This essay is part of the second presentation of an educational project of the American Society of Zoologists. The purpose of the project is to offer suggestions for improving the first-year biology courses in the universities. The method consists of emphasizing the conceptual framework of the biological sciences, showing how scientific information is obtained and evaluated, pointing out the strengths and limitations of scientific procedures, and above all showing the relevance of science for human hopes and welfare. Each year a major topic will be considered. Last year it was Evolutionary Biology. This year it is Human Ecology.