The Secret Life of the Dog Horizon

We have an extraordinary relationship with dogs.

We love them like no other animal on the planet.

What makes our relationship so special, is perhaps the dog's

ability to be able to read our emotions so effectively.

They've been around longer than any other pet.

There are now eight million dogs living in the UK alone.

The dogs are wonderful.

We've got over 400 breeds across the world and every one of them has something special about them.

But only now are we beginning to realise just how important that relationship could be.

New research is revealing ever more

intricate connections between human and dog.

Without that initial starting phase of dog domestication, civilisation just would not have been possible.

So why do we love an animal that was once a fearsome predator?

TRANSLATION: This fire-breathing dragon has turned into a human friend.

Could they in some ways be more intelligent than even our closest relative?

Suddenly, there were dogs doing something that not even chimps could do.

And in the future, what impact might dogs have on all our lives?

They're going to help us tackle some of the most dangerous diseases of

our time, diseases that are killing millions of people every year.

Corrie!

-Come here.

-Every owner will spend an average of £20,000 on their beloved dog in its lifetime.

-Good boy. Sit.

We treat them as if they are fellow human beings

with all the thoughts, feelings and emotions of a family member.

-Good girl.

-It's an incredibly close relationship.

We share our lives, our homes, even our beds with them.

-We're very close. We're best friends.

-Pippin sleeps with us.

He loves being in the bed with his head on the pillow.

He just seems to fit in with

-your lifestyle.

-She's there with my slippers first thing in the morning.

She's part of the family, she IS the family.

For decades, science has dismissed dogs as being unworthy of legitimate study.

But all that has changed.

Scientists are now attempting to understand dogs like never before.

How deep is the bond between us?

Where did this relationship come from? And ultimately, why is it dogs that are man's best friend?

Dogs are all over the world, they're everywhere.

Anywhere you find humans, you will almost certainly find dogs.

We're now beginning to realise that we can answer certain questions

in dogs that we can't really answer in any other species.

There's been this explosion in dog research, I think,

because they are specially tuned into humans and this makes dogs extremely interesting as a model.

Here at the University of Lincoln, Professor Daniel Mills is fascinated by dogs.

Using state-of-the-art technology, he wants to find evidence of how close our relationship really is.

What we're trying to do here is see the world from a dog's perspective rather than just impose our own

views as to how we think the dog sees the world.

He's attempting to discover if dogs are as good at reading our emotions as their owners claim.

He'll know what I'm thinking even before it's turned into a thought bubble.

He is clearly an animal, I accept that he is totally an animal.

I am not under any illusions that he isn't but he's more knowing than I would expect an animal to be.

He will look at me with sorrowful eyes and then give me one big lick on the hand as if to say it's all right.

It's this sixth sense that dogs have.

One of the things that a lot of people comment on

is that dogs seem to be naturally attuned to them and be able to sense their moods and whatever.

Part of our work here is to look into the scientific basis of that.

The key to a dog's ability to read our emotions might lie in something we all do without knowing it.

When we express our emotions in our faces, we don't do it symmetrically.

It's been shown that if you take somebody's face when they're expressing some emotion like

happiness or anger or something like that, there is a difference between the left and right side.

Composite faces consisting of two right or two left sides look very different.

One theory is maybe our emotions

are more faithfully presented in the right side of our face, and that's the side that we tune into.

When we look at a face, we have what's known as a natural

left gaze bias so you naturally look much more towards the left, ie the right-hand side of somebody's face.

Eye tracking software has demonstrated that

when presented with a human face, we nearly always look left first.

Daniel Mills wanted to find out if dogs used the same trick to read human faces.

Shifting the direction of your gaze we thought

thought was fairly unique to people until we started looking at dogs.

Tess, Tessy!

To test the theory, his team recreated this experiment with dogs.

-Bruce, what's that?

-They presented a series of images showing human faces,

dog faces and inanimate objects and recorded the direction of a dog's gaze with a video camera.

We found that dogs when they are looking at pictures of dog faces

or objects, they will look randomly on the left or the right.

But when it came to human faces, they made a remarkable discovery.

So now we have Tess looking at a human face so first she's looking in the middle of the screen.

Here is the first eye movements on the left.

She's in the middle and she's going on the left, and then the dog is going to be even more on the left.

So now this is Moose and then we can see really well that this is a left gaze.

From here to here.

We can see the white here.

