The world has more the 7000 languages, but this language is depleting fast. The prime concern of this depleting number of languages is that with each language extinct, we lose valuable information about the planet, about the ecosystem. It is estimated that 80% of the species of the Earth are unknown, but that doesn't mean that the local people don't know it. Much of what we know is not documented but is in people's heads, and as languages get extinct, we lose that knowledge.
The extinction of languages happens when people abandon their own language for a more popular language. Of the 50 remaining native languages in California, none is taught to schoolchildren. In Australia, a team found three speakers of a language called Magati Ke. In Western Australia, three speakers of the Yawuru language were found.In the outback, they located a man with a rudimentary knowledge of Amurdag, a language that was declared extinct.