People love to speculate on when, how, and why dogs and people became friends. A study published on July 19 shows that it might just be genetic.

Here’s the story. A condition in humans, Williams-Beuren Syndrome, is the result of a missing section of genetic material, a section of DNA that contains about 27 genes, according to an article in Inside Science. The syndrome affects about 1 in 10,000 people, the article says; these individuals are “hypersocial,” with bubbly, extroverted personalities, as well as some other traits.

It seems that someone else’s bubbly, extroverted personality (I’m looking at you, Cali) might be related to a similar genetic hiccup.

In the course of studies of domestication and how it has caused doggy genetics to differ from wolf genetics, Bridgett vonHoldt, the lead author of the study, tested the friendliness of dogs and 10 hand-raised, tamed wolves. They measured how much time the dogs and wolves chose to spend in close proximity to humans and whether they worked at a challenge or sought human assistance. Predictably, the dogs both spent more time with the people and sought their help in solving the puzzle. Dogs do enjoy having staff.

However, the results had some variation, and in looking for reasons that some wolves were more sociable than others, the researchers found a clue: The genetic area that showed differences in the more- and less-social wolves corresponded to the genetic area that is missing in people with Williams-Beuren Syndrome. Friendly dogs and wolves had similar genetic variants; unfriendly wolves had genetic variants similar to each other and different from the dogs and the friendly wolves.

The researchers looked deeper. They examined the corresponding genes in dogs from 13 breeds. Breeds known to be friendly had profiles similar to the friendly members of the initial research group, while breeds known to be more standoffish had profiles that looked more like the unfriendly wolves. The study says that this genetic region is “known to be under positive selection in the domestic dog genome” — over generations of breeding, people have selected for the “friendly” genetic variation; these mutations are rare in wolves and even rarer in coyotes, which tend to be far less social than dogs and wolves. The same genes had been linked to friendliness in mice in earlier research.

Of course, a small segment of genetic material is not the only thing that influences social behavior. And theories about the domestication of wolves abound. But evidence is accumulating for a theory that basically says that that wolves chose to hang out with early humans. The friendlier, or less timid, wolves started scavenging near human camps and trash heaps. Over time, young pups and friendly adults inched closer to actual contact, until a great partnership was formed.

I have always been skeptical of the various human-centered narratives that had humans capturing and holding captive and bending to their will fierce wolves, all thousands of years before humans had metalworking abilities and tools that would make it possible to hold onto a wolf who didn’t want to stick around. I doubt that those unfriendly wolves, even the hand-reared ones, would stay put if tied to a tree with a leather strap. There had to be something else going on.

That the roots of friendship could center on food makes sense (again, looking at you, Cali). But even that explanation is not enough. While dogs and wolves are opportunistic — which means they will eagerly take advantage of opportunities to help themselves to a snack — early  humans were unlikely to have huge quantities of extra food available to just hand out to large-toothed scavengers skulking on the periphery of camp. On the other hand, if the scavengers were friendly and potentially useful …

An explanation that includes a choice on the part of the wolves, or at least some wolves makes more sense than the whole deal being human-instigated and controlled. And, as more people study the human-canine connection, more bits of information point to dogs playing an active role in establishing a mutually beneficial relationship with people, like this suggestion that some wolves were genetically inclined to be friendly and seek human company.

An additional reason that this study could be important is that researchers have long sought genetic explanations for complex behavior; this could be an important first step.

None of that really makes a genetic mutation a truly satisfying explanation for that waggy tail, wriggly, “let me show you my toy” greeting I get at the door … but the bottom line is, the dog-human friendship is pretty wonderful. If that’s where it started, well, I’ll take it.