Is Overimitation a Uniquely Human Phenomenon? Insights From Human Children as Compared to Bonobos

Imitation is a key mechanism of human culture and underlies many of the intricacies of human social life, including rituals and social norms. Compared to other animals, humans appear to be special in their readiness to copy novel actions as well as those that are visibly causally irrelevant. This study directly compared the imitative behavior of human children to that of bonobos, our understudied great ape relatives. During an action-copying task involving visibly causally irrelevant actions, only 3- to 5-year-old children (N = 77) readily copied, whereas no bonobo from a large sample did (N = 46). These results highlight the distinctive nature of the human cultural capacity and contribute important insights into the development and evolution of human cultural behaviors

Orientation toward humans predicts cognitive performance in orang-utans

The authors acknowledge the Swiss National Science Foundation and following foundations who have financially supported this project: A. H. Schultz Foundation, Paul Schiller Foundation and the Claraz Foundation in Switzerland and Waldemar von Frenckells Foundation, Ella and Georgh Ehrnrooths Foundation, Otto A. Malms Donationsfond, Nordenskiöld Samfundet and Oskar Öflunds Foundation in Finland.Non-human animals sometimes show marked intraspecific variation in their cognitive abilities that may reflect variation in external inputs and experience during the developmental period. We examined variation in exploration and cognitive performance on a problem-solving task in a large sample of captive orang-utans (Pongo abelii & P. pygmaeus, N = 103) that had experienced different rearing and housing conditions during ontogeny, including human exposure. In addition to measuring exploration and cognitive performance, we also conducted a set of assays of the subjects’ psychological orientation, including reactions towards an unfamiliar human, summarized in the human orientation index (HOI), and towards novel food and objects. Using generalized linear mixed models we found that the HOI, rather than rearing background, best predicted both exploration and problem-solving success. Our results suggest a cascade of processes: human orientation was accompanied by a change in motivation towards problem-solving, expressed in reduced neophobia and increased exploration variety, which led to greater experience, and thus eventually to higher performance in the task. We propose that different experiences with humans caused individuals to vary in curiosity and understanding of the physical problem-solving task. We discuss the implications of these findings for comparative studies of cognitive ability.Publisher PDFPeer reviewe

Bodily mimesisas “the missing link” in human cognitive evolution

It is fairly uncontroversial that there is a large gap between the communicative and cognitive systems of non-human animals and those of human beings. There is much less consensus, however, on what the nature of this gap is, and even less on how it was bridged in evolution

Experimental approaches to the study of early hominin technology and cognition using great apes as behavioural models

Humans are a ubiquitous species on the planet and our success in adapting and transforming the environments we inhabit is arguably the result of our ability to successively improve traits across generations to increase our fitness (Henrich, 2017). This process is known as cumulative culture (Boyd & Richerson, 1996; Tomasello, 1999) and involves the modification and transmission of detailed information via the direct observation (e.g. copying) of a model's actions or products. Despite the growing interest in human cumulative culture, its origins are still debated. Some authors have proposed that early stone tools represent the earliest signs of cumulative cultural evolution in our lineage. According to this hypothesis, early hominins could not have learnt how to produce or use early stone tools individually without copying a model. A more parsimonious hypothesis regarding the learning mechanisms underlying the production and use of early stone tools could be derived from great apes (Tennie et al., 2009), who learn most of their tool behaviors individually without the need of copying a model (Chapter 2; Tennie et al., 2009). According to this hypothesis, early hominins acquired early stone tool making and using abilities via individual learning catalyzed by non-copying social learning mechanisms. Given that it is not possible to test early hominins directly in behavioral experiments, I investigated if and how two species of great apes (chimpanzees and orangutans) could acquire early stone tool making and using abilities in a series of baselines and social learning experiments (Chapters 2 to 5). The main finding from these experiments is that not all behaviors involved in the production and use of early stone tools are learnt in the same way by naïve, unenculturated chimpanzees and orangutans. Orangutans, but not chimpanzees, spontaneously perform percussive actions in which an active element is used to strike a hard surface. In one occasion, this behavior led to the detachment of sharp-edged stones from a flint core. In addition, one orangutan spontaneously used a human-made flake as a cutting tool to severe the lid of a baited puzzle box. Finally, after seeing demonstrations performed by a human model of how to make and use flakes, one orangutan and two chimpanzees engaged in percussive actions using an artificial hammer to strike a core. The results from these experiments show that certain behaviors such as the unintentional production of sharp-edged stone tools and the use of readily-made flakes as cutting tools can be individually learnt by orangutans. By phylogenetic proxy, such findings suggest that our last common ancestor with orangutans might have already presented the cognitive and physical abilities necessary to perform these behaviors 13 Ma. However, some behaviors such as the intentional production of sharp-edged stone tools for their subsequent use as cutting tools, seem beyond the individual and social learning abilities of ecologicallyrepresentative (unenculurated) chimpanzees and orangutans. It is therefore possible, that the intentional production of sharp-edged stone tools only emerged in our lineage when certain abilities (such as copying social learning mechanisms) evolved in our lineage. If this were to be the case, the intentional production of sharp-edged stone tools would represent the starting or catalyzing point of cumulative culture in our lineage

