Escaping optimization traps: the role of cultural adaptation and cultural exaptation in facilitating open-ended cumulative dynamics

James Winters

doi:10.1057/s41599-019-0361-3

Abstract

Explaining the origins of cumulative culture, and how it is maintained over long timescales, constitutes a challenge for theories of cultural evolution. Previous theoretical work has emphasized two fundamental causal processes: cultural adaptation (where technologies are refined towards a functional objective) and cultural exaptation (the repurposing of existing technologies towards a new functional goal). Yet, despite the prominence of cultural exaptation in theoretical explanations, this process is often absent from models and experiments of cumulative culture. Using an agent-based model, where agents attempt to solve problems in a high-dimensional problem space, the current paper investigates the relationship between cultural adaptation and cultural exaptation and produces three major findings. First, cultural dynamics often end up in optimization traps: here, the process of optimization causes the dynamics of change to cease, with populations entering a state of equilibrium. Second, escaping these optimization traps requires cultural dynamics to explore the problem space rapidly enough to create a moving target for optimization. This results in a positive feedback loop of open-ended growth in both the diversity and complexity of cultural solutions. Finally, the results helped delineate the roles played by social and asocial mechanisms: asocial mechanisms of innovation drive the emergence of cumulative culture and social mechanisms of within-group transmission help maintain these dynamics over long timescales.

Highlights

IntroductionWhile polar bears evolved thick layers of blubber, large paws, and specialized carnassials to survive and hunt in Arctic environments, the Inuit achieved comparable outcomes by modifying and extending existing technologies to invent parkas, mukluks, and harpoons
Two general processes are usually invoked as explanatory concepts of technological evolution: the first is an optimizing process where technologies are refined towards a functional objective and the second is a repurposing of existing technologies towards a new functional goal
This paper showed that: (i) Cultural dynamics often lead to optimization traps when the strength of optimization is strong relative to the rate of exploration; (ii) Escaping these optimization traps relies on a feedback loop between exploration and optimization that results in a concomitant growth in the complexity and diversity of solutions; (iii) This initial emergence of open-ended cumulative culture is reliant on asocial generative mechanisms of innovation; (iv) But maintaining these open-ended dynamics increasingly requires social transmission

Summary

Introduction

While polar bears evolved thick layers of blubber, large paws, and specialized carnassials to survive and hunt in Arctic environments, the Inuit achieved comparable outcomes by modifying and extending existing technologies to invent parkas, mukluks, and harpoons. These distinct advantages are often attributed to the ability of cultural evolutionary dynamics to facilitate a cumulative process: here, solutions with higher payoffs need not be independently rediscovered, but can instead be transmitted from individual-toindividual via social learning mechanisms (Boyd and Richerson, 1985; Dean et al, 2014; Mesoudi and Thornton, 2018). This cumulative process provides a powerful explanation for the fit between technological solutions and ecological problems via cultural adaptation: by generating different solutions for a given problem, a population can gradually select from this pool of variation and move closer to an optimal solution (Boyd and Richerson, 1985, 1995; Enquist et al, 2007; Henrich, 2015; Laland, 2018; Richerson and Boyd, 2005)

Results

Discussion

Conclusion