Original subtitles

[narrator] There are some dogs so noble,

so heroic,

they've done as much for humankind as any person has.

Like Laika, who gave her life to expand our frontier.

[newscaster] This dog may well be the forerunner

that points the way to journeys to the moon.

[narrator] And Frida, who rescued a dozen souls buried under rubble.

[reporter] ...giving so many renewed hope that even more lives would be saved.

[narrator] And Kuno, honored for running ahead into open fire

and taking down the enemy.

He'd saved lives when it mattered.

[narrator] Today, dogs are sniffing out COVID,

invasive species,

and cancer, as early as stage I.

They lead the blind,

cushion people's heads during seizures,

and provide comfort when others can't.

Clearly, humans and dogs have a special thing going on.

[man] Go.

[narrator] And yet they're certainly not the smartest animal.

-[barks] -[woman laughs]

[dog whines]

[narrator] Or our closest animal relative.

So why, out of all species on Earth,

are dogs man's best friend?

And what does that say about us?

[theme music playing]

[man 1] It certainly appears that the dogs are reasonably content.

[man 2] Behind every pampered poodle lies a long history of human intervention.

[man 3] Little fellows don't know where they're going, but they're on their way.

[barking]

Here's our new little baby, Miss Beazley.

Oh. [laughs]

[man] Are you enjoying being on TV? You have no idea how famous you are.

That's part of your charm.

There are estimated to be

over 800 million dogs on the surface of this planet.

[Gyllenhaal] And more than half of them are pets.

We're living in a time

when humans are driving thousands of species extinct,

but there are a handful of species

that have really figured out how to get along with people,

and dogs are the number one example of that.

And then when you look at how dogs live with us,

how well we take care of them, at least at its best,

I mean, it's a great life.

Dogs were the first domesticated animal.

[Gyllenhaal] Which is surprising.

Our ancestors had all these nice plant-eating animals roaming around,

and yet, first up, they tamed wolves,

meat-eating predators that could kill them.

No one knows for certain how wolves and humans first got friendly,

but one leading theory is...

The scavenger hypothesis talks about this idea

that people would throw that extra meat to wolves,

and wolves would create this association

that human beings aren't that bad, through food.

[Gyllenhaal] Humans didn't just neutralize the threat.

We created a new kind of protection.

[Schell] So if you have wolves on your side,

even against other wolves,

they'll provide signals of "Hey, something is coming."

So, before ADT became ADT, right,

dogs were our security companions.

[Gyllenhaal] And since the friendliest wolves got more scraps,

over generations, the wolves got tamer and tamer,

transforming into an entirely new species.

In 1959, Russian scientist Dmitry Belyaev tried to replicate that on another animal.

[squeals]

He rounded up a bunch of silver foxes

and selected the tamest to parent the next generation.

And then he did the same with their pups, and then their pups,

and so on and so on.

Fifteen generations later...

[in Russian] The selection turned what were once aggressive and sneaky foxes

into animals as friendly as a dog.

[Gyllenhaal in English] Their biology had changed.

They had about half the amount of stress hormones

as their wild ancestors.

The adrenal gland that produces those stress hormones

had actually become smaller,

and their serotonin levels increased,

which produced happier animals.

Their appearance changed, too.

Their tails became curlier,

their bodies rounder,

and ears floppier,

more juvenile facial features,

increasingly adorable.

And, well,

more like dogs.

[Schell] Cuteness unlocks this parenting mode.

So imagine a baby, right? A really, really small infant.

Your instincts are going to kick in

to want to protect that really small thing.

[Gyllenhaal] Dogs replaced the survival skills they lost

with new ones,

mainly pulling on our heartstrings.

[Coren] The so-called puppy dog eyes is an entreaty

that dogs seem to reserve for people

to get something, to get a treat, to get a pat,

or that kind of a thing. Doesn't work on other dogs.

[woman] Are you being bad?

[Gyllenhaal] And we are suckers for it.

[woman] But you're cute.

[Gyllenhaal] One study at a shelter

found that the more frequently a dog used the puppy dog eyes,

the more quickly they were adopted.

[Schell] Right, baby, are you ready?

[Gyllenhaal] Dogs pulled off something extraordinary.

Sit.

[Gyllenhaal] Despite a huge language barrier,

they figured out how to talk to us.

-Speak. -[barks]

See? He's trying to communicate right then and there. He wants a treat.

I talk with him and he...

does what I ask him to. Basically, that's how it is.

It's easy to pick up on the body language

after, you know, you've spent so much time with them raising them.

Tell me? What do you want? Thank you.

So, we have a system here

where if he wants something, he will definitely let me know.

They tend to have, like, little behaviors

that'll, like, indicate what they want or what they're trying to say.

But I don't know. It's not always right.

[Gyllenhaal] Dogs can communicate dozens of feelings and desires.

But here are the basics.

There are some things you can learn from the dog's barks.

The first is whether the bark is high in pitch.

[high-pitched bark]

[Gyllenhaal] That's a happy, happy dog.

Or low in pitch.

[low-pitched bark]

[Gyllenhaal] A guarded dog.

