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Parr L.A.,Emory University | Heintz M.,University of Chicago | Lonsdorf E.,Lester sher Center For The Study And Conservation Of Apes | Wroblewski E.,University of Minnesota
Journal of Comparative Psychology

Faces provide important information about identity, age, and even kinship. A previous study in chimpanzees reported greater similarity between the faces of mothers and sons compared with mothers and daughters, or unrelated individuals. This was interpreted as an inbreeding avoidance mechanism where females, the dispersing gender, should avoid mating with any male that resembles their mother. Alternatively, male faces may be more distinctive than female faces, biasing attention toward males. To test these hypotheses, chimpanzees and rhesus monkeys matched conspecifics' faces of unfamiliar mothers and fathers with their sons and daughters. Results showed no evidence of male distinctiveness, rather a cross-gender effect was found: chimpanzees were better matching moms with sons and fathers with daughters. Rhesus monkeys, however, showed an overwhelming bias toward male-distinctiveness. They were faster to learn male faces, performed better on father-offspring and parent-son trials, and were best matching fathers with sons. This suggests that for the rhesus monkey, inbreeding avoidance involves something other than facial phenotypic matching but that among chimpanzees, the visual recognition of facial similarities may play an important role. © 2010 American Psychological Association. Source

Brosnan S.F.,Georgia State University | Hopper L.M.,Lester sher Center For The Study And Conservation Of Apes
Animal Behaviour

Innovation is a way by which animals adopt a new behaviour or apply a current behaviour to a novel situation. Although exploring a new behaviour is itself risky for the animal, a growing body of research indicates that it is fairly widespread across animal species. While there have been explorations of when innovation is most likely and which individuals are most likely to innovate, less has been explored about the psychological mechanisms underlying innovation. Here we consider some psychological limits on innovation. We focus on five factors that my limit the invention of novel behaviours (neophobia, conservatism, conformity, functional fixedness and the endowment effect). The feature common to each of these is that individuals tend to stick with existing behaviours, or the existing uses of those behaviours, rather than exploring novel options. This in turn limits animals' willingness to try less common behaviours unless they are forced through circumstances to explore alternate strategies. Despite the similar functional outcomes, it is critical to understand the underlying mechanisms present in different situations in order to make strong predictions about when innovation is, or is not, expected to emerge. We then consider how transmission biases and social learning mechanisms influence and limit the spread of inventions among individuals. Of course, these 'limits' are beneficial in other circumstances, and throughout this review we consider the trade-offs for these psychological mechanisms. © 2014 The Association for the Study of Animal Behaviour. Source

Chelluri G.I.,Lester sher Center For The Study And Conservation Of Apes | Chelluri G.I.,University of Chicago | Ross S.R.,Lester sher Center For The Study And Conservation Of Apes | Wagner K.E.,Lester sher Center For The Study And Conservation Of Apes
Applied Animal Behaviour Science

In captive animal facilities, human staff members are a relevant part of the animals' social environment in addition to providing care and managing the social group. Structured, predictable interactions and relaxed, spontaneous contacts may all affect the animals' behavior and well-being, both immediately and in the long term. This study examined the association between unstructured, affiliative caretaker-animal interactions and the behavior of zoo-housed chimpanzees (Pan troglodytes) and Western lowland gorillas (Gorilla gorilla gorilla). The interactions in question included play, spontaneous feeding, and other positive vocal and visual interactions performed through a protective mesh barrier. Behavioral data collected over 48 months were used to identify correlates of caretaker interactions among key behaviors relevant to welfare assessment, including agonism, sexual behavior, abnormal behavior, prosocial behavior, and self-directed behavior, as well as the presence of wounds. In observational sessions containing one or more caretaker interactions, chimpanzees and gorillas both showed higher agonism (P=0.044 and P=0.042, respectively) and lower self-directed behavior (P=0.035 for chimpanzees and P=0.001 for gorillas) than in control samples. Agonism rose in chimpanzees from an average of 0.01-0.12% of overall behaviors, and in gorillas from 0% to 0.1%, while self-directed behavior decreased in chimpanzees from an average of 9.54-7.81% and in gorillas from 11.02% to 7.38%. Chimpanzees also showed lower intraspecific prosocial behavior in samples with caretaker interactions (P=0.044), decreasing from an average of 11.5% to 5.52% of overall behaviors. Finally, gorillas exhibited less abnormal behavior in caretaker interaction samples than in control samples (P=0.029), decreasing from a mean of 2.42-1.77% of overall behaviors. In chimpanzees, higher agonism and lower prosocial behavior are indicative of greater arousal, although we would expect self-directed behavior to rise rather than decrease in that situation. The results in gorillas are mixed with respect to welfare outcomes: higher agonism is indicative of arousal, but lower abnormal and self-directed behaviors suggest a decrease in stress and anxiety. These findings underscore the importance of understanding the influence of all forms of interaction with heterospecifics and demonstrate a need for welfare assessments that include even positively intended interactions. © 2012 Elsevier B.V. Source

Ross S.R.,Lester sher Center For The Study And Conservation Of Apes | Vreeman V.M.,Lester sher Center For The Study And Conservation Of Apes | Lonsdorf E.V.,Lester sher Center For The Study And Conservation Of Apes | Lonsdorf E.V.,University of Chicago

Chimpanzees are endangered in their native Africa but in the United States, they are housed not only in zoos and research centers but owned privately as pets and performers. In 2008, survey data revealed that the public is less likely to think that chimpanzees are endangered compared to other great apes, and that this is likely the result of media misportrayals in movies, television and advertisements. Here, we use an experimental survey paradigm with composite images of chimpanzees to determine the effects of specific image characteristics. We found that those viewing a photograph of a chimpanzee with a human standing nearby were 35.5% more likely to consider wild populations to be stable/healthy compared to those seeing the exact same picture without a human. Likewise, the presence of a human in the photograph increases the likelihood that they consider chimpanzees as appealing as a pet. We also found that respondents seeing images in which chimpanzees are shown in typically human settings (such as an office space) were more likely to perceive wild populations as being stable and healthy compared to those seeing chimpanzees in other contexts. These findings shed light on the way that media portrayals of chimpanzees influence public attitudes about this important and endangered species. © 2011 Ross et al. Source

Sanz C.M.,Max Planck Institute for Evolutionary Anthropology | Sanz C.M.,Washington University | Caspar S.,Copenhagen University | Caspar S.,Honey Bee Research Institute | And 2 more authors.
American Journal of Primatology

Several populations of chimpanzees have been reported to prey upon Dorylus army ants. The most common tool-using technique to gather these ants is with ''dipping'' probes, which vary in length with regard to aggressiveness and lifestyle of the prey species. We report the use of a tool set in army ant predation by chimpanzees in the Goualougo Triangle, Republic of Congo. We recovered 1,060 tools used in this context and collected 25 video recordings of chimpanzee tool-using behavior at ant nests. Two different types of tools were distinguished based on their form and function. The chimpanzees use a woody sapling to perforate the ant nest, and then a herb stem as a dipping tool to harvest the ants. All of the species of ants preyed upon in Goualougo are present and consumed by chimpanzees at other sites, but there are no other reports of such a regular or widespread use of more than one type of tool to prey upon Dorylus ants. Furthermore, this tool set differs from other types of tool combinations used by chimpanzees at this site for preying upon termites or gathering honey. Therefore, we conclude that these chimpanzees have developed a specialized method for preying upon army ants, which involves the use of an additional tool for opening nests. Further research is needed to determine which specific ecological and social factors may have shaped the emergence and maintenance of this technology © 2009 Wiley-Liss, Inc. Source

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