Dorothy M. Fragaszy

On the relation between social dynamics and social learning

Abstract Experimental studies on social learning in animals have commonly centred on the psychological processes responsible for learning, and neglected social processes as potential influences on both the likelihood of social learning and the type of information that can be acquired socially. A model relating social learning to social dynamics among members of a group is presented. Three key hypotheses of the model are (1) behavioural coordination in time and/or space supports the process of social learning; (2) different kinds of coordination differentially support acquisition of different kinds of information; and (3) the various forms of behavioural coordination will be differentially affected by social dynamics. Several predictions relating inter-individual and group differences in social dynamics to social learning that follow from these hypotheses are presented.

Performance in a tool-using task by common chimpanzees (Pan troglodytes), bonobos (Pan paniscus), an orangutan (Pongo pygmaeus), and capuchin monkeys (Cebus apella).

Performance by individual animals of three species of great apes (Pan troglodytes, Pan paniscus, and Pongo pygmaeus) and capuchin monkeys (Cebus apella) was assessed by presenting a food treat inside a clear tube. The subjects readily used a straight stick to obtain the food. When sticks were bundled together, the apes immediately unwrapped the bundle to obtain an individual stick, whereas capuchins attempted to insert the bundled sticks. When a misshapen stick was provided, apes, but not capuchins, showed an improvement in terms of modifying the misshapen stick before insertion. Our results indicate that all these species can solve these tasks. However, only the performance of apes is consistent with emerging comprehension of the causal relations required for the avoidance of errors in the more complex tasks.

Socially biased learning in monkeys.

We review socially biased learning about food and problem solving in monkeys, relying especially on studies with tufted capuchin monkeys (Cebus apella) and callitrichid monkeys. Capuchin monkeys most effectively learn to solve a new problem when they can act jointly with an experienced partner in a socially tolerant setting and when the problem can be solved by direct action on an object or substrate, but they do not learn by imitation. Capuchin monkeys are motivated to eat foods, whether familiar or novel, when they are with others that are eating, regardless of what the others are eating. Thus, social bias in learning about foods is indirect and mediated by facilitation of feeding. In most respects, social biases in learning are similar in capuchins and callitrichids, except that callitrichids provide more specific behavioral cues to others about the availability and palatability of foods. Callitrichids generally are more tolerant toward group members and coordinate their activity in space and time more closely than capuchins do. These characteristics support stronger social biases in learning in callitrichids than in capuchins in some situations. On the other hand, callitrichids’ more limited range of manipulative behaviors, greater neophobia, and greater sensitivity to the risk of predation restricts what these monkeys learn in comparison with capuchins. We suggest that socially biased learning is always the collective outcome of interacting physical, social, and individual factors, and that differences across populations and species in social bias in learning reflect variations in all these dimensions. Progress in understanding socially biased learning in nonhuman species will be aided by the development of appropriately detailed models of the richly interconnected processes affecting learning.

The behaviour of capuchin monkeys,Cebus apella, with novel food: the role of social context

Social influences affect individual responsiveness to key features of the environment, such as food. Galef (1993,Anim. Behav.,46,257-265) has predicted that social facilitation should affect food choice more powerfully when the food is novel than when it is familiar. This prediction was tested in monkeys. Eleven capuchin monkeys were tested individually (Individual condition) and in a group (Social condition) with eight familiar foods presented simultaneously (experiment 1). In experiment 2, the same subjects received 20 novel and four familiar foods presented singly in Individual or in Social testing conditions. More food was expected to be eaten in the Social condition than in the Individual condition, particularly when food was novel. In experiment 1, testing condition (Individual or Social) did not affect consumption of familiar foods. In experiment 2, capuchins ate more familiar foods than novel foods in both conditions. However, they were more interested in another individuals food when foods were novel than when they were familiar. Consumption of, and responses to, the novel foods were more frequent in social testing than in individual testing; testing conditions did not affect consumption of, or response to, the familiar foods. Nine of 10 individuals ate more types of novel foods in the Social condition that in the Individual condition. In short, social facilitation of eating was evident, but only with novel foods. These findings support Galefs prediction and suggest that social facilitation can have a role in enlarging dietary selection in capuchins.

The fourth dimension of tool use: temporally enduring artefacts aid primates learning to use tools

All investigated cases of habitual tool use in wild chimpanzees and capuchin monkeys include youngsters encountering durable artefacts, most often in a supportive social context. We propose that enduring artefacts associated with tool use, such as previously used tools, partly processed food items and residual material from previous activity, aid non-human primates to learn to use tools, and to develop expertise in their use, thus contributing to traditional technologies in non-humans. Therefore, social contributions to tool use can be considered as situated in the three dimensions of Euclidean space, and in the fourth dimension of time. This notion expands the contribution of social context to learning a skill beyond the immediate presence of a model nearby. We provide examples supporting this hypothesis from wild bearded capuchin monkeys and chimpanzees, and suggest avenues for future research.

Comparison of Development and Life History in Pan and Cebus

We examined growth and development in capuchins and chimpanzees in relation to weaning, onset of reproduction, and reproductive life span. Striking differences are evident in neurobehavioral status at birth (more mature in capuchins), the relative duration of infancy (longer in chimpanzees), and the proportional weight of the infant at the time of weaning (greater in capuchins). Although capuchins and chimpanzees spend a similar proportion of life in a weaned but reproductively immature state, chimpanzees spend so much more of their lives as nursing infants that reproductive output per individual is much lower than in capuchins. Discussion centers around tolerated transfers of food (food-sharing) as a potential adaptation to limited foraging success by immature foragers. Perhaps food transfers from adult to infant, which is a more prominent feature of behavior in chimpanzees than in capuchins in natural environments, allow a very small weanling chimpanzee to survive.

