Talking Back in Time; Prehistoric Origins of Language Attract New Data and Debate
Bower, Bruce, Science News
The compulsion to open our mouths and gab sometimes gets a bad rap. Consider the phrases "talk is cheap" and "actions speak louder than words." Or as an old blues song puts it, "Your mind is on vacation, and your mouth is working overtime."
Behavioral scientists, however, regard humanity's conversational stream with awe. Psychologists, for instance, have dubbed spoken language "the jewel in the crown of cognition." Yet the evolutionary origins of this bauble of babble are hotly contended.
Two general schools of thought currently square off on this issue. "Early-origin" theorists argue that the ability to speak developed gradually over at least 2 million years among human ancestors, although opinions vary regarding the complexity of the speech of fossil species.
A "late-origin" alternative holds that anatomically modern humans rapidly transformed communication with simple sounds and gestures into grammatical speech sometime between 50,000 and 100,000 years ago.
New linguistic and anatomical research offers some ammunition for early-origin advocates, although disputes within and between theories show no sign of diminishing.
The first shot comes from Johanna Nichols, a linguist at the University of California, Berkeley. At the American Association for the Advancement of Science's annual meeting in February, Nichols presented evidence that the common ancestor of the world's modern languages arose at least 100,000 years ago, suggesting ancient roots of premodern types of vocal communication. She obtained this estimate by calculating the time necessary to achieve current worldwide linguistic diversity.
"It's possible to reconstruct a picture of language in very ancient times, at the dawn of the global expansion of modern humans, based on standard comparative linguistics," Nichols maintains.
Until now, comparative linguistics revolved around studying corresponding use of sounds in a few languages at a time. This approach traces language roots back some 8,000 years at most.
Nichols instead charted statistical ten-dencies in nearly 200 of the 300 known language stocks, the oldest groups of related languages established through comparative linguistics. Examples of stocks include Indo-European and Austronesian (which encompasses many native languages of the Pacific islands). Most stocks extend back about 6,000 years.
Language stocks multiply more rapidly in tropical areas along coastlines and more slowly in the drier interior of continents, especially in regions where political empires and agriculture predominate, Nichols asserts. Thus, the island of New Guinea harbors at least 80 stocks -- the greatest density of languages found anywhere in the world -- while much larger Australia contains only about 30.
Moreover, Nichols also estimates that the linguistic ancestors of Eurasian and North American stocks branched into an average of 1.6 daughter tongues.
Assuming that current stocks extend back 5,000 years and derive from individual languages that spawned an average of 1.6 daughter tongues each, it would take at least 100,000 years to create today's linguistic diversity, she concludes. Her calculation assumes that ancestral environments threw up few roadblocks to the creation of new languages, much as in New Guinea.
Nichols also finds that considerable linguistic variety existed by 50,000 years ago, when humans began to migrate from Asia to the Pacific and later the Americas. About a dozen stable features of languages -- such as changing word meaning with voice pitch, assigning gender to nouns, and overt distinctions between singular and plural nouns -- appear in distinctive clusters as modern stocks move from west to east, the Berkeley researcher holds. This reflects the diversification of languages as people migrated from Africa to points east, according to Nichols.
Her analysis also suggests that colonization of the Americas began around 35,000 years ago, much earlier than the common archaeological estimate of 12,000 years ago. …