What’s with all the new dog breeds? We ask an expert

·3-min read

The animal charity Blue Cross is campaigning to stop pugs and French bulldogs being featured in advertisements. It hopes to slow demand for thea flat-faced pooches where “overbreeding” is causing breathing and walking difficulties. Yet new breeds of dogs are introduced each year. How are there so many? And what does this mean for dogs? I asked evolutionary biologist Frank Hailer.

Is it true that all dogs are descended from one line of wolf?
All dogs derive from a one-time domestication event – a single wolf that became a companion animal. And there’s no genetic evidence of other wild species except the grey wolf contributing to modern dogs. At the same time, it’s probably more complex.

That event was ages ago, though.
In the range of 16,000 to 40,000 years ago.

Whereas most modern dog breeds have been around for only the past 300 years.
Three hundred at most. A lot of breeds have been formed more recently. The concept of controlling dog breeding and defining specific breeds hasn’t been around long.

I still find the whole thing mad! How can we just make a new dog breed? How long does it take?
There’s no scientific threshold to define a new breed – it’s the various kennel clubs who do that. So if we cross two existing breeds and make something we didn’t have before, then only let them mate with one other, theoretically, that’s a new dog breed within very few generations. That’s probably how most of our dog breeds came about: humans controlling based on qualities we want or find pleasing.

I’m a cat person – but I do wonder if so many dog breeds would exist without human interference?
No. Speciation happens in the wild, but it is a very slow process.

I read that, despite the diversity in humans – height, sex, skin and hair colour, etc – the difference in our genes is only about 5%. But between different dog breeds, a chihuahua and a great dane, say, it could be up to 27.5%. Is the category of “dog” too big? Do we need a new one?
There are various ways of measuring difference, and what you are describing is frequency of genetic traits. Because we’ve been inbreeding dogs, the overall gene pool is small. Another way to measure difference is DNA, and that’s where we see dogs are similar to each other because they’ve had up to 40,000 years to develop into something different from a wolf. As for a new category of animal, yes – that’s a matter of time. But a very long time.

Related: Will our pets suffer when we go back to work? We ask the expert

What would happen if we stopped controlling breeding? I know you’ve written about the stray dogs of Moscow, which have lived without human interference for 150 years.
They are fascinating, because some of our favourite dog traits disappeared – the wagging tails and friendliness to humans. There’s an experiment from Russia where they bred red foxes for lack of aggression. The foxes started to get floppy ears and wagged their tails.

But what’s next for our beloved pugs? Could we breed them back to healthy?
The short nose is clearly derived from human preferences. If you look at historical photos of bulldogs, 100 years ago they had much longer noses. If we have the power to make noses short, we have the power to make them longer. If we call dogs our best friend, we do need to look out for them.

• Join Coco Khan, Tim Dowling and other Guardian writers for an entertaining look behind the scenes of the Saturday magazine at 8pm on 29 June. Book an event ticket here.

Our goal is to create a safe and engaging place for users to connect over interests and passions. In order to improve our community experience, we are temporarily suspending article commenting