Fig. 4.

Effects of population size, population subdivision, and distribution of knowledge among subgroups on tool repertoire of a population at equilibrium. After 100,000 time steps of each simulation, the equilibrium is estimated by averaging the number of tools in the last 10,000 time steps. Each point is a mean of this estimated equilibrium for 20 runs with the same parameter values; error bars bound two SEs. The plot has three x axes corresponding to the points of the same color. These axes have been scaled to illustrate the effect of population subdivision on effective cultural population size: The effect of changes in population subdivision is similar to the effect of changes in absolute population size. The black points represent the equilibrium number of tools for nonsubdivided populations of varying sizes (N). The red points represent the equilibrium number of tools for populations (N = 100) with varying subdivision sizes, where C_elite is the percent of the population with knowledge of the entire tool repertoire and the remainder of the population knows only 50% of the tools. The blue points represent the equilibrium number of tools for a subdivided population (C_elite = 0.1, N = 100) in which a certain proportion, indicated along the blue axis, of the overall tool repertoire is known only to the cultural elite and the rest is known to all individuals.