Specialization in the vicarious learning of novel arbitrary sequences in humans but not orangutans

Sequence learning underlies many uniquely human behaviours, from complex tool use to language and ritual. To understand whether this fundamental cognitive feature is uniquely derived in humans requires a comparative approach. We propose that the vicarious (but not individual) learning of novel arbitrary sequences represents a human cognitive specialization. To test this hypothesis, we compared the abilities of human children aged 3–5 years and orangutans to learn different types of arbitrary sequences (item-based and spatial-based). Sequences could be learned individually (by trial and error) or vicariously from a human (social) demonstrator or a computer (ghost control). We found that both children and orangutans recalled both types of sequence following trial-and-error learning; older children also learned both types of sequence following social and ghost demonstrations. Orangutans' success individually learning arbitrary sequences shows that their failure to do so in some vicarious learning conditions is not owing to general representational problems. These results provide new insights into some of the most persistent discontinuities observed between humans and other great apes in terms of complex tool use, language and ritual, all of which involve the cultural learning of novel arbitrary sequences

Naïve orangutans (Pongo abeliiand Pongo pygmaeus) individually acquire nut‐cracking using hammer tools

Nut-cracking with hammer tools (henceforth: nut-cracking) has been argued to be one of the most complex tool-use behaviors observed in nonhuman animals. So far, only chimpanzees, capuchins, and macaques have been observed using tools to crack nuts in the wild (Boesch and Boesch, 1990; Gumert et al., 2009; Mannu and Ottoni, 2009). However, the learning mechanisms behind this behavior, and the extent of nut-cracking in other primate species are still unknown. The aim of this study was two-fold. First, we investigated whether another great ape species would develop nut-cracking when provided with all the tools and appropriate conditions to do so. Second, we examined the mechanisms behind the emergence of nut-cracking by testing a naïve sample. Orangutans (Pongo abelii and Pongo pygmaeus) have the second most extensive tool-use repertoire among the great apes (after chimpanzees) and show flexible problem-solving capacities. Orangutans have not been observed cracking nuts in the wild, however, perhaps because their arboreal habits provide limited opportunities for nut-cracking. Therefore, orangutans are a valid candidate species for the investigation of the development of this behavior. Four nut-cracking-naïve orangutans at Leipzig zoo (P. abelii; Mage = 16; age range = 10–19; 4F; at the time of testing) were provided with nuts and hammers but were not demonstrated the nut-cracking behavioral form. Additionally, we report data from a previously unpublished study by one of the authors (Martina Funk) with eight orangutans housed at Zürich zoo (six P. abelii and two P. pygmaeus; Mage = 14; age range = 2–30; 5F; at the time of testing) that followed a similar testing paradigm. Out of the twelve orangutans tested, at least four individuals, one from Leipzig (P. abelii) and three from Zürich (P. abelii and P. pygmaeus), spontaneously expressed nut-cracking using wooden hammers. These results demonstrate that nut-cracking can emerge in orangutans through individual learning and certain types of non-copying social learning

The plight of the sense-making ape

This is a selective review of the published literature on object-choice tasks, where participants use directional cues to find hidden objects. This literature comprises the efforts of researchers to make sense of the sense-making capacities of our nearest living relatives. This chapter is written to highlight some nonsensical conclusions that frequently emerge from this research. The data suggest that when apes are given approximately the same sense-making opportunities as we provide our children, then they will easily make sense of our social signals. The ubiquity of nonsensical contemporary scientific claims to the effect that humans are essentially--or inherently--more capable than other great apes in the understanding of simple directional cues is, itself, a testament to the power of preconceived ideas on human perception

Call Cultures in Orang-Utans?

BACKGROUND: Several studies suggested great ape cultures, arguing that human cumulative culture presumably evolved from such a foundation. These focused on conspicuous behaviours, and showed rich geographic variation, which could not be attributed to known ecological or genetic differences. Although geographic variation within call types (accents) has previously been reported for orang-utans and other primate species, we examine geographic variation in the presence/absence of discrete call types (dialects). Because orang-utans have been shown to have geographic variation that is not completely explicable by genetic or ecological factors we hypothesized that this will be similar in the call domain and predict that discrete call type variation between populations will be found. METHODOLOGY/PRINCIPAL FINDINGS: We examined long-term behavioural data from five orang-utan populations and collected fecal samples for genetic analyses. We show that there is geographic variation in the presence of discrete types of calls. In exactly the same behavioural context (nest building and infant retrieval), individuals in different wild populations customarily emit either qualitatively different calls or calls in some but not in others. By comparing patterns in call-type and genetic similarity, we suggest that the observed variation is not likely to be explained by genetic or ecological differences. CONCLUSION/SIGNIFICANCE: These results are consistent with the potential presence of 'call cultures' and suggest that wild orang-utans possess the ability to invent arbitrary calls, which spread through social learning. These findings differ substantially from those that have been reported for primates before. First, the results reported here are on dialect and not on accent. Second, this study presents cases of production learning whereas most primate studies on vocal learning were cases of contextual learning. We conclude with speculating on how these findings might assist in bridging the gap between vocal communication in non-human primates and human speech