The notion of a living world is one of humanity’s oldest beliefs. Once scorned by scientists, the facts supporting this concept have now become tenets of modern Earth system science, a relatively young field that studies the living and non-living components of the planet as an integrated whole. Life did not evolve passively in response to its environment, as scientists have long assumed. Instead, it evolved with Earth, shaping its climate and terrain at every scale. Becoming Earth transports the reader to some of the world's most extraordinary places to explore how these symbiotic relationships evolved, from an underwater kelp forest on the coast of California to a former gold mine two miles below the Earth’s surface. We see how microorganisms participate in many geological processes, producing new minerals and converting rock from one state to another. We learn how large mammals maintain grasslands and prevent permafrost from melting, and coral reefs and shellfish store huge amounts of carbon, improve water quality, and defend shorelines from severe weather. Jabr introduces us to the people protecting and restoring life's planet-stabilizing processes and protecting ancient ecological harmonies, and he opens our eyes to life’s imprint on every part of the planet today, from the heart of the Amazon rainforest to the soil in our backyards.