Cats and dogs.
Across the UK, we own around 18 million of them.
That's one for every two households in the country.
No other animals come close in our affections.
In this series, we'll reveal how these four-legged furballs
became the nation's best-loved pets.
Are they living with us because we feed them or because they love us?
We'll see how the latest scientific discoveries are shedding new light
on our obsession with these extraordinary creatures.
DOG BARKS
This time, we're investigating humanity's most loyal companion.
The dog.
Sit.
I love my dog more than words can say.
I would dive in front of traffic for her.
I would do anything for her.
Today, dog science is undergoing a revolution.
Genetics is revealing the evolutionary tricks
that transformed wild beasts... WOLF GROWLS
..into perfect pets.
COMPUTER BEEPS
Ground-breaking experiments are getting to the roots
of a dog's intelligence.
He's actually reading.
And technology is quite literally making it possible
to read their minds.
Many now think we're on the cusp of answering the biggest questions
about the relationship between humans and dogs.
I feel that we've cracked the puzzle of domestication.
In America, a four-legged friend is providing a new pathway
for human rehabilitation.
Meet Max.
He's part of a ground-breaking programme.
It uses dogs to try and transform the behaviour
of antisocial and violent individuals.
Are you ready to go in?
Max will ultimately be a service dog...
..but much of his training takes place behind bars
at this prison facility in California.
He'll be in the care of long-term inmates
convicted of serious crime, from armed robbery to murder.
Many are repeat offenders, resistant to reform.
Some, like Gerry Castillo,
arrived in prison facing deep-rooted psychological challenges.
Hi. How are you? Good. How are you?
Good.
I was spending a lot of time by myself.
I had issues of, say...
..low self-esteem, you know, low confidence.
I was antisocial.
The prison environment only seems to make these problems worse.
It's a place where you don't have feelings. Everything is shut off.
People don't talk about emotions unless it's anger.
Statistically, over half of all prisoners in the US
will reoffend on release.
So some prisons seek ways to reverse that trend.
In this facility, that means dogs.
One wing has been transformed into a virtual kennel club.
The prisoners here are each responsible for a dog.
Man and animal live together 24/7.
I've got to get up in the mornings and feed him and train him
and take him out to potty and just care for him the whole day.
Even if I'm having a bad day.
Max's time inside will transform him into an elite service dog.
Dave, watch the position.
Just keep going. Circle.
But it's the transformation in the inmates
that seasoned prison staff find most remarkable.
Leave your dog on a sit, stay.
It's amazing.
Max, here.
It has changed so many of them.
Good boy.
It's wonderful to see the caring attitude that goes to it,
the gentleness that's put forth for the dogs.
You wouldn't expect to see that on the streets.
I see it here first-hand and it's amazing.
You know, he makes my day.
We bonded. He knows me better than me.
I want you guys to sit down first
and lure them over your legs.
By getting a dog, it's like I'm back with a family member.
I can actually interact with somebody
and share my feelings with somebody.
You can hug your dog.
Max has lifted my self-esteem,
given me a purpose
to...to do things...
..for someone else.
They should be nice and calm.
There is now mounting evidence that, even with these hardened convicts,
a relationship with a dog can change their whole outlook on life.
Good.
Since this programme has started, I've had six inmates
who have left on parole and they have not come back,
they have not hurt anybody else,
they're still maintaining their lives on the outside.
Let's do another nice little jog.
This programme taught them that there's more to life
than just themselves and being selfish.
These programmes are demonstrating the power of connection
between humans and dogs.
Our relationship from a species to species level
just seems to be so amazing and enmeshed.
Some may ask, how did humans ever come to find an animal
that seems perfectly fit for us?
How did they ever come to exist?
The answer to this canine mystery lies in the distant past
with an animal not famed for its friendliness.
WOLVES HOWL
The wolf.
WOLF HOWLS
Folklore is filled with tales of these intimidating predators.
Even today, a wolf's eerie howl can freeze the blood.