The next thing, are there a lot of them? [barks twice quickly]

[Gyllenhaal] Meaning "I'm stressed or excited."

Or are there few of them?

[barks quietly]

[Gyllenhaal] "This is mildly interesting."

The pattern of the barks is also important.

[barking]

That bark is basically the "call the pack" bark.

It means "Come over here and check this out."

[Gyllenhaal] But remember, dogs descend from wolves,

and if they spotted a deer and alerted their pack by barking...

They've lost their lunch.

So dogs have, in fact, developed wonderful body language skills.

The dog's tail serves as an emotional thermometer,

which a dog uses to tell you how he's feeling.

Is it high or is it low?

How is it wagging, okay? Fast or slow?

[Gyllenhaal] You can also read a lot of information in the ears.

[Coren] Aggressive.

Submissive.

Relaxed.

[Gyllenhaal] Humans are okay at picking up these signals,

but our relationship works because dogs are extremely good at reading us.

The dog's ability to smell plays a big part in that.

They are really wired to take in the world through odor and through their noses.

[Gyllenhaal] When they inhale, the air doesn't just go to their lungs.

Some of it splits off into a chamber specifically for odor detection.

It allows them to run and smell at the same time,

which we're not very good at.

[Gyllenhaal] Depending on the breed, a dog's sense of smell is around 10,000

to 100,000 times better than ours.

And when they're on a walk, they're always on the lookout

for the scent of another dog's pee.

Or, as Dr. Otto would call it...

"Pee-mail." So, when every dog pees on the post,

the dog gets all that information about who was here, what they felt like.

[Gyllenhaal] Dog pee is like human Facebook.

They can learn about another dog's age, sex,

mood, availability for mating.

And if they've ever met before.

This world that we experience has these extra layers

that our dogs experience and we just don't know about.

[Gyllenhaal] When you walk through this room, you might notice:

"That house plant needs a little watering."

"Looks like my husband spent the afternoon on the couch."

"And now he's baking. What is that? Chocolate chip cookies?"

"Seems like he's having a pretty chill day."

But a dog walking through that same space might see things a little differently.

"That plant has a disease."

"There are bed bugs in that sofa."

"Mom has her period."

"Dad is making something with eggs, vanilla extract, and flour."

"Also, he's having a low-level anxiety attack."

Dogs can detect all kinds of things we're feeling.

Which may explain in part why they're such effective service animals.

Everything in her world was just so overwhelming and so frustrating.

And not being able to speak, not being able to articulate

what she needed, what she wanted, what she was overstimulated by,

she lived in a constant state of frustration.

[Gyllenhaal] The Clarkes have five children

and two of them, Meadow and her brother Colton,

are on the autism spectrum.

[Maria] With Meadow, the hardest part with her was

she battled a lot with self-injurious behaviors.

Banging her head, trying to break windows in our home,

slamming chairs.

Anything that you can...

She could get her hands on, pretty much.

[Maria] She was a pretty violent little kiddo.

Basically, all the medical professionals wanted to do was to put her away.

We had one doctor just tell us

it would be easier for us to just sign away our rights

and put her into foster care, and move on with our lives.

[Joe] All right, come on. Let's go. Come on, Coco.

Let's do one, come on.

[Gyllenhaal] The Clarkes learned about a new intervention

that had worked for other children with autism.

A service dog.

[Maria] They're considered mobility support dogs.

Colton and Meadow might just close their eyes

because the world around them is just too much.

Ollie will just navigate him through his environment.

[Gyllenhaal] And they did more than that.

[Maria] When the kids are feeling overwhelmed, the dogs will nudge them...

I love you, Ollie.

[Maria] ...cue the kids to sit down,

and they'll lick their hands, and just help them calm down.

Mwah!

The transformation that Meadow made

as soon as she got Una was instantaneous.

She stopped hitting herself right away.

[Gyllenhaal] It was as if Una didn't just sense how Meadow was feeling,

but really understood it.

[Maria] Good girl, Una.

[Gyllenhaal] The kids felt less alone.

I feel like, as a mom, you're supposed to be the one that knows it all.

And with our children, it's really hard.

You never know what's too much, what's not enough.

Their dogs know

just when to come in for a kiss and when to back away.

They know just when a touch is too much and when it's not enough.

-[Colton] Good job! -They seem to always get it right.

Come on. Grab your handle.

[Gyllenhaal] And a recent study offers a new clue as to why dogs

seem so emotionally attuned to us.

A team of researchers had volunteers watch clips

designed to make them feel things.

Like the scariest part of The Shining...

-Here's Johnny! -[screaming]

...and this infectiously joyful scene from The Jungle Book...

♪ The simple bare necessities ♪

...while collecting their sweat.

The sweat was then presented to dogs, who were hooked up to heart monitors.

This is a tube of fearful sweat,

and this is a typical reaction.

The dog's heart rate speeds up, and it scampers away to a corner.

And this dog is smelling happy sweat.

It starts wagging its tail and jumps, as if it wants to play.

The pups seem to mirror the emotions the volunteers had felt.