Patterns of individual diet choice and efficiency of foraging in wedge-capped capuchin monkeys (Cebus olivaceus).

Capuchin monkeys (Cebus olivaceus) exhibit extensive intragroup variability in foraging and diet. To consider how age, sex, and individual identity contribute to this variability, the authors examined foraging and diet in 18 wedge-capped capuchin monkeys in 1 social group in the wild. Age-sex classes did not differ in the time spent ingesting food, the reliance on plant foods, the foraging actions used or substrates exploited, or in the efficiency of exploiting animal foods. They did differ, however, in the time spent finding food, time devoted to animal foods and to vigorous foraging, and the efficiency of foraging. The sexes differed more than age groups. Individual differences within age-sex class were less extensive than expected and were more evident in juveniles than adults. Within-group variability in foraging reflected catholic selection and equivalent treatment of substrates by all individuals, rather than individual specializations.

CHAPTER 4 – Social Learning in Monkeys: Primate “Primacy” Reconsidered

The recognition that humans share many traits with other primates can have, as an unintended correlate, an uncritical willingness to ascribe human traits to other primate species. Behavioral researchers are more likely to provide higher order “cognitive” explanations for behavior in primates than members of other orders, perhaps reflecting some intuitive notion that cognitive continuity extends from humans to other primates, but not to other orders. In this chapter, it is put forward that apparently natural inclination to attribute a special character to social learning in monkeys, relative to social learning in other animals, is unwarranted. This is not to say that social influences are not important to primates, as to other orders. Rather, the comparative psychological issue is whether a different set of underlying mechanisms supports social learning in primates than in other orders. This chapter propagates that it is easy, for laymen and scientists alike, to look at nonhuman primates and to envisage human-like cognition as being behind their behavior. It is argued that this attitude has stood in the way of an objective assessment of social learning capacities in nonhuman primates, particularly monkeys. It is showed that in the case of capuchin monkeys dealing with novel or difficult food, simple social tendencies are sufficient to explain what is observed.

Kinematics and Energetics of Nut-Cracking in Wild Capuchin Monkeys (Cebus libidinosus) in Piaui´, Brazil

Wild bearded capuchins (Cebus libidinosus, quadrupedal, medium-sized monkeys) crack nuts using large stones. We examined the kinematics and energetics of the nut-cracking action of two adult males and two adult females. From a bipedal stance, the monkeys raised a heavy hammer stone (1.46 and 1.32 kg, from 33 to 77% of their body weight) to an average height of 0.33 m, 60% of body length. Then, they rapidly lowered the stone by flexing the lower extremities and the trunk until the stone contacted the nut. A hit consisting of an upward phase and a downward phase averaged 0.74 s in duration. The upward phase lasted 69% of hit duration. All subjects added discernable energy to the stone in the downward phase. The monkeys exhibited individualized kinematic strategies, similar to those of human weight lifters. Capuchins illustrate that human-like bipedal stance and large body size are unnecessary to break tough objects from a bipedal position. The phenomenon of bipedal nut-cracking by capuchins provides a new comparative reference point for discussions of percussive tool use and bipedality in primates.

Acquisition of foraging competence in wild brown capuchins ( Cebus apella ), with special reference to conspecifics' foraging artefacts as an indirect social influence

[Wild brown capuchins (Cebus apella) in Raleighvallen, Suriname forage on larvae hidden inside bamboo stalks via searching and extractive behaviours. We found that developing proficiency at obtaining larvae from bamboo stalks extends through several years of juvenescence. Older juveniles pass through a transition from a juvenile pattern to an adult pattern of foraging efficiency and diet selection. Whereas most studies have investigated the contribution of direct interactions between a naive individual and a competent forager on the acquisition of foraging expertise, we focused on indirect social influence through foraging artefacts left in the habitat by conspecifics. Young individuals foraged at bamboo stalks more often shortly after than shortly before encountering bamboo segments previously opened by foragers to extract larvae. We discuss this result in terms of stimulus enhancement and social facilitation. In capuchins, learning how to forage on difficult foods does not necessarily occur in the presence of other group members, and social influences can be delayed in time and separate in space from others. This study provides an original view on how the gradual acquisition of foraging competence in brown capuchins is aided jointly by physical maturation and indirect social input that provides opportunities to practice appropriate foraging actions., Wild brown capuchins (Cebus apella) in Raleighvallen, Suriname forage on larvae hidden inside bamboo stalks via searching and extractive behaviours. We found that developing proficiency at obtaining larvae from bamboo stalks extends through several years of juvenescence. Older juveniles pass through a transition from a juvenile pattern to an adult pattern of foraging efficiency and diet selection. Whereas most studies have investigated the contribution of direct interactions between a naive individual and a competent forager on the acquisition of foraging expertise, we focused on indirect social influence through foraging artefacts left in the habitat by conspecifics. Young individuals foraged at bamboo stalks more often shortly after than shortly before encountering bamboo segments previously opened by foragers to extract larvae. We discuss this result in terms of stimulus enhancement and social facilitation. In capuchins, learning how to forage on difficult foods does not necessarily occur in the presence of other group members, and social influences can be delayed in time and separate in space from others. This study provides an original view on how the gradual acquisition of foraging competence in brown capuchins is aided jointly by physical maturation and indirect social input that provides opportunities to practice appropriate foraging actions.]