first documented cases of traditions in this taxon and only the second case of multiple traditions in a New World monkey species. Of the 22 behavioral variants recorded across all sites, on average 57% occurred in the social domain, 19% in food-related domains and 24% in other domains. This social bias contrasts with the food-related bias reported in great ape cross-site comparison studies and has implications for the evolution of human culture. No pattern of geographical radiation was found in relation to distance across sites. Our findings promote A. geoffroyi as a model species to investigate traditions with field and captive based experiments and emphasize the importance of the social domain for the study of animal traditions.Research at Barro Colorado Island was supported by grants from the National Science Foundation (SBR-9711161), the Leakey Foundation, the Department of Anthropology, University of California, Berkeley (www.berkeley.edu) and a Short-term Fellowship from the Smithsonian Tropical Research Institute (www.stri.org). Research at Corcovado National Park's Sirena Biological Station was supported by NSF award 0233248 (with R. Sussman), the Wenner-Gren Foundation, the Leakey Foundation, the American Society of Primatologists (www.asp.org), and Washington University in St. Louis (www.wustl.edu). Funds for Sirena's field lab facility were provided to L. E. Gilbert (Univ. of Texas at Austin) by NSF BSR 8315399 and a matching WWF grant, and funds for updating Sirena's trail system and installation of spatial reference system were provided by the Mellon Foundation through the Institute of Latin American Studies at UT Austin. Research at Santa Rosa and Punta Laguna was supported by The British Academy (www.britac.ac.uk), the Wenner-Gren Foundation (www.wennergren.org), the Leakey Foundation (www.leakeyfoundation.org) and the North of England Zoological Society (www.chesterzoo.org). CJS was supported by a Gladstone bursary from the University of Chester (www.chester.ac.uk) and by the Santander University Scheme (www.santander.co.uk). Research at Runaway Creek was supported by the Natural Sciences and Engineering Research Council of Canada

Traditions in spider monkeys are biased towards the social domain

Cross-site comparison studies of behavioral variation can provide evidence for traditions in wild species once ecological and genetic factors are excluded as causes for cross-site differences. These studies ensure behavior variants are considered within the context of a species' ecology and evolutionary adaptations. We examined wide-scale geographic variation in the behavior of spider monkeys (Ateles geoffroyi) across five long-term field sites in Central America using a well established ethnographic cross-site survey method. Spider monkeys possess a relatively rare social system with a high degree of fission-fusion dynamics, also typical of chimpanzees (Pan troglodytes) and humans (Homo sapiens). From the initial 62 behaviors surveyed 65% failed to meet the necessary criteria for traditions. The remaining 22 behaviors showed cross-site variation in occurrence ranging from absent through to customary, representing to our knowledge, the first documented cases of traditions in this taxon and only the second case of multiple traditions in a New World monkey species. Of the 22 behavioral variants recorded across all sites, on average 57% occurred in the social domain, 19% in food-related domains and 24% in other domains. This social bias contrasts with the food-related bias reported in great ape cross-site comparison studies and has implications for the evolution of human culture. No pattern of geographical radiation was found in relation to distance across sites. Our findings promote A. geoffroyi as a model species to investigate traditions with field and captive based experiments and emphasize the importance of the social domain for the study of animal traditions.Research at Barro Colorado Island was supported by grants from the National Science Foundation (SBR-9711161), the Leakey Foundation, the Department of Anthropology, University of California, Berkeley (www.berkeley.edu) and a Short-term Fellowship from the Smithsonian Tropical Research Institute (www.stri.org). Research at Corcovado National Park's Sirena Biological Station was supported by NSF award 0233248 (with R. Sussman), the Wenner-Gren Foundation, the Leakey Foundation, the American Society of Primatologists (www.asp.org), and Washington University in St. Louis (www.wustl.edu). Funds for Sirena's field lab facility were provided to L. E. Gilbert (Univ. of Texas at Austin) by NSF BSR 8315399 and a matching WWF grant, and funds for updating Sirena's trail system and installation of spatial reference system were provided by the Mellon Foundation through the Institute of Latin American Studies at UT Austin. Research at Santa Rosa and Punta Laguna was supported by The British Academy (www.britac.ac.uk), the Wenner-Gren Foundation (www.wennergren.org), the Leakey Foundation (www.leakeyfoundation.org) and the North of England Zoological Society (www.chesterzoo.org). CJS was supported by a Gladstone bursary from the University of Chester (www.chester.ac.uk) and by the Santander University Scheme (www.santander.co.uk). Research at Runaway Creek was supported by the Natural Sciences and Engineering Research Council of Canada. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

