Chasing Vanishing Languages

More than half of the world's 7,000 languages are expected to die out by the end of the century, often taking with them irreplaceable knowledge about the natural world. David Harrison, a linguistics professor at Pennsylvania's Swarthmore College, has identified five "hotspots" where languages are vanishing most rapidly. He has traveled the world to interview the last speakers of critically endangered languages as part of the National Geographic Society's Enduring Voices Project.