Before dogs were our friends, they were our hunting companions, tracking and taking down everything from deer to wild boar. At least that’s the speculation; scientists have little proof that ancient canines actually played this role. Now, a study of more than 100 dog burials in prehistoric Japan claims to provide the strongest evidence yet that early dogs did indeed help people hunt—and may have been critical to human survival in some parts of the world.

“Until now, people have just said it rather than demonstrated it,” says Melinda Zeder, an archaeozoologist at the Smithsonian Institution National Museum of Natural History in Washington, D.C., who wasn’t part of the work. The study, she notes, dug into Japanese archaeological literature rarely seen by foreign scientists. “These findings have been hiding in plain sight.”

The project began when graduate student Angela Perri, then at Durham University in the United Kingdom, went on a hunt of her own. She wanted to get a sense of how dogs may have aided early humans in taking down game, so she did her best to approximate the activity: In 2011, she joined a group of Japanese businessmen on a wild boar hunt in a dense forest near Hiroshima. “It was terrifying,” says Perri, now a zooarchaeologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. “The boar sound like a train. They’re very aggressive, and they have big tusks. At any moment, one could come charging at you.”

But it was the dogs that made the biggest impression. The hunters had brought along a pack of about five bloodhounds and Shiba Inus—a medium-sized breed with a foxlike face—which shot into the forest to track the prey. “After about 10 minutes, you could hear them barking,” Perri says. “It would have taken us 4 hours to find the boar by ourselves.” Once the hunters caught up, the dogs proved even more valuable, warning when the boars were near and protecting the humans.

Inspired, Perri began scouring the Japanese scientific literature for reports of ancient dogs. She focused on the Jōmon culture, a group of hunter-gatherers who inhabited the archipelago from about 16,000 to 2400 years ago. Jōmon living in the Arctic-like northern islands of Japan subsisted on dolphins and whales, whereas those from Japan’s more tropical southern extreme engaged in more traditional fishing. Those in the middle—on the east coast of Japan’s largest island, Honshu—gathered shellfish but mainly lived off the forest. At first, this was a cold pine forest filled with large animals like elephants and bison. Then, as the world warmed early in the Holocene epoch, about 10,000 to 12,000 years ago, the pine gave way to a dense woodland of oak, maple, and birch inhabited by smaller prey like deer and wild boar.

Dogs, Perri reasoned, would have been highly valued in this Holocene forest, as they would be ideally suited to track, chase down, and hold these smaller prey animals. And indeed that’s what she found when she scanned the Japanese archaeological literature. Starting about 9000 years ago, the Honshu Jōmon began to bury their canine companions in shell middens—huge piles of seashells where they also typically interred their human dead. Like people, the dogs (which may have resembled Shiba Inus) were placed singly and appear to have been arranged in particular postures. “They looked like they curled up and went to sleep,” Perri says. Some had suffered what appeared to be hunting injuries—broken legs and teeth—and many of their bones had healed, suggesting people had taken care of them. Some were also found with grave goods, like shell bracelets and deer antlers. “They were treating their dogs the same way they treated their human hunters,” she says.

Perri uncovered records of 110 burials in all, until about 2500 years ago, when the locals turned to agriculture. After this, canines appear in the archaeological record only as random piles of bones, often butchered, suggesting they were simply eaten and thrown away. The same was true all along in the Jōmon populations to the north and south, which did not need dogs for hunting.

The fact that the Japanese dogs were only revered in a time and place where they would have made ideal hunting companions strongly suggests that they did indeed play this role, Perri reports this week in Antiquity . She also points to a 2500-year-old bronze bell found on the east coast of Honshu that contains an engraving believed to depict an event from even further in the past: a boar surrounded by a hunter and his pack of dogs.

“I think it’s a perfectly credible and logical case,” says Darcy Morey, a zooarchaeologist at Radford University in Virginia who has studied ancient dog burials. But, he says, “it’s all still circumstantial—there’s no smoking gun.” It’s possible, he says, that the Jōmon of this time and place revered their dogs for spiritual or other reasons, rather than their hunting prowess.

Zeder agrees, noting that these Jōmon may have been more sedentary than their kin in the north and south, and thus valued dogs for their ability to protect campsites. To build a stronger case for dogs as hunting companions, she says she’d want to see something like a change in dog breeds over time, with a shift toward characteristics that would make them larger and swifter—and thus better hunters. Still, Zeder credits Perri with searching for evidence of early dogs as hunting companions rather than just assuming it. “She’s looking for data that actually supports this idea,” Zeder says.

As for why the Jōmon seem to have severed their special relationship with dogs with the advent of farming, Zeder says it may be a disparity in loyalty. “Humans were a bit of a fair-weather friend—we were not as reliable as they were,” she laughs. “We could do to be a little more doglike.”