The role of sucrose and sensory systems in fruit selection and consumption of Ateles geoffroyi in Yucatan, Mexico

Our aim was to evaluate the role of sucrose and the role of smell, taste and touch in the selection and consumption of fruit in wild spider monkeys. We recorded the feeding bouts of 14 adults for 9 mo in the Otoch Ma’ax Yetel Kooh Reserve, Punta Laguna, Yucatan, Mexico. For each of 2346 inspections on fruits of six species the consumption or rejection and the use of touch, smell and taste was recorded. Ten fruit samples (five ripe and five unripe) from each species were collected and the sucrose concentration was determined with a refractometer. As expected, sucrose concentrations were higher in ripe than unripe fruits. The difference in sucrose concentration between ripe and unripe fruits was positively associated with the proportion of inspections on ripe fruits and the proportion of consumed ripe fruits. Furthermore, the senses of touch and taste were used more often when fruits were ripe, whereas the sense of smell was used more often when fruits were unripe. The results suggest that sensory cues and sucrose concentration play important roles in fruit selection in spider monkeys

Sleeping-tree fidelity of the spider monkey shapes community-level seed-rain patterns in continuous and fragmented rain forests

Repeated use of sleeping trees (STs) by frugivores promotes the deposition and aggregation of copious amounts of seed, thus having key implications for seed dispersal and forest regeneration. Seed-rain patterns produced by this behaviour likely depend on the frequency of use of these sites, yet this hypothesis has been poorly tested. We evaluated community-level seed-rain patterns produced by the spider monkey (Ateles geoffroyi) over 13 mo in latrines located beneath 60 STs in the Lacandona rain forest, Mexico. Because this primate is increasingly ‘forced’ to inhabit fragmented landscapes, we tested whether sleeping-tree fidelity (STF) differed among sites and between continuous and fragmented forests. We also tested whether seed-rain patterns were associated with STF within each site and forest type. STF was highly variable among STs (average = 7 mo, range = 1–12 mo), but did not differ among study sites or forest types. STF was positively associated with seed abundance, species diversity and species turnover. Nevertheless, STF tended to be negatively related to seed community evenness. These results are likely due to the most frequently used STs being in areas with greater food density. Our results demonstrate that site fidelity shapes community-level seed-rain patterns and thus has key ecological implications

You are Not Welcome: Social Exchanges between Female Spider Monkeys (Ateles geoffroyi)

Group living leads to competition for food between group members. Two types of intragroup food competition may occur: scramble competition, in which all group members use the same resource, such that feeding opportunities are equal for everyone; and contest competition, in which some group members monopolize resources through aggression and dominance. In species in which females disperse from the natal group and immigrate into other groups, immigrant females increase group size and thus possibly food competition. Under these circumstances, other females may use aggression to discourage new females from joining the group. We assessed the distribution of aggression, embraces, and kisses among female spider monkeys (Ateles geoffroyi) in relation to group tenure. We recorded social interactions during 1688 10-min focal animal samples on 11 females in Santa Rosa, Costa Rica. We found that aggression was rare between long-term resident females and aggression rates were not higher during feeding than in other contexts, suggesting there was little contest competition. Long-term residents and less recently immigrant females showed higher aggression rates toward the most recent immigrants than toward other females, especially during the first months after a female immigrated, which coincided with the dry season. We did not find similar patterns for embrace and kiss. These results suggest that other females target aggression toward the most recent immigrants to reduce scramble competition. This finding suggests that group tenure should be included in socioecological models for species with female dispersal. © 2017 Springer Science+Business Media, LL