When people do that, really feeling what someone else feels,

we call that empathy.

You have to have your head to the camera, not your butt.

Come on. Sit back down.

Good girl. There we are. Good girl.

Okay, we're back.

So, in psychology, we're often nervous about giving animals human qualities,

and I have been a stern critic of that myself.

The personal turning point for me was bringing Xephos into our lives...

Hello, sweetie.

...and realizing that there was something quite remarkable about this animal.

And it wasn't her intelligence, but it was her amazing capacity for affection.

The scientific turning point for me came in pieces.

[Gyllenhaal] One of the first came in 2016.

I got hot dogs here for you. Excellent.

[Wynne] There's a scientist, Gregory Berns, who has trained dogs

to lie perfectly still in MRI scanners.

And so now you have the capacity

to do these fantastically rich, detailed images

of the activity in the brain of a dog, which had never been tried before.

[woman] All the way. There you go. Good girl.

[Gyllenhaal] Once in the MRI, Berns' team gave the dogs this signal, which meant...

[Wynne] A piece of sausage is on its way.

[Gyllenhaal] And another signal, which meant...

[Wynne] Your beloved human is just round the corner

and is gonna appear in just a moment.

Great job, Zoe. Good job!

[Gyllenhaal] In most cases, the dog's reward center lit up the same amount.

And one in five dogs...

[Wynne] Find the expectation of their human

even more rewarding than the expectation of a piece of sausage.

So you do love me. [chuckles]

[Gyllenhaal] Most dog owners would hope so.

Uh, yeah. He loves me.

And I love him.

I know they do. Absolutely.

They love me every time I see them.

Not all humans love me every time they see me.

Yes, my dog loves me.

I do believe my dog loves me.

He'd better love me. [laughs]

How do you define love?

[Gyllenhaal] We can't define love.

That's why it's inspired great poetry

and the coolest '80s music videos.

♪ What is love? ♪

♪ Tell me is it really love? ♪

♪ Is this love? ♪

♪ I wanna know what love is ♪

[Gyllenhaal] But if you were to define love and make a checklist,

liking someone more than a hot dog

would be kind of a bare minimum requirement.

And empathy, which we know dogs have,

would probably be on there, too.

When you love someone, you do things for them,

and dogs obviously do that.

And loyalty?

Dogs check that box, too.

But love is something more than that.

It's this deep feeling of connection

that makes the rest of the world feel less important.

And in 2015,

researchers actually tested whether dogs could feel that,

by measuring their levels of oxytocin,

which is known as the love hormone

because it spikes in parents and their babies when they hold them.

And in newly enamored couples.

[Wynne] They brought people with their dogs into the laboratory,

and they just had the person sit down and look their dog in the eye.

[Gyllenhaal] And it turned out the levels of oxytocin go up

in both sides of the partnership.

[Wynne] The love is embodied in the hormones in their bodies.

[Gyllenhaal] Researchers called this

an interspecies oxytocin-mediated positive loop.

In science,

we feel this compulsion to have a technical vocabulary.

[Gyllenhaal] But we might as well call it love.

One of my really good colleagues, Dr. Bridgett vonHoldt

at Princeton University,

is one of the leading experts

when it comes to all things canid genome.

[Gyllenhaal] She wanted to see what really made wolves and dogs different

at the most fundamental level,

and one gene, linked to openness, jumped out.

That's why dogs have performed so many heroic feats,

rescuing us from rubble,

and running ahead of us into open fire.

And that ancient selection process that made dogs friendlier and cuter

coded an openness for love into their DNA.

And that's their superpower.

You can train rats to do the exact same work.

That can be done, has been done.

But when you actually want people to use those animals

to go out and find explosives, find drugs,

the dog is just a thousand times easier to work with

'cause the dog really wants to be there helping you.

I got married last week, so I'm really thinking about love a lot.

[laughs]

You have to love yourself before you can love other people.

And what I find, though,

is that before I learned to love myself quite so much, my dog still loved me.

-Franklin tiger. -Franklin tiger.

[Maria] Our dogs don't care how loud they scream

or how bad their day has been.

They-- They love them, too.

[Gyllenhaal] Archaeologists have found an over 14,000-year-old grave

where two dogs were buried with a couple.

And another 12,000-year-old grave

where a woman was buried with her hand resting on a puppy.

[Wynne] There's a book by an ancient Greek called Arrian

from a little bit less than 2,000 years ago.

And in there he talks about

how much he loved his dog.

These are pretty much the first books that humans wrote about anything,

and they're writing about how much they love their dogs

and how much their dog loves them.

[Gyllenhaal] Dogs evolved and prospered because we took care of them,

but the comfort and connection they gave us

may have been important for our survival as well.

[Schell] I would say all of that evidence

does, in fact, say, "Yeah. Deja loves us and we love her."

[Wynne] Everything that any other living being

might do, might show,

in their behavior and in their biology, and in their brains,

your dog shows all of those things.

So, if you can be convinced that any other living being loves you,

then you've gotta be convinced that your dog loves you.

Don't you, sweetie?

[closing theme music playing]