The complexity of language drops away further from Africa and may be used a as tool to trace human migration out of Africa, says a New Zealand researcher. The number of ‘speech sounds’ found in different human languages has declined since our dispersal from Africa, says evolutionary psychologist Quentin Atkinson, from the University of Auckland in northern New Zealand.
The concept adds weight to genetic evidence for an initial migration out of Africa, he writes in the journal Science today. Phonemes are units of sound that help us recognise different words (like /k/ in the words ‘skin’ and ‘kill’). Throughout Africa, phonemic diversity is very high. But in distant regions such as South America and Oceania these sound inventories are much smaller, showing a similar pattern to our genetic history, the study shows.
“When we left Africa we took language with us along with our genes,” Atkinson said.
Past studies have shown that the phoneme number decreases as a population gets smaller. This result fits into a genetic model known as the serial founder effect, which describes the loss of gene diversity in small, migrated populations. The study is the first to investigate if phonemic diversity and genetic modelling could be used to trace our origins.
To test the idea, Atkinson collected 504 languages from the World Atlas of Language Structures (WALS), and examined the geographic variation in phoneme inventory size, along with demographic, taxonomic and locational data. This information was analysed to see whether the data were consistent with founder effect patterns.