Clayton R. Magill and Katherine H. Freeman discuss how water availability and ecosystem changes influenced early human habitats.

Interview with 2012 Cozzarelli Prize Winners Sean Palecek and Xiaojun Lian

Welcome to Science Sessions, the PNAS podcast program. Listen to brief conversations with cutting-edge researchers, Academy members, and policymakers as they discuss topics relevant to today's scientific community. Learn the behind-the-scenes story of work published in PNAS, plus a broad range of scientific news about discoveries that affect the world around us.