Published: April 18, 2014

Some 20,000 species across the globe are at high risk of extinction, experts say – many here in the United States – and some of our natural fauna have already disappeared. So in this Earth Day episode, the American History Guys explore how Americans have grappled with the idea of extinction over time, and what the loss of native species has meant for our ecosystems and everyday lives.

When did we first realize that species could go extinct? To what extent did earlier extinctions shape the emergence of today’s environmentalism? And how have ideas about biological extinction factored into American thinking about human cultures? These are just some of the questions the American History Guys and their guests explore in this episode, with stories on our obsession with dinosaurs, the bird that helped birth the conservation movement, the unlikely fish that galvanized a new generation of environmental activists, and much more.