Westminster Dog Show 2010 winner Sadie the Scottish Terrier is a little loaf of black furry adorableness. Short, with soulful eyebrows, a silky coat, and an exclamation point of a tail, she looks nothing like the dogs she beat in the final round to capture Best in Show.
The Doberman? Tall, brown, fierce. The Whippet? Tiny, legs like sticks, not much hair to speak of. The Puli? Is that a dog, or a mop?
But variety is in the eye of the beholder. Where a spectator at Westminster sees many varieties of dogs, a scientist who studies their basic make-up might not. That’s because, genetically speaking, dog breeds are almost the same.
Take Boxers and Poodles – two breeds whose genomes have been thoroughly analyzed.
“They’re pretty much identical,” says Dr. Ostrander, one of the nation’s top experts in canine genetics.
A breed of dog is like a geographically isolated population of humans, she says. They will develop differences from their neighbors across the impassable mountain range, but they generally will be the same race.
For pure-bred dogs, the isolation is a product of breeding. A show Scottie must have two parents that were also recognized Scotties. Dobermans need not apply. At least, not if their progeny is to appear at Westminster.
Differences in dogs are caused by a small number of genes that produce a large effect. For instance, one reason Sadie the Scottie is so cute is because of her short little legs. Research has helped establish that breeds with such legs – Corgis, Dachshunds, Scotties, Bassets – all have one extra copy of a normal gene to thank for their diminutive stature.
This means that all these breeds are closely related.
“We know they got [short legs] from a common ancestor,” says Ostrander.
A dog show is all about the great sweep of canine kind. There are short dogs, tall dogs, black dogs, brown dogs, fast dogs, slow dogs, and so on, to paraphrase Dr. Seuss. Where did all these breeds come from?
The announcer at Westminster has wonderful origin stories, which involve ancestors herding for the Magyars and 13th century English monks, and so on. Are those true?
Well, yes and no. Science is tracing a picture of dog development which does not always match official breed histories.
Generally speaking, there are four groups of dogs with shared ancestry, according to the research of the Dog Genome Project, an effort of the National Human Genome Research Institute.
The first group is composed of dogs with the oldest forebears. These are mostly, but not entirely, breeds from Asia and North Africa. They include the Afghan, the Alaskan Malamute, the Basenji, the Lhasa Apso, the Pekingese, and the Shar Pei.
The second group are big mastiff-like dogs. These include the Bernese Mountain Dog, Bulldogs, German Shepherds, Labradors, Newfoundlands, and so on.
Group three are herding dogs, such as the Collie and the Shetland Sheepdog.
The fourth group, modern hunting dogs, is pretty much everything else. It includes various terriers, spaniels, and retrievers, plus Beagles, Chihuahuas and Great Danes. This latter cluster is the result of human breeding efforts which, evolutionally speaking, are quite recent.
Some dogs thought to have ancient forebears, such as the Norwegian Elkhound, have turned out to have much more recent origins, according to geneticists.
Ostrander puts it this way: “What we find is a lot of breeds really do have a thread that travels back as far as they think it does, but it is encased in a rope of more recent genetic events.”
She points out that many old breeds were essentially recreated in the 19th and early 20th centuries from a few survivors, with other dogs mixed in.
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