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Science (New York, N.Y.) Oct 2020Humans prioritize close, positive relationships during aging, and socioemotional selectivity theory proposes that this shift causally depends on capacities for thinking...
Humans prioritize close, positive relationships during aging, and socioemotional selectivity theory proposes that this shift causally depends on capacities for thinking about personal future time horizons. To examine this theory, we tested for key elements of human social aging in longitudinal data on wild chimpanzees. Aging male chimpanzees have more mutual friendships characterized by high, equitable investment, whereas younger males have more one-sided relationships. Older males are more likely to be alone, but they also socialize more with important social partners. Further, males show a relative shift from more agonistic interactions to more positive, affiliative interactions over their life span. Our findings indicate that social selectivity can emerge in the absence of complex future-oriented cognition, and they provide an evolutionary context for patterns of social aging in humans.
Topics: Aging; Agonistic Behavior; Animals; Female; Male; Object Attachment; Pan troglodytes; Social Behavior
PubMed: 33093111
DOI: 10.1126/science.aaz9129 -
Cognition Jul 2023How we judge the similarity between objects in the world is connected ultimately to how we represent those objects. It has been argued extensively that object...
How we judge the similarity between objects in the world is connected ultimately to how we represent those objects. It has been argued extensively that object representations in humans are 'structured' in nature, meaning that both individual features and the relations between them can influence similarity. In contrast, popular models within comparative psychology assume that nonhuman species appreciate only surface-level, featural similarities. By applying psychological models of structural and featural similarity (from conjunctive feature models to Tversky's Contrast Model) to visual similarity judgements from adult humans, chimpanzees, and gorillas, we demonstrate a cross-species sensitivity to complex structural information, particularly for stimuli that combine colour and shape. These results shed new light on the representational complexity of nonhuman apes, and the fundamental limits of featural coding in explaining object representation and similarity, which emerge strikingly across both human and nonhuman species.
Topics: Adult; Animals; Humans; Hominidae; Judgment; Pan troglodytes; Models, Psychological; Pattern Recognition, Visual
PubMed: 37104894
DOI: 10.1016/j.cognition.2023.105419 -
PeerJ 2022Social play is ubiquitous in the development of many animal species and involves players adapting actions flexibly to their own previous actions and partner responses....
Social play is ubiquitous in the development of many animal species and involves players adapting actions flexibly to their own previous actions and partner responses. Play differs from other behavioural contexts for which fine-scale analyses of action sequences are available, such as tool use and communication, in that its form is not defined by its function, making it potentially more unpredictable. In humans, play is often organised in games, where players know context-appropriate actions but string them together unpredictably. Here, we use the sequential nature of play elements to explore whether play elements in chimpanzees are structured hierarchically and follow predictable game-like patterns. Based on 5,711 play elements from 143 bouts, we extracted individual-level play sequences of 11 Western chimpanzees () of different ages from the Bossou community. We detected transition probabilities between play elements that exceeded expected levels and show that play elements form hierarchically clustered and interchangeable groups, indicative of at least six games that can be identified from transition networks, some with different roles for different players. We also show that increased information about preceding play elements improved predictability of subsequent elements, further indicating that play elements are not strung together randomly but that flexible action rules underlie their usage. Thus, chimpanzee play is hierarchically structured in short games which limit acceptable play elements and allow players to predict and adapt to partners' actions. This "grammar of action" approach to social interactions can be valuable in understanding cognitive and communicative abilities within and across species.
Topics: Animals; Humans; Pan troglodytes; Feeding Behavior; Social Interaction; Communication
PubMed: 36411837
DOI: 10.7717/peerj.14294 -
Proceedings. Biological Sciences Apr 2022In zoos, primates experience markedly different interactions with familiar humans, such as the zookeepers who care for them, compared with those with unfamiliar humans,...
In zoos, primates experience markedly different interactions with familiar humans, such as the zookeepers who care for them, compared with those with unfamiliar humans, such as the large volume of zoo visitors to whom they are regularly exposed. While the behaviour of zoo-housed primates in the presence of unfamiliar, and to a lesser extent familiar, humans has received considerable attention, if and how they spontaneously distinguish familiar from unfamiliar people, and the cognitive mechanisms underlying the relationships they form with familiar and unfamiliar humans, remain poorly understood. Using a dot-probe paradigm, we assessed whether primates (chimpanzees and gorillas) show an attentional bias toward the faces of familiar humans, with whom the apes presumably had a positive relationship. Contrary to our predictions, all subjects showed a significant attentional bias toward unfamiliar people's faces compared with familiar people's faces when the faces showed a neutral expression, both with and without a surgical face mask on, but no significant attentional bias when the faces showed a surprised expression. These results demonstrate that apes can spontaneously categorize humans based on familiarity and we argue that the attentional biases the apes showed for unfamiliar human faces reflect a novelty effect.