She's even moving her head.

As far as we know, no other animal has this relationship with the human face.

Dogs don't do this with each other.

Incredibly, it seems they've acquired a new skill to enable them to read our emotions.

Being able to detect when somebody is angry or potentially harmful,

you could understand that there may be a biological advantage in being able to read people's emotions.

Equally, it makes sense for a dog to approach somebody when they're smiling.

If dogs can read human emotion, and increasingly the scientific evidence is beginning

to point in that direction, that's going to form the basis of a very powerful bond between human and dog.

Evidence like this appears to underpin our conviction

that dogs understand us in a way that other animals cannot.

But for many dog owners, this unique relationship is much more than a one-way street.

I like to think we understand him.

Yes, but he woofs and we talk.

That's because he wants to be part of the conversation.

If he's bored, he'll take a deep sigh and go...

SHE WHINES LIKE DOG

He's got a bark when he wants to go out and he's got a bark...

SHE WOOFS

And a bark when he hears strange noises.

Sometimes when he tells the kittens off, he goes...

like that. SHE WOOFS

If you're in a certain mindset, you can almost understand what they're thinking.

The idea that we can understand barking almost like a language has always been dismissed by scientists.

But in Hungary, they are trying to see if there's any evidence to back up the claims made by dog owners.

Here, at Eotvos Lorand University in Budapest,

is the world's first research facility dedicated to investigating the human/dog relationship.

Dr Adam Miklosi wants to see if we humans really can understand dogs' barks.

Today, he's out on a field expedition collecting recordings.

Scientists used to think that barking is a random noise without any specific information or content.

However, we have a different idea.

Dogs might tell us something about their emotions, anger, fear, happiness, despair.

These are basic emotions which I think humans might be able to recognise in the barking sound.

To test this idea, Adam and his team acted out

a number of scenarios, provoking dogs to bark in different ways.

But when the recordings are played back to people, will they be able to match the bark to the emotion?

Alone bark.

THE DOG BARKS

That sounds like a dog asking for attention.

-It's anxious.

-It's sad.

Distressed.

Want to be let off a chain or something like that.

THE DOG BARKS

-I think that one's playful.

-Excitement.

It seems as though they're actually asking their owner for something.

It sounds as if it may want a ball or a toy or something.

She could be playing with it.

THE DOG BARKS

Angry.

This is a sound that she would make if she saw somebody behind the fence walking along.

it's a stranger encroaching on territory.

The results of Miklosi's research are remarkable.

It's proved there's incredibly strong agreement between people about what different barks mean.

'Overall in the study, you could see that people can discriminate'

six barks and most of them were quite successful in this.

Dr Miklosi has developed a system to analyse the barks.

It's helped him decode how dogs communicate meaning.

I measure the three features of this sound.

One was the frequency, the other was the tonality and the third was the interval between the barking sounds.

Probably, this is also what the judgment of people is

based when they are describing the bark in terms of emotional content.

But what's more surprising is not our ability to interpret the barks, but what it reveals about dogs.

In the natural world, dogs' wild relatives don't really bark.

Amazingly, it seems that during the course of domestication, dogs may have evolved

their elaborate vocal repertoire especially to communicate with us.

'At the basic level, everyone can do it and there is a good chance that'

barking is a very good means to communicate with humans.

The evidence from these recent experiments seems to confirm what dog owners have asserted all along,

that we're incredibly attuned to each other in a way that no other two species are.

But new research has uncovered that the bond between humans and dogs may be even deeper.

Research has turned to the most powerful bond, that between mother and baby, for clues.

It's really hard to describe.

It's just an amazing feeling.

In Sweden, Professor Kerstin Uvnas-Moberg has been studying the role

of the hormone oxytocin in bonding mothers with their newborn babies.

Oxytocin is a little, little heptide hormone.

It's just nine amino acids.

It's produced in a very old part of the brain called the hypothalamus

and oxytocin helps the mother quickly establish the positive feelings and the bond to the baby.

Each time a mother breast feeds, she has a new release of oxytocin and this reinforces the bond.

It's sort of in a way

difficult to understand how you can be familiar with somebody

-who is actually a stranger so quickly, don't you think?

-Yes.

Professor Uvnas-Moberg believes oxytocin plays a similar role in the bond between dogs and their owners.

A lot of people would say, "Oh, it's not possible, dogs and humans, we're not the same.

