Zhejiang University linguist Kevin Tang (Dept. of Linguistics & Institute of Linguistics and Applied Linguistics in Foreign Languages) is part of an international, multi-disciplinary research team that identified variants of a dyslexia gene that correlate with consonant use, establishing a role for genetics in differences in languages between populations, according to the study, which was published in the April issue of Proceedings of the National Academy of Sciences (PNAS).(doi:10.1073/pnas.1710472115).
The multi-disciplinary research team, consisting of geneticists, a statistician, linguists, a paediatrician and a developmental psychologist from Yale University, Zhejiang University and Brock University, examined the genetics and sound inventories of 43 different populations on five continents to see the extent to which genes play a role in subtle language differences.
The team examined DCDC2, a gene that is strongly associated with the brain's capacity to process phonemes. In particular, they focussed on READ1, a component of the DCDC2 gene, which has been consistently linked to dyslexia. A phoneme is a basic unit of sound that makes up words in a language, such as 'p' and 'b' in “pat” and “bat” in English and in “怕”and “爸” in Mandarin Chinese. The team looked at two major characteristics of languages: vowels and consonants. Different languages utilize different numbers of vowels and consonants. Some languages, like Estonian and Finnish, have relatively more vowels, while others, like Spanish and Quechua, have fewer vowels. Some languages have a small number of consonants – e.g. Nasioi, an East Papuan language spoken on Bougainville, a large island to the east of New Guinea, has 8 consonants – while others have a large number of consonants – e.g. Sandawe, a language isolate, spoken in North Central Tanzania in the Dodoma Region, Kondoa District, has 44 consonants.
The team traced READ1 sequences in nonhuman primates, Neanderthals, Denisovans, and modern humans and found that the regulatory sequence changed between 550,000 and four million years ago. They also compared READ1 variants among 43 populations with the numbers of consonants and of vowels present in the languages spoken by those populations. It was found that the number of consonants – but not of vowels – correlated with the frequency of RU1-1, a READ1 variant in the language’s population.
There are more than 7,000 languages spoken globally. They are thought to have been shaped by a range of factors such as migration, conquests and geographic isolation of populations, the researchers say. The surprising finding in this study is that genetic factors might also play a role in language change.
“Traditionally language change is not often attributed to genetics, full stop,” says Kevin Tang, an assistant professor of Linguistics at Zhejiang University.
The brain uses distinct strategies to process and encode vowels and consonants, which are modified by dyslexia genes. Genetic variations of these genes, along with other cultural and linguistic processes, may account for differences in consonant use between populations, the researchers conclude.
“While this study highlighted how biological differences could contribute to the mechanisms of language change, it is important to note that any language can be learned by any person, and even languages that have seemingly different linguistic structures– for instance, spoken versus signed languages – are still rooted in essentially the same cognitive processes,” says Kevin Tang.
Author contributions: M.M.C.D. and J.R.G. designed research; M.M.C.D., K.T., C.M.M., C.G., N.R.P., and B.M.B. performed research; C.M.M. contributed new reagents/analytic tools; M.M.C.D., C.M.M., J.G.M., A.K.A., D.T.T., and J.C.F. analyzed data; M.M.C.D., K.T., and J.R.G. wrote the paper; and J.G.M. and D.T.T. provided background material.
For other reports on this study, see:
· Quartz: https://qz.com/1264305/can-genes-change-the-way-languages-evolve/
· Neuroscience news: http://neurosciencenews.com/gene-variation-language-8831
· and others: https://pnas.altmetric.com/details/37682661/news
