Language defines a culture, through the people who speak it and what it allows speakers to say. Words that describe a particular cultural practice or idea may not translate precisely into another language. Many endangered languages have rich oral cultures with stories, songs, and histories passed on to younger generations, but no written forms. With the extinction of a language, an entire culture is lost. Much of what humans know about nature is encoded only in oral languages. Indigenous groups that have interacted closely with the natural world for thousands of years often have profound insights into local lands, plants, animals, and ecosystems—many still undocumented by science.