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More than seven thousand languages are spoken around the globe, and researchers have picked up on a curious fact: as you move from the Earth’s poles toward the equator, you hear more languages. Why do humans speak so many languages? And why so many more in the tropics? Do languages diversify the way animal species do?Dr. Michael Gavin, an ecologist in Colorado State University’s Department of Human Dimensions of Natural Resources, is looking for answers on islands in the South Pacific.This program originally aired August 15, 2017.