Topics: Animals; Attention; Attentional Bias; Hominidae; Humans; Pan troglodytes; Recognition, Psychology
PubMed: 35473378
DOI: 10.1098/rspb.2021.2599 -
Animal Cognition Sep 2023Object interactions play an important role in human communication but the extent to which nonhuman primates incorporate objects in their social interactions remains...
Object interactions play an important role in human communication but the extent to which nonhuman primates incorporate objects in their social interactions remains unknown. To better understand the evolution of object use, this study explored how objects are used in social interactions in semi-wild chimpanzees (Pan troglodytes). We used an observational approach focusing on naturally occurring object actions where we examined their use and tested whether the production of object actions was influenced by the recipients' visual attention as well as by colony membership. The results show that chimpanzees adjusted both the type of object used, and the modality of object actions to match the visual attention of the recipient, as well as colony differences in the use of targeted object actions. These results provide empirical evidence highlighting that chimpanzees use objects in diverse ways to communicate with conspecifics and that their use may be shaped by social factors, contributing to our understanding of the evolution of human nonverbal communication, language, and tool use.
Topics: Animals; Animal Communication; Language; Nonverbal Communication; Pan troglodytes
PubMed: 37314595
DOI: 10.1007/s10071-023-01792-z -
Heredity Aug 2020Populations of the common chimpanzee (Pan troglodytes) are in an impending risk of going extinct in the wild as a consequence of damaging anthropogenic impact on their...
Populations of the common chimpanzee (Pan troglodytes) are in an impending risk of going extinct in the wild as a consequence of damaging anthropogenic impact on their natural habitat and illegal pet and bushmeat trade. Conservation management programmes for the chimpanzee have been established outside their natural range (ex situ), and chimpanzees from these programmes could potentially be used to supplement future conservation initiatives in the wild (in situ). However, these programmes have often suffered from inadequate information about the geographical origin and subspecies ancestry of the founders. Here, we present a newly designed capture array with ~60,000 ancestry informative markers used to infer ancestry of individual chimpanzees in ex situ populations and determine geographical origin of confiscated sanctuary individuals. From a test panel of 167 chimpanzees with unknown origins or subspecies labels, we identify 90 suitable non-admixed individuals in the European Association of Zoos and Aquaria (EAZA) Ex situ Programme (EEP). Equally important, another 46 individuals have been identified with admixed subspecies ancestries, which therefore over time, should be naturally phased out of the breeding populations. With potential for future re-introduction to the wild, we determine the geographical origin of 31 individuals that were confiscated from the illegal trade and demonstrate the promises of using non-invasive sampling in future conservation action plans. Collectively, our genomic approach provides an exemplar for ex situ management of endangered species and offers an efficient tool in future in situ efforts to combat the illegal wildlife trade.
Topics: Animals; Conservation of Natural Resources; Ecosystem; Endangered Species; Pan troglodytes
PubMed: 32346130
DOI: 10.1038/s41437-020-0313-0 -
American Journal of Primatology Nov 2022Vocal learning, the ability to modify the acoustic structure of vocalizations based on social experience, is a fundamental feature of speech in humans (Homo sapiens)....
Vocal learning, the ability to modify the acoustic structure of vocalizations based on social experience, is a fundamental feature of speech in humans (Homo sapiens). While vocal learning is common in taxa such as songbirds and whales, the vocal learning capacities of nonhuman primates appear more limited. Intriguingly, evidence for vocal learning has been reported in chimpanzees (Pan troglodytes), for example, in the form of regional variation ("dialects") in the "pant-hoot" calls. This suggests that some capacity for vocal learning may be an ancient feature of the Pan-Homo clade. Nonetheless, reported differences have been subtle, with intercommunity variation representing only a small portion of the total acoustic variation. To gain further insights into the extent of regional variation in chimpanzee vocalizations, we performed an analysis of pant-hoots from chimpanzees in the neighboring Kasekela and Mitumba communities at Gombe National Park, Tanzania, and the geographically distant Kanyawara community at Kibale National Park, Uganda. We did not find any statistically significant differences between the neighboring communities at Gombe or among geographically distant communities. Furthermore, we found differences among individuals in all communities. Hence, the variation in chimpanzee pant-hoots reflected individual differences, rather than group differences. Thus, we did not find evidence of dialects in this population, suggesting that extensive vocal learning emerged only after the lineages of Homo and Pan diverged.
