Social learning mechanisms of cultural evolution

Human cultural traditions are accumulated bodies of knowledge that have been built over time through innovation coupled with social learning. An evolutionary approach to culture examines culture traits as aspects of an organism’s phenotype that are inherited through social learning processes. This dissertation applies theory from the literature on cultural evolution to understand mechanisms and strategies of this learning process in humans, and consists of three projects from data generated by two studies. For both studies, I used a novel experimental task: participants were asked to build weight-bearing devices from a length of weaving reed and a portion of modeling clay. In the first project, using an experimental microsociety design, I tested the hypothesis that imitation is required for cultural accumulation. By manipulating visual access to behavior, I found evidence of cultural accumulation only when participants were able to view others building devices. This result is consistent with the hypothesis that imitation is required for cumulative cultural evolution. In the second project, I tested the hypothesis that learners are able to infer the success of models by using model-based biases. I found that participants were more likely to copy the device designs of others who had performed well, than they were to copy device designs of those who had performed poorly. This difference held only in conditions in which participants could witness others building devices, as predicted by the use of model-based biases such as skill bias. In the third project, I tested participants’ flexibility in the use of asocial and social information, in order to understand the contribution of individual learning constraints to cultural evolution at a population level. Participants built weight-bearing devices in three phases: an asocial learning phase, and two social learning phases. I measured both the performance of the weight-bearing devices and the use of social information. My results indicate that participants adjusted the degree to which they copied others relative to changes in their performance between the asocial and social phases. These data suggest that cultural evolution may rely on learners who are flexible, rather than fixed, in their learning strategies.Ph. D.Includes bibliographical referencesby Helen Charlotte Wasielewsk