As acceptance of the Anthropocene grows among scientists and the public, decisions must be made on whether and how to define this geologic epoch. Designating a starting point for the Anthropocene may be less important than understanding the cultural processes that contributed to human domination of Earth's natural systems. Just as climate changes and their consequences often occur over centuries, millennia, or more, archaeological records show that humans have been active agents of environmental change for thousands of years. Their effects, often dramatic and cumulative, have grown from local, to regional, and now global phenomena. We discuss five options for defining the Anthropocene, most of which recognize a deeper history of widespread and measurable effects of human activities on the Earth's surficial biological and physical systems. A primary goal of debating and defining the Anthropocene should be to educate the public about the effects humans have had on natural systems for millennia, the compounding nature of such impacts, and the pressing need to reverse current trends.