When did the first humans start speaking? Did we always have this ability, inherited from our immediate ancestors? These questions sound impossible to answer — but not quite so. A new study, drawing on a wealth of genetic data, suggests that the capacity for language was present at least 135,000 years ago in humans alive at the time.

Unlike previous attempts to date the origins of language, which relied on fossils or cultural artifacts, this study takes a novel approach: it uses the genetic divergence of early human populations to estimate when our ancestors first possessed the cognitive tools necessary for language.

“The logic is very simple,” says Shigeru Miyagawa, a linguist at MIT and co-author of the study. “Every population branching across the globe has human language, and all languages are related.”

By analyzing when these populations began to split, the researchers concluded that the capacity for language must have existed before or around 135,000 years ago.

Population Splits and Their Relation to Language

To reach this conclusion, Miyagawa and his team reviewed 15 genetic studies published over the past 18 years. These studies included analyses of the Y chromosome, mitochondrial DNA, and whole genomes. By examining single nucleotide polymorphisms (SNPs) — tiny variations in DNA — they traced the earliest split in the human family tree to around 135,000 years ago. This split gave rise to the Khoisan peoples of Southern Africa, who are among the most genetically distinct human populations alive today.

If the linguistic capacity had emerged in humans after the initial divergence, one would expect to find modern human populations that either do not have language, or that have some communication capacity that differs meaningfully from that of all other human populations. Neither is the case. “So human language capacity must have been present by then, or before,” Miyagawa explains.

This date serves as a “lower boundary” for when language capacity must have emerged. But since Homo sapiens is at least 300,000 years old, one may reasonably assume that language may have been a feature of our ancestors for all our species’ history.

But having the capacity for language is not the same as using it. The researchers propose that language likely began as an internal cognitive system before evolving into a tool for social communication. “Language is both a cognitive system and a communication system,” Miyagawa says. “My guess is prior to 135,000 years ago, it did start out as a private cognitive system, but relatively quickly that turned into a communications system.”

A Debate as Old as Language Itself

Miyagawa has spent decades studying the similarities between languages as diverse as English, Japanese, and Bant. He believes that the complexity of human language sets it apart from any other form of animal communication.

“Human language is qualitatively different because there are two things, words and syntax, working together to create this very complex system,” he says. “No other animal has a parallel structure in their communication system. And that gives us the ability to generate very sophisticated thoughts and to communicate them to others.”

Miyagawa points out that language isn’t just about communication. It shapes both thinking and consequently behavior. Around 100,000 years ago, archaeological records show a sudden explosion of symbolic artifacts — engraved ochre, shell beads, and geometric patterns on ostrich eggshells. These findings, from sites like South Africa’s Blombos Cave, show that language must be accompanied by a leap in cognition and cultural behavior.

“Language, with its complex system of mental representations and rules for combining them, is able to create new ways to connect existing symbols and predict new ways of behavior,” the researchers wrote in their study published in Frontiers in Psychology. In other words, language didn’t just allow humans to communicate — it allowed them to think in new ways, thus paving the road for art, technology, and culture.

These ideas, namely that language serves as a “trigger” for modern human behavior and culture, are not exactly new. But the new study adds a crucial piece of evidence: a concrete timeline.

Some researchers argue that language evolved gradually, shaped by natural selection over hundreds of thousands of years. Others believe it emerged suddenly, in a kind of cognitive “big bang.” We still don’t know how language evolved exactly but with a clearer minimum date, the jigsaw puzzle is one step closer to completion.

“Our approach is very empirically based, grounded in the latest genetic understanding of early Homo sapiens,” he says. “I think we are on a good research arc, and I hope this will encourage people to look more at human language and evolution.”