Crossing the Darwinian Threshold: the Classification of Cultural Phenomena and the Emergence of Traditions This is a draft: comments are most welcome. Citations: please contact me first, I will be glad to update you with the latest information. 25 th May 2018 Christopher D Buckley chrisbuckley888@hotmail.com Abstract In the last two decades there has been a concerted effort to ‘unify’ the study of culture through Darwinian approaches borrowed from biology. This reapplication has produced some notable successes, especially with the more long-lived aspects of culture, such as language and tool use traditions. Yet many aspects of culture do not obviously fit within a Darwinian framework, either because they are aperiodic (do not replicate), or because they are singular and not susceptible to population-based approaches. With these issues in mind, I introduce a broader overview of cultural processes that can encompass both Darwinian and non-Darwinian behaviors, and that permits a detailed comparison of biological and cultural processes. I then combine this overview with ideas derived from the work of Carl Woese that describe the development of biological systems from their first beginnings. I show how Woese’s concept of a ‘Darwinian Threshold’, originally conceived to explain the early history of life, can describe the trajectories of cultural as well as biological phenomena. In biology, the Darwinian Threshold is a theoretical construct that lies several billion years in our past, but in the cultural field it is both accessible to study and part of daily life. I discuss examples of the application of these ideas to understanding the emergence of technologies, based on published examples, and a new case study examining the emergence of a scientific institution (the Royal Society of London).