Historian, demographer, and ecologist Hobhouse (Seeds of Change, 1986, not reviewed) here offers an original and sweeping world history of the past 500 years based on the ever-changing triangulation of three natural forces: population, food supply, and disease. Beginning with Columbus in 1492, the author traces the successful global proliferation of Western European animals, plants, and scientific methods to combat disease. In adapting to these influxes, he notes, nations have undergone a process of challenge and response that has led to varying rates of success. Overall, the result has been an enormous global population increase--from 400 million in 1492 to 13-15 times that today, or five to six billion. In this century alone, global population will double twice; it will do so a third time within only another 41 years. Does this mean the defeat of Malthus, who predicted that population will always outstrip food supply, allowing famine to right the balance again? Hobhouse answers brilliantly: ""It would be an absurd end for mankind if, having defeated the restraint of disease, having apparently solved the food supply problem, and having avoided nuclear war, this species should fall victim to pollution, to drown in its own ordure. Malthus, apparently defeated, would be laughing in his grave."" The ""three important problems already threatening mankind"" are, Hobhouse argues, ""the greenhouse effect, the destruction of the ozone layer, and acid rain."" All three are the direct result of overpopulation and overconsumption; in fact, only 20% of the global population, according to the author, currently lives in a truly sustainable way. More efficient use of resources is Hobhouse's partial solution, and here he is biased in favor of free enterprise and nuclear energy over coal pollution. Hard-edged and realistic, a significant addition to ecological studies.