The world today has about 7,500 spoken or signed languages. Yet this number could be much lower than what was observed over the course of human history. A study published in the journal Science estimates that linguistic diversity reached a peak of several tens of thousands of languages before gradually declining.
The researchers sought to reconstruct this evolution over about 12,000 years, since the beginning of the Holocene. Since ancient languages rarely left direct traces, they combined data from anthropology, demography, and linguistics with a statistical model simulating several scenarios.
To estimate the situation at the beginning of this period, the team relied on 171 hunter-gatherer and fishing societies. It also integrated estimates of the world population 12,000 years ago, then between 4.4 and 7 million inhabitants.
According to simulations, this population probably spoke between 4,500 and 6,200 languages. Linguistic diversity then increased over several millennia, alongside population growth and the development of more sedentary agricultural societies. Distinct groups could then retain their own languages.
The peak was likely reached between about 3,000 and 1,000 years ago. This period thus corresponds to the end of prehistory, Antiquity, and the beginning of the Middle Ages.
Linguistic diversity may have continued to increase with population growth, even as the first states developed. It then began to decline when large kingdoms and empires integrated previously separate groups.
The languages of dominant powers then spread through administration, trade, population movements, or conquest. The languages of absorbed communities sometimes disappeared, while others transformed. Latin, for example, evolved into several Romance languages, including French, Italian, and Spanish.
European colonization, undertaken several centuries later, reinforced this concentration around dominant languages. However, it did not alone trigger the global decline. The authors estimate that it had begun much earlier, with the expansion of large states and empires of Antiquity.
The results remain a statistical reconstruction, not an exact census of ancient languages. They nevertheless suggest that today's roughly 7,500 languages are the survivors of a diversity up to 10 times greater. About half of them are now endangered, especially when children stop learning them.