//Summary* - The central question of the Anthropocene: - why did behaviorally modern humans gain the unprecedented capacity to change an entire planet? - cannot be answered by genetic changes in human behavior. - To explain why human societies scaled up to become a global force capable of changing the Earth and why there are so many different forms of human societies and ecologies shaped by them, - explanations must be sought beyond the theories of - biology, - chemistry or - physics. - Here I introduce a new evolutionary theory, sociocultural niche construction, - aimed at explaining the origins of human capacity to transform the Earth . - As will be seen, this theory also explains why - behaviorally modern human societies came to - transform ecology in so many different ways over the past 50,000 years as they expanded across the Earth. //