Want to understand someone’s personality? Take a good look at their dog. There’s a decent chance you’ll learn about as much from the dog as you will their best friend or spouse. (Come to think of it, we ARE talking about man’s best friend here.)

While the presence of other pet types (or the absence of pets) also says something about your personality, it turns out ‘man’s best friend’ really is a breed apart when it comes to understanding ourselves.

Everything I know I learned from dogs. – Nora Roberts

First domesticated more than 30,000 years ago purely for hunting and protective purposes, over time dogs became human companions, then friends, and eventually family members.

Today, numerous studies show we choose our dogs based on our own personalities, and that our canine friends, in turn, adopt key features of their owners’ personalities.

Even more important, we humans learn a ton from our dogs, like:

• Loving unconditionally – humans talk about it, dogs do it
• Living in the here and now
• Learning to forgive and forget
• Being adaptable
• Getting outside and playing
• Stopping to smell (and maybe pee on) the flowers

Or as more than a one dog trainer has pointed out, dogs are easy to train – it’s the owners who are difficult.

The Eyes Have It

Eager to test the idea that people look like their dogs, UCSD psychologist Michael Roy visited three San Diego dog parks and took separate photos of people and their dogs.

Next, he asked volunteers to try and match the photos of the dogs with those of their owners. The result: in a majority of cases the volunteers were able to successfully match owners and pets.

If I could be half the person my dog is, I’d be twice the human I am. – Charles Yu

Roy’s hypothesis has been retested multiple times and always with similar results. One such study showed that women with long hair preferred lop-eared dogs while women with short hair tended to choose prick-eared dogs.

Interestingly, when the eyes of the owners and pets were covered in the Roy’s photos, the volunteers were unable to match the dogs with their owners, suggesting we choose our dogs to some degree based on the size and shape of their eyes.

Studies confirm that the eyes of dogs and their owners are the physical feature most likely to be similar.

In fact, a subsequent study conducted by researchers in Japan demonstrated “that dogs and owners resemble each other in the eye region.”

Who Gets the Dog?

But it’s in personality that people and their dogs are most alike.

Using modern personality science’s Big Five theory of personality, researchers have repeatedly demonstrated that dogs and their owners exhibit similar trait-based behaviors.

If there are no dogs in heaven, then when I die I want to go where they went. – Will Rogers

In a study by researchers at Michigan State University, more than 1,600 people answered questions about themselves and their dogs. What they found was that the descriptions owners gave of their own personalities closely aligned with how they described their pets.

So if you’re a social, outgoing type, your dog will likely wag its tail at other dogs and humans. If you’re inactive and carrying some extra weight, your dog will start taking up residence beside you on the couch. And if you are an anxious, fearful sort, don’t be surprised if your dog either snarls at others or whimpers behind your legs. The researchers even found that dogs in loving homes were easier to train and better behaved.

And while, like humans, much of a dog’s personality is rooted in its DNA, over time its personality will change to more closely align with that of its owner. This is especially true if raised as a puppy when early experiences shape behavioral tendencies and preferences. If an owner experiences high levels of stress, so too will his or her dog.

If a dog will not come to you after having looked you in the face, you should go home and examine your conscience. – Woodrow Wilson

Just how much does a dog’s personality mirror that of its owner? In a study conducted by Borbala Turcsan at Budapest’s Eotvos University, the similarities between dog and owner were “actually higher than the similarity found in married couples and friends,” said Turcsan.

So if you’re curious about someone’s personality, get to know their dog. It’ll teach you everything you need to know.