Evolution, Development, and Human Social Cognition. Explaining the causal origins of what are taken to be uniquely human capacities for understanding the mind in the first years of life is a primary goal of social cognitive development research, which … Expand.
Recent wild animal studies have led to the realization that some of the population differences observed in some species possess close similarities to human cultures. This has inflamed a long-standing … Expand. Evolutionary precursors of social norms in chimpanzees: a new approach. Moral behaviour, based on social norms, is commonly regarded as a hallmark of humans. Hitherto, humans are perceived to be the only species possessing social norms and to engage in moral behaviour.
View 1 excerpt, cites background. Synthetic primatology: what humans and chimpanzees do in a Japanese laboratory and the African field. Cognitive cladistics and cultural override in Hominid spatial cognition. Social understanding in chimpanzees: New evidence from a longitudinal approach.
Behavior, it would now seem, is not necessarily an open window into the mind. If it were, humanity's quest to end its intellectual and spiritual isolation from the rest of the natural world would … Expand. View 1 excerpt. This chapter addresses the proposition that the study of the role of culture in cognitive development must be conducted in a broad, historical perspective that includes the history of the human … Expand.
View 1 excerpt, references background. The Cultural Origins of Human Cognition. This work builds a bridge between evolutionary theory and cultural psychology. The author is one of very few people to have done systematic research on the cognitive capacities of both nonhuman … Expand. Highly Influential. Then, while talking to her son, who was still sitting in the position he used to crack the nuts, she presented the dehiscent line of the nut to him, placed the nut carefully on the bushknife still held by her son and cracked 3 nuts as a demonstration.
Then, her son took back his hammer and carefully placed a nut on the blade as explained to him but failed to open it. As a consequence, the mother repeated the same process a second time. The son cracked some more nuts with limited success before stopping. Interestingly, his younger sister then took his tools and tried to crack nuts with even less success.
Seeing this, he showed her the dehiscent line and how to place the nut correctly. We also saw similar pedagogic interactions when children were cracking the Irvingia nuts Our observations of teaching interactions in humans and chimpanzees add new aspects to our knowledge about the teaching abilities in both species. In addition, our observations support an evolutionary approach whereby the emergence of teaching is expected only when it can provide a benefit that could not be acquired by individual or social learning alone 36 , This approach expects that teaching should be observed in different animal species, and that the degree of sophistication of the teaching interactions increases as the benefits to the learner increase in the context of a given technique.
Supporting this expectation, teaching has been reported in animal species known for their cognitive skills, such as dolphins, carnivores, and certain primates Humans have broadened teaching to different types of horizontal teaching interactions such as between peers, whereas this is absent in chimpanzees as far as we know.
Such forms of verbal reinforcement were considerably more successful in the transmission of, e. In agreement with the previous observations on the limited effect of teaching interactions on the learning curve of the apprentice 14 , 15 , we did not see any statistical effect of the presence of teaching on the immediate nut-cracking performance. Based on a Western conception that teaching must result in an improvement, this has been proposed as a criterion for teaching Our observations of teaching in the context of nut cracking did not fulfill this requirement in the short-term, although the teachers clearly intended to transfer information to the apprentices.
We argue that knowledge of how a movement has to be enacted does not immediately lead to improvement of that movement until all the physical knowledge is fully integrated through extensive practice. In conclusion, the comparison of the acquisition of nut-cracking showed that both chimpanzees and humans learn the skill in a very similar way, that the learning is a years- long process, and that experts regularly provide information to apprentices during this process.
The unexpected observation that chimpanzees learned the nut cracking more rapidly and reached adult performance earlier than humans does not support the predictions of the technical intelligence nor the life history hypothesis. This is the first comparison of the acquisition of a technical skill habitually performed by the two species as they forage in their natural environment.
It provides important new insights about potential differences in the two species and highlights the importance of making cross-species comparisons in situations that are directly comparable. Their nut-cracking behavior was studied in detail between and 7. The population cracks 5 different nut species, including the hard nut, Panda oleosa , which is the nut species used in the present study. A detailed analysis of young chimpanzees learning the nut-cracking technique was presented in 8 and this data set will be used for the present comparison.
All individuals in the community have been identified since and were fully habituated to human observers within the following three years, allowing us to know the precise age of the younger individuals.
For older individuals, age was estimated based on physical and behavioral characteristics as well as by previous experience from aging individuals with the Gombe chimpanzees see 7 for more details about the aging procedures.
The Mbendjele foragers live in the Northern part of the Republic of Congo. They maintained a hunting and gathering way-of-life, spending long periods in temporary camps gathering natural fruits, nuts, honey, and fishes in the forest. Aging children, as in all non-literate societies, can be challenging and we based our estimates on the years-long work of DB with this group as she was able to fluently communicate with them to improve the age estimates of younger individuals.
