It is a deep question, from deep in our history: when did human language as we know it emerge? A new survey of genomic evidence suggests our unique language capacity was present at least 135,000 years ago. Subsequently, language might have entered social use 100,000 years ago.

Our species, Homo sapiens, is about 230,000 years old. Estimates of when language originated vary widely, based on different forms of evidence, from fossils to cultural artifacts. The authors of the new analysis took a different approach. They reasoned that since all human languages likely have a common origin—as the researchers strongly think—the key question is how far back in time regional groups began spreading around the world.

"The logic is very simple," says Shigeru Miyagawa, an MIT professor and co-author of a new paper summarizing the results.

"Every population branching across the globe has human language, and all languages are related."

Based on what the genomics data indicate about the geographic divergence of early human populations, he adds, "I think we can say with a fair amount of certainty that the first split occurred about 135,000 years ago, so human language capacity must have been present by then, or before."

The paper, "Linguistic capacity was present in the Homo sapiens population 135 thousand years ago," appears in Frontiers in Psychology.

Co-authors include Rob DeSalle, a principal investigator at the American Museum of Natural History's Institute for Comparative Genomics, and Ian Tattersall, curator emeritus of human origins at the American Museum of Natural History, and others.

The new paper examines 15 genetic studies of different varieties, published over the past 18 years: three used data about the inherited Y chromosome, three examined mitochondrial DNA, and nine were whole-genome studies.

All told, the data from these studies suggest an initial regional branching of humans about 135,000 years ago. That is, after the emergence of Homo sapiens, groups of people subsequently moved apart geographically, and some resulting genetic variations have developed, over time, among the different regional subpopulations.

The amount of genetic variation shown in the studies allows researchers to estimate the point in time at which Homo sapiens was still one regionally undivided group.

Miyagawa says the studies collectively provide increasingly converging evidence about when these geographic splits started taking place.

The first survey of this type was performed by other scholars in 2017, but they had fewer existing genetic studies to draw upon. Now, there are much more published data available, which, when considered together, points to 135,000 years ago as the likely time of the first split.

The new meta-analysis was possible because "quantity-wise we have more studies, and quality-wise, it's a narrower window [of time]," says Miyagawa, who also holds an appointment at the University of São Paulo.

Like many linguists, Miyagawa believes all human languages are demonstrably related to each other, something he has examined in his own work. For instance, in his 2010 book, "Why Agree? Why Move?" he analyzed previously unexplored similarities between English, Japanese, and some of the Bantu languages. There are more than 7,000 identified human languages around the globe.