"dogs and humans, it's very, very different."

But I would say that people who have dogs, who are used to animals and used to interaction with animals,

they would say, "Oh, that's not so strange."

To test the theory, blood samples were taken

from dogs and their owners before and during a petting session.

'We had a basal blood sample and there was nothing and then we

'had the sample taken at one minute and three minutes.'

You could see this beautiful peak of oxytocin.

'The fascinating thing is that the peak of oxytocin is similar'

to the one we see in breast feeding mothers.

Surprisingly, it's not just the owners who are affected.

Blood samples taken from dogs reveal a similar burst of oxytocin.

It is a mutual kind of interaction, you know.

The owner touches with her hands and they both smell,

hear and see each other. That is a very nice way of triggering oxytocin release in the two of them.

Oxytocin has a powerful physiological effect.

It lowers the heart rate and blood pressure, leading to reduced levels of stress.

Research indicates that owning a dog could even extend your life.

If you have a dog,

you are much less likely to have a heart attack and if you have a heart attack, you are three to four

times more likely to survive it if you have a dog than if you don't.

So where does this incredible relationship come from?

When did it start and how?

It's a question that has puzzled scientists ever since Darwin.

He recognised the special relationship we have with dogs but was at a loss to explain it.

Darwin couldn't even say for sure which animal was the true ancestor of the dog.

It's a complex puzzle that both archaeologists

and molecular geneticists have been working to solve.

There's a huge amount of variation in present-day dogs.

Consider the difference between a Pekinese and a Great Dane.

Could they really all be descended from one wild ancestor?

It could have been a coyote that might have intergressed with a wolf and then that may

have been slightly selected upon to create one particular breed of dog, or jackals or African wild dogs.

Any number of these other dog-like species that are out there

must have come together and that's where that variation must have come.

Until the advent of molecular genetics, archaeology had few firm answers.

All you have to play with are the bones and so when you look at the bones, if you don't have

a very small flat-faced round-headed pug in the archaeological record, you don't know where that came from.

Those are questions that before genetics you really couldn't answer.

To unravel the evolutionary origins of dogs, molecular

geneticists compared DNA from dogs with that of their wild relatives.

Specifically, they looked at mitochondrial DNA sequences

which are passed unchanged down the maternal line.

What's so useful for scientists is that mitochondrial DNA changes little over time

and so acts as a kind of signature left by an animal's ancestors.

Those markers in domestic dogs show them to be much more

closely related to grey wolves than they are to any other species.

There's no admixture so we never see a mitochondrial signature of

an African wild dog, jackal or coyote in a domestic dog.

Thousands upon thousands of mitochondrial DNA that has been

extracted from domestic dogs, every single one of them just looks just like a grey wolf.

It's now without doubt that dogs are domesticated wolves,

but how and when did it happen?

-Again, the archaeological record is inconclusive.

-What is clearly a dog?

Clearly, a dog is something which is clearly not a wolf.

Well, here's a wolf skull and as you can see it's a long, quite low skull with a relatively flat top.

The teeth are quite large and the thing is quite narrow.

Compare that with a domestic dog.

This is a cairn terrier and as you can see,

the process of domestication has gone really quite a long way.

The whole face is very much shorter, it's been contracted towards the brain case.

The brain case itself has a much steeper front and a much more bowed upper surface.

If you found that, you would be in no doubt you were dealing with a domestic dog.

But this is a domestic Alsatian and telling these apart really would be substantially difficult.

And since early dogs were probably very wolf-like, it's hard to pinpoint

when domestication happened by looking at the shape of the bones.

The best I can give you is around 12 or 13,000 years ago.

We start seeing the first things that everybody would accept as being domestic dogs.

But mitochondrial DNA offered a different set of clues.

The original genetic data that were coming out seemed to suggest that domestication was happening on

a far earlier timescale than was suggested by anything in the archaeological record.

The first dates that were coming out were on the order of 100,000

years or more, which a lot of archaeologists raised their eyebrows at.

It's hotly debated exactly when dogs were domesticated,

but there's one thing archaeologists and geneticists agree on:

our relationship with dogs goes back thousands of years further than with any other pet.

It was a time when we were still hunter-gatherers.

Dogs were certainly the first animal to be domesticated, and they fit into hunting and

gathering societies probably better than any other species out there.