WOLF HOWLS
Yet genetic research has revealed that all dogs
originally evolved from the grey wolf.
An animal that has roamed across the northern hemisphere
for at least 300,000 years.
The grey wolf may look like a modern dog,
but it's a very different creature.
An apex predator...
WOLF GROWLS
..with a bone-splintering bite.
So how did that...
TOY SQUEAKS
..turn into this?
At the Royal Belgian Institute of Natural Sciences,
palaeoarchaeologist Mietje Germonpre oversees a collection
of Ice Age wolf bones.
So I have here a skull of a typical wild wolf.
So it's a big skull, it's from a big animal,
and what is very special is this long elongated snout.
Now I will show you a skull of a modern dog.
So you see immediately that the snout is much shorter and wider.
The relative proportions of the skulls of wolves and dogs
are markedly different.
But, in 2008, Mietje made an intriguing discovery.
She was studying a 30,000-year-old wolf skull,
named after the Goyet Cave in Belgium
from where it had been excavated in the 19th century.
And, at that time, the discoverers thought it was the skull of a wolf,
but I was not very happy with that because it looked different to me.
Mietje's careful measurements backed up her hunch.
This was no ordinary wolf.
The skull is clearly smaller than the skull of wild wolves,
the snout is wider and shorter -
more comparable to the skull of modern dogs.
The shape of the skull seemed halfway between a wolf
and a modern dog.
A kind of proto dog.
The Goyet skull was not unique.
Hunting through other European collections,
Mietje uncovered other dog-like wolf skulls,
also around 30,000 years old.
Could these strange-shaped European wolves
be the ancestors of modern dogs?
Bones alone can't answer that question.
Scientists would need a much more precise tool.
Oxford University is home to the Palaeo-Barn DNA Laboratory.
Greger Larson is the lead researcher.
We are trying to establish a pattern through time and space
of the different genetic signatures that dog populations
and wolf populations have had across the world
over the last 20 to 30,000 years.
Thanks to recent advances in ancient DNA technology,
examinations can now be conducted on prehistoric bone...
..allowing them to compare Mietje's 30,000-year-old specimens
to modern dog DNA.
If dog domestication took place 30,000 years ago
and there was an unbroken line between those dogs and the dogs
that we currently have sleeping on our sofas, then you would expect
that the genetics of those dogs 30,000 years ago
would match the modern populations,
but the limited genetic information that we have
from the canids that would be dogs from 30,000 years ago
doesn't match modern dogs at all.
Mietje's potential 30,000-year-old European proto dogs
appear to have left no descendants.
But Gregor's team also tested samples from nearly a hundred
other prehistoric canids...
..and in this data, they have found the earliest known ancestors
of the modern dog.
Between 12 and 15 or 16,000 years ago,
we do find specimens that are starting to possess
genetic signatures that match those that we find in modern populations.
But it isn't as simple as a single ancestral line.
They found several spread across Eurasia.
So it looks like, within dogs,
we have three geographically partitioned populations
that are differentiated genetically and geographically.
The three ancestral dog populations and Mietje's extinct proto dog
do, however, share one thing in common.
Something that gives a clue to how dogs appeared in the first place.
They were all found at sites associated with another creature.
Humans.
Archaeological evidence shows that, 40,000 years ago,
modern humans began moving into northern Eurasia.
And, apparently, initiating a transformation
in the wolves they encountered.
Really, something was going on there.
Once modern humans arrived in Europe,
we see that the wolf remains start to change.
WOLVES HOWL
The evidence suggests dog-like wolves may have appeared
several times over the thousands of years since people arrived,
always in places where wolves and humans shared hunting grounds.
The formation of a close relationship between people
and wolves led to dogs, because that's what dogs are -
they are an emergent property of a very close relationship
between wolf populations and human populations.
But how did it happen?
How does a wild animal become a domesticated pet?
The answer may be found not with lifeless bones, but with the help
of one of the wolf's distant living canid relatives.
