In a study published in Science (pay wall) last week, Blasi, Moran et al. propose that labiodental sounds (in English, /f/ and /v/) may have developed as a result of changing human diet.
Our ancestors ate harder foods, which ground down our front teeth. This gave us a bite where our top and bottom teeth met. Though possible, labiodental sounds would have been difficult to produce and thus unlikely to appear in language, the authors argue.
As our diets began incorporating softer foods, our top teeth weren’t ground down as much, so the teeth stayed closer to the front of our mouths. The authors suggest that because of this, labiodental sounds became easier to produce and thus were introduced into the pantheon of potential sounds for language. These sounds now feature in many languages worldwide.
Whilst not without detractors (this is science after all, the debate never ends), it’s an interesting theory nonetheless.
(via the Science in Action podcast.)