At this stage when we're hunting and gathering and killing wild animals,

after you finish with them you're creating a relatively large pile

of bone and leftover meat, things that these wolves would have been very attracted to.

Those wolves that were able to take advantage of that resource, and were a little bit less afraid and could

approach the human camp, were then setting themselves up into a closer relationship with humans.

We are carnivores,

we are social carnivores, we hunt in groups and we hunt in daylight.

There are not many other species that do that.

The wolf is a social carnivore that hunts by daylight, and therefore,

there's natural potential for teamwork between those two species.

We became much better hunters with dogs.

We are more successfully taking down large game, which means we have more food to eat, which means we can have

more offspring, which means the overall populations of humans grow.

Dog domestication may have helped pave the way for a fundamental change in human lifestyle.

It's hard to see how early herders would have moved and protected

and guarded their flocks without domestic dogs being in place.

And one has to wonder whether agriculture would ever really have

made it as a viable alternative to hunting and gathering.

Some believe that the influence of dogs on our development was not just important, but pivotal.

Dogs absolutely turn the tables.

Without dogs, humans would still be hunter gatherers.

And without that initial starting phase of dog domestication,

civilisation would not have been possible.

We look at our dogs and we see an intelligence,

an ability to interact with us unlike any other domesticated animal.

But are dogs really that clever, or are they just dumb animals taught

to perform tricks that mimic human behaviour?

I think she's very smart. She learns tricks fairly quickly.

If I am packing a suitcase, they will go and sit in

the suitcase because they know that suitcase is going to go somewhere.

When I'm talking to him most of the time,

his little head usually jilts to the side as if he knows what I'm saying.

I do talk to her and she picks up on what I say to her.

I know it sounds stupid, but I do have a conversation with my dog.

But how does the intelligence of a dog really compare in the animal kingdom?

New research is discovering that in certain ways, dogs may actually think

more like us than any other animal, including our nearest relative, the chimpanzee.

Of all the questions around the evolution of human cognition,

of course, people would focus in on chimps quite naturally.

Suddenly, there were dogs doing something not even chimps could do.

Cognitive psychologist Juliane Kaminski from

the Max Planck Institute in Germany, has been comparing chimps with dogs in a series of revealing experiments.

At Leipzig Zoo, Juliane is testing chimps to see if they can understand

human gestures, like pointing, to find a hidden treat.

As simple as it seems to us, even our nearest primate relatives failed the task miserably.

She's not really focusing on me and she's simply making her own choice.

Most of the time you can see that she makes a decision long before I give my gesture.

She doesn't even wait for my information.

It's such an uncooperative attraction, so it's like really I'm providing information for her to

find food, which is just simply something which would never happen in a chimp group, really.

A chimp wouldn't go like, "Oh, look there's the banana",

and then another chimp could go and get it.

Since we're the only species that makes this gesture,

it would be remarkable if any animal could understand it.

But dog owners take it for granted that their dogs respond to pointing.

Good boy!

For Kaminski, it's proof of their extraordinary social intelligence.

If you really look at that gesture, it's an informative gesture.

So it's in its essence a very cooperative

interaction, so I'm really helping you to find something.

And for dogs, following, pointing seems to be very natural, and it makes dogs extremely interesting.

In fact, dogs are so tuned into our social cues,

they can even pick up on something as subtle as the direction of our gaze.

Humans have unique almond-shaped eyes with exposed white sclera visible on each side.

One hypothesis is that we have evolved those eyes because we use it for communication.

With human eyes you can really tell easily which direction I'm looking.

We think that maybe dogs are really tuned into that,

and really are interested in human eyes because of that.

But these aren't skills that dogs use with each other.

They are abilities dogs only use with humans.

I think it's very, very easy to imagine that they develop special skills in

interacting with humans, because that's their new social partner.

So they kind of learn to interpret human communication, which is different from dog communication.

So they kind of learned a second language, so you could probably say they are bilingual, yes.

Even puppies as young as six weeks old seem to intelligently respond to human gestures.

At least some of the time!

The fact they're quite young puppies can do something,

if they learn it, they learn it very quickly, and it's obviously that

they are ready to do it - so from the very beginning they are ready to receive human communication.

As dog owners, we think we understand the limits of our dogs' intelligence.

But now some dogs are challenging our assumptions.

We may have to reconsider how clever dogs are.

Juliane Kaminski has discovered a remarkable dog living in Austria, just outside Vienna.