The fox.
Almost 2,000 miles east of Moscow...
..lies the location of one of the longest-running
and most well-known genetics experiments in the world.
Russian scientists have been breeding foxes here
for more than 60 years.
Their aim has been to better understand
the effect of human contact on wild animals.
The foxes are caged, but enjoy international standards of care.
Today, they're being inspected by scientists Anastasiya Kharlamova
and Daria Shepeleva.
The experiment is based around a simple measure of human toleration.
Each untamed silver fox undergoes the same test.
The test reveals the strength
of each fox's adrenal fight or flight response.
The level of reaction depends on the size
of the individual animal's adrenal gland.
Within a population, there is always a range of responses.
Once a year, those foxes with the most extreme personalities
are bred to seed new populations.
FOX SNARLS
The Russians found that, within just ten generations,
they could induce dramatic changes.
This shed contains foxes bred for intolerance to humans.
FOX GROWLS
FOX SNARLS
The experimenters have discovered they can create animals
that are extremely antisocial.
But they have also discovered that if you breed foxes
for tolerance to humans, something quite remarkable happens.
Antisocial reactions are largely absent.
They have become as relaxed in human company as a household pet.
They even wag their tails.
Something no wild fox would naturally do.
The experiment suggests that, by selecting for human toleration,
in just a few generations, a wild animal can be made to behave
just like a domestic pet.
But there have been other surprising changes.
Some foxes even develop curly tails.
Curly tails and white patches are both often seen
in other domesticated animals.
What's great about that experiment is that what it demonstrates
is that, by a continued very strong selection for a behavioural trait,
that you can then get an increase in frequency of a wide range
of other traits that were not being selected for at all.
What that suggests is that there's a lot of linkages between
the overall shape and size and way in which the animal is put together
from an anatomical perspective and the way that it behaves.
Some scientists believe genetic data from the fox experiment
indicates that this combination of behavioural and physical changes
are part of a domestication syndrome...
..probably caused by a genetic mutation
that reduces the effect of special neural crest cells.
During development, these multi-purpose cells
control the ultimate size of the adrenal gland,
determining how friendly the animal will tend to be.
But the same cells also affect the size of the face and legs,
rigidity of the ears and tail
and the extent of colour in the coat.
Select for friendliness,
and it appears many other qualities may be affected as well.
The methodology of the Russian experiment
has been challenged recently.
However, it remains widely accepted that selection for behaviour
can rapidly domesticate a wild animal.
But in the journey from wolf to dog, who made that selection?
Most scientists now believe it was the wolves themselves.
Wolves are extraordinarily adaptable.
Different packs specialise in hunting different types of prey.
It's thought that when humans first arrived in Eurasia,
some packs may have adopted a novel survival strategy.
It's not crazy to think that there may have been a population of wolves
that found themselves attracted to people and started following people
in the same way that other wolf populations
have started following caribou.
Rather than hunting, these wolves would thrive
by scavenging close to human encampments.
But only the boldest would hang around for long.
These adventurous wolves would breed with each other
and, over generations,
evolve into an increasingly human-tolerant subspecies -
the domestic dog.
Survival of the fittest
turned out to be survival of the friendliest.
Over the last 15,000 years,
dogs have turned up in all shapes and sizes.
At this show in North Carolina, there are dogs of every sort.
My favourite breed would be the French Bulldogs.
They're just super funny, different than other breeds.
My favourite breed of dog is the Anatolian Shepherd dog.
She's killed three coyotes, numerous fox and bobcats.
She wants to get that fly over there at the moment.
Chacha's got a great personality but it also is the poodle.
They're very... They feel what you feel.
What I like about the Rottweiler is their brain.
They are very motivated to work, to do whatever I ask.
How beautiful.
Wow.
Veterinarian Debbye Turner is fascinated by this variety.
Look at that!
That's the occupational hazard. Yeah.
Domesticated dogs have been around for thousands of years
and they all come from their wolf ancestor.
