From Mandarin and English to the many Indigenous languages spoken around the world, humans today communicate through roughly 7,500 languages. But humanity's linguistic diversity may once have been far greater, according to a new study published in the journal Science.
Researchers think humans may have spoken as many as 20,000 to 75,000 different languages during a period they have called the linguistic "golden age." That abundance did not last. As some populations expanded over time, scientists think their languages spread too, at the expense of many others.
Because many ancient languages may have vanished without a trace, researchers tried to reconstruct the global history of linguistic diversity using other clues. They combined computational models, population estimates, and ethnographic data to trace the rise and fall of languages around the world during the Holocene, starting about 12,000 years ago.
Their modeling suggests that before agriculture took root some 12,000 years ago, humans spoke between 4,500 and 6,200 languages. After people domesticated plants and animals, however, the global population grew, and so did the number of languages. Linguistic diversity may have peaked between 1000 B.C.E. and 1000 C.E. before declining again as certain large populations and their languages spread more widely. Because language and culture often go hand in hand, the researchers suspect many cultural traditions also vanished.
The study does not identify specific historical events, regions, or population groups that might have contributed to this global decline. It suggests only that linguistic diversity underwent a major decline in the relatively recent past.
One surprising result was "how recent the peak appears to have been," study co-author Claire Bowern, a historical linguist at Yale University, says in a statement. She notes that the period of greatest linguistic diversity may not have occurred in the remote Paleolithic, but during a later era of expanding early societies.
Global linguistic diversity continues to decline today. At least four languages disappear every year, according to the editor's summary of the research.
Some hypotheses have placed much of modern language loss around 500 years ago. The new findings indicate that the decline may predate that period, stretching back at least 1,000 years. Lead author Damian Blasi, an anthropologist and computer scientist at Harvard University and the Catalan Institution for Research and Advanced Studies, argues that language diversity can shrink without a single dominant historical force.
Although today's languages represent a fraction of those that may have existed, they still contain a wide variety of features, from click sounds and tonal shifts to different approaches to grammar. If the researchers are right, even this vast modern diversity may represent only a small share of humanity's linguistic possibilities. "Are there people who developed languages with some traits that we can barely imagine now?" Chiara Barbieri, a geneticist at the University of Cagliari, asks. "It makes your head spin."
Researchers often assume that linguistic features are widespread today because they offer some advantage, such as being easy to learn or efficient to use. But "extinction may have shaped linguistic diversity much more profoundly than we previously appreciated," Blasi says. The languages and features that persist today might not be "inherently superior." They may simply be survivors of what he calls a "massive and highly selective historical bottleneck," preserved as the populations using them grew and spread.
However, not everyone is convinced that the study accurately captures the history of linguistic diversity. The researchers might be "on the right track," but their work remains "highly speculative," says Lyle Campbell, a linguist at the University of Hawai'i at Manoa who was not involved with the study. The team is trying to reconstruct a remote past that is extremely difficult to measure directly.