Language complexity declined in move out of Africa

Each language is made up of a number of sounds, from 140 in the Kalahari Desert to 11 in the Amazon Forest – but could they all have a common origin?

HUMAN LANGUAGE most likely originated in Africa just once and then followed our early ancestors as they spread out and populated the world. A study of more than 500 languages from around the world, including Irish, also suggests that language complexity declined the further away from Africa that migrating humans got.

Linguists continually argue about whether language arose once or many times. There is also disagreement about how far back our ability to speak actually goes, and when we acquired this powerful tool of human development.

Dr Quentin Atkinson, a biologist at the University of Auckland in New Zealand, believes he has settled these disputes. He picked apart 504 languages from every corner of the globe, pulling out the individual sounds needed to produce the language.

He found that the “click” languages of the bushmen of the Kalahari Desert were the most complex, using more than 140 distinct sounds or “phonemes”.

By comparison, English only needs about 45, German has 41 phonemes and Mandarin has 32, he writes in the current issue of the journal Science.

His study suggests that the further away from Africa that humans got, the less complex their languages became. The more recently settled the population grouping the less complex the phoneme structure of their language.

Language is presumed to have arisen at least 50,000 years ago, when human migration out of Africa was thought to have begun. It could be much older however and emerged perhaps 100,000 years ago.

It is difficult to prove when language arose, but Atkinson argues that it arose just once and then went through ongoing modification as individual groups broke off and made their own way in the world.

His assertion that this is how language spread out parallels findings already established and beyond question in genetics relating to the dispersal of human biological diversity around the world in a process known as the serial founder effect.

Humans began to occupy lands beyond Africa, but population bottlenecks would occur. Small groups would “bud off” and move on, taking with them a reduced level of genetic diversity. At each bottleneck a reduced subset migrated away, further lowering diversity.

“Here I show that the number of phonemes used in a global sample of 504 languages is also clinal [a change in traits occurring over a geographical area] and fits a serial founder effect model of expansion from an inferred origin in Africa,” Atkinson writes.

He found that Garawa, a now extinct Australian Aboriginal language used 22 phonemes. The peoples who settled the Hawaiian Islands needed less, just 13 phonemes while the Piraha Amazonian tribesmen use 11 phonemes.

“This result, which is not explained by more recent demographic history, local language diversity or statistical non-independence within language families, points to parallel mechanisms shaping genetic and linguistic diversity and supports an African origin of modern human languages,” Atkinson writes.