Alex Thornton

Experimentally induced innovations lead to persistent culture via conformity in wild birds

In human societies, cultural norms arise when behaviours are transmitted through social networks via high-fidelity social learning. However, a paucity of experimental studies has meant that there is no comparable understanding of the process by which socially transmitted behaviours might spread and persist in animal populations. Here we show experimental evidence of the establishment of foraging traditions in a wild bird population. We introduced alternative novel foraging techniques into replicated wild sub-populations of great tits (Parus major) and used automated tracking to map the diffusion, establishment and long-term persistence of the seeded innovations. Furthermore, we used social network analysis to examine the social factors that influenced diffusion dynamics. From only two trained birds in each sub-population, the information spread rapidly through social network ties, to reach an average of 75% of individuals, with a total of 414 knowledgeable individuals performing 57,909 solutions over all replicates. The sub-populations were heavily biased towards using the technique that was originally introduced, resulting in established local traditions that were stable over two generations, despite a high population turnover. Finally, we demonstrate a strong effect of social conformity, with individuals disproportionately adopting the most frequent local variant when first acquiring an innovation, and continuing to favour social information over personal information. Cultural conformity is thought to be a key factor in the evolution of complex culture in humans. In providing the first experimental demonstration of conformity in a wild non-primate, and of cultural norms in foraging techniques in any wild animal, our results suggest a much broader taxonomic occurrence of such an apparently complex cultural behaviour.

Individual variation in cognitive performance: developmental and evolutionary perspectives

Animal cognition experiments frequently reveal striking individual variation but rarely consider its causes and largely ignore its potential consequences. Studies often focus on a subset of high-performing subjects, sometimes viewing evidence from a single individual as sufficient to demonstrate the cognitive capacity of a species. We argue that the emphasis on demonstrating species-level cognitive capacities detracts from the value of individual variation in understanding cognitive development and evolution. We consider developmental and evolutionary interpretations of individual variation and use meta-analyses of data from published studies to examine predictors of individual performance. We show that reliance on small sample sizes precludes robust conclusions about individual abilities as well as inter- and intraspecific differences. We advocate standardization of experimental protocols and pooling of data between laboratories to improve statistical rigour. Our analyses show that cognitive performance is influenced by age, sex, rearing conditions and previous experience. These effects limit the validity of comparative analyses unless developmental histories are taken into account, and complicate attempts to understand how cognitive traits are expressed and selected under natural conditions. Further understanding of cognitive evolution requires efforts to elucidate the heritability of cognitive traits and establish whether elevated cognitive performance confers fitness advantages in nature.

Punishment and cooperation in nature

Humans use punishment to promote cooperation in laboratory experiments but evidence that punishment plays a similar role in non-human animals is comparatively rare. In this article, we examine why this may be the case by reviewing evidence from both laboratory experiments on humans and ecologically relevant studies on non-human animals. Generally, punishment appears to be most probable if players differ in strength or strategic options. Although these conditions are common in nature, punishment (unlike other forms of aggression) involves immediate payoff reductions to both punisher and target, with net benefits to punishers contingent on cheats behaving more cooperatively in future interactions. In many cases, aggression yielding immediate benefits may suffice to deter cheats and might explain the relative scarcity of punishment in nature.

Lessons from animal teaching

Many species are known to acquire valuable life skills and information from others, but until recently it was widely believed that animals did not actively facilitate learning in others. Teaching was regarded as a uniquely human faculty. However, recent studies suggest that teaching might be more common in animals than previously thought. Teaching is present in bees, ants, babblers, meerkats and other carnivores but is absent in chimpanzees, a bizarre taxonomic distribution that makes sense if teaching is treated as a form of altruism. Drawing on both mechanistic and functional arguments, we integrate teaching with the broader field of animal social learning, and show how this aids understanding of how and why teaching evolved, and the diversity of teaching mechanisms.

Social learning and the development of individual and group behaviour in mammal societies

As in human societies, social learning may play an important role in shaping individual and group characteristics in other mammals. Here, we review research on non-primate mammals, concentrating on work at our long-term meerkat study site, where longitudinal data and field experiments have generated important insights into the role of social learning under natural conditions. Meerkats live under high predation pressure and occupy a difficult foraging niche. Accordingly, pups make extensive use of social information in learning to avoid predation and obtain food. Where individual learning is costly or opportunities are lacking, as in the acquisition of prey-handling skills, adults play an active role in promoting learning through teaching. Social learning can also cause information to spread through groups, but our data suggest that this does not necessarily result in homogeneous, group-wide traditions. Moreover, traditions are commonly eroded by individual learning. We suggest that traditions will only persist where there are high costs of deviating from the group norm or where skill development requires extensive time and effort. Persistent traditions could, theoretically, modify selection pressures and influence genetic evolution. Further empirical studies of social learning in natural populations are now urgently needed to substantiate theoretical claims.