And, when you think about that, that's just absolutely incredible
that a big old, erm, Irish Wolfhound
comes from the same ancestor
that a little tiny Maltese comes from.
So what was the first dog, the ancestor of all these animals, like?
To find out, geneticists have been decoding the dog family tree.
Their results show that some lineages split away
more than 5,000 years ago,
creating descendants who, today, may reflect
the appearance of the original dogs.
The Japanese Akita is one of these ancient breeds.
These dogs separated from the genetic line very early on.
They're called a Spitz type dog,
which means they retain many of the characteristics,
the physical characteristics, of their wolf ancestors,
so they have a wedge-shaped head,
they've got these pointy pricked ears,
they have a double coat
and the curled tail over their backs.
Sharing the same curly tail trait is the African Basenji.
Basenji is the grandad of ancient dogs.
However, they're not that trainable.
They will not do obedience tricks like other breeds.
Come back here.
And here's an example! He wants the cookie on the table.
There's something else very wolf-like about a Basenji.
BASENJIS HOWL
Its yodel.
These breeds reveal much about how dogs may have appeared and acted
after their first transition from pack hunters to scavengers...
BASENJI HOWLS
..and provide clues as to why they first appealed to humans.
You won't see Basenjies doing tricks,
but, because of their closeness to their wolf ancestors,
they are considered very adept hunters.
As dogs were evolving from wolves into truly domesticated dogs,
their traits begin to change.
They were smaller, their snout length changed,
the strength of the muscles that support the jaw changed,
even the strength and size of their teeth,
so they lost the ability to take down big prey.
But they didn't lose everything. Dogs are still the standard bearers
when it comes to detecting things with their nose.
A dog's nose contains 50 times as many olfactory sensors
as a human nose...
..giving them a sense of smell 100,000 times more acute.
Combined with sharp sight and hearing,
superb stamina and a docile temperament...
..for humans, they were a ready-built hunting companion.
The reason why the relationship between dogs and humans
in a hunting situation is so perfect
is because they complement one another.
The dogs are the chasers, the humans are the finishers.
15,000 years ago, the first working partnerships were formed.
Over the following millennia, humans would breed dogs
to take advantage of their useful wolf-like abilities.
But there are signs that, even early on, humans were starting
to influence the appearance of the dogs around them.
Animal behaviourist Juliane Kominski recently made a comparative study
of the faces of dogs and wolves.
We were interested to see whether there's anything
about dogs' expressions or communication that is in some ways
unique and specially adapted to life with humans.
To their surprise, they discovered that dogs possessed
a whole new muscle grouping not present in wolves.
So, the muscle that we are so interested in and excited about
is somewhere here above the eye,
and what it does is it pulls the inner eyebrow upwards.
What's so advantageous about this movement?
The answer could be that it attracted human attention.
So it makes the eyes of a dog appear larger,
potentially more infant-like, so more appealing to humans.
We have a natural tendency to look after anything
that looks infant-like.
But it also resembles a movement
that humans produce when we are sad.
So, again, potentially appealing to humans
in that it makes us feel sorry for the dog
and we want to attend to the dog
and kind of triggers this nurturing response.
This eyebrow muscle evolution implies that a good relationship
with humans may have played a key role in survival
for prehistoric dogs.
Dogs that produce that movement more
must have had a selection advantage over other dogs.
And that's how you now see the trait -
this phenomenon in the dog population.
Expressive eyebrows are a rare early example
of human selection for looks.
But despite our long shared history, evidence reveals that it was not
until very recently that a dog's looks truly began to matter to us.
Genetic studies indicate that a sudden explosion of diversity
in shape and size can be traced to a breeding craze
that began in Europe just a few hundred years ago.
The very first kennel club was established in 1873 in England
and it is from there that we get the vast majority of the varieties
and the breeds that we see today.
Kennel clubs were breeding organisations
originally meant to preserve local dog characteristics.
But members began to select and share dogs with extreme traits
to an extent never attempted before.
