Book excerpt: Highlighting the importance to ecological studies of incorporating humans and their effects on ecosystems, leading experts from a variety of disciplines address a number of important issues, including: * the prominent role of humans in the function of ecosystems on Earth * why humans have been ignored in ecological studies * approaches taken by social scientists, historians, geographers, economists, and anthropologists in the study of human activities * the emergence of a new ecological paradigm accommodating human activities * methods for studying subtle human effects, and human- populated ecosystems * future research and training required to include humans effectively as components of ecological systems. Of interest to students and researchers in ecology, and to policy-makers and environmental managers. In addition, it makes social scientists aware of new opportunties for integrating their ideas with those of ecologists.