She's conducted a series of experiments, and is amazed at the dog's intelligence.

Known only the pseudonym Betsy, the true identity of this

seven-year-old border collie is a closely guarded secret.

She can distinguish objects by name,

which is really amazing, and she has many, many words.

Kase.

Das Zebra.

With a vocabulary of over 340 words, Betsy is pushing the boundaries of what we think dogs are capable of.

Karotte.

Sandwich.

I think it was when she was four or five months old,

when she spontaneously started to connect human words to items.

When we were discussing shall we play with the rope,

or with the ball, she immediately started to bring those items. So it was actually her idea.

And from this time on we started to really train her on different words.

It was maybe one toy per week, and it worked.

I think on average a well-trained dog maybe knows like 15 commands or something.

There are just very few individuals who can do what she does.

I can tell that I tried it with my own dog and it didn't work at all.

So he could maybe distinguish two objects after a while and after extensive training,

but she is really able to learn this easily and more than 300 objects, that's pretty amazing.

Betsy's understanding of vocabulary rivals that of a two year old,

so Kaminski decided to test her on other key developmental milestones.

Can you go find me one of them over there? Yeah?

Two year olds are just beginning to understand

the use of physical symbols, such as scale models in communication.

Though it looks easy, it requires abstract thinking way beyond the capability of almost all animals.

But would Betsy be able to do this too?

SHE SPEAKS GERMAN

This was something the owners have never tried before, so when I came and I said, "I want to do this,"

they were like, "No way, that's not going to work", but I was the first one doing it with her.

And she had no problem doing it right from the beginning.

This is surprising because in its essence if I hold out an object,

she turns it into something communicative,

and that's so interesting.

-What about this one?

-Children also begin to grasp that a drawing or photograph can depict a real object.

-Thank you very much, well done.

-No other dog has ever achieved this under trial conditions.

But once again, Betsy picked this up almost immediately.

In its essence the picture is something very different as the object, so it's a piece of paper

and it's two-dimensional, but it's representing something, so she obviously interprets

that as representing an object, a three-dimensional object, and that's so interesting that she does this.

I know exactly what you want.

This is the one you want and I'm going to go and get it for you.

SHE SPEAKS GERMAN

Kaminski is unsure how many dogs might have similar abilities, but Betsy is proof

that certain dogs may have the potential to be more intelligent than we ever thought possible.

So how did the dog acquire these unique abilities?

Did they evolve them over thousands of years,

or is it the way dogs have been brought up in a human environment that counts?

Dogs and wolves are still the same species today.

They can easily interbreed.

Overall, wolves and dogs are 99.8% genetically identical.

Given they're biologically so similar, is it the way we raise them in our homes that makes a dog?

Scientists in Hungary set out to answer this question.

-We wanted to see whether the special relationships between humans

and dogs are due to nature or nurture.

So we wanted to see what happens if a wolf is raised

in a human environment, in a home, whether it would act like a dog or not.

A litter of five-day old wolf cubs was taken from a wolf sanctuary outside Budapest.

A group of young researchers became their adoptive parents, caring for them 24 hours a day.

As a control for the experiment, they'd already raised puppies.

Now they aimed to raise the wolf cubs the same way.

So we were especially nice with our cubs, because we wanted to maintain a very good relationship with them.

They were really cute, so it was not very difficult to carry them everywhere we were going.

And we also slept together with the cubs.

So the bonding, it was good.

I really liked my cubs and there was a really strong relationship between us.

But then something began to change.

Despite raising the cubs in the same way as the puppies, by eight weeks the differences had started to show.

Dog puppies were always interested in what I was doing.

There is a very strong co-operative

tendency in dogs and this was missing in wolves.

They had their own ideas, they were not much interested in my activities.

The researchers wanted to find out what was going on, and decided to run a series of tests

comparing the wolf cubs with puppies of the same age.

TOY YAPS

Unlike dogs, the wolf cubs didn't respond to pointing.

In fact they hardly made eye contact with humans at all.

The cubs were behaving as they would do in the wild.

CUB GROWLS

She was really possessive.

If she wanted to grab an object, it was really difficult to get it back.

And if we wanted to open the refrigerator and have breakfast,

the pup was immediately in the middle of the refrigerator and grabbed something.

It is not like with a dog that you say, "No, you shouldn't."

It just didn't care.

The battles continued to get worse.

