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April 14, 2011

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Language may have originated in Africa

April 14, 2011
Courtesy of Science
and World Science staff

A new anal­y­sis of lan­guage from around the world sug­gests hu­man speech orig­i­nat­ed in cen­tral and south­ern Af­ri­ca.

Ver­bal com­mu­nica­t­ion then likely spread around the globe, evolv­ing along­side mi­grat­ing hu­man popula­t­ions, with no fur­ther in­de­pend­ent “o­rig­in” events, ac­cord­ing to a sci­ent­ist car­ry­ing out the stu­dy.

Quen­tin At­kin­son of the Un­ivers­ity of Auck­land, New Zealand, an­a­lyzed “pho­nemes,” or per­cep­tu­ally dis­tinct un­its of sound that make words dif­fer­ent, used in 504 hu­man lan­guages to­day. He found that the di­alects con­tain­ing the most pho­nemes are spo­ken in Af­ri­ca while those with the few­est are spo­ken in South Amer­i­ca and on trop­i­cal is­lands in the Pa­cif­ic Ocean. 

The glob­al pat­tern mir­rors that of hu­man ge­net­ic di­vers­ity, At­kin­son ex­plained, which al­so de­clined as hu­mans ex­pand­ed their range from Af­ri­ca to col­o­nize oth­er re­gions. Bi­ol­o­gists say ge­net­ic di­vers­ity is typ­ic­ally low­er in more re­cently pop­u­lated ar­eas due to a “bot­tle­neck ef­fec­t,” in which newly in­hab­it­ed ar­eas are col­o­nized by small “founder” groups with rel­a­tively lim­it­ed gene pools.

The lan­guage pat­terns re­flect a si­m­i­lar ef­fect, At­kin­son said: ar­eas that were most re­cently col­o­nized in­cor­po­rate few­er pho­nemes, where­as ar­eas that have hosted peo­ple for mil­len­ni­a—par­tic­ul­ar­ly sub-Saharan Af­ri­ca—still use the most pho­nemes. This de­cline in pho­neme us­age can­not be ex­plained by de­mo­graph­ic shifts or oth­er lo­cal fac­tors, he added, and “points to par­al­lel mech­a­nisms shap­ing ge­net­ic and lin­guis­tic di­vers­ity” among hu­mans.

At­kin­son re­ported the find­ings in the April 15 is­sue of the re­search jour­nal Sci­ence.

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A new analysis of language from around the world suggests human speech originated in central and southern Africa. Verbal communication then likely spread around the globe, evolving alongside migrating human populations, without any further independent “origin” events, according to a scientist carrying out the study. Quentin Atkinson of the University of Auckland, N.Z., analyzed “phonemes,” or perceptually distinct units of sound that make words different, used in 504 human languages today. He found that the dialects containing the most phonemes are spoken in Africa while those with the fewest are spoken in South America and on tropical islands in the Pacific Ocean. The global pattern mirrors that of human genetic diversity, Atkinson explained, which also declined as humans expanded their range from Africa to colonize other regions. Biologists say genetic diversity is typically lower in more recently populated areas due to a “bottleneck effect,” in which newly inhabited areas are colonized by small “founder” groups with relatively limited gene pools. The language patterns reflect a similar effect, Atkinson said: areas that were most recently colonized incorporate fewer phonemes, whereas areas that have hosted people for millennia—particularly sub-Saharan Africa—still use the most phonemes. This decline in phoneme usage cannot be explained by demographic shifts or other local factors, he added, and “points to parallel mechanisms shaping genetic and linguistic diversity” among humans. Atkinson reported the findings in the April 15 issue of the research journal Science.