Lecture by Paul Ehrlich during the 2008 Reunion Homecoming Classes Without Quizzes program. Professor Ehrlich discusses the changes in the environmental situation forty years ago and today, telling how humanity took over the planet, and how it is now using its dominance to destroy its own life-support systems. He emphasizes the critical issues facing the world that are getting almost no attention in the current presidential race.Paul Ehrlich, Professor of Biological Sciences, Bing Professor of Population Studies and president of the Center for Conservation Biology at Stanford, is an internationally prominent ecologist and evolutionist and the recipient of numerous national and international scientific awards.