Through most of humanity's 40,000-year history, people were hunter-gatherers who exercised more than we do, ate more fiber and less fat, and took in very little salt or sugar, little or no alcohol, and no tobacco. Though unprotected by modern medicine, our paleolithic ancestors knew nothing of heart attacks, diabetes, cancer, or other ""diseases of civilization."" Moreover, recent research suggests that it would behoove us to alter our diets and habits in order to accommodate our paleolithic physiology. Though none of the above will be new to readers of newspaper nutrition columns, the message has rarely been so exhaustively and authoritatively conveyed as by this uniquely qualified M.D.-anthropologist team. With due recognition of the range of human adaptability and the differences among preagricultural human groups, the authors go beyond the usual pronouncements on fat, sugar, and exercise to compare and assess everything from old and new micronutrient intake, and cooking methods and noise levels to social organization, age of menarche, and relations between the sexes. (Anthropologist Shostak is the author of Nisa: The Life and Words of a !Kung Woman, 1981), and her intimate knowledge of those surviving hunter-gatherers considerably enlarges the discussion.) One outcome is the novel recommendation that dieters alter periods of ""shortage"" with periods of normal eating, and that periods of heavy aerobic exercise be interspersed with periods of rest or of strength-building exercise. Some of this may be speculative extrapolation; but, overall, the detailed and conscientious juxtaposition of preagricultural and postindustrial life-styles makes for sound advice, a catchy framework, and interesting reading as well.