Wita, a Trio shaman of Kwamalasamutu Village, Suriname with a staff and a plant in his hands

There are nearly 7,000 languages on Earth, but experts say about half of them are endangered, meaning only a small and declining number of often elderly people speak the language. Major world and national languages crowd out indigenous ones, and it's estimated that more languages became extinct in the 20th century than at any other time in history.

For scientists, the loss of a language represents a very real loss of knowledge. And that knowledge could save lives at a time when drug companies search tropical forests for biologically-based medical breakthroughs, and many if not most plant and animal species remain unknown to Western science.

Professor David Harrison of Swarthmore College decries the loss of scientific knowledge when languages die

At last week's meeting of the American Association for the Advancement of Science, David Harrison of Swarthmore College in Pennsylvania said saving endangered languages could help scientists harness knowledge that might otherwise be lost.

"Vast domains of knowledge about meteorology, mathematics, weather cycles, plant and animal behavior, how to domesticate plants and animals, how to control genetic stocks exists," Harrison stressed. "It is out there, it is fragile, it is very rapidly eroding."

Revitalizing a dying language can help heal a community according to Daryl Baldwin, an expert on the Myaamia language and culture that once thrived in the American Midwest

When a language goes, so does culture. The Miami are a native people that once thrived in the American Midwest. Three centuries ago, their Myaamia language was widely spoken. But the language began to die out as the tribe was forced from its ancestral homeland and its members became more assimilated in mainstream America. It was essentially extinct by the 1960s. However, the language had been well documented, and Daryl Baldwin and his Myaamia Project have been working to revitalize both the language and the culture it represents.

"For communities that have been socially disrupted, the language provides an avenue by which they can mend and heal," said Baldwin, "because embodied in that language is a great deal of information about how we relate to each other and how we relate to our landscape. And so language revitalization has been incredibly enriching. It's been daunting. Language loss is about social change; language reclamation is also about social change."

Hawaiian culture thrives but the language is threatened says William Wilson of the University of Hawaii

Revitalizing an endangered language is never easy. In Hawaii, the U.S. state that was an independent monarchy until 1893, the culture is strong, but the language has faced severe challenges, such as a law that prohibited teaching it in schools until two decades ago. William Wilson of the University of Hawaii says it is important to expose young Hawaiians to the language, and the subject now is taught to school children.

"So that's increasing the numbers of speakers," Wilson said. "In 1986, when we started, there were less than 50 children in all of Hawaii that could speak Hawaiian fluently. Now we have about 2,000 in our school system. More importantly, there are actually families that speak Hawaiian at home. And so we've started infant-toddler programs, where those children can come together before they go to preschool."

Leanne Hinton of the University of California says 1:1 intensive programs are preserving native languages in her state

On the mainland, California has a tremendous heritage of language diversity, with as many as 100 native languages having been spoken there. Many are now endangered or gone entirely. Leanne Hinton of the University of California says one-on-one intensive programs are helping sustain threatened languages.

"One of them is the master-apprentice language learning program, which pairs the last speakers of native languages with younger members of the tribe who want to learn it. And we teach them the fundamentals of language immersion, and they are supposed to spend 10 or 20 hours a week just living their lives together in the language and without recourse to English," Hinton explained.

Despite efforts like these, indigenous and other minority languages will continue to be threatened, and many likely will die off. But aggressive programs can help ensure the survival of other languages, along with the knowledge and culture they embody.