For his first book, science reporter Joseph takes a long look at the Gala hypothesis, from genesis to current revelations. Genesis honors go to 70-year. old James Lovelock--the English maverick scholar and inventor, trained in chemistry and medicine--and to microbiologist Lynn Margulis, 20 years younger and pleased to be named coauthor of the theory. Gaia was the Greek goddess of the earth, resurrected by Lovelock as metaphor for the hypothesis that the earth operates as a superorganism, capable of self-adjustment; and that living forms on earth control the climate and surface environment, and have done so since the first microbes appeared a billion years after the planet was formed. Generally despised and rejected by orthodox science at the outset, Gaian theorists, Joseph shows, have modified their views, gained adherents (including Lewis Thomas), and earned the intense attention and discussion of world-renowned scholars at a weeklong session of the American Geophysical Union in San Diego in 1988. The conclusion? Yes, living organisms influence the planet; and, yes, many would go as far as to say life modifies the planet; but control? No way. Nevertheless, the interdisciplinary nature of the meeting, the graciousness of Lovelock and other Gaians, and the overall level of discourse stimulated new thinking and fruitful collaborations. In the meantime, Joseph explains, the Gaian industry has gathered momentum with a rebirth of Goddess cults and paganism, feminism and environmental politics, cosmic consciousness and spirituality, New Age music and healing--all trappings Margulis despises. Lovelock, too, would dismiss the excesses, but is admittedly more mystical and ""dreams of blazing the trail of geophysiology,"" by which is meant a search for the Earth's ""vital organs"" (perhaps rain forests?). A conscientious exposition, based on eyewitness reporting and thoughtful interviews by a sympathetic but fair commentator.