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How Are New Dog Breeds Created?

I love dogs, I’ve always loved dogs. But there’s always the debate... purebred or

mutt?

It’s a great year to be a dog lover! Apparently 7 new dog breeds will be shown at the Westminster

dog show! I don’t know about you, but dog shows… give me mixed feels. On a personal

level, PUUPPIES, but the science part of me wants to know, why are there so many different

dog breeds and is that good for the species?

I mean domesticated dogs might have been around for 40,000 years and all pretty much looked

like wolves. But the few hundred dog breeds we know and love today, have only been around

for a couple of hundred years at the most. Humans tinkered with dogs, selecting for temperament

or physical traits. Things like distinguishing markings, the color of a coat and other physical

features like head and body shape.

A new dog breed has to meet very specific requirements to qualify as an official breed.

Many organizations like the American Kennel Club demand proof that every dog used to make

the new breed was a certified purebred. And in many cases, breeders need to get their

dogs DNA and genotype tested to show a “an acceptable DNA variation sample for the breed”.

Since 2003, researchers have been able to see exactly what that genetic pool looks like

thanks to an effort lead by Ewen Kirkness at The Institute for Genome Research which

sequenced the dog genome.

They also studied the genomes of different breeds. And not surprisingly they found that

the variation of genes was greater between dogs of different breeds than they were within

the same breed. So, a black lab and a golden lab will have less variation than a black

lab and a bulldog. But what’s interesting is that variation can be as much as 27.5 percent

between dogs of different breeds, even though essentially, they are the same species. Now

compare that to humans who only have a genetic variation of 5.4 percent.

When humans mess with dog’s shape and coloring, they are actually messing with their genes.

Like size is pretty much controlled by one gene on chromosome 15 called insulin-like

growth factor-1. (IGF1), which is known to influence body size in humans and mice. But

it’s mutation can be found in a lot of unrelated smaller breeds, suggesting it’s ancient.

Even though it’s a few thousand years old, it’s a change that still happened faster

than it would happen naturally. So all the tinkering humans do to dog breeds, dramatically

changes dog’s genes faster than nature would.

With all that genetic tinkering, some weird stuff happened. Not surprisingly, breeding

for aesthetic purposes has some.. unintended consequences. Like pug encephalitis and hip

problems in German shepherds. And one study in PLOS One found that changing a dog’s

face, changes their brains too. In dogs with short snouts, their brains have rotated 15

degrees backwards and the smell region in their brain is in a completely different place

from other breeds. And these kinds of brain changes are common in other dogs too.

Another study also published in PLOS One found that Chiari malformation in dogs actually

changes their skull and brain formation. It’s a physical defect that occurs in a lot of

small dogs that are bred to look more “doll like”. It basically makes the forehead bigger

but also changes the brain shape. It can cause chronic conditions like headaches, problems

with walking or even paralysis. One of the lead authors of the study Clare Rusbridge,

described the condition “as trying to fit a big foot into a small shoe.” Which just

sounds utterly painful.

The physical defects caused by inbreeding is a huge problem and it’s one of the reasons

why some breeders are calling for stricter regulations and practices. Thankfully there

are responsible breeders who are using genetic science to ensure they are breeding to maintain

genetic diversity, resulting in new breeds that are both healthy and happy.

While we’ve bred dogs to be stronger, smaller, or even more docile, they all come from a

wolf like ancestor thousands of years ago. At some point, dogs evolved to become man’s

best friend? When did this take place?

So what’s your fav dog breed? Mine’s a mutt.