Sharing similar locations in both species, they process voices and emotions of other individuals similarly. Both groups respond with greater neural activity when they listen to voices reflecting positive emotions such as laughing than to negative sounds that include crying or whining. Dogs and people, however, respond more strongly to the sounds made by their own species. “Dogs and humans meet in a very similar social environment but we didn’t know before just how similar the brain mechanisms are to process this social information,” Andics says.
These striking similarities help clarify the timeline and stages of mammalian evolutionary history. Until now researchers had identified voice-sensitive brain regions only in humans and macaque monkeys, whose last common ancestor lived 30 million years ago. The last common ancestor of humans and dogs—a mammalian carnivore with a brain the size of an egg—existed around 100 million years ago. The canine finding thus suggests that the voice-sensitive brain regions in both species evolved at least that long ago, if not earlier. Other mammals on the same evolutionary branch as humans and hounds that also arose from that last mutual ancestor are likely share the same brain areas as well.
But dog owners might be most interested in what this study says about our special relationship with canine pets. Humans domesticated dogs somewhere between 18,000 and 32,000 years ago, and since then they have become people’s best friends, hunting partners, guards and even purse accessories. Andics thinks the parallel brain sensitivity to voices and emotions may account in part for our unique bond. “This similarity helps explain what makes vocal communication between dogs and humans so successful,” he says. “It’s why dogs can tune into their owners’ feelings so well.”