When I was a wee undergrad, I remember a professor in my class saying that in biology, "extinction is the name of the game."
Sadly, it seems that this rule of thumb also extends to language: linguists have argued that half of the world's 6,000 languages will be lost this century.
Our pal mental_floss has an intriguing post about such 10 languages that have gone extinct in the United States in the past few decades alone:
1. The Eyak language was spoken near the mouth of the Copper River in Alaska up until about two days ago. January 21 was the day that Marie Smith Jones died, the last known full-blooded Eyak and the only person known to be fluent in the language. She tried to help preserve it by creating a dictionary so others could learn it someday. Although Marie had nine children, none of them learned the language because it was considered improper to speak anything but English at the time.
2. Yana was last spoken in north-central California about 95 years ago by the Yahi people. The last native speaker went by the name Ishi, and, like Marie Smith Jones, was instrumental in preserving the language (with help from linguist-anthropologist Edward Sapir). Ishi and his family were around during the Three Knolls Massacre of 1865, which killed off about half of the remaining Yahi people. The rest of them slowly died off, and when Ishi (which means “man” in Yana) succumbed to tuberculosis in 1916, that was the end of the spoken language. Ishi’s story has been featured in several books and movies.