Humanity may have once spoken many more languages ​​than today, with tens of thousands in use between 3,000 and 1,000 years ago. This far exceeds the more than 7,500 unique languages ​​currently used around the world.

The findings, published July 23 in Science¹suggest that the rise of agriculture fueled an initial linguistic boom as people abandoned a nomadic, hunter-gatherer lifestyle and settled in small, isolated communities. If accurate, these results suggest that language extinction is not an exclusively modern phenomenon, says Heidi Harley, a linguist at the University of Arizona in Tucson.

The true historical diversity of languages ​​suggested by this analysis is “mind-blowing,” he says. “The sheer number of languages ​​they projected existed, it was like, ‘What? That’s crazy.'”

Lost languages

Aside from written sources, evidence for language in the archaeological record is sparse, meaning researchers often know “surprisingly little” about historical linguistic diversity, says Joe Salmons, a historical linguist at the University of Wisconsin-Madison.

This has led researchers to propose very different explanations for how linguistic diversity has evolved over time. For the most part, those estimates are “backwards numbers,” says co-author Claire Bowern, a historical linguist at Yale University in New Haven, Connecticut.

In their study, Bowern and his colleagues set out to trace the global trajectory of linguistic diversity over the past 12,000 years. They began by estimating how many languages ​​were spoken 12,000 years ago, around the end of the last ice age. To do so, they divided the approximate total global population at that time by the average size of hunter-gatherer groups of the same ethnic and cultural background. For this model, the researchers worked under the assumption that these groups of about 800 people spoke the same language, an inference based on 20th-century research on Alaska Native groups and global historical linguistic diversity.

Their calculation suggested that between 3,300 and 7,800 languages ​​were spoken 12,000 years ago.

The team then set out to estimate how linguistic diversity has evolved over time, using statistical models. Because the structure of many societies changed at the end of the last glacial period, moving from nomadic hunter-gatherer groups to agricultural communities and expanding into nation states, the model assumed that groups speaking the same language eventually became larger.

Despite this, the analysis suggests that linguistic diversity increased over the following millennia as agriculture spread globally, and peaked about 2,000 years ago, when tens of thousands of languages ​​were in use, about ten times more than were spoken at the end of the last ice age.

It is unclear why this happened, but Bowern suspects that one factor was the transition from nomadic settlements to more permanent settlements. This is supported by research in New Guinea and Vanuatu, which suggests that the dialects and languages ​​of small agricultural settlements differ more markedly from those of their neighbors than those of hunter-gatherers in the same region.