The Tsembaga Maring are a group of slash-and-burn farmers occupying a small territory on the northern slopes of the Central Highlands of New Guinea. Taking them to be part of a complex ecological system which includes their human neighbors as well as the flora and fauna with which they share their territory, Rappaport argues that their elaborate ritual cycle, which ostensibly refers to spirits, in fact operates as a homeostatic mechanism regulating the size of the pig population, acreage in cultivation, fallow periods, energy expenditure in subsistence activities, protein ingestion, man-land rations, and the frequency of fighting. The sustained functional analysis relies upon quantitative data and shows how, when, and to what degree cultural and noncultural variables affect one another. The findings challenge the view that religious rituals have no effect upon the external world as well as the assumption that ecological studies of human groups require an analytical framework fundamentally different from those employed in the study of other animals. This study not only fills a gap in New Guinea ethnography but also constitutes a major contribution to ecological anthropology, the study of religion, and functional analysis.

Roy Rappaport argues that religion is central to the continuing evolution of life, although it has been been displaced from its original position of intellectual authority by the rise of modern science. His book, which could be construed as in some degree religious as well as about religion, insists that religion can and must be reconciled with science. Combining adaptive and cognitive approaches to the study of humankind, he mounts a comprehensive analysis of religion's evolutionary significance, seeing it as co-extensive with the invention of language and hence of culture as we know it. At the same time he assembles the fullest study yet of religion's main component, ritual, which constructs the conceptions which we take to be religious and has been central in the making of humanity's adaptation. The text amounts to a manual for effective ritual, illustrated by examples drawn from anthropology, history, philosophy, comparative religion, and elsewhere.