15 years after the premiere of the PBS/National Geographic documentary ‘Journey of Man’ and the publication of Spencer’s book, Spencer and Razib talk about the impact they have had on the public’s understanding of genetics and human prehistory. This episode is an hour-long journey through the development of human population genetics, the startling insights provided by the Y-chromosome, and which 2003 population genetic ‘certainties’ have - and haven’t - held up to more recent scrutiny. Destined to be a classic.