Partial connectivity increases cultural accumulation within groups

Abstract

Complex technologies used in most human societies are beyond the inventive capacities of individuals. Instead, they result from a cumulative process in which innovations are gradually added to existing cultural traits across many generations. Recent work suggests that a population's ability to develop complex technologies is positively affected by its size and connectedness. Here, we present a simple computer-based experiment that compares the accumulation of innovations by fully and partially connected groups of the same size in a complex fitness landscape. We find that the propensity to learn from successful individuals drastically reduces cultural diversity within fully connected groups. In comparison, partially connected groups produce more diverse solutions, and this diversity allows them to develop complex solutions that are never produced in fully connected groups. These results suggest that explanations of ancestral patterns of cultural complexity may need to consider levels of population fragmentation and interaction patterns between partially isolated groups. cultural evolution | innovation | population size | social network | technological trajectory P eople everywhere rely on technology for their survival (1). In even the simplest foraging societies, essential tools are beyond the inventive capacities of individuals; they result from a cumulative process by which innovations are gradually added to existing cultural traits across many generations (2). Recent work suggests that a population's ability to develop complex technologies is positively affected by its size and connectedness (3-5). Large interaction networks allow individuals to learn from many others, and theory predicts that increased opportunities to learn socially reduces the rate of cultural loss and increases the rate at which people improve existing cultural traits. This prediction is supported by evidence from both field and laboratory studies (5-10). However, some authors have been reluctant to embrace this idea, pointing out discrepancies between measures of population size and observed cultural complexity (11)(12)(13)(14). It seems likely that factors other than social network size affect the evolution of cultural complexity, and these factors may obscure the effect of the population size under some conditions.One possibility is that social network structure matters as well. Economists have recently investigated how levels of connectedness in networks affect a group's ability to solve problems of varying complexity (15,16). In agreement with previous work in cultural evolution, they found that high levels of connectivity help groups to solve simple tasks. However, they also suggest that wellconnected networks perform poorly at solving complex tasks (15,16). The complexity of a problem can be represented by mapping all possible solutions onto a measure of performance, which results in what has been called a fitness landscape (17). Simple problems are associated with smooth landscapes, each with a unique optimum that will be reached b...

Cumulative culture can emerge from collective intelligence in animal groups

“…Notably, the filtering process highlighted in (c) is also recognized as an important mechanism in CCE2324. The combination of these phenomena adds a hitherto little explored time-depth perspective11—the notion that current performance is contingent on a previous history of performances—to collective behaviour through empirical demonstration, and introduces an important conceptual link between collective intelligence and CCE.…”

The evolution of inequality

“…Although larger groups do indeed have more potential for conflict, it is not clear why increases in population density should necessarily produce larger groups rather than larger numbers of groups through fissioning. Another potential role of population size hinges on the argument that cultural innovations are more easily generated and maintained in larger populations, with fewer innovations lost to drift . Since PII is based on complex cultural institutions, it could be that only large populations can generate and maintain PII.…”

“…Another potential role of population size hinges on the argument that cultural innovations are more easily generated and maintained in larger populations, with fewer innovations lost to drift. [101][102][103] Since PII is based on complex cultural institutions, it could be that only large populations can generate and maintain PII. However, the empirical evidence of widespread general associations between population size and cultural complexity is subject to debate.…”

The social dynamics of collective problem-solving

“…Overall, our study shows that, depending on the chosen measure of performance, the impact of social learning can change dramatically. Social learning has different effects, depending on whether one is interested in the collective performance (e.g., the group comes up with a unique collective solution (Kempe and Mesoudi, 2014) or develops a new cultural innovation (Derex and Boyd, 2016;Derex and Boyd, 2015)), or in the average individual performance (see, e.g., (Lazer and Friedman, 2007;Mason and Watts, 2012;Barkoczi and Galesic, 2016)). Here, it is interesting to point out that the measures of performance are not limited to the two instances that we have studied in this work.…”

“…Here, it is interesting to point out that the measures of performance are not limited to the two instances that we have studied in this work. Other research has, for instance, considered the group's ability to find the problem's global optimal solution (Cooper et al, 2010;Derex and Boyd, 2016). In this case, any solution that is not the optimal one is not taken into account in the calculation of success, which comes down to considering landscapes with very low dispersion.…”