- [Narrator] Dog owners will be the first to tell you how smart, how cute, and how unique their best boy or girl is.

And evolutionarily speaking, they're right.

Our relationship with dogs spans thousands of years and has fundamentally changed their evolution as a species.

They are one of the few animals on the planet that's adapted to communicate with us.

Like those adorable pleading eyebrows.

Dogs developed a specific muscle, the levator anguli oculi medialis, to achieve what scientists call the inner eyebrow raise presumably because humans favor dogs that could make those sad puppy dog eyes.

Dogs' ancestor, the wolf, doesn't have this muscle and that's just one of their skills.

- Puppy, look.

So we found out that dogs are really good at reading cooperative gestures.

If I point to something to help you find it, that's a cooperative gesture and dogs are very good at understanding that.

- [Narrator] That ability to read human social cues is very rare in the animal kingdom.

Even our closest relatives, the chimpanzees, don't have it.

Hannah is studying the finer details of how and when puppies achieve these skills at Duke's Canine Cognition Center.

One way to understand dog evolution is to compare these puppies to their closest ancestor, the wolf.

- So as dogs were evolving from wolves, one hypothesis is that they were selected for friendly temperaments.

Whether they kind of self-selected at first, the ones who were most friendly, least aggressive, or fearful towards humans would've been the ones who more successfully came into human camps and were able to benefit from that.

And then maybe further on down the line, people were intentionally selecting the most friendly ones to keep as pets and help as hunting companions and things like that.

- [Narrator] The research team hypothesized that if dogs were selected for friendliness, dog puppies would show an innate ability to communicate with humans compared to wolf puppies.

So they compared a group of wolf puppies to a group of dog puppies.

The wolf puppies were smothered in love from humans, bottle fed, snuggles at night, constant 24/7 human companionship.

The dog puppies had less human interaction.

They were raised in a kennel with most of their early weeks spent with their mothers.

Then they tested both groups with a variety of games, including one called the Unsolvable Task.

- [Hannah] So for this one, we have a clear Tupperware container and we'll put a piece of food in the container and close it so that they're not able to open it on their own and then we just measure how much eye contact the puppy makes with the person.

And so what we found is that dog puppies on average tended to make more eye contact than the wolf puppies.

The dog puppies might try to get at it, scratch at it, bite at it for a little bit, and then they would often sit back and just look up at the person like, "please help me!"

Whereas the wolf puppies, they would just keep trying and trying on their own.

Maybe sometimes they'd just wander away and lay down and they didn't make as much eye contact with the human as the dog puppies did.

- [Narrator] So even without that extra human attention, dogs still have the ability to rely on human social cues.

The study supports the idea that dogs evolved from wolves as the friendliest and most social wolves were allowed in human camps, giving them an advantage over the more surly wolves.

- And there's even some evidence that dogs have kind of hijacked they call it our emotional pathways, where making eye contact with them releases the same kinds of bonding hormones as it does making eye contact with a baby or a significant other or something like that.

- [Narrator] These social communication skills also make dogs the perfect service animal.

Duke is using the latest research on canine cognition to improve service dog training.

- So dogs have a lot of jobs now.

They are helping so many people.

They're better than technology in a lot of instances.

They're not just service dogs, but they're working dogs, and every organization has the same problem is that there's just not enough of them.

I think just TSA have a 20,000 dog shortage.

There are millions of people who could use them.

- Yeah, there it is.

Good job, buddy.

- So our question is, well, how do you scale?

And so what we do is that we take the puppies from 8 to 20 weeks, which is their period of most rapid brain development, and we give them all this cognitive aptitude testing, kind of like a little head start program, and we're trying to find out what makes the profile of a service dog so we can at a very young age take them and then run them through a series of games and then figure out, well, what dog is gonna be best for which job?

- [Narrator] Duke works with Canine Companions, a nonprofit that provides service dogs for free, but it takes years of intensive training and lots of money to get these puppies ready for service.

- These dogs truly allow people who otherwise could not live without the care and help of another human, allow them to live independently.

People who can't bend down to pick up items that they drop, people can't open a door or open a refrigerator, turn on and off a light, these dogs can do all of that.

They are incredible and amazing.

If we can better identify which dogs are more likely to make it, then we can invest more into those dogs and get more dogs to more people.

There are so many people on the waiting list that are in need of these dogs and that's really fulfilling to know that these dogs are gonna change someone's life, so I love it.

[giggles]