Geneticists have discovered that, as a result of this intensive breeding,
the look of Western dogs has become controlled
by just a handful of extremely potent genes.
In a human, over 100 genes will determine a few inches' difference
in a person's height.
But, in a dog, just seven super-selected genes now control
the size difference between the smallest and the largest.
In nearly all breeds, just one gene is responsible for short legs...
..and mutations in just three genes are responsible
for the majority of coat types, from smooth
to long-haired...
..to whatever this is.
DOG BARKS
So, most dogs today look the way they do
because of intensive human breeding for novelty.
But people still value dogs for far more than just their looks...
..and that's because of what humans can do with them.
For thousands of years, the dog's natural instincts were exploited
to help humans hunt, herd and protect.
DOGS BARK
But, in the last century, their roles have multiplied.
Dogs are amazing. We can train them to do a variety of tasks.
So, from very simple ones that amuse us
to very useful things.
Trained dogs are already a huge benefit to society.
But, in Atlanta, some researchers are now taking them
to the next level.
All right.
In a lab at Georgia Tech University, a team is combining dogs
with technology to create the perfect service dog.
He does love it.
Wait a minute.
Melody Jackson runs the FIDO Project.
FIDO stands for
facilitating interactions for dogs with occupations
and our entire mission is to help dogs
communicate more clearly with their handlers.
Sit.
Wait. Good boy.
The FIDO team are experimenting with how well dogs
can operate technology.
OK.
All right.
There you go. Good boy. Good job.
The thing we're testing here is, can he understand the correlation
between something he's doing here
and something that's happening over there?
So, we kind of started this as a fun little project to see,
can a dog drive a robot?
All right.
Clearly they can.
I'm sorry, this is hilarious. He's just putting his foot on there.
He's learned that if he just holds it down, it keeps the robot going.
LAUGHTER
He just loves it. "Did I do it? Did I do it?"
He's just having a great time.
OK, you ready to do a little training?
By training them to be tech savvy,
they're hoping to open a route to better communication
between dog an owner.
Good girl. That's it. Yes.
What if that dog could actually call emergency services?
Could call 911 with your GPS location
to let someone know you're having a seizure and you need medical help?
Go get help.
Yes. Very good.
They're pinning their hopes on wearable technologies.
These have signalling systems operated by the dogs themselves.
So what can dogs naturally do as puppies?
They can tug on things, they can touch things with their noses,
they can bite things,
and so we based our sensors on those abilities.
So, we've taken natural behaviours and we've turned them
into something that's useful to humans.
This is a vest that was made specifically for Laser
because he has giant ears.
So, it has a sensor on it called a capacitive sensor,
and this works just like the cellphone does.
Whenever you touch it with something that has water in it,
like your finger or a dog's nose,
it activates this little sensor here.
So, this vest is programmed
to have a speaker speak a phrase.
So, this would be, if I was unconscious, he would go and find
the nearest person and then speak this phrase
and then have the person come back to help me.
Go. Get help.
Laser, go get help. There. Get help, buddy. Get help.
Come on, buddy.
Good job, bud. Good job.
You are the best boy. You are the best boy, helping your momma.
Ultimately, the vests will allow owners to offer choices
or express opinions.
So this is called a discrimination vest
because it has two sensors on it.
This could represent two different sounds, two different phrases
that we want the dog to speak, and it allows the dog to select
the appropriate phrase for whatever the situation is
that the dog is trying to help in.
Get it.
Beautiful.
Get it.
Good job, buddy.
None of this would work without the dog's amazing brain.
Let's work on shaping that left one more. It seems to be easier.
Well, we have been thrilled
with our experiments with wearable technology
because they learned it much faster than we expected.
Get it.
Yes.
The longest it took for any of the dogs
to learn any of the sensors was 27 minutes.
You're not going to have a cat at an airport sniffing out drugs
or a horse telling you that you're about to have a seizure,
but dogs are able to do this in a way that vastly supersedes
any other animal, and I think that's what makes them special.
