"Why does everybody agree that atmospheric oxygen... comes from life, but no one speaks about the other gases coming from life?"

“The fundamental division of forms of life on Earth is not that between plants and animals, as is commonly assumed, but between prokaryotes—organisms composed of cells with no nucleus, that is, bacteria—and eukaryotes—all other life forms.”

“is so much more like people than Stanley Miller’s mixtures of chemicals, because it already has these system properties. So to go from a bacterium to people is less of a step than to go from a mixture of amino acids to that bacterium.”

“The oxygen crisis that began only two billion years ago prompted the evolution of respiring bacteria. These microbes that used oxygen to derive biochemical energy more efficiently than ever before eventually took over most of the world. Some of the oxygen-breathing bacteria became symbiotic, merging with different bacteria to form nucleated cells, which, after becoming sexual, evolved into fungi, plants, and animals.”

“Soil is not unalive. It is a mixture of broken rock, pollen, fungal filaments, ciliate cysts, bacterial spores, nematodes and other microscopic animals and their parts. 'Nature,' Aristotle observed, 'proceeds little by little from things lifeless to animal life in such a way that it is impossible to determine the exact line of demarcation.' Independence is a political, not a scientific, term.”

“Life is bacterial and those organisms that are not bacteria have evolved from organisms that were. ...Gene exchanges were indispensable to those that would rid themselves of environmental toxins. ...Replicating gene-carrying plasmids owned by the biosphere at large, when borrowed and returned by bacterial metabolic geniuses, alleviated most local environmental dangers, provided said plasmids could temporarily be incorporated into the cells of the threatened bacteria. The tiny bodies of the planetary patina spread to every reach, all microbes reproducing too rapidly for all offspring to survive in any finite universe. Undercover and unwitnessed, life back then was the prodigious progeny of bacteria. It still is.”

“Life today is an autopoietic, photosynthetic phenomenon, planetary in scale. A chemical transmutation of sunlight, it exuberantly tries to spread, to outgrow itself. Yet by reproducing, it maintains itself and its past even as it grows. Life transforms to meet the contingencies of its changing environment and in doing so changes that environment. By degrees the environment becomes absorbed into the processes of life, becomes less a static, inanimate backdrop and more and more like a house, nest, or shell—that is, an involved, constructed part of an organic being.”