May 30 2007
The neurological development of language is an excellent example of overall brain development and function. Specifically, the language centers in the brain learn the language(s) they are exposed to in the first four years of life. So far, the evidence has suggested that language is completely learned. From the linguistic point of view, it also seems that language is purely a cultural construct. Now, however, a new study, for the first time, suggests that there is a genetic component at least to one type of language ability.
Dan Dediu and Robert Ladd at the University of Edinburgh in the United Kingdom have published a study in which they look at 49 different populations worldwide and compared the use of vowels and consonants as well as the use of tonal language with the frequency of specific variants of two genes known to be involved in brain development – ASPM-D and microcephalin-D. They found no correlation with consonant and vowel use, but did find a highly significant correlation between these variants and the lack of a tonal component to language.
Tonal languages are those that use inflection to convey meaning, like Chinese. Tonal languages are found in southeast Asia and sub-Saharan Africa, but are not found anywhere in Europe or North America. Previous studies have shown that people from cultures that use a tonal language have a superior ability to perceive tones than those that do not, and also that there is great variability within populations to perceive tones. Now there is evidence to suggest that these differences are not all learned and that they may have a genetic component.
There are two probable explanations for the genetic correlation. It is possible that tonal languages developed within populations that had a genetic aptitude for distinguishing inflection. It is also possible that the cultural development of tonal languages created a selective pressure favoring the ability to distinguish tones. These explanations are also not mutually exclusive, these two factors may have both been at work and were mutually reinforcing.
Either way, it’s pretty neat. It is still more evidence of how precise and subtle neurological ability is, and also of the incredible power that genes have over brain development and function.
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