So, what is the source of a dog's amazing ability to learn?
Animal behaviourist Clive Wynne
is obsessed with understanding what's going on in a dog's head.
Most psychologists study the minds of people,
I became fascinated in the minds of everything except people,
and so I became very interested with dogs
and very, very quickly
I became totally, totally grabbed
by this amazing animal.
They're absolutely fascinating.
Their minds, their intellect, their cognition.
Zaph.
Go.
Good girl.
For many years, scientists have believed that dogs are great
learners because they possess an almost unique intelligence.
One key proof was their skill at the pointing test.
OK, Zaph.
Oh, what a clever doggy.
What a clever doggy. Well done.
Most pet dogs, most of the time, will follow a human point.
It seems quite undramatic to ask, because we're used to it,
but, actually, it turns out that not very many animals will do this.
Even our closest primate cousin, the chimpanzee,
struggles with this test.
But is exceptional brain power really what makes a dog so special?
Maybe the answer lies in the minds of their ancestors.
WOLVES HOWL
In the woods outside Vienna, Austria,
Friederike Range is taking her wolf for a walk.
Here at the Wolf Science Centre,
they're carrying out cutting edge research on wolf cognition.
Sit.
We're ready to go.
All of Friederike's wolves have been brought up by humans.
I've known Argon 11 years and three months.
So, I hand-raised him and his other pack mates.
Alongside its wolves, the centre raises a group of dogs,
giving both sets of animals an identical amount of human contact.
We bring up the wolves and the dogs in the same way
so they have the same experience, and this is really crucial
if you want to compare them
and compare their behaviour or cognition.
Friederike's team conduct identical intelligence tests
on their dogs and wolves.
Just get it there.
So, what we are doing here is testing co-operative abilities
in our dogs and wolves. For this, we have this table.
The food on the table can only be reached
if both ends of the rope are pulled at the same time...
..so the animal must understand that it has to co-operate
with a human partner.
This dog shows how it's done.
Waiting for the human, he executes the task perfectly.
That was nice.
But what about a wolf?
He's actually waiting.
Perfect.
For years, it was thought wolves were incapable of making
the cognitive leap necessary to work with humans.
But these experiments are proving the opposite.
And this result is not unique.
The team's work is showing wolves can be highly intelligent
in multiple ways.
I don't think that the dog is smarter than a wolf.
I think most of our studies show that actually
the wolves are much smarter.
Wolves have even been shown to match dogs at the pointing test.
So, despite appearances, hanging out with humans
did not improve the dogs' natural intelligence.
This ability is not something that developed in dogs
during the process of domestication.
It was already latent in the wolves
from which all of our dogs are descended.
Good boy.
If dogs are no more intelligent than wolves,
then why is a dog more trainable?
Some think it may be down to attitude.
For Clive, the mind-set of his pet dog Zaphos, holds a clue.
I could tell straight away that Zaphos wasn't smart.
She's not a super intelligent dog.
But there was something remarkable about her
and that was so obvious once I saw it,
this ability, this capacity, this desire,
to form strong emotional bonds.
That she's always trying to make friends,
that she's extremely loving.
And, erm, I began to wonder,
could this be the crux ability that has made dogs so successful?
To demonstrate his theory, Clive uses a simple experiment...
..called the Circle Test.
It quantifies how socially engaged an animal is.
The animal is placed in a room with a human for two minutes.
An observer totals the amount of time the animal spends
inside the circle near the person.
Paired with their owners, dogs spend more than 60% of their time
inside the circle.
Even with a stranger, dogs stay close for over half the time.
Dogs just seem to like people.
But wolves behave differently.
This is not a lab environment.
but the results from this Circle Test are still compelling.
This young woman was involved in raising this wolf,
they've known each other all the wolf's life,
and, um, nonetheless,
the wolf doesn't spend so much time inside this circle
as a dog would do.
The wolf spends even less time with its handler
than a dog would with a stranger.
