September 17: Nicolas Fay

When do Larger Populations Enhance Cumulative Cultural Evolution?

Nicolas Fay (University of Western Australia)

Tuesday, September 17
11:00am – 12:30pm
S38, 7 George Square

The extent to which large populations enhance cumulative cultural evolution (CCE) is contentious. Due to the greater access to variation and better-adapted artefacts, larger populations have the potential to enhance CCE, but this potential is not always realised. I will discuss our recent paper showing that these potential benefits are eliminated by an associated increase in working memory (Fay et al., 2019, PNAS). I will then present a recent large-scale experiment (N=407) that tested if the ability to selectively filter variants, thereby overcoming human working memory constraints, is necessary for larger populations to enhance CCE. Participants repeatedly built virtual arrowheads over 15 trials, either individually (Individual Learning Condition) or as a member of a 3-person or 6-person population (Social Learning Conditions). There were three Social Learning Conditions: View 1-Model, View All-Models: Select Order and View-All Models: Random Order. In the Social Learning conditions participants were told the score associated with each of the arrowheads produced by the other members of their group. In the View 1-Model condition they could choose one arrowhead to learn from, i.e., they could apply a selective filter. In the View All-Model conditions participants viewed all the arrowheads produced by the other members of the their group, i.e., there was no selective filter. In the Select Order condition they could choose the order they viewed the arrowheads and in the Random Order condition they viewed the arrowheads in a prescribed random order. Performance on the arrowhead task improved over trials in all conditions (i.e., CCE was observed). Social learning outperformed Individual Learning. Finally, and as predicted, CCE was boosted by population size only in the View 1-Model condition, indicating that a selective filter is critical if larger populations are to enhance CCE.