Some of the 200 representatives of the world's estimated 5,000 indigenous tribes, including the South Africain Khoisan - the earliest inhabitants of Africa's southern tip.
Credit: AFP Photo / Alexander Joe
SYDNEY: The complexity of language drops away further from Africa and may be used as tool to trace human migration out of Africa, said 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.
Small populations, less phonemes
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.
Tracing our origin
The results showed some striking similarities to genetic studies on human evolution and origin.
"The patterns of phonemic diversity look like a serial founder effect," said Atkins, who has a keen interest in genetics and the evolution of languages. "This is similar to the genetic evidence that traces our species back to Africa."
The highest number of phonemes was found in Africa, followed by Asia and Europe - just as the genetic model predicted.
Explains why Africa is unique
Colin Groves, a biological anthropologist at Australian National University in Canberra who was not involved in the study, said that the results "fit absolutely with other data".
Groves, who has undertaken research on human evolution, also notes that Africa is the only continent that has Khoisan 'clicking' languages, which can be helpful evidence when making time estimates of when humans dispersed out of Africa.
"Africa has always seemed unique in having Khoisan languages, and this might be an explanation: Khoisan and other languages split before speakers of the latter began to disperse from Africa," he said.
