Today we're talking about evolution–basically the history of all life on Earth. The thing is, why are we talking about this. Well, the story of life, all the way back to single celled microbes billions of years ago, is all part of our human story. An important facet of the story of life is the story of death. This episode will look at the various mass extinctions along the way, and we'll also talk about the sixth mass extinction, which is going on now, and is kind of driven by humans. Sorry everybody.

• John Green
• Hank Green