PIP: The author, a Brandeis University biologist who attended the 1994 International Conference on Population and Development, cautions against optimism regarding the global impact of this gathering in the absence of revolutionary changes in four areas: reproductive practices, sexual behavior, human consumption of natural resources, and population crowding. Few speakers at Cairo addressed the ecologic and climatologic consequences of overpopulation and environmental destruction, despite indications that the earth is reaching the limits of its environmental support system. Another concern is the conflict between contraceptive methods that are most effective in preventing pregnancy and the condom use that is essential to halt the spread of acquired immunodeficiency syndrome (AIDS). In countries such as China, where the AIDS epidemic's threat has been minimized by the government, massive educational campaigns will be required to convince sterilized couples that they must now practice safe sex. Also criticized is the assumption that population stabilization is achievable through a balance in birth and death rates. It is likely that environmental instability and other factors will lead to substantially increased mortality in the years ahead. Needed is a new global ethics based on biological realities and valuation of the environment.