Intentional transmission of knowledge optimises cumulative cultural evolution

Human evolutionary success has been attributed to the capacity to accumulate knowledge and skills over generations, via cultural transmission. But explanations for the distinctiveness of human culture remain heavily debated. Accounts appealing to human cognitive sophistication must explain users’ limited mechanistic understanding of many cultural traits, whereas accounts that emphasise cultural adaptations as emergent outcomes of selective retention over generations must explain what precludes this in other species. In humans the transmission process itself may implicate cognitive capacities not available to other species, but to date there has been little direct evidence linking differences in cognitive capacity with differences in social transmission behaviour that impact the accumulation of cultural information. Using an experimental task, here we show that adults, but not young children, exhibit strategic preferences in the information they transmit to potential learners. This strategic selection promoted the cultural accumulation of beneficial discoveries, relative to randomly selected task information. Children, despite task competence, did not show such strong strategic transmission preferences, and accordingly obtained no additional benefit from intentional, over inadvertent, knowledge transmission until 9–10 years old. This late development supports the view that human cultural transmission may implicate cognitive abilities dependent on cultural experience, unavailable to other species.