Beginning with Homo erectus at least a million years ago, hominins have used fire to engineer the world around them. The earliest uses of fire surely included cooking, changing the energy yields of foods. Such innovations altered the course of our evolution, facilitating the evolution of species that could adapt quickly using tools and social ingenuity. Within the last 200,000 years, hominins also used fire to change the material properties of stone, pigments, sap, and wood. While these changes represent a fundamental shift in the role of humans as dominant shapers of their environments through years of evolution and innovation, ecosystems adjusted as early humans remained embedded within them. However, humans are not now simply shifting to another sustainable balance - we are pushing environmental thresholds across one tipping point after the next. (#37907)