Abstract:

The emergence of human societies with complex language and cumulative culture is considered a Major Evolutionary Transition. Yet why a similar transition has not occurred in other species is perplexing, given the potential fitness advantages of accumulating culture. Here, Boyd & Richerson’s ("Why culture is common, but cultural evolution is rare," 1996) discrete-cultural-trait model is extended to incorporate arbitrarily strong selection; conformist, anti-conformist and unbiased frequency-dependent transmission; random and periodic environmental variation; finite population sizes; and multiple 'skill levels.' From their infinite-population-size model with success bias and a single skill level, Boyd and Richerson concluded that social learning is favoured over individual learning under a wider range of conditions when social learning is initially common than initially rare. We find that this holds only if the number, n, of individuals observed by a social learner is sufficiently small. However, with a finite population or a combination of success-biased and conformist or unbiased transmission, this result holds with larger n. Assuming social learning has reached fixation, the increase in a population’s mean skill level is lower with smaller populations and frequency-dependent transmission. Hence, multiple barriers to cultural accumulation may explain its rarity.

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@KaledaDenton