Original broadcast date: March 11, 2022. From our planet's underwater caves to its ancient soils, there are entire worlds right beneath our feet. This hour, we explore the subterranean forces that shape our lives above the ground. Guests include cave diver Jill Heinerth, death care advocate Katrina Spade, soil scientist Asmeret Asefaw Berhe, and paleontologist Nizar Ibrahim. TED Radio Hour+ subscribers now get access to bonus episodes, with more ideas from TED speakers and a behind the scenes look with our producers. A Plus subscription also lets you listen to regular episodes (like this one!) without sponsors. Sign-up at plus.npr.org/ted.