A comparison of worldwide phonemic and genetic variation in human populations

Abstract

genotyped populations and phonemes, the smallest units of sound that can distinguish meaning between words. Languages do not hold information about deep ancestry as genes do, and phoneme evolution is complex: phonemes can be transmitted vertically from parents to offspring or horizontally between speakers of different languages, and phonemes can change over time within a language (21–23). We compare the geographic and historical patterns evident in phonemes and genes to determine the traces of human history in each data type. Phonemic data were compiled by M.R. (the Ruhlen database); for 2,082 languages with complete phoneme inventories and referenced sources in this database, we annotated each language with geographic coordinates (Fig. 1A) and the number of speakers reported (24). We also analyzed PHOIBLE (PHOnetics Information Base and Lexicon) (25), a linguistic database with phoneme inventories for 968 languages. For 139 globally distributed populations in the Ruhlen database (114 in PHOIBLE), we matched each population’s genetic data to the phoneme inventory of its native language (20), producing novel “phoneme–genome datasets” that allow joint analysis of genes and languages. Significance Linguistic data are often combined with genetic data to frame inferences about human population history. However, little is known about whether human demographic history generates patterns in linguistic data that are similar to those found in genetic data at a global scale. Here, we analyze the largest available datasets of both phonemes and genotyped populations. Similar axes of human geographic differentiation can be inferred from genetic data and phoneme inventories; however, geographic isolation does not necessarily lead to the loss of phonemes. Our results show that migration within geographic regions shapes phoneme evolution, although human expansion out of Africa has not left a strong signature on phonemes.