Humans exhibit a rich and complex material culture with no equivalent in other animals. The unique human capability to accumulate cultural innovations across time allows us to develop powerful technology and drives technological progress. Despite a growing literature investigating cumulative culture, the underlying processes at play in the accumulation of cultural knowledge remain puzzling. The overarching aims of this proposal are to identify the requirements of human cumulative culture both at the individual and population levels and improve our understanding of factors that affect the pace of cultural accumulation. During the course of this action, we will develop innovative experimental methods to investigate three important and timely lines of research and shed new light on the complex processes that underlie cultural accumulation: 1) Identify the cognitive requirements of innovation production and transmission, 2) Evaluate the interplay between population structure and cultural accumulation, 3) Evaluate the effects of ecological factors on the rate of innovation. This action will use lab experiments from psychology and economics and will bring knowledge from anthropology and biology to help explain why only humans are able to accumulate cultural information across time and why rates of cultural accumulation have varied in our evolutionary past.