Sixty years ago, geologists tried to drill down through the Earth’s crust to pull up a piece of the Earth’s mantle. Their mission didn’t go exactly as planned. But it sowed the seeds for a new field of science that’s helped us rewrite not only the history of the planet, but, potentially, our definitions of life itself. The documentaries featured in this episode are "The First Deep Ocean Drilling: Mohole, Phase 1" and "Project Mohole: Report No. 1." For further reading, sign up for our newsletter here:  http://vox.com/unexplainable-newsletter Show transcript and articles at:  http://vox.com/unexplainable Email us! unexplainable@vox.com We read every email. Learn more about your ad choices. Visit podcastchoices.com/adchoices