After the second month, we started to have more and more conflicts

and the wolves wanted to destroy everything.

And of course when the cub is a small cub,

it's nothing, but when they reach 40 or 50 kg, you know,

it starts to be really dangerous.

We just could not keep them in the house any more.

Hoo!

After four months the cubs had to be returned to the reserve.

The experiment had proved that upbringing has little impact.

It's impossible to turn a wolf into a dog, no matter how much you nurture it.

So according to our experiences, the dog is not a socialised wolf at all.

These differences we experienced in the community viability

and in the social behaviour of dogs, this is the effect of domestication.

The difference must lie in the way dogs have been bred by humans over thousands of years.

Their unique abilities are now part of their nature.

But how did dogs evolve these innate attributes?

What was the process that made them intrinsically tame?

A remarkable experiment in Siberia may hold the key to understanding how wolves turned into dogs.

CAR HORN TOOTS

50 years ago, Soviet scientists set up a breeding programme to try and domesticate silver foxes.

The scale of the project has opened a remarkable window on domestication.

It's become a focal point for scientists across the world.

Here on a farm outside the city of Novosibirsk,

the experiment still continues today, overseen by Dr Lyudmila Trut.

The breeding programme began in 1959 when the first foxes were selected from local fur farms.

TRANSLATION: We approached the animals in the cages

and recorded their reactions to us.

We could see that some of the foxes showed aggressive behaviour.

Others were frightened.

But only 1% of them showed neither signs of fear nor aggression.

This 1% was selected to become the founding generation of a new population of foxes.

At every generation, the selection process was repeated with only the tamest foxes being allowed to breed.

Within just three generations, the aggressive behaviour began to disappear.

TRANSLATION: The radical changes came through in the eighth generation,

when foxes started to seek contact with humans

and show affection to them.

The amazing thing was that cubs who had just started to crawl, opened their eyes

and started showing affection to humans

while breathing heavily, wagging their tales and howling.

This kind of response was a big surprise to us.

Half a century on, the 50th generation of foxes are tamer than ever.

It's an accelerated model of how dogs might have been domesticated from wolves.

But tame foxes alone cannot unravel the mystery of domestication.

A parallel group of silver foxes have also been bred to retain their aggressive behaviour.

TRANSLATION: It just bit my hand.

TRANSLATION: I didn't even open the cage.

I just put my hand up and it managed to bite me through the bars.

This isn't a fox - it's a dragon.

It's allowed researchers to make unique comparisons between tame and aggressive foxes.

TRANSLATION: We did an experiment with cross-fostering

where we gave tame cubs to aggressive mothers.

and vice versa. We found out that the mother's behaviour does not influence that of the cub.

This cub was brought up by a tame mother.

It showed something remarkable, that the difference

between tame and aggressive foxes is largely in their genes.

TRANSLATION: We even took the experiment one stage further and transplanted embryos

from aggressive mothers into tame mothers,

but the results were the same. It proved that you can't change the gene of aggressiveness

and it will be kept and preserved for the next generation.

Geneticists have already located several genetic regions responsible for tameness.

They're now taking blood samples from tame and aggressive foxes

in an attempt to pinpoint the specific genes.

Dr Anna Kukekova, a molecular geneticist based at Cornell University in the USA,

has travelled over 5,000 miles to study the foxes.

Behaviour is complex.

We're pretty sure there will be not a single gene different

with the orchestra of genes

which is responsible for this behaviour.

She's hoping that once the precise genes are identified, it will lead

to a better understanding of the biology of tameness.

He is like a doggy, you know, like the puppy

who's very happy when somebody picks him up from the floor.

It's unbelievable how they trust, how they trust people and I just really admire these animals.

TRANSLATION: So within 50 years of our intensive selection process,

this fire-breathing dragon has turned into a human friend.

If foxes were brought up in a domestic environment,

interacting with other animals and humans, they would make fantastic pets.

They are as independent as cats, but, at the same time, as devoted as any dog could be.

But it's not just the fox's behaviour that has changed.

Just a few generations into the experiment, scientists began to notice a curious phenomenon.

The normal pattern and silver colour of the coat changed dramatically in some of the tame foxes.

Their tails often became curly instead of straight.

Some young foxes kept their floppy ears for much longer than usual,

and their limbs and tails generally became shorter than their wild counterparts.

In effect, the tame silver foxes were beginning to look more like dogs.

