This story appears in the March 2016 issue of Playboy. Subscribe

The cavemen are pissed off, their ragged blades swinging at your head. But what the hell are they saying? Language was French publisher Ubisoft’s big challenge when, two years ago, it began work on the next game in its Far Cry series. For Far Cry Primal (PC, PS4, Xbox One), Ubisoft has created a Stone Age world full of cavemen who started the world’s first wars. Yet the words used 12,000 years ago weren’t apelike grunts and screams. Those hairy guys had a remarkably complex language—one no gamer alive today understands.

“We used Proto-Indo-European, the mother of all tongues,” says game director Thomas Simon. It’s downright weird to hear hulking protagonist Takkar speak with what consultant Andrew Byrd, a linguistics professor, calls “something like German” with some Middle English thrown in. Byrd created a distinct version of PIE for each of Primal’s three tribes. One version has 15 vowels.

“Communicating was actually more complex then,” says lead story writer Kevin Shortt. Far Cry developers asked Byrd for a stripped-down language, says Shortt, “then went with the premise that actions speak louder than words.” Players may even pick up the words for “bear” or “tiger” when characters shout them repeatedly.

The game makers also looked at films such as 1981’s Quest for Fire, in which the gestures of the prehuman characters are so impassioned, evocative and witty, no language is needed. “We wanted our actors to emulate that,” says Simon.

For three separate shoots last year, Byrd’s wife, Brenna, also a professor and linguistics expert, flew to Toronto to teach Primal’s actors PIE “as if it were a real, current language.” But when you’re exploring alone, there’s no language at all. Against a wash of ominous wind, the crack of a branch can herald a beast sneaking from behind to rip flesh from your bones.

“Humans used to be part of the food chain, not on top of it,” explains Simon with a grin. “We wanted to reinforce the feeling that nature is full of terror.” Yet through the savagery, as the strange, ancient tongue becomes ever more familiar, you learn that communication isn’t just a means of survival; it’s an essential key to evolution itself.