At least 15,000 years ago, a single language started to break up. It broke into about seven different languages and, over the next 5,000 years, splintered into thousands more. Those languages became what's spoken by billions throughout Europe and Asia.
The seven languages are part of a "superfamily" of Eurasiatic languages, the Guardian reports, a long-debated theory on the history of human speech. It's tough to definitively trace back words when about half of words are replaced by completely different words every 2,000 to 4,000 years, but the British team advancing the super-languages theory has already shown in another study that certain words stay the same for tens of thousands of years longer. Using a computer model to search for words that only changed very, very rarely, the team determined which modern words likely sounded similar to the same words in ancient languages, then checked their results against a list of words reconstructed by linguists. That pointed them to a split from a common language at about 15,000 years ago.
Also interesting are some of the "ultraconserved" words that seldom changed throughout history: Frequently used words like "I" and "we" understandably have a long history but also, inexplicably, the verb "to spit." Apparently spitting is essential to our development as humans.