Gaia's Body

Is Earth alive? Put more rigorously, is the biosphere a self- sustaining meta-organism? This is the essence of Gaia theory: if the biosphere really is a single coherent system, then it must have something like a physiology. It must have systems and processes that perform living functions. OK, then, what systems, what processes, what functions? Gaia''s Body is Tyler Volk''s answer to this question....