Joel E. Cohen is the Abby Rockefeller Mauzé Professor of Populations at the Rockefeller University. At Columbia University, he is Professor of International and Public Affairs and Professor of Earth and Environmental Sciences. He heads the Laboratory of Populations at Rockefeller and Columbia Universities. His research deals with the demography, ecology, epidemiology and social organization of human and non-human populations. In 1999, Cohen was the co-recipient of the Tyler World Prize for Environmental Achievement for his work in advancing the environmental understanding of human population dynamics. (#23339)