The fact that the wolf doesn't want to spend as much time
inside the circle with the person shows us that the wolf
doesn't have that same intense level of social connection with people
as a dog can have.
To those who know wolves well, this is no surprise.
A dog, it can usually always get you to do what he wants.
The wolves couldn't care less.
They do it if they want to do it
and you can work very hard to convince them,
and sometimes you're successful,
but, if they don't want to, there's nothing you can do.
Dogs inherited their intelligence from their wolf ancestors.
But they have also evolved a strong desire to bond with humans
that makes them uniquely trainable.
Yes! Good girl.
Often in working dogs, what makes them good is the partnership.
Good girl.
That dog and that human that it cares about -
they're the unit.
The unit is the person and the dog together.
Come here.
That's my girl. I love you, too.
A dog's attraction to humans clearly evolved during domestication.
But is this genuine affection?
Or are they just in it for the food?
High five.
I think Skye cares for me like I do for him,
but I do worry that he just thinks I'm some guy
who's obsessed with him that makes him...drags him around the park.
Do you love me, Bee? Bee?
I think she does love me.
Well, I love her enough for the both of us.
Gauging a dog's true emotions is a challenge.
We can't ask them.
But could we read their minds?
Back in Atlanta, another experiment is under way.
Cailin is visiting Emory University.
Come on. Good girl. All right.
Good morning. Hey.
Hey, Cailin. Good to see you.
She's part of a special project run by Dr Gregory Berns.
I know. OK.
Are we going to do some work today?
He's attempting to resolve the biggest question about dogs.
Ear plugs in.
The party line would say that dogs, in some way, are scam artists.
That, in fact, the only reason that they live with us
is because we feed them and because we provide shelter.
She is ready.
So, at the core of this project are the questions
are dogs living with us because we feed them
or are they living with us because they love us?
And, to me, that's all the difference in the world.
To understand just what a dog is thinking,
Berns has trained dogs to lie in a brain-imaging MRI machine.
Good girl. All right.
You know, the traditional ways to understand what dogs are thinking
is to look at their behaviour,
but the problem with that is that dogs will often
do things we don't expect.
Brain imaging gets around these problems by going directly
to the brain and, in essence, bypassing behaviour
and go directly to the organ that causes everything to happen.
Come around and stand here.
The dogs in the study are trained to relate toys
to different outcomes.
When it sees a red car, the dog learns to expect praise.
Good girl.
When it sees a blue knight, it learns to expect some sausage.
By comparing those two conditions,
the anticipation, in particular, to food versus human,
we can go in and look at the reward system of the brain
and see which one is higher or not.
Or are they equal, perhaps?
The level of pleasure the dog experiences
is determined by the amount of the neurotransmitter dopamine
the brain releases.
This is revealed on the scan by increased blood flow
to specific regions.
Good girl. Stay.
So, Lori, if you want to fade out of view and then we'll do the toys.
Gregory has conducted this experiment on numerous dogs...
..and the scans are a revelation.
So, these coloured areas represent what dog's brains do
when they're anticipating food and, actually, it isn't showing
very much happening, which means that, on average, the dogs
probably didn't care as much about the food as we thought.
But when expecting praise...
..the dopamine levels regularly go higher.
Now we actually do see quite a bit of activity.
What that speaks to is the fact that praise
is very interesting to the dogs.
That was a good job.
The brain scans show unambiguously that most dogs love praise
just as much as food, and some dogs love praise even more.
Good girl.
A dog's uniquely strong desire to bond
may be particularly beneficial to humans.
Who's a good girl?
These results show that the social bond
is as strong as the food that we're providing to dogs
and that it's intrinsically rewarding in and of itself.
And, to me, that's about as close as you can say that a dog loves you.
And dogs seem quite happy to spread the love beyond humans.
What makes dogs special
is dogs can form very strong, loving connections
to members of any other species,
never mind other members of their own species. Any other species.
