From the wrinkled face of a pug to the wolf-like snarl of a husky, dogs come in all shapes and sizes. But have you ever wondered which breeds are closest to their wild ancestors? A new study has found that the answer may lie in how they communicate – specifically, in how they howl.

The study, published in Nature Climate Change, observed how 68 dogs reacted to the sound of wolves howling. The researchers then compared the dogs’ responses to their genetic closeness to wolves. The findings showed that ancient breeds – those that are more closely related to wolves – were more likely to respond to the sound of howling with a howl and were also more stressed out by it. More modern breeds were less likely to howl and more likely to bark in response.

The Role of Sex and Age

Sex was another defining factor in a dog’s likelihood to respond with a howl or a bark. Intact males, which have higher levels of testosterone, were more likely to bark than neutered males, which the researchers suggest could be linked to fear. There was also an age association with the trend, as younger dogs (less than two years old) tended to howl about the same across the board. Dogs two years or older, however, were more likely to respond with barks and howls depending on their breed’s distance from wolves.

The Domestication Effect

The findings support the idea that howling is something most dogs can do, but its function as a form of communication has grown weaker with increasingly modern breeds that are genetically more distant from their howling, wolfy ancestors. And that this effect becomes more pronounced as dogs get older. Howling could therefore be considered yet another canine trait that’s been fundamentally changed by the domestication of these animals, turning what was once a crucial tool for communication into something that kicks in when Mariah Carey comes on the radio.

So the next time you’re out walking your pup, take a moment to appreciate the howl and ponder about its wild roots.