The texts of the 16th century were first to record the F-word for posterity. It appeared in William Dunbar’s poem A Brash of Wowing in 1503 and later, thanks to an angry monk, in a note scrawled in the margin of a 1528 copy of De Officiis, Cicero’s moral manifesto.

But according to researchers, the English language might never have enjoyed a richness of F-words had it not been for early farmers and the food processing they favoured. Dairy products and other soft foods, such as gruel, porridge, soup and stews, helped shape our faces, the researchers claim, and allowed us to form the sounds “f” and “v”, known as labiodental fricatives.

The international team reached their conclusion while testing a theory put forward by the late American linguist Charles Hockett. In 1985, Hockett proposed that the overwhelming absence of sounds such as “f” and “v” in languages spoken by hunter-gatherers was partly down to their diet.

He argued that chewing tough foods subjected the mouth to strong forces that wore down the teeth and caused the lower jaw to grow larger, eventually leading the lower teeth to align with those in the upper jaw. Without the usual overbite, it is hard to press the bottom lip against the upper teeth, making “f” and “v” sounds unviable.

Hockett’s theory was rejected at the time but as the researchers gathered evidence for their study they came to suspect he was right. Computer models of the jaw showed that with a normal human overbite, it takes 29% less energy to form labiodental consonants than when the upper and lower teeth are aligned.

When the researchers studied “f” and “v” sounds in languages around the world, they found that hunter-gatherer languages had only about a quarter of the number found in languages spoken by farming societies. Further analysis found that labiodental consonants could have spread rapidly in languages since the dawn of agriculture, to the point that they are found in half of the 7,000 or so languages still spoken.

“We find that labiodentals couldn’t have emerged much before about 4,000 years ago,” said Damián Blasi at the University of Zurich. “That’s really recent in terms of anatomically modern humans.” The arrival of the new labiodentals may have driven a fresh diversification of language across Europe and Asia.

The researchers, writing in the Science journal, describe how early modern humans would typically have lost the overbite they were born with after growing up on a diet of hard-to-chew food. But farming, milling and cooking in pottery vessels paved the way for softer foods, and so the overbite remained and new sounds became possible.

Retaining an overbite did not lead directly to labiodental consonants but it allowed people to make the sounds more easily, Blasi said. They were then more likely to enter into language. As softer foods continue to spread around the world, ever more languages are expected to adopt the sounds, the scientists believe.

Blasi believes the finding should force a rethink of the factors that could drive the evolution of language. He said: “We’re taught about language in the context of the humanities, and that is completely separated from the biological underpinnings of language. But all of our speech apparatus is made up of bones and muscles, which are affected by mechanical forces. They change when you change your diet.”

Although the F-word did not appear in English dictionaries until the 18th century, it cropped up in historical court records as early as the 13th century. The Englishman John le Fucker was put away for a double murder in 1278, while Roger Fuckebyethenavele became an outlaw when he failed to show at a Cheshire court in 1310. The origins of the nicknames are unclear but there is a chance the men had radically different reputations for sexual competence.