Description: "The air we breathe is twenty-one percent oxygen, an amount higher than on any other known world. While we may take our air for granted, Earth was not always an oxygenated planet. How did it come to be this way? Donald Canfield covers this vast history, emphasizing its relationship to the evolution of life and the evolving chemistry of Earth. He guides readers through the various lines of scientific evidence, considers some of the wrong turns and dead ends along the way, and highlights the scientists and researchers who have made key discoveries in the field."--From publisher description.
Review Quotes: "[Canfield's] excellent descriptions of the scientific process show how competing hypotheses, and the scientists who present them, vie for supremacy. Canfield also offers a philosophical perspective: scientific understanding provides true insight into the structure of the natural world."-- "Publishers Weekly"