<p>Chinmay Kalluraya and Matthew Daugherty explain how vertebrates acquired a gene critical for vision from bacteria.</p>

Racial disparities in air pollution exposure

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.