Using a complex network of chemical signals, trees talk to each other and form alliances with fellow trees, even other species. In fact, whole forests exist as a kind of superorganism. And some trees are incredibly old. Did you know a single bristlecone pine can live up to 6,000 years? And the root mass of aspens might live 100,000 years? We explore the science and history of trees and talk with Richard Powers about his epic novel "The Overstory." Original Air Date: April 28, 2018 Guests:  Mark Hirsch — Richard Powers — Suzanne Simard — Amos Clifford — Daegan Miller Interviews In This Hour:  A Year In The Life Of A Tree — Listening to the Mother Trees — Richard Powers on Writing the Inner Life of Trees — Bathing in the Beauty of the Trees — General Sherman, Karl Marx, and Other Aliases of Earth's Largest Tree