Human speech originated in central and southern Africa, according to new research on languages. It is then said to have spread around the globe alongside migrating human populations.

A comprehensive study of phonemes, or the perceptually distinct units of sound that differentiate words, used in 504 human languages reveals that the dialects containing the most phonemes are spoken in Africa, those with the fewest in South America and on tropical islands in the Pacific Ocean.

This pattern of phoneme usage around the world mirrors the pattern of human genetic diversity, which also declined as humans expanded their range from Africa to colonize other regions, reveals an analysis in the 15 April issue of Science

Data compiled by Quentin Atkinson from the University of Auckland, shows a movement of languages out of the African continent to other areas of the world. Atikson says, "It seems like the obvious explanation is that people carried language - along with their genes - with them as they expanded out of Africa."

Atkinson's findings further reveal that areas that were most recently colonised adapt fewer phonemes into their local languages while regions that have hosted human life for a long time still use the most phonemes, sub-Saharan Africa in particular.

According to Atkinson's study, the highest levels of phonemic diversity are found in language families associated with the people of Southeast Asia. His research frames comple language as one of the earliest archaeological symbols of mordern human culture, indicating that it was a key cultural innovation that ultimately led to our colonisation of the globe.

In conclusion Atkinson says: "Modern humans are just one big, genetic family with a single common ancestor, one of the things I like about these results is that, to the extent that language is an identity, we all seem to be part of one big, cultural family as well."