A bracing account of how our current planetary crisis emerged from the worst cataclysmic destruction in human history, which Clifton Crais terms the Mortecene--the killing age. We are used to speaking of the Anthropocene and the outsized impact humans have had on the planet. But we sometimes lose sight of a fundamental truth at the heart of modern world history: the legacy of human predation, slavery, and imperialism that has devastated the natural world and led us to our present moment. As historian Clifton Crais shows in this magisterial work, the period that we most associate with human progress--which gave us the Enlightenment, the rise of democracies, the Industrial Revolution, and more--was at the same time catastrophically destructive. In this bracing, landmark book, Crais urges us to view the growth of global capitalism between 1750 and the early 1900s not as the Anthropocene, but as the Mortecene: the Killing Age. Killing brought the world together and tore it apart, as profiteering warlords committed mass-scale slaughter of humans and animals across Africa, Asia, and the Americas. The newfound ease and profitability of killing created a disturbing network of global connections and economies, eliminating tens of millions of people and sparking an environmental crisis that remains the most urgent catastrophe facing the world today. Drawing on years of scholarship and marshaling myriad sources across world history, The Killing Age turns our vision of past and present on its head, illuminating the Mortecene in all its horror--how it shaped who we are, what we value and fear, and the precarious present we inhabit today.