Humans have faced existential risks since our species was born. Because we are Earthbound, what happens to Earth happens to us. Josh points out that there’s a lot that can happen to Earth - like gamma ray bursts, supernovae, and runaway greenhouse effect. (Original score by Point Lobo.) Because humanity is an Earthbound species – we have no way to get ourselves off of Earth and live elsewhere in the universe quite yet – if something terrible happens to Earth, it happens to us as well. Because Earth has a long history of terrible ]t would be in our best interests to get busy on working to get ourselves off of Earth as soon as possible and become a spacefaring species because Earth has a long history of suffering terrible, life-erasing events. There have been at least five mass extinctions in Earth’s history, from the one brought on by an asteroid that killed off the dinosaurs and about three quarters of the species on Earth to another one hundreds of millions of years earlier that was triggered by a gamma ray burst, when a meager four percent of all life on Earth managed to hang on. What are the mechanics behind catastrophes on these scales and what impacts would they have on humanity? In this episode, Josh looks at what are called natural existential risks and explores what some of them would be like for humans and Earth itself. Interviewees: Robin Hanson, George Mason University economist (creator of the Great Filter hypothesis); Ian O’Neill, astrophysicist and science writer; Toby Ord, Oxford University philosopher.