From giant Sequoia’s only found in the California Sierra Mountains to Italy’s ancient olive trees, and New Zealand's kauri tree. Around the world, ancient trees are under threat due to climate change. These botanical giants are critical for the health of their ecosystems and hold clues to Earth’s history.

We speak with Jared Farmer, professor of history at the University of Pennsylvania and the author of “Elderflora: A Modern History of Ancient Trees” about the history and traditions of these trees and how they keep us in touch with our humanity.