I want to expand on last week’s post (about the FoxP2 gene) by considering another piece of research about genetics. A paper published last May by Dan Dediu and Robert Ladd of the University of Edinburgh (author’s summary available on-line here, complete with links to the full article) argues that a population’s “genetic structure” can exert an influence on the features of the language spoken by that population. Specifically, they demonstrate that populations that speak tonal languages have one sort of genetic structure, while non-tonal populations have another.
Tonal languages are those like Chinese and many African languages that distinguish between words by altering their pitch. Non-tonal languages use consonants and vowels. Tonal languages use consonants, vowels, and pitch. A non-tonal language like English distinguishes between words by changing a vowel, a consonant, or both. Thus, we distinguish between do and shoe by keeping the vowel sound but altering the consonant. Grammatical distinctions can be made by the same changes. The Latin amas (you love) amat (he loves) depends on a change from s to t to make a grammatical distinction. In Swahili the change from k to v can distinguish between singular and plural forms: kitabu (book), vitabu (books). Tonal languages have three ways to change a word; thus, Chinese can keep the same consonant-vowel pattern do and do, and yet still distinguish between the two words by speaking one with a high pitch and the other with a low pitch. Tones can also make grammatical distinctions. The Masai language, for example, says the equivalent of saw he she, no matter who did the seeing and who was seen. Speakers use tone to indicate which word is the object and which the subject. Personally, I’ve always been glad I never had to learn a tonal language.
The Dediu and Ladd paper says there is genetic difference between populations that speak tonal languages and those that do not. For this blog, it raises the question of what kind of language was originally spoken, a tonal or non-tonal language. More generally, it suggests a new way of thinking about the process of speech origins.