Cultural diffusion in humans and other animals

Experimental approaches to studying cumulative cultural evolution

In humans, cultural traditions often change in ways which increase efficiency and functionality. This process, widely referred to as cumulative cultural evolution, sees beneficial traits preferentially retained, and it is so pervasive that we may be inclined to take it for granted. However, directional change of this kind appears to distinguish human cultural traditions from behavioural traditions that have been documented in other animals. Cumulative culture is therefore attracting an increasing amount of attention within psychology, and researchers have begun to develop methods of studying this phenomenon under controlled conditions. These studies have now addressed a number of different questions, including which learning mechanisms may be implicated, and how the resulting behaviours may be influenced by factors such as population structure. The current article provides a synopsis of some of these studies, and highlights some of the unresolved issues in this field.

Identifying innovation in laboratory studies of cultural evolution: rates of retention and measures of adaptation

In recent years, laboratory studies of cultural evolution have become increasingly prevalent as a means of identifying and understanding the effects of cultural transmission on the form and functionality of transmitted material. The datasets generated by these studies may provide insights into the conditions encouraging, or inhibiting, high rates of innovation, as well as the effect that this has on measures of adaptive cultural change. Here we review recent experimental studies of cultural evolution with a view to elucidating the role of innovation in generating observed trends. We first consider how tasks are presented to participants, and how the corresponding conceptualization of task success is likely to influence the degree of intent underlying any deviations from perfect reproduction. We then consider the measures of interest used by the researchers to track the changes that occur as a result of transmission, and how these are likely to be affected by differing rates of retention. We conclude that considering studies of cultural evolution from the perspective of innovation provides us with valuable insights that help to clarify important differences in research designs, which have implications for the likely effects of variation in retention rates on measures of cultural adaptation.

The Evolution of Individual and Cultural Variation in Social Learning

It is often assumed in experiments and models that social learning abilities - how often individuals copy others, plus who and how they copy - are species-typical. Yet there is accruing evidence for systematic individual variation in social learning within species. Here we review evidence for this individual variation, placing it within a continuum of increasing phenotypic plasticity, from genetically polymorphic personality traits, to developmental plasticity via cues such as maternal stress, to the individual learning of social learning, and finally the social learning of social learning. The latter, possibly restricted to humans, can generate stable between-group cultural variation in social learning. More research is needed to understand the extent, causes, and consequences of this individual and cultural variation.

Seeding an arbitrary convention in capuchin monkeys: the effect of social context

The study of social learning in non-human animals has advanced beyond attempts to determine which animals are capable of learning socially to investigations of the factors that influence transmission. Capuchin monkeys (Sapajus sp.) are adept social learners of various behaviours including extractive foraging techniques and social customs. Here, we conducted an open diffusion experiment to determine whether capuchins would learn an arbitrary convention from a knowledgeable demonstrator. In addition, we investigated whether rank, sex and social context affected acquisition and expression of the behaviour. Participation in the experiment was strongly influenced by dominance rank in the group setting. However, when tested individually, the majority of individuals participated and faithfully copied the convention that was seeded into their group. Our findings demonstrate that capuchins can acquire an arbitrary convention via social learning, but that social context must be carefully considered in studies of social learning.

Dopamine-System Genes and Cultural Acquisition: The Norm Sensitivity Hypothesis

Previous research in cultural psychology shows that cultures vary in the social orientation of independence and interdependence. To date, however, little is known about how people may acquire such global patterns of cultural behavior or cultural norms. Nor is it clear what genetic mechanisms may underlie the acquisition of cultural norms. Here, we draw on recent evidence for certain genetic variability in the susceptibility to environmental influences and propose a norm sensitivity hypothesis, which holds that people acquire culture, and rules of cultural behaviors, through reinforcement-mediated social learning processes. One corollary of the hypothesis is that the degree of cultural acquisition should be influenced by polymorphic variants of genes involved in dopaminergic neural pathways, which have been widely implicated in reinforcement learning. We reviewed initial evidence for this prediction and discussed challenges and directions for future research.