Questions of life and death, sex, marriage, and the family, are searchingly examined in Albert Rosenfeld's survey of contemporary medical research. The Science Editor of Life, one of the best science writers around, has gone a step beyond exposition to ask the ethical and moral questions appropriate to discussions of organ transplants, artificial insemination, sperm banks, uterine implants, molecular engineering of DNA, and control of the brain through drugs or electrical stimulation. We are on the brink of a second genesis, he says, in which man the manipulator is in control. But which men shall decide to do what and to whom? And what answers are already being proposed, for example, in the definitions of life and death? Rosenfeld supplies some of the answers offered by individual investigators of international committees, at the same time giving excellent summaries of the state of the art of physiological tampering with the individual whether at the molecular or higher levels of organization. He adds his own speculations on the drastic and dramatic implications for society inherent in this second genesis. Not only will the theologians have to rethink notions of deity and morality, but the basic notions of the uniqueness and mortality of the individual are open to question in a day in which synthetic parts, organ transplants, and brain drugs may wreak essential personality changes. When you add the possibility of deep-freezing human beings, the questions multiply. Rosenfeld has written a book for everyman, urging concern and responsibility rather than the traditional it-won't-happen-in-my-lifetime attitude. The message is that it's happening now.