Over 3,000 years ago, in the region now known as Kazakhstan, six dogs were carefully interred. The exact reason—whether they were cherished companions or ritually sacrificed—remains uncertain. Nevertheless, such archaeological discoveries are invaluable to scientists tracing the integration of dogs into human history. These finds offer a window into canine DNA, revealing the mechanisms by which dogs moved between human groups and undertook their own continental migrations.

Advancements in ancient DNA sequencing have shown that human populations, over thousands of years, migrated into new territories in successive waves, sometimes blending with existing inhabitants and other times replacing them entirely. Researchers sought to determine if similar patterns applied to animals living alongside humans. They analyzed DNA from 17 dogs that lived in Eurasia during the last 10,000 years, including one from the Kazakh burial site. A study published on November 13 in the journal Science indicates that dogs often journeyed with their human companions to new lands, and remarkably, even if the human newcomers eventually departed, the dogs sometimes remained.

Dogs have coexisted with humans for a surprisingly long time—pre-dating both urban centers and agricultural practices, they were already part of our lives, explains Laurent Frantz, a professor at the Ludwig Maximilian University of Munich and a co-author of the research paper. Domesticated animals like chickens, horses, pigs, sheep, goats, and cows joined human societies much later than dogs. These early canines appear to have been quite mobile, even millennia ago; prior research by Frantz and his colleagues suggests that dogs present in North America before European colonization originated from Eurasia, mirroring human migration patterns.

However, locating dog remains among the extensive quantities of other animal bones left by humans can be surprisingly challenging. Frantz recounts, “I frequently travel with a colleague who specializes in horses. We sift through boxes from these sites, constantly encountering sheep bones.” Yet, he notes, dogs were more often afforded special burials, interred with a degree of care in their own graves, compared to other animals.

For their study in Science, Frantz and his team focused on a significant period in Asian history: the advent of bronze technology in China. This metalworking skill spread from western to eastern Asia roughly 5,000 to 4,000 years ago, a development that, according to Frantz, “completely reshaped society.” The communities responsible for introducing bronze technology also brought horses, cattle, and sheep. The researchers questioned whether new dog types accompanied them as well.

By analyzing previously unexamined DNA from dogs across Eurasia spanning the last 10,000 years, the research team assembled a compelling narrative. Initially, before the Bronze Age, dog populations in western and eastern Eurasia were genetically distinct. In the intermediary region of Botai in Kazakhstan, some dogs even possessed Arctic ancestry, potentially linked to the local cold climate or the specific needs of the Botai people.

Yet, as the human migrations associated with bronze dissemination progressed eastward, genetic evidence suggests that the Botai people largely vanished, absorbed by the incoming groups. Frantz describes this as “in a way, the end of the world.” He adds, “Their way of life ceased to exist, and a significant portion of their genetics disappeared.” This pattern extended to Botai’s dog populations.

Upon bronze technology reaching East Asia, a different scenario unfolded: Local populations adopted the newcomers’ bronze techniques and their dogs, but not their human genes. Frantz observes, “What’s truly fascinating about the dogs is that they appear to spread more like technology than like people.”

Audrey Lin, a paleogeneticist at the American Museum of Natural History who was not involved in this particular study, agrees that this comparison is fitting. She states, “They are a technology.”

While DNA cannot definitively reveal the specific roles dogs played alongside humans millennia ago, it is probable they were utilized for hunting, herding, or perhaps as an alert system during nighttime. This suggests that the trade of dogs would have been a logical practice.

Frantz intends to further investigate how dogs expanded across Southeast Asia and into Australia. Beyond the anthropological insights dogs can offer, he is also keen to understand how they adapted to such prolonged coexistence with humans. They journeyed with hunter-gatherers, were selectively bred by Romans, and inhabited remote Siberian islands—all long before global exchanges became commonplace.

He concludes, “We still have many questions concerning dogs themselves.”