Dogs May Have a Brain Region Dedicated to Human Faces

You know your dog loves you ... or does she just love shelter and belly rubs and treats? If you ever fret over this mystery, science is here with a new tidbit of reassurance. Dogs are so hyper-devoted to us, it seems that they've evolved a special region of their brain for processing human faces.

The Depths of Dog Love

We call dogs "man's best friend" because, at a species level, dogs and humans have a connection. Humans domesticated dogs thousands of years ago, so we've been companions for a long time. (40 thousand years, by some estimates!) We've basically evolved to love each other.

The love runs deep, too. Dogs understand us better than monkeys do, even though genetically, monkeys are our closer relatives. At times, dogs understand humans better than we understand each other. They can recognize our faces and read our facial expressions; they can even take on our moods. (If you think it makes your dog sad when you cry, you're right!)

Researchers grew curious: Would millennia of understanding and cohabiting with humans show up, somehow, in a dog's neural pathways? It seemed possible. Then again, even when you know a relationship is going well, you don't know how well until they give you a drawer at their apartment — or, you know, a designated region in their brain.

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Mapping the Canine Brain

In a new study, researchers specifically focused on how dogs recognize faces. Which regions of their brains do they use for processing dog faces? Human faces? Is there any difference? To explore this, they used fMRI brain scans on a dozen dogs, all trained to hold still for the duration of a brain scan. (They were very good dogs; only 5 percent of the data was mucked up by dog movement.)

Inside the fMRI machine, researchers showed the dogs pictures of dog and human faces. Some of the faces were familiar — canine pals from the kennel, or the dog's (human) trainer — while others were of strangers. To add even more variety to the images, researchers showed the dogs three photos of each human face: one with a negative expression, another with a positive expression, and a third that looked neutral.

All the faces, regardless of species, sparked activity in the dogs' canine temporal cortices, the part of their brain where dogs handle facial recognition. However, the human faces — regardless of their expression and familiarity — triggered activity in a slightly different area than the dog faces. In other words, there could be a special region of the canine temporal cortex devoted to humans.

For now, though, it's unclear if this region is for humans exclusively, or if dogs would use this area to process any face from another species. (Given dogs' borderline creepy ability to read human faces and feelings, though, this brain region probably works better on human faces than on, say, iguana faces.) It also remains unclear if all dogs process human and dog faces separately, or if it's just dogs who have trained intensively with humans, like the dogs in this study.

For now, though, it seems like dogs' millennia-long relationship with humans has literally restructured their brains. Honestly, it's probably reshaped our brains, too. If dogs didn't exist, there's no way we'd say "Who's a good boy?" this much.