Life changes its surroundings. Beavers build dams that alter the course of rivers. Forests can feed thunderstorms with their moisture. And those changes can, in turn, create new habitats that allow for the evolution of new kinds of life. For my new “Matter” column in the New York Times, I discuss a hypothesis about a truly global act of bio-engineering that may have happened 700 million years ago. Sponges may have transformed the oceans, flushing them with oxygen. And thanks to that change, more complex animals were able to evolve. We may have sponges to thank for being here, in other words. You can read the whole thing here.