What do Spanish, Hindi and English all have in common? They all descended from the same mother tongue: Anatolian, or more commonly Proto-Indo-European.

In fact, there's about a 50 percent chance that any given person speaks a language from the Indo-European family, as Shoaib Daniyal recently reported for Quartz. Indo-European languages, a family that includes about half the languages spoken today. But there are still a lot of questions about who founded that original tongue, and when, and how it spread. Linguists do know that Proto-Indo-European was a language unique to a tribal culture in ancient Eurasia. They know that these ancient humans only spoke their language, they never wrote it down, and today it's extinct. (Of course, that hasn't stopped linguists from trying to reconstruct the language.) But they don't know exactly when and where the language truly began, or how it came to birth so many of our modern tongues. 

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Under one hypothesis, the ancestral tongue is 6,000 years old. It originated among tribal nomads on the Pontic Steppe, at the intersection of Kazakhstan, Russia and Ukraine. These nomads had significant military prowess and had domesticated horses. Such innovative feats allowed them to spread their language by travel and conquest.

Evolutionary biologists recently usurped this nomadic theory. In 2012, a team from the University of Auckland in New Zealand estimated that Proto-Indo-European is even older, perhaps originating 8,000 to 9,500 years ago. As for its geographic origins, they pointed to Anatolia, or modern day Turkey. By their account, the first speakers practiced animal domestication and agriculture. As these practices spread, so did their language.