Claidière, N., S. Kirby, et al. (2012). “Effect of psychological bias separates cultural from biological evolution.” Proceedings of the National Academy of Sciences 109(51): E3526.
A comment on: MacCallum, R. M., M. Mauch, et al. (2012). “Evolution of music by public choice.” Proceedings of the National Academy of Sciences 109(30): 12081-12086.
Our comment can be found in full below (or on the PNAS website) and the answer is here:
Leroi, A. M., R. M. MacCallum, et al. (2012). “Reply to Claidière et al.: Role of psychological bias in evolution depends on the kind of culture.” Proceedings of the National Academy of Sciences 109(51): E3527.
MacCallum et al. (1) used an innovative Darwinian method to demonstrate the importance of consumers’ preferences in shaping the evolution of music, a fact that has often been overlooked and deserved attention. Their experimental design, however, emphasizes the role of selection at the expense of other fundamental features of human cultural evolution that need to be taken into account to study the evolution of real musical culture.
MacCallum et al. (1) used a genetic algorithm in which a population of musical tunes evolves according to Darwinian principles. Every generation, new tunes are created through recombination of tunes and random mutation of tune properties. The descendant tunes are then rated by consumers, and the ratings are used to determine their relative fitness and whether or not they will “reproduce” (i.e., be involved in the production of the next generation). In this way, MacCallum et al. (1) essentially
implemented a search algorithm to find pleasing tunes, albeit one with key similarities to biological evolution. The authors showed that selection through consumers’ ratings progressively drive the system toward more pleasing chords and rhythms that correspond to Western popular culture. Crucially, however, the authors assumed
that mutation and recombination are rare random events.
This assumption is fundamental in explaining their results, because the relative importance of Darwinian selection compared with that of mutation in explaining the outcome of an evolutionary process depends on the randomness and frequency of transformations that occur between two generations. More frequent nonrandom (“directed”) mutations would have a greater influence on the outcome of evolution.
Assuming that changes during reproduction are few and undirected offers a much better approximation in genetics than in the cultural domain. Theoretical and empirical results show that individuals actively transform and recombine information according to psychological biases and that these biases drive the evolution of culture (2), both in humans and nonhuman animals (3). For example, Kirby et al. (ref. 4) have studied the evolution of language (which shares many properties with music) in a series of iterated learning experiments. These show that artificial languages, when put through an evolutionary process in which there is no selection but where the variation comes from the participants’ learning biases, acquire fundamental properties of real language. This result is strikingly similar to that of MacCallum et al. (1), despite the lack of selection.
These results show that frequent, nonrandom transformative processes, resulting from psychological biases, are crucial in models of cultural evolution, requiring a difference in emphasis from models inspired by biology, such as genetic algorithms. This is not to deny a role for selection; both factors need to be taken into
account when trying to understand the evolution of real music, real language, and, more broadly, real culture (5). In this respect, the study of MacCallum et al. (1) opens up a wide range of possible developments that invites further studies on the relative strength of transformative processes and Darwinian selection and on their role in shaping cultural evolution.
1. MacCallum RM, Mauch M, Burt A, Leroi AM (2012) Evolution of music by public choice. Proc Natl Acad Sci USA 109(30):12081–12086.
2. Sperber D, Hirschfeld LA (2004) The cognitive foundations of cultural stability and diversity. Trends Cogn Sci 8(1):40–46.
3. Claidière N, Sperber D (2010) Imitation explains the propagation, not the stability of animal culture. Proc R Soc Lond B Biol Sci 277(1681):651–659.
4. Kirby S, Cornish H, Smith K (2008) Cumulative cultural evolution in the laboratory: An experimental approach to the origins of structure in human language. Proc Natl Acad Sci USA 105(31):10681–10686.
5. Claidière N, Sperber D (2007) The role of attraction in cultural evolution. J Cogn Cult 7 (1):89–111.
Van de Waal, E., N. Claidière, et al. (In press). “Social learning and spread of alternative means of opening an artificial fruit in four groups of vervet monkeys.” Animal Behaviour.
