The Cultural Evolution of Adaptive-trait Diversity when Resources are uncertain and Finite

In this paper we seek to build on existing mathematical studies of cultural change by exploring how the diversity of adaptive cultural traits evolves by innovation and cultural transmission when the payoff from adopting traits is both uncertain and frequency dependent. The model is particularly aimed at understanding the evolution of subsistence trait diversity, since the payoff from exploiting particular resources is often variable and subject to diminishing returns as a result of overexploitation. We find that traits that exploit the same shared resource evolve most quickly when intermediate rates of cultural transmission promote fluctuation in trait diversity. Higher rates of cultural transmission, which promote predominantly low diversity, and lower rates, which promote predominantly high diversity, both retard the adoption of traits offering higher payoff. We also find that the distribution of traits that exploit independent resources can evolve towards the theoretical Ideal Free Distribution so long as the rate of cultural transmission is low. Increasing the rate of cultural transmission reduces trait diversity, so that a more limited number of ‘niches’ are occupied at any given time.