For adults, the age estimation has to be considered to become less precise the older they have been estimated. The Panda nuts are one of the hardest nut species growing in Africa, requiring about 16 tons of weight to crack open Panda oleosa trees produce a few hundred nuts each year, but are relatively rare and dispersed in the forest. The shell of the nut is very resistant causing the kernels to remain edible months after having fallen to the ground.
The nut contains 3 to 4 kernels individually embedded within the hard wood of the shell. Chimpanzees crack the nuts by balancing them on a root used as an anvil, and pounding them with a heavy stone hammer with repeated hits. Stone hammers vary in weight from 0. The Mbendjele people mostly use a bushknife and more rarely use an axe as anvils, held on the ground with their foot so that the cutting blade is pointing upwards Then, with one hand, they hold the Panda nut in place on the blade and, with their other hand hit it with a light wooden hammer made from the wood of an abundant sapling.
Two strategies are used to access the kernels see 11 for more details. Chimpanzees place the nuts so that the maximum kinetic energy from the hammer is placed between the two dehiscent lines and the opercula opens under the force leaving large parts of the kernel intact.
Imprecise hits risk smashing the whole nut, requiring much more time to sort edible bits from the shell. Powerful hits are used first to break the nut open, and subsequently very soft hits are applied by the chimpanzees, after repositioning carefully the nut, in an attempt to access each individual kernels with the least damage.
Only skilled nut-crackers are able to extract some of the kernels intact, the majority of them being cut in one or two pieces as the shell was broken apart. Alternatively, the Mbendjele place the base of the opercula of each kernel precisely on the sharp cutting blade of the bushknife and then hit the nut with a wooden hammer until the blade cuts the whole opercula loose, exposing the intact kernel. They repeat this until they have exposed all the kernels and then place the open nuts on a large Marantaceae sp.
The use of the cutting blade and precise positioning of the nut allows for intact extraction of almost all kernels. Apprentices of both species are, however, still far from the ideal and cut often the kernels in smaller pieces than experts.
Data collection occurred between May and August , when women had access to edible nuts laying on the ground. One month was spent training on data collection methods to ensure good inter-observer reliability. Video recordings were used whenever more than one individual was involved in nut cracking and any time young were attempting the technique.
In our two study populations, we recorded nut-cracking instances in the forest with a focal sampling method As reported in our previous study 11 , the Mbendjele use a metal tool, a bushknife or axe, as an anvil to crack the nuts, and each family normally had one of each. Collecting data on the children with the Mbendjele proved to be more difficult than expected as independent children rarely followed their mothers in the forest.
Nevertheless, we succeeded in collecting 43 nut sequences with children of different ages whenever they followed their mothers in the forest. Realizing that we would not be able to collect enough data on the children in the forest, we collected Panda nuts in the forest at the end of the season and brought them back to camp for the children to crack.
We did this only after their mothers had returned to camp from foraging in the forest. Cracking the nuts in camp could be easier than in the forest. The ground in camp had been cleared from leaves and branches littering the forest floor, making positioning the bushknife potentially easier. However, we did not gain the impression that this affected performance and this would actually favor humans in the present comparison. The first measure reflects not only the efficiency of the tools selected, as we showed that heavier stone hammers allow the user to open nuts with fewer hits, it also accounts for the dexterity of the nut-cracker to manipulate the hammer.
The chimpanzees eat each kernel as they expose them, while the Mbendjele carry the nuts back to camp before consumption. To account for this difference, we compared only the time needed to open the nuts in both species see as well Furthermore, to allow for an ontogenetic study we transformed the first measure, as young of both species have been seen attempting to open the nuts for many months and sometimes even years without successfully opening any.
Expert-apprentice interactions occurring before June were reported on site and after June were analyzed from the video recordings following the same ethogram. Videos were also used to transcribe the oral instructions and comments exchanged between expert and apprentice. CB recorded the interactions directly in the forest when recording the nut cracking sequences. AM, who stayed longer in the forest, recorded on a video all children nut-cracking sequences.
Later, CB did the coding of the videos including all expert-apprentice interactions, while DB did all the translations of the vocal exchanges occurring between expert and apprentice.
We expected to see new elements compared to what we saw in chimpanzees and therefore kept an open mind to detect all possible variations in the interventions coming from experts.
As our focus was of a comparative dimension, we concentrated on non-vocal elements and used clear behavioral operational descriptions of the observations. If spoken instructions, comments or remarks were produced by the experts at the same time, they were recorded and considered only if they were directly related to the expert-apprentice nut-cracking interactions.
Since a standard Generalized Linear Model 60 cannot model the obviously non-linear i. This modeled the effect of age, group, and their interaction as key terms but also included sex and the presence of help on the number of nuts cracked per unit time.