Two-action experiments, in which observer individuals watch models use one of two alternative methods to achieve the same goal, have become recognized as a powerful method for studying social learning. We applied this approach to vervet monkeys, Chlorocebus aethiops, using an artificial fruit (‘vervetable’) which could be opened by either lifting a door panel on its front, or alternatively by sliding the panel to the left or right. In each of two groups a model was trained to lift the door and in two others the model slid it to either the left or right. Members of each group could then watch their model before the group was given access to multiple baited vervetables. Over the course of 100 openings we found a significant tendency for the lift and slide approaches to spread preferentially in the groups in which they were seeded. The same was true for slide left versus slide right, indicating these monkeys can attend to and learn from a fine level of detail in what others do. This effect cannot be explained by mere local enhancement since monkeys grasped a knob centred in the door to perform all techniques. Instead, imitation or emulation is implicated. No significant diminution of the tendency to adopt the seeded technique occurred among individuals learning later rather earlier in the study. Our results show that vervet monkeys have the capacity to learn from others by either emulation or imitation and what they learn has the potential to spread across their group.
Claidière N, Bowler M, Whiten A (2012) Evidence for Weak or Linear Conformity but Not for Hyper-Conformity in an Everyday Social Learning Context. PLoS ONE 7(2): e30970. doi:10.1371/journal.pone.0030970
Conformity is thought to be an important force in cultural evolution because it has the potential to stabilize cooperation in large groups, potentiate group selection and thus explain uniquely human behaviors. However, the effects of such conformity on cultural and biological evolution will depend much on the way individuals are influenced by the frequency of alternative behavioral options witnessed. Theoretical modeling has suggested that only what we refer to as ‘hyper-conformity’, an exaggerated tendency to perform the most frequent behavior witnessed in other individuals, is able to increase within-group homogeneity and between-group diversity, for instance. Empirically however, few experiments have addressed how the frequency of behavior witnessed affects behavior. Accordingly we performed an experiment to test for the presence of conformity in a natural situation with humans. Visitors to a Zoo exhibit were invited to write or draw answers to questions on A5 cards and potentially win a small prize. We manipulated the proportion of existing writings versus drawings visible to visitors and measured the proportion of written cards submitted. We found a strong and significant effect of the proportion of text displayed on the proportion of text in the answers, thus demonstrating social learning. We show that this effect is approximately linear, with potentially a small, weak-conformist component but no hyper-conformist one. The present experiment therefore provides evidence for linear conformity in humans in a very natural context.
Claidière, N. and J.-B. André (2012). “The Transmission of Genes and Culture: A Questionable Analogy.” Evolutionary Biology 39(1): 12-24.
See the following comments too:
- Hallgrimsdottir, H. (2012). “The GTM Analogy: The “Organismic” Metaphor Revisited?” Evolutionary Biology 39(1): 27-29.
- Weiss, K. (2012). “Analogy Recapitulating Homology?” Evolutionary Biology 39(1): 25-26.
Abstract: Modes of cultural transmission are, by analogy with modes of genetic transmission, ways in which cultural information is transmitted between individuals. Despite its importance across the behavioral sciences and for theories of cultural evolution, no attempts have been made, to our knowledge, to critically analyze this analogy. We here aim at such detailed comparison and show that the fundamental role of modes of transmission in biology results mainly from two properties of genetic transmission: (i) what is transmitted generally does not influence the way in which it is transmitted; (ii) there is a limited number of simple and stable modes. In culture however, modes of transmission generally lack these two fundamental properties. In particular, in culture it is often the rate of evolutionary change that determines the mode of transmission. We offer some tentative explanation regarding the origins of such a fundamental difference and we conclude that cultural transmission modes are not causal mechanisms that govern the transmission of culture but mere descriptions of the way culture happens to be transmitted at a given time in a given community. This shows the limit of the analogy between biological and cultural evolution and suggests that evolutionary models and theories differ substantially between the two domains.
Claidière N, Whiten A (2012) Integrating the study of conformity and culture in humans and nonhuman animals. Psychological Bulletin 138: 126-145.
