Babies have an astonishing talent that adults entirely lose. By the age of one, they can recognise the significant noises around them and group them into a language. When we have lost this capacity as adults, it becomes enormously difficult to distinguish between sounds that are glaringly different to a native speaker. It all sounds Greek to us. This is because the range of possible sounds that humans use to convey meaning may be as high as 2,000, but few languages use more than 100 and even then the significant noises－the phonemes (音素) of a language－each cover a range of sounds and so vague distinctions which would change the meaning of a word in other languages.
But where do these phonemes come from and
why do they shift over time? New research suggests that the apparently
arbitrary distribution of some sounds around the world may be partially
explained by diet. This is unexpected. We'd rather think of language as product
of our thought 
rather than of the arrangement of our teeth. In reality, though, any given language must be both.
Hunter gatherer languages very seldom use the sounds known as labiodentals (唇齿音)－those such as f and v－that are made by touching the lower lip with the upper teeth. Only two of the hundreds of Australian aboriginal languages use them, for example. But in cultures that have discovered farming, these consonants (辅音) are much more common. The argument goes that farmers eat more cooked food and more dairy than hunter gatherers. Either way, they need to chew mush less, and to bite less with their front teeth. So farmers grew up with smaller lower jaws and more of an overbite than their ancestors who had to bite through harder foods. It became easier for them to make the labiodental consonants instead of purely labial (唇音) ones: one example is that f come to take the place of p. Romans said "pater" but English speakers (unless they're Rees－Moggs) say "father".
Beyond these particular changes, the story highlights the way in which everything distinctively human is both material and spiritual: speech must combine sound and meaning, and the meaning can't exist or be transmitted without a real object. But neither can it be reduced to the purely physical, as our inability to understand or even to recognise foreign languages makes clear. The food we eat shapes our jaws, and our jaws in turn shape the sounds of our language. The ease with which we eat probably shapes our thought too, as anyone who has suffered toothache could testify. What we eat may have shaped the sounds of our language, but how we eat changes how we feel and what we use language to express. A family meal is very different from a sandwich at the office desk, even if the calorie is the same. Food has purposes and meanings far beyond keeping us alive and pleasing the Palate (味觉).
