Cumulative cultural evolution is facilitated by relatively indiscriminate information sharing rather than reputation-based partner choice

A necessary prerequisite for the accumulation of beneficial knowledge, aka cumulative cultural evolution, is the sharing of information via social learning. Yet little work in the field of cultural evolution has examined the mechanisms that support information sharing in the face of exploitative information free-riding and information hoarding. We ran a series of online interactive experiments (N = 716) combined with computational reinforcement and social learning models to test whether the mechanism of reputation-based partner choice can effectively support information sharing. Participants in groups chose whether to engage in costly innovation, and whether to share the resultant knowledge with others. Sharers received increased reputations for sharing, and participants could use these reputations to select recipients of knowledge. We found strong priors for information sharing that persisted throughout the experiments in participants from both the UK and China. However, partner choice was generally too weak to explain the presence of widespread information sharing, which persisted even when we reduced the benefit of innovation, introduced exploitative bots, and removed reputations altogether. We suggest that our participants’ over-sharing of information may reflect a past trade-off between individual- and group-level selection, where weak partner choice balances the individual-level costs and group-level benefits of information sharing.