Dogs appear to be not just loving,
but almost indiscriminately affectionate.
What could explain this extraordinarily powerful
emotional trait?
The answer may lie with some very special genes.
Hi.
How are you? Nice to finally meet you.
Come on in to our humble home.
Hi. Welcome.
OK, you ready to make some doughnuts?
Let's cook her up, sister. All right. You got it, girl.
16-year-old Callie Truelove lives with Williams syndrome.
It's a debilitating genetic condition
affecting one in 10,000 people.
Two-thirds cups of water.
This is gorgeous water.
We're going to whisk it, whisk...
It's caused by alterations in around 30 genes
generating multiple developmental and learning challenges.
I'm going to put them in the oven.
There ain't nothing like southern style cooking.
Hopefully we can...
But through it all, Callie radiates an incredible warmth
towards the people around her.
She just loves people.
From the time she was able to go to somebody by herself,
she's always been very friendly.
Yes, let's do it.
Ah, they're so gorgeous.
And I love each and every single human being
on this whole entire world.
If I could just hug all of them at once, I would,
cos I love them so much.
Here's what you're going to do. You're going to take a doughnut...
She absolutely does love every single person that she meets.
I've pastored a church for 20 years
and Callie has reached more people just with her everyday life
than I possibly could in a lifetime.
I think you should have this guy.
Callie's hyper-sociability is a side effect of her condition.
It's related to alterations in just three genes
that can affect personality.
Mmm. Mm-mm.
We've got a pet down here.
Surprisingly, people with Williams syndrome
may not be the only ones affected by these altered genes.
Oh, Doodle.
This is my service dog, Doodle Dandy.
And he's my heartbeat, he's my sunshine,
and I can't imagine my life without him.
Good boy.
He's helped me through a whole lot
and he's just the best dog in the whole wide world.
And I ain't ashamed to say it.
New research suggests that Callie and Doodle Dandy
share more than just a friendship.
Oh, you're so sweet.
Geneticists working with Clive have recently discovered
the same rare mutations that cause Callie's hyper-sociability
are present in the dog genome.
But they are not found in wolves...
..suggesting these rare mutations were acquired by dogs
during domestication.
What causes dogs to be so much more sociable,
so much more socially engaged and desiring loving relationships
than are wolves are due to three of the genes
that are involved in Williams syndrome.
I feel that we've cracked the puzzle of domestication.
We've identified in the genetic material what it is
that makes dogs so unique, makes them so special and so successful.
More research is still needed, but these rare mutations
may prove to be the secret source of the unshakeable bond
between our two species.
I think that's brilliant because I knew, when he was little,
he had my personality,
but I didn't know he shared the same gene almost,
so that...that is so cool.
I promise that I'm always going to be here for you no matter what,
through thick and thin.
Dogs have been on quite a journey.
WOLVES HOWL
A natural instinct to exploit their new human neighbours
led some wolves to evolve from dominant predators
to docile companions.
Humans have tinkered with them through selective breeding,
perfecting useful instinctual traits and playing with their looks.
And it seems like, somewhere along the way,
we bred in an extreme motivation to learn extraordinary skills
because we bred in the most important trait of all.
You can hug your dog.
The discovery that dogs experience love, that's why they're so perfect.
That's the thing that explains not only how dogs became
so domesticated, but it explains why they're man's best friend,
and why we've been together for 15,000 years.
We're the best duo in all of evolutionary history.
Who knows you better than your best friend?
SHE LAUGHS
Who's a good kitty?
Next time, we'll be exploring the world of cats.
Cats are brilliant.
People really underestimate the brilliance of a cat.
We'll be getting under their skin to expose the roots
of our ancient partnership...
We can really drill down and say definitively
where domestic cats come from.
..reveal details of our troubled relationship...
Their mummified cat, they gave it away,
and then their house burned down. Gosh.
..and explore the source of their uncanny powers.
These sounds are plugging straight into our emotions.
We pretend to know what they're thinking. Are we right?
Maybe not.