Topics: Acoustics; Animals; Hominidae; Humans; Individuality; Pan troglodytes; Vocalization, Animal
PubMed: 36093564
DOI: 10.1002/ajp.23430 -
Neuroscience and Biobehavioral Reviews Mar 2022In this article we review publications relevant to addressing widely reported claims in both the academic and popular press that chimpanzees working memory (WM) is... (Review)
Review
In this article we review publications relevant to addressing widely reported claims in both the academic and popular press that chimpanzees working memory (WM) is comparable to, if not exceeding, that of humans. WM is a complex multidimensional construct with strong parallels in humans to prefrontal cortex and cognitive development. These parallels occur in chimpanzees, but to a lesser degree. We review empirical evidence and conclude that the size of WM in chimpanzees is 2 ± 1 versus Miller's famous 7 ± 2 in humans. Comparable differences occur in experiments on chimpanzees relating to strategic and attentional WM subsystems. Regardless of the domain, chimpanzee WM performance is comparable to that of humans around the age of 4 or 5. Next, we review evidence showing parallels among the evolution of WM capacity in hominins ancestral to Homo sapiens, the phylogenetic evolution of hominins leading to Homo sapiens, and evolution in the complexity of stone tool technology over this time period.
Topics: Animals; Biological Evolution; Hominidae; Humans; Memory, Short-Term; Pan troglodytes; Phylogeny
PubMed: 34919985
DOI: 10.1016/j.neubiorev.2021.12.019 -
Current Biology : CB Oct 2021Humans reason not only about actual events (what is), but also about possible events (what could be). Many key operations of human cognition involve the representation...
Humans reason not only about actual events (what is), but also about possible events (what could be). Many key operations of human cognition involve the representation of possibilities, including moral judgment, future planning, and causal understanding. But little is known about the evolutionary roots of this kind of thought. Humans' closest relatives, chimpanzees, possess several cognitive abilities that are closely related to reasoning about alternatives: they plan for the future, evaluate other's actions, and reason causally. However, in the first direct test of the ability to consider alternatives, Redshaw and Suddendorf claim that chimpanzees are not able to represent alternative possibilities. Here, using a novel method, we challenge this conclusion: our results suggest that, like human cognition, chimpanzee thought is not limited to what is, but also involves reasoning about what could be the case.
Topics: Animals; Cognition; Humans; Judgment; Morals; Pan troglodytes; Problem Solving
PubMed: 34699798
DOI: 10.1016/j.cub.2021.09.012 -
Proceedings. Biological Sciences Dec 2017Various non-human animal species have been shown to exhibit behavioural traditions. Importantly, this research has been guided by what we know of human culture, and the... (Review)
Review
Various non-human animal species have been shown to exhibit behavioural traditions. Importantly, this research has been guided by what we know of human culture, and the question of whether animal cultures may be homologous or analogous to our own culture. In this paper, we assess whether models of human cultural transmission are relevant to understanding biological fundamentals by investigating whether accounts of human payoff-biased social learning are relevant to chimpanzees (). We submitted 4- and 5-year-old children ( = 90) and captive chimpanzees ( = 69) to a token-reward exchange task. The results revealed different forms of payoff-biased learning across species and contexts. Specifically, following personal and social exposure to different tokens, children's exchange behaviour was consistent with proportional imitation, where choice is affected by both prior personally acquired and socially demonstrated token-reward information. However, when the socially derived information regarding token value was novel, children's behaviour was consistent with proportional observation; paying attention to socially derived information and ignoring their prior personal experience. By contrast, chimpanzees' token choice was governed by their own prior experience only, with no effect of social demonstration on token choice, conforming to proportional reservation. We also find evidence for individual- and group-level differences in behaviour in both species. Despite the difference in payoff strategies used, both chimpanzees and children adopted beneficial traits when available. However, the strategies of the children are expected to be the most beneficial in promoting flexible behaviour by enabling existing behaviours to be updated or replaced with new and often superior ones.
Topics: Animals; Child, Preschool; Choice Behavior; Female; Humans; Male; Pan troglodytes; Reward; Social Learning
PubMed: 29187629
DOI: 10.1098/rspb.2017.1751