What this shows is that when you select against aggression,

you get almost all the same suite of changes that you see when you compare dogs to wolves.

American anthropologist, Professor Brian Hare has visited the breeding programme in Siberia.

He believes it shows that if you select for tameness, changes in appearance will naturally follow.

I think the surprise when thinking about dog origins is that

there's so many ways that dogs are different from wolves.

So is it that you had to select for each of these traits individually?

Well, the answer from the fox work is no.

If you just select for behaviour, a lot of the morphological and physiological changes

between wolves and dogs, get dragged along.

You end up with this crazy variance, you know

floppy ears, curly tails, you know, all these other things that are really cute to talk about.

So you get a lot of stuff for free when you select against aggression.

It's enabled him to draw some surprising conclusions about the process of domestication.

When you're selecting against aggression, what you're doing is you're favouring juvenile traits.

Juveniles and infants show much less aggression than adults

and so what the idea is, is that you know

basically you've frozen development at a much earlier stage

and so you have an animal as an adult that looks and behaves much more like a juvenile.

The theory is that dogs are in many ways like juvenile wolves.

It explains how dogs could have begun to look so different from the wolves they came from.

It's amazing that you get this variance

that's hidden under the surface that expresses itself.

And then later people can directly decide, "I really like the one

"with the curly tail and I'm going to put them together."

And then you can end up having dogs that you know sort of shift in ways that people want them to go.

In the past few hundred years, we've taken dogs' infantile features

and emphasised them even further through selective breeding.

We've created hundreds of breeds to fulfil different roles,

but some of them have been bred purely for their looks.

I think this kind of breeding really tells us a lot

about what kind of people we are, what it is that we like about dogs.

How would you to describe Laddy in one word.

Uh...

..cute.

Cute, yeah.

Cute, adorable and funny.

I just look at her and I just smile.

She's particularly cute when she's sleeping.

We all know we find them cute, but what is it exactly that makes us respond to dogs so powerfully?

Psychiatrist, Morton Kringlebach,

has a theory as to why the way dogs look has such a profound impact on us.

The need to nurture I think is something that is so deep in us

that we find it very difficult to resist.

Dogs, puppies have very infant-like features and maybe that's one of the reasons why we think

they are so cute is that they remind us of the infants that we are - so to speak - programmed to like.

There's something about the way that the facial features are organised that makes us want to care for them.

It's about having a large forehead, it's about having large eyes, big ears...

And there's something about that that almost unconsciously we cannot help ourselves but actually like.

Are you feeding him now?

We're just going to go one more scan.

Dr Kringlebach is interested in exploring how strongly we respond to these infantile features.

A state of the art MEG scanner was used to measure people's brain activity

while they were looking at images of baby faces and adult faces.

We found that within a seventh of a second there was activity in the frontal part of the brain,

just over the eyebrows, in the orbitofrontal of cortex that was present when you were looking

at the infant faces but not when you were looking at the adult faces.

This part of the brain is very much involved in emotional responses, and so what we think we may

have stumbled across here is really in many ways the brain equivalent of the parental instinct.

There's almost like a wired-in automatic reaction.

Kringlebach is now testing to see if we have a similar response to dogs' cute features.

The data is still being analysed but he suspects

there will be a comparable signature in regions of the brain associated with nurturing responses.

Just as with the infant, when you're looking at dogs,

you find it very hard to control your emotions, you find it very hard not to get that need to nurture.

Wow, look at that! What a nice belly!

Oh, you're so cute, yes you are. Oh, yeah!

But responding to pets as though they were children can be seen in a very different light.

I think we can think of little puppies brought home as parasites.

They don't do anything useful, they're not perceived

as a food source, they're not perceived as a guard dog.

They are simply brought home for fun.

They are essentially moving our focus away from having children on to having pets.

I think it's safe to say that dogs have evolutionally been very successful.

If you compare them to wolves, you'll see that wolves are now an endangered species

while dogs, of course, are all around the world.

The cuckoo is perhaps quite a good analogy, because the baby cuckoo, of course,

being planted in somebody else's nest, prompts mother bird to look after baby cuckoo,

even though there's nothing in it for the mother bird at all.

They actually, through their behaviour, through their looks, get exactly what they want.

They may be parasitic in that we cannot help ourselves, but what we get

in return is probably sometimes much greater than what we put in.

Experiments have proved what dog owners have always suspected.