Innovative problem solving in wild meerkats

Behavioural innovations may have far-reaching evolutionary and ecological consequences, allowing individuals to obtain new resources and cope with environmental change. However, as innovations are rarely observed in nature, their emergence is poorly understood. What drives individuals to innovate, and what psychological mechanisms allow them to do so? We used three novel food extraction tasks to address these questions in groups of wild meerkats, Suricata suricatta. Innovatory tendencies were unrelated to body condition and foraging success, but were affected by age, rank and sex. Juvenile individuals were most likely to interact with tasks, but seldom solved them, perhaps owing to their small size or lack of dexterity. Instead, adult subordinates made up the bulk of the innovators. In cooperatively breeding societies, the inability of subordinate helpers to compete physically with dominant breeders may drive them to seek out solutions to novel problems. Most innovators were males, which, as the dispersing sex, may be particularly prone to solve novel problems, and innovators virtually always persisted longer than other group members when interacting with tasks. Most successful individuals solved tasks more than once, and learned to inhibit ineffective prepotent responses across successive presentations of the same task. They did not learn to manipulate functional parts of the apparatus more efficiently, however, nor did they extract general rules allowing them to solve novel tasks faster. Contrary to recent suggestions that innovation may be cognitively demanding, these results suggest that simple, conserved learning processes and dogged perseverance may suffice to generate solutions to novel problems.

Identifying teaching in wild animals

After a long period of neglect, the study of teaching in nonhuman animals is beginning to take a more prominent role in research on social learning. Unlike other forms of social learning, teaching requires knowledgeable individuals to play an active role in facilitating learning by the naive. Casting aside anthropocentric requirements for cognitive mechanisms assumed to underpin teaching in our own species, researchers are now beginning to discover evidence for teaching across a wide range of taxa. Nevertheless, unequivocal evidence for teaching remains scarce, with convincing experimental data limited to meerkats, pied babblers, and tandem-running ants. In this review, our aim is to stimulate further research in different species and contexts by providing conceptual and methodological guidelines for identifying teaching, with a focus on natural populations. We begin by highlighting the fact that teaching is a form of cooperative behavior that functions to promote learning in others and show that consideration of these key characteristics is critical in helping to identify suitable targets for future research. We then go on to discuss potential observational, experimental, and statistical techniques that may assist researchers in providing evidence that the criteria that make up the accepted operational definition of teaching have been met. Supplemental materials for this article may be downloaded from http://lb.psychonomic-journals.org/content/supplemental.

Comparative cognition for conservationists

Highlights • Animal behaviour affects conservation and is driven by underlying cognition.• Using cognitive principles can modify behaviour across taxonomic groups.• We discuss concepts previously unexplored in conservation contexts.• We create a novel guide for applying cognition to diverse conservation issues.

The rise and fall of an arbitrary tradition: an experiment with wild meerkats

Humans often follow the choices of others, even when profitable alternatives exist, leading to the maintenance of arbitrary traditions. Arbitrary traditions have also been shown to persist in captive groups of other animals, but it is unclear whether they do so in the wild where there are ample opportunities for exploring alternatives. We conducted the first experiment examining the maintenance of arbitrary traditions in wild mammal groups. We trained ‘demonstrators’ in seven meerkat groups to obtain rewards from one out of the two distinctive landmarks. Two control groups had no trained demonstrators. Naive individuals initially ignored the landmarks, but were more likely to approach them and obtain rewards following encounters with demonstrators. Individuals in control groups were less likely to obtain rewards. While control groups showed no landmark preference, experimental groups initially preferred the landmark chosen by demonstrators, even though an equally rewarding alternative was nearby, leading to the establishment of local traditions. However, individuals that learned that one landmark was profitable began to explore the other rather than conforming to the majority behaviour, so traditions collapsed over time. This suggests that where conformist tendencies are lacking, the maintenance of traditions in natural populations depends on the relative influence of social and individual learning.

Social learning about novel foods in young meerkats

Animals are often neophobic towards novel foods, but will incorporate them into their diet after interacting with experienced conspecifics. Such social learning is likely to be particularly important for young animals, for which most foods are unfamiliar. It has been suggested that in some species adults actively promote learning about unfamiliar foods by teaching offspring, although firm evidence is lacking. I examined social influences on learning about novel foods among wild meerkats, Suricata suricatta, a species where older group members teach pups prey-handling skills. In two experiments, naive pups were significantly more likely to eat hardboiled egg, a food item not normally present in the diet, and scorpions, a common prey type, if they had interacted with experienced conspecifics. I then investigated whether helpers teach pups to eat unfamiliar prey by preferentially feeding rare items and through direct feeding, where food items are transferred mouth to mouth. Rare prey items were fed more frequently than common items, although this may reflect nutritional characteristics. Direct feeding was most commonly used by juvenile helpers, which typically contribute relatively little to cooperative activities, and was more frequent if other helpers were nearby. This suggests that direct feeding may be a means of reducing the costs of feeding by improving the efficiency of energy transfer and minimizing the risks of kleptoparasitism. I conclude that learning about novel foods is likely to occur as a by-product of provisioning by helpers. There was little evidence that helpers actively teach pups what to eat.