Genetic variation tied to consonant use across populations

A study identifies potential genetic variants tied to differences in the ability to process word sounds across populations. Variations in READ1, a genetic sequence that regulates expression of the gene DCDC2, are tied to dyslexia and thought to influence normal speech variation, reading performance, and auditory processing of basic word sounds. Jeffrey Gruen and colleagues compared READ1 sequences in nonhuman primates, Neanderthals, Denisovans, and modern humans, and found that the regulatory sequence acquired changes specific to modern humans between 550,000 and 4 million years ago. Comparison of READ1 variants across 43 modern human populations from five continents with the numbers of consonants and vowels prevalent in those populations revealed that the number of consonants--but not vowels--was positively correlated with the frequency of RU1-1, a READ1 variant; the human brain uses distinct strategies to process and encode vowels and consonants. The correlation was unaffected by the populations' geographic proximity, genetic relatedness, or linguistic relatedness. Hence, the authors suggest, differences in READ1 sequence, and resultant differences in DCDC2 expression, may account for differences in word-sound processing across populations. Specifically, the low prevalence of RU1-1 in some populations may be associated with diminished ability to distinguish between consonants, resulting in progressive shrinkage of the populations' consonant inventory. According to the authors, subtle but discernible genetic variations, magnified by cultural processes, might account for differences in consonant use across populations.

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Article #17-10472: "Worldwide distribution of the DCDC2 READ1 regulatory element and its relationship with phoneme variation across languages," by Melissa DeMille et al.

MEDIA CONTACT: Jeffrey Gruen, Yale Child Health Research Center, New Haven, CT; 203-737-2202; e-mail: jeffrey.gruen@yale.edu