Personality dimensions and their behavioral correlates in wild virunga mountain gorillas (Gorilla beringei beringei)

This article may not exactly replicate the final version published in the APA journal. It is not the copy of record.Studies of animal personality improve our understanding of individual variation in measures of life-history and fitness, such as health and reproductive success. Using a 54 trait personality questionnaire developed for studying great apes and other nonhuman primates, we obtained ratings on 116 wild mountain gorillas (Gorilla beringei beringei) monitored by the Dian Fossey Gorilla Fund’s Karisoke Research Center in Rwanda. There were eight raters who each had more than 1.5 years of working experience with the subjects. Principal component analyses identified four personality dimensions with high inter-rater reliabilities --- Dominance, Openness, Sociability, and Proto-Agreeableness --- that reflected personality features unique to gorillas and personality features shared with other hominoids. We next examined the associations of these dimensions with independently collected behavioral measures derived from long-term records. Predicted correlations were found between the personality dimensions and corresponding behaviors. For example, Dominance, Openness, Sociability, and Proto-Agreeableness were related to gorilla dominance strength, time spent playing, rates of approaches and rates of interventions in intra-group conflicts, respectively. These findings enrich the comparative-evolutionary study of personality and provide insights into how species differences in personality are related to ecology, social systems, and life history

Human-animal interactions from an evolutionary perspective: Symbioses as extended ultrasociality

Abstract The field of human-animal interactions (HAI) is focused primarily on human-companion animal relationships, especially the impact of such relationships on human health. Here, we demonstrate how a wider, integrative approach, consisting of an evolutionary framework, provides new insights into the varieties of HAIs and their emergence and significance during human evolution. Along with other HAI researchers, we show that those HAIs which develop into interrelationships can best be treated as ecological symbioses that involve fitness interdependence among the symbionts and entail the evolution of phenotypic traits that support the adaptive features of the symbionts. We present the novel idea that the formation of mutualistic symbiotic relationships through the process of domestication depended on the prior evolution of hominin hypersociality and ultrasociality in modern humans. Hypersociality was characterized by high levels of social cooperation and social tolerance that became increasingly important for human social life and cooperative hunting. The further development of ultrasociality in modern humans consisted of the development of large-scale (i.e., beyond the hunting band) cooperative social networks of genetically unrelated individuals. This depended on the evolution of further enhancements in socio-cognitive skills, especially representational abilities (e.g., theory of mind), symbolic capacities, and formation of tribal societies with complex social institutions. These modern cognitive and socio-cultural features were made possible by significant brain reorganization during the past 60,000 years. Tribal social institutions were founded on normative moral sentiments and behavior and regulated and ultimately reduced levels of lethal violence. The extension of fitness interdependent, cooperative relationships to large networks of unrelated individuals (i.e., ultrasociality), we argue, was foundational in modern humans to the formation of mutualistic symbioses (i.e., process of domestication) with other animals. Because they are an outgrowth of ultrasociality, we suggest that the term “extended ultrasociality” appropriately describes human interrelationships with domesticated animals. We further suggest that these human-animal interrelationships are unique in that they become imbued with and immersed in our symbolic world, as is demonstrated by the earliest representational art in caves after 50,000 years when enhanced modern human representational and symbolic capacities were evolving. An evolutionary framework invites new questions and avenues for research

Mountain gorilla tug-of-war: Silverbacks have limited control over reproduction in multimale groups

To determine who fathers the offspring in wild mountain gorilla groups containing more than one adult male silverback, we genotyped nearly one-fourth (n = 92) of the mountain gorillas (Gorilla beringei beringei) living in the Virunga Volcanoes region of Africa. Paternity analysis of 48 offspring born into four groups between 1985 and 1999 revealed that, although all infants were sired by within-group males, the socially dominant silverback did not always monopolize reproduction within his group. Instead, the second-ranking male sired an average of 15% of group offspring. This result, in combination with previous findings that second-ranking males fare best by not leaving the group but by staying and waiting to assume dominance even if no reproduction is possible while waiting, is not consistent with expectations from a reproductive skew model in which the silverback concedes controllable reproduction to the second-ranking male. Instead, the data suggest a “tug-of-war” scenario in which neither the dominant nor the second-ranking male has full control over his relative reproductive share. The two top-ranked males were typically unrelated and this, in combination with the mixed paternity of group offspring, means that multimale gorilla groups do not approximate family groups. Instead, as long-term assemblages of related and unrelated individuals, gorilla groups are similar to chimpanzee groups and so offer interesting possibilities for kin-biased interactions among individuals

Glucocorticoid response to naturalistic interactions between children and dogs

Although research has shown that pets appear to provide certain types of social support to children, little is known about the physiological bases of these effects, especially in naturalistic contexts. In this study, we investigated the effect of free-form interactions between children (ages 8–10 years) and dogs on salivary cortisol concentrations in both species. We further investigated the role of the child-dog relationship by comparing interactions with the child's pet dog to interactions with an unfamiliar dog or a nonsocial control condition, and modeled associations between survey measures of the human-animal bond and children's physiological responses. In both children and dogs, salivary cortisol decreased from pre- to post-interaction; the effect was strongest for children interacting with an unfamiliar dog (compared to their pet dog) and for the pet dogs (compared to the unfamiliar dog). We found minimal evidence for associations between cortisol output and behaviors coded from video, but children scoring higher on survey measures of the human-animal bond exhibited the greatest reductions in cortisol when interacting with dogs. Self-reported loneliness was not related to cortisol or the human-animal bond, but measures of both loneliness and the human-animal bond were higher among children who participated after the onset of the COVID-19 pandemic, relative to those who participated before the pandemic. This study builds on previous work that investigated potential stress-buffering effects of human-animal interaction during explicit stressors and demonstrates important physiological correlates of naturalistic interactions between children and dogs, similar to those that occur in daily life.12 month embargo; first published 13 March 2024This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]