Towards the end of their compelling and persuasive target article, Lew-Levy and Amir discuss how childhood peer cultures might vary across contexts. I think it is worth elaborating further on the drivers of this variation.

Lew-Levy and Amir identify variation first in the type of cultural trait involved (see Section 7.1: “What can peer culture reveal about cultural evolution?”). Children are more likely to innovate in spatial (e.g., location of food), linguistic (e.g., new vocabulary or grammatical rules), and social (e.g., communication norms) domains, rather than technological domains. Second, there is variation across societies (see Section 7.4: “How do peer cultures vary across contexts?”). While the influence of peer cultures seems frequent and persuasive in small-scale (e.g., forager) societies, it seems less likely in post-industrial societies where, while peer cultures still seem to be relatively autonomous (e.g., the playground games and rhymes of British children observed by the Opies), they are less likely to contribute to society-wide cultural innovation and change.

Both of these observations might plausibly be explained by variable cultural acquisition costs (Mesoudi, Reference Mesoudi2011). Even in small-scale societies, technology typically comprises multiple interacting parts that must be assembled in several steps, often without obvious causal links between a tool’s eventual performance and its form or manufacturing process (Harris, Boyd, & Wood, Reference Harris, Boyd and Wood2021). And even if a novel technology works better than existing forms, there are still numerous social barriers preventing it from actually being adopted by others (Rogers, Reference Rogers1995). This makes technological innovation intrinsically harder than, say, linguistic or social innovation, where new word forms or customs can be invented and acquired easily, including by children. For technology, the lengthy acquisition of previously accumulated cultural knowledge represents a much greater limitation on the contributions that children can make to society-wide innovation, compared to non-technological domains.

Similarly, post-industrial societies have seen the exponential accumulation of scientific and technological knowledge over the last few centuries (Enquist et al., Reference Enquist, Ghirlanda, Jarrick and Wachtmeister2008; May, Reference May1966; Price, Reference Price1963), accelerated by key cultural innovations such as the scientific method, mass communication, and tools such as microscopes and computers. As knowledge accumulates, however, so does the time and effort needed to acquire what previous generations have discovered or invented. Evidence for such increasing cultural acquisition costs comes from analyses showing that the mean age at which prominent scientists and inventors made their most significant advance increased from 32 years in 1900 to 38 years in 2000, with this increase specifically attributable to increased training periods (Jones, Reference Jones2010). Consequently, it is not surprising that children are unable to innovate in post-industrial societies and have been relegated to receptacles of existing knowledge. Formal systems of education likely partly arose in response to these increasing acquisition costs, further removing children from situations in which they can influence wider cultural change.

Perhaps, however, this is too coarse-grained and too pessimistic. Derex (Reference Derex2021) recently argued that cumulative cultural evolution exhibits two dynamics: (i) periods of incremental optimisation of existing knowledge, interspersed with (ii) the opening of a new niche or domain, typically exploiting a new natural phenomenon. While the former requires the lengthy acquisition of incrementally accrued knowledge, the latter may be more amenable to innovation without lengthy acquisition costs, given the lack of established knowledge to acquire. For example, the advent of home computers in the 1980s led to a British computer games industry led by self-taught teenagers who mastered programming in their bedrooms entirely independently from either their parents or their teachers, at least until computer technology became so advanced that large teams of professionally trained programmers were needed (Andrews, Reference Andrews2020).

Further considerations of the dynamics of cumulative cultural evolution, particularly regarding the costs of acquiring previously accumulated knowledge and how this limits the opportunities for innovation, might help to elucidate exactly when, for what traits, and in what kind of societies, children are likely to contribute to society-wide cultural adaptation.