Thursday, April 14 (HealthDay News) -- Just as the genetic heritage of humans can be traced to Africa, the world's languages also originated there and spread across the globe, a new study suggests.

New Zealand researcher Quentin Atkinson analyzed the phonemes -- distinct units of sound that differentiate words -- used in modern speech and found that their pattern mirrors that of human genetic diversity.

As humans migrated out of Africa and began colonizing other regions, genetic diversity decreased. According to the study, phoneme diversity tended to decrease, too.

In a study appearing in the April 15 issue of Science, Atkinson suggests that today's phoneme usage fits a "serial founder effect" model of expansion from Africa, where dialects using the most phonemes are spoken. Those with the fewest phonemes are spoken in South America and on tropical islands in the Pacific Ocean, he said.

"If our languages can be traced to Africa, and language is a marker of cultural ancestry, then . . . we are a family in a cultural as well as a genetic sense," said Atkinson, a post-doctoral researcher in the department of psychology at University of Auckland. "I think that is pretty cool."

Atkinson said he undertook the research because he knew that languages used fewer sounds in small populations and thought it would be interesting to determine if a "linguistic founder effect" existed that would explain how language evolved.

In general, he said, areas of the world that were more recently colonized incorporate fewer phonemes into local languages, while long-populated regions such as sub-Saharan Africa still use the most phonemes.

"I found a clear decrease in diversity with distance from Africa," Atkinson said.

Jeffrey Laitman, professor and director of the Center for Anatomy and Functional Morphology at Mount Sinai School of Medicine in New York City, called the study "an extraordinary piece of detective work that sheds light on the process of human evolution . . . through the lens of language."

"It has been very difficult for individuals to get a handle on this and trace back," said Laitman, also a professor of otolaryngology. "It gives us extraordinary insight into an area that's not been looked at like this."

Despite the fact that language originated in Africa, however, that doesn't mean dialects still spoken there are more complex or varied than others far away, said Suzanne Kemmer, an associate professor of linguistics at Rice University in Houston.

"Africa shows a lot of complexity and diversity because it's a source area," said Kemmer, also director of cognitive sciences. But, "you can always show that a language that is thought to be less complex is more complex in some way."

Atkinson agreed, noting that some North American languages use more sounds than African ones.

"There is a lot of variation around the globe, even within regions," he said. "The finding is about a statistical trend or average. It is also worth remembering that languages code meaning in many different ways and so having more sounds doesn't really mean a language is more complex in terms of expressivity."

More information

Learn about the origins of the English language at Merriam-Webster.