Conformity, defined here by the fact that an individual displays a particular behavior because it is the most frequent they witnessed in others, has long been recognized by social psychologists as one of the main categories of social influence. Surprisingly, it is only recently that conformity has become an active topic in animal and evolutionary biology. As in any new and rapidly growing field however, definitions, hypotheses and protocols are diverse, not easy to organize in a coherent way and sometimes seriously conflict with each other. Here we pursue greater coherence by reviewing the newer literature on conformity in behavioral ecology and evolutionary biology in light of the foundational work in social psychology. We suggest that the knowledge accumulated in social psychology can be exploited by behavioral ecologists and evolutionary biologists to bring conceptual clarity to the field, avoid some experimental pitfalls and help design new and challenging experiments. In particular, we propose that the notions of ‘informational’ and ‘normative’ conformity that, until now, have not been recognized in recent literature can resolve some important controversies. In turn, research on animal culture should be of great interest to social scientists, because understanding human culture and human uniqueness requires an evolutionary analysis of our cognitive capacities and their evolutionary origins. Our review suggests excellent opportunities for social and natural scientists to join forces in building an interdisciplinary and integrative approach to the pervasive phenomenon of conformity.
Claidière, N. and Sperber, D. (2010) “The natural selection of fidelity in social learning.” Communicative and Integrative Biology, 3:4, 1-2
Social learning mechanisms are usually assumed to explain both the spread and the persistence of cultural behaviour. In a recent article, we showed that the fidelity of social learning commonly found in transmission chain experiments is not high enough to explain cultural stability. Here we want to both enrich and qualify this conclusion by looking at the case of song transmission in song birds, which can be faithful to the point of being true replication. We argue that this high fidelity results from natural selection pressure on cognitive mechanisms. This observation strengthens our main argument. Social learning mechanisms are unlikely to be faithful enough to explain cultural stability because they are generally selected not for high fidelity but for generalisation and adjustment to the individual’s needs, capacities and situation.
Claidière, N. and D. Sperber (2010). “Imitation explains the propagation, not the stability of animal culture.” Proceedings of the Royal Society B: Biological Sciences 277(1681): 651-659.
For acquired behaviour to count as cultural, two conditions must be met: it must propagate in a social group, and it must remain stable in the process of propagation. It is commonly claimed that imitation is the mechanism that explains both the spread of animal culture and its persistence. We review the literature on transmission chain studies in chimpanzees and other animals. We use a formal model to argue, that imitation, which may well play a major role in the propagation of animal culture, cannot be considered faithful enough to explain its stability. We show that adding to the capacity for imitation a relatively strong conformist tendency of the kind suggested by Boyd and Richerson is relevant but unlikely to be sufficient. We consider the contribution that other psychological or ecological factors might make to the persistence of animal culture observed in the wild.
A colour sorting task reveals the limits of the universalist/relativist dichotomy: colour categories can be both language specific and perceptual. Claidière N., Jraissati Y. and Chevallier C. Journal of Cognition and Culture 2008 8(3-4): 211-233(23)
We designed a new protocol requiring French adult participants to group a large number of Munsell colour chips into three or four groups. On one, relativist, view, participants would be expected to rely on their colour lexicon in such a task. In this framework, the resulting groups should be more similar to French colour categories than to other languages categories. On another, universalist, view, participants would be expected to rely on universal features of perception. In this second framework, the resulting groups should match colour categories of three and four basic terms languages. In this work, we first collected data to build an accurate map of French colour terms categories (Experiment 1). We went on testing how native French speakers spontaneously sorted a set of randomly presented coloured chips and, in line with the relativist prediction, we found that the resulting colour groups were more similar to French colour categories than to three and four basic terms languages (Experiment 2). However, the same results were obtained in a verbal interference condition (Experiment 3), suggesting that participants rely on language specific and nevertheless perceptual, colour categories. Collectively, these results suggest that the universalist/relativist dichotomy is a too narrow one.
The animal variations: When mechanisms matter in accounting for function. Viciana H. and Claidiere N. Behavioural Brain Sciences 2007 30(4): 424-425
A comment on Ramsey G, Bastian ML, van Schaik C. Animal innovation defined and operationalized. Behavioral and Brain Sciences (2007), 30:393-407
We contend that Ramsey et al’s definition of animal innovation sensu process may be partially misleading when investigating mechanisms underlying animal innovation. By excluding social learning from the ”process” of innovation, they may be reproducing a dichotomous schema that does not accurately correspond to our knowledge of the acquisition of novel behavioral variants. This gives us some reason to doubt the functional specification of the defined ”process” of innovation. Continue reading…