Furthermore, we included the observation duration as an offset term The model was fitted using the following equations:. The sigmoidal equation accounts for the sigmoidal nature of ontogenetic trajectories, bounds the fitted values to values larger than zero, and allows the shapes of the trajectories to differ between humans and chimpanzees. The coefficients c 0 , c 2 , and c 6 express the steepness of the increase and when the steepest increase takes place c 0 and c 2 as well as the asymptotic adult performance c 6 for chimpanzees, and the coefficients c 1 , c 3 , and c 7 express how these features of the ontogenetic trajectory differed between humans and chimpanzees the coefficients c 4 and c 5 express the effects of sex and presence of help, respectively.
We then used maximum the likelihood to determine the estimated coefficients c 0 to c 7 best explaining the observed number of cracked nuts assuming a negative binomial error distribution. We assumed two independent values of theta, the dispersion parameter 61 , for Mbendjele and chimpanzees to account for the possibility of extra variation between them.
To avoid pseudo-replication 62 we aggregated the data per individual and fitted the model to the aggregated data. The stability of the models was good as indicated by the range of estimates obtained when excluding individuals one at a time. The model was fitted for the absolute and the relative age. We fitted two essentially identical models with absolute and relative age, respectively, as predictors for the probability of an individual strike to crack the nut.
These models lacked the offset term for the observation time and were implemented with binomial error structure. The sample sizes were 83 and 79 for the negative binomial and binomial model, respectively.
Several of the full or null models lacking group and its interactions did not converge, even when we increased the maximum number of iterations or altered the optimizer. However, stability estimates, confidence intervals, and plots of the data and models suggest that the results can be trusted nevertheless. Since non-converging models preclude likelihood ratio tests we based inference on confidence intervals. The data collected for this study were strictly non-invasive and were approved by the Ethical Board of the Max Planck Society.
The Mbendjele people had been fully informed about the aim and the methods of the project and provided their informed consent for being included in our study and for the observers to follow them during their natural forays in the forest.
For all participants under the age of 18 years old, a direct parent has provided an informed consent. Byrne, R. Oxford Science Publishing, Mithen, S. Ambrose, S.
Paleolithic technology and human evolution. Science , — Coevolution of composite-tool technology, constructive memory and language. Article Google Scholar. Stout, D. Technology, expertise and social cognition in human evolution. Hecht, E. Acquisition of Paleolithic toolmaking abilities involves structural remodeling to inferior frontoparietal regions.
Brain Strut. Boesch, C. Visalberghi, E. Selection of effective stone tools by wild bearded capuchin monkeys. Gumert, M. Long-tailed macaques select mass of stone tools according to food type. Society B. Kaplan, H. A theory of human life history evolution: diet, intelligence and longevity. Technical intelligence and culture: nut cracking in humans and chimpanzees. PubMed Article Google Scholar. Ericsson, A. The influence of experience and deliberate practice on the development of superior expert performance.
Lombard, M. Hunting and hunting technologies as proxy for teaching and learning during Stone Age of SouthernAfrica. Cambridge Archaeol. Skill and cognition in stone tool production: an ethnographic case study from Irian Jaya. Roux, V. Skills and learning difficulties involved in stone knapping: the case of stone-bead knapping in Khambhat, India.
World Archaeol. Schniter, E. Skill ontogeny among Tsimane forager-horticulturalists. Weedman, K. Bril, B. Functional mastery of percussive technology in nut-cracking and stone-flaking actions: experimental comparison and implications for the evolution of the human brain.
Royal Soc. Povinelli, D. World without Weight: Perspectives on an alien mind. Oxford: Oxford University Press The emergence of humans: the coevolution of intelligence and longevity with intergenerational transfers. PNAS 99 15 , — Nature 13 1 , 27—46 Google Scholar. Fahy, G. Stable isotope evidence of meat eating and hunting specialization in adult male chimpanzees. PNAS 15 , — Spagnoletti, N. Stone tool use by adult wild bearded capuchin monkeys Cebus libidinosus : frequency, efficiency and tool selectivity.
Journal of Human Evolution 61 , 97— Sirianni, G. When to choose which tool: multidimensional and conditional selection of nut-cracking hammers in wild chimpanzees. Animal Behaviour , — The author argues that only with consideration of within-species population differences in the cognitive domains and the use of well-matched cross-species experimental procedures will an objective understanding of the different cognitive abilities between species emerge.
This will require a shift in the theoretical approach adopted by many in experimental and comparative psychology. Abstract Two major theoretical approaches have dominated the quest for uniquely human cognitive abilities: a developmentalist approach stressing the importance of environmental and social conditions, and a predominant approach in experimental and comparative psychology, the deterministic approach suggesting the effect of environmental and social conditions to be minimal.
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