After thousands of years living together, dogs are attuned to us like no other animal.

New research has taken our understanding of how dogs evolved

to a whole new level and getting us closer to exactly what it means to be tame.

Now dogs could be about to provide us with the greatest gift of all.

When it comes to combating human disease, dogs could hold many of the answers.

They're going to help us tackle some of the most dangerous diseases

of our time that kill millions of people every year.

Dr Elinor Karlsson, a geneticist at the Brode Institute, Harvard, is on the hunt

for gene mutations that could throw light on human diseases.

I think there's hundreds of diseases that are in common between dogs and humans.

There's diabetes, there's various cardiac diseases, there's epilepsy,

there's a lot of different cancers - bone cancers, breast cancers, brain tumours.

The narrow gene pool within a dog breed

makes it far easier to pinpoint genetic mutations than in humans.

For more than 200 years, people have been making up all of these different breeds,

and now we can just use them to study genetics.

If you looked in a population of humans, all the people in a country like the UK,

you'd have quite a lot of genetic variation across them. People would be quite different from one another.

But within a breed, dogs are very similar to each other.

Particular dog breeds are prone to certain diseases, and this makes them incredibly useful to study.

Today, the team are taking blood samples from boxers,

a breed that is susceptible to a fatal heart disease called cardiomyopathy.

What happens is they have

irregular heartbeat,

and it compromises blood flow in their body,

so it can cause collapse and also it can cause sudden cardiac death.

It's an invisible disease that affects humans, too, causing sudden death in apparently healthy people.

The DNA in boxers' blood could hold vital clues to the genetic causes of the disease.

Dr Karlsson is part of the team that in 2005 mapped the dog genome,

all 2.4 billion letters of the dog's DNA code.

Once we had the dog genome sequence, we could design a gene chip, which would allow us to compare

all of our sick dogs and our healthy dogs and find the genes that are causing diseases.

Using a genotyping machine, Dr Karlsson is able to simultaneously analyse thousands of regions of DNA

from boxers with and without cardiomyopathy.

What you see when you compare sick dogs to healthy dogs and go across the genome from chromosome one

to chromosome two and across is that most of the points

are right near zero and there's not a lot of differences between the healthy dogs and the sick dogs,

until you get to chromosome 17, and there all of a sudden you have a huge number of differences.

This is exciting, because this means

this is the region of the genome that holds the gene causing our disease.

Karlsson's team have honed in on this region to pinpoint the exact gene.

We've found a gene related to sudden cardiac death.

We think there's another one because we haven't told the whole story yet.

But we think we know what the mutation is in that gene causing the disease.

Now the mutation has been identified,

the team have been able to locate the corresponding gene in humans.

It's accelerated a process that, without dogs, could have taken decades.

By knowing what gene is causing it in dogs,

we have an idea that this gene can cause this disease in humans.

I think that there's probably a lot of diseases that are so complicated in humans

that if we didn't have dogs it would take us a long time to start piecing it together.

Dogs basically give us a huge head start on that.

So I think this puts the benefits that dogs give us on a whole new level, and I think

if they can help us cure those diseases, then we can really say that dogs are good for our health.

It's a very important part of life to actually know a dog.

And especially a dog that adores you like this has got to be good for yourself.

It's kind of impossible to have a bad day

when you're coming home to a wet nose and a waggy tail, I think.

I can't imagine life without her.

It's quite strange. We weren't lacking anything before we had him,

and yet now we would feel that we were lacking if he wasn't here.

They just enrich your life.

They are the best thing ever.

They keep you young.

For a pet that's been around so long,

dog research is an astonishingly new area of science.

It's a very basic human need to have social relationships,

and one of the wonderful things about dogs, of course, is they offer you a way of giving unconditional love

and receiving unconditional love in the other end.

Dogs are the ones that live with us in the same environment.

They've been selected to live in this new environment, and they are specially tuned into humans,

so humans are their natural social partner.

But we're only just beginning to recognise their full potential.

Understanding dogs has the capacity to give us insights into disease,

the human mind and our very existence.

I think one reason that there are almost seven billion people on earth is in large part

due to the role that dogs have played in our evolutionary existence.

While we can have good relationships with a wide variety of animals, historically, our relationship

with dogs seems to have been the longest one with any domestic animal.

Personally, I don't think it's any coincidence that the dog is referred to as man's best friend.

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