How Many People Can the Earth Support?

Cohen clearly demonstrates that the question he poses in the title of his book has no ready answer. Quality of life, both physical and cultural, must be taken into consideration, as must possible technological advances. Whatever the actual number, however, Cohen argues that it is finite and that we are rapidly approaching it. Rather than be a polemic for any particular course of action, the book's purpose is to define the factors that go into determining Earth's carrying capacity and thus increase the probability that appropriate action will ultimately be taken. There are two shortcomings: too much material is repeated, and the book is not written for a well-defined audience. Part history of human population growth, part critique of previous estimates of Earth's cargo space, part call to environmental action and part discourse on the interrelationship between fertility and economic well-being, this encyclopedic tome meanders between the technical and the introductory. Cohen heads the Laboratory of Populations at Rockefeller University in Manhattan. (Nov.)