Thomas Jefferson wasn't just obsessed with mastodons for no reason. Instead, he was in an intense dispute with a French naturalist named Georges-Louis Leclerc, Comte de Buffon. Leclerc argued that the American continent was 'degenerate', and all animals and life forms in the joint were weaker, smaller, and less-developed than those in Europe. In the second part of this special two-part series, returning guest Lauren Vogelbaum regales the gang with the final chapter of Jefferson's strange beef with Leclerc... and how this conflict eventually led to the concept of biological extinction.