Why did professional skateboarding arise in southern California in the 1970s? Was it a coincidence, or was it a perfect storm of multiple factors? It’s fairly well-known that a drought in southern California in the mid-1970s led to a ban on filling backyard swimming pools, and these empty pools became playgrounds for freestyle skateboarders in the greater Los Angeles area. But a new cross-disciplinary study from the University of Cambridge shows that beyond the drought, it was the entanglement of environmental, economic and technological factors that led to the explosive rise of professional skateboarding culture in the 1970s. The authors say that professional skateboarding could not have started anywhere else, at any other point in time. Their study, reported in the journal PNAS Nexus, shows how small environmental changes can have profound effects on human behaviour, and stimulate cultural and technical innovation.