The relationship between genes and language is probably the most difficult and delicate area of the language evolution debate. On the one hand, your individual language is clearly not chosen by your genes (a child can learn whichever language it is raised with) but the capacity for language has always been assumed to have a clear genetic basis, even if the Chomskian linguists have made no effort to explain how it evolved. The discovery of the FOXP2 gene gave hope that some part of the genetic basis of language had been found, but as yet there have been no major genetic breakthroughs to explain the Language Acquisition Device. What little examination there has recently been on the genetic basis for language, has begun to focus on the idea that there is a far for sophisticated relationship between the genetic and the linguistic layer. In this interesting model, subtle iterated changes can manifest in language over generations, motivated by slight genetic variations. A brilliant new paper by the Edinburgh LEC’s own (and rather lovely) Bob Ladd and Dan Dediu has really put the cat amongst the pigeons by finding a correlation between allele frequency in two genes and the proportion of tonal languages.
Its more an interesting correlational hypothesis at the moment than a proven link, but it does offer an interesting window onto the relationship between genes and language. Previous work into two genes, ASPM and Microcephalim showed that there were two common variants (alleles). The distribution of these genes throughout the world’s population is quite uneven and they are spreading quickly. Ladd and Dediu noticed that not only are these genes implicated in brain development, but they correlate nicely with the distribution of tonal languages throughout the world. They argue that this might be explained by the gradual imposition of slight genetic restrictions upon language across generations. Clearly each tonal language is different and this is not by any means the most significant way of categorizing a language, but if true it would indicate an incredibly subtle and iterated relationship between the genetic aspects of language, and the mechanisms of learning and cultural transmission.
Whatever your take on the causes of this correlation, the degree of similarity are striking. Perhaps another step forwards towards understanding the relationship between genes language and culture?