- [Voiceover] Well, my brother and I were sitting
on a tropical beach, watching a dog walk by,
and we just asked the question, you know,
what is that dog?
It's a key population because it's the most numerous
population of carnivores in the world.
So there's a billion dogs on the planet, and three quarters
of them are village dogs.
(repetetive piano music)
- Today we're at Cornell University
in Ithaca, New York, to meet Adam Boyko, an assistant
professor at the faculty of veterinary medicine.
- [Voiceover] He's recently published a very cool paper
about dog domestication.
- So, did we domesticate dogs, or did they domesticate us?
- Yeah, that's a really good question, and I'm sure that
he's got a lot to say about that.
- Hi Adam!
- Hi Irene, how's it going?
- Good, how are you?
- Hey Jaques, thanks for coming.
- Great to see you.
- So, who do you have here?
- I have Sam, he's a gorgeous yellow labrador retriever.
He's our latest volunteer in the genetic diversity study.
- I hear we're going to take some genetic samples from him.
- That's right, we're gonna put him in the biobank
and we're gonna look at his DNA.
- What are you expecting to see?
- Well, for Sam, I know that he has short fur,
I know that he's got yellow fur, so I know he's homozygous
for FGF5 and TYRP1.
TYRP1 is the b-locus in dogs, and it's the same locus
in humans that causes blond hair.
- Oh, that's really cool.
- He's also a little on the small side for a labrador,
so I'm expecting he has at least one copy
of the small IGF1 allele.
- (laughs) Labs get hip dysplasia like other big dogs.
- That's right, having samples from healthy dogs like Sam,
to compare with the dogs that we see in the clinic
is really important for finding the genetic predispositions
for diseases like that.
- What's the sampling process?
- Well, we use these saliva swabs.
Sam, ready?
Ready for your sample?
Here we go.
Open up.
(everyone laughs)
Don't eat the swab. Don't eat the swab.
- I think you've got plenty there.
- Yeah, there we go.
Thank you, Sam (laughs).
- Adam, we've now collected the sample,
so how do you analyze it?
- Well we extract DNA from that swab in the lab,
and then we put the DNA on a genotyping array.
- How do you relate all of this back to
the clinical usefulness?
- Knowing the genes that predispose for risks
of these diseases also gives us ideas for ways to treat
the disease, and might offer us insights for treating
homologous diseases in people.
- Are there breeds that are specific for each disease?
- Yeah, so we see very high rates of cancer, for instance,
in golden retrievers.
- I see they have found markers for pointing behavior.
- Yeah, we would love to uncover the genetic basis
for all these different behaviors.
You know, not just for being able to improve our breeding
of working dogs, but also our understanding for how
the brain works.
For example, most of the behaviors we associate
with hunting dog breeds, they're all modified
from the prey drive behavior that wolves have.
So, pointers orient towards the prey, but they don't
charge towards the prey.
Herders will charge towards the prey, but they don't
bite the prey.
Retrievers will bite the prey, but they won't
consume the prey.
- So Adam, here we have a Siberian wolf,
the dog's ancestor.
And here we have an extreme
of breeding, which is the English bulldog.
How many genetic variations are between the wolf
and a dog like this?
- Surprisingly you're talking about maybe a few dozen genes.
When wolves became domesticated into dogs,
they didn't immediately start looking like this.
So they had to go through this domestication process
where we had, um, you know, strong natural selection
to become tame.
Following that selection for tameness came more selection
for a new diet that they had.
And smaller body size, and smaller canine teeth,
and less of a sagittal crest here, for catching
chewing muscles.
Then people could start selecting for whatever traits
they wanted in their dogs, and it really took off
in the Victorian era, when they started pedigree breeding,
and so when you look at purebred dogs, you have more
selective sweeps, but this time for more
morphological traits, such as extreme size,
small or large--
- What is a selective sweep?
Can you explain it to us?
- So when you have a variant that becomes
positively selected in a population, over time that variant
becomes more and more common until it's completely
what we say swept through the population
and every individual now is fixed for that variant.
Not only the selected variants, but all the other variants
that happen to be on the chromosome.
- [Jaques] And those could be disease genes?
- In some cases those can be disease genes.
In a case like this, we call it genetic draft,
where it's like a race car drafting alongside another one.
And that is also a real problem for genetic disease in dogs.
- How many sweeps do you see?
- There's been about three dozen sweeps at domestication,
turning a wolf into a village dog.
And then, depending on the breed, you probably have
another dozen or so sweeps.
- So what are you learning about dogs?
Dog breeds and diseases?
- Doberman pinschers have canine compulsive disorder,
so a large number of them compulsively, you know,
bite at their paws, or chew blankets.
We actually see it's the same gene that causes
obsessive-compulsive disorder in people.
So in fact, the dogs probably are obsessing,
but we just don't know it because we can't ask them.
- So what was your inspiration to start looking
at the village dogs?
- There was this debate about where dogs originated.
Trying to figure that out by looking a purebred dogs
is like trying to figure out human origins
by sequencing all the royal families of Europe.
(bell dinging)
Village dogs contain more of the variation that was present
in our earliest dog ancestors, and therefore can be used
to infer what happened early on in domestication in dogs.
- What did you find from that?
- What we found is that there's a center of diversity
in Central Asia in the village dogs, and so that makes
Central Asia a likely domestication origin for the dogs.
- What gets you excited about this work?
- Well what gets me excited now
is that as the genetic tools are getting better and better
we're gonna start to be able to go get the roots
of complex disease, you know, things like cancer,
things like hip dysplasia.
We will improve dog health as well as human health.
- That was really surprising learning how much dogs
share with us.
Not only our environment, but also so many genetic factors.
- [Jaques] And the more we can know about improving
the dog's health, the more we know about improving
human health.
(repetetive piano music)