It’s a rare scientist who would name a research project after the family pet, but for Dr. Gordon Lark, it seemed the natural thing to do.

That’s because the geneticist’s work would have been dramatically different if not for Georgie, the Lark family dog and a disease that plagues his breed. In a study of hundreds of dogs like Georgie, Lark and his research team have described how breeds from a common ancestor may have diverged so dramatically in a short amount of time.

The new research describes the genetic elements that affect bone formation in dogs. Using DNA from blood samples, along with X-rays and meticulous pedigrees from 330 dogs of the same breed, the University of Utah’s Lark and his collaborators found genes that influence the growth and development of the canine skeleton.

The findings, published recently in the Proceedings of the National Academy of Sciences, suggest that certain breeds of dogs may be useful models for geneticists with a range of interests from evolution to human disease.

Georgie, a Portuguese water dog, died of an autoimmune disease in 1986. Ten years later, Lark called a breeder to discuss buying a new puppy. It was a serendipitous encounter. The breeder, Karen Miller, also had a penchant for genetics.

Miller’s own dog had died of Addison’s disease, a poorly understood genetic disorder that also affects people. “I said to him, ‘Dr. Lark, if you’ll help me to determine the mode of inheritance of Addison’s, I will give you a puppy for free.’ And that turned out to be the most expensive dog anyone has ever acquired,” Miller says.

She suggested that Lark transform his soybean lab into a hub of dog genetics. He decided to give it a shot. The same techniques he had used for years in plants, he imagined, could provide clues toward understanding mammalian evolution, when used in dogs.

The Georgie Project was born.

An ideal subject

The Portuguese water dog, kept for centuries by European fishermen, is prized for its energetic, obedient nature and superior swimming skills. The seafaring dog’s numbers waned in the early 1900s, and by 1940 the breed had gone nearly extinct. It was reconstituted from only a few animals and introduced into U.S. kennels in 1971. Two kennels were responsible for most of the lines, and so the majority of Portuguese water dogs in the United States are highly related.

What’s more, U.S. breeders of the dog maintain immaculate pedigree records, providing a valuable tool for scientists to dissect any given dog’s genetic history.

The breed is an ideal study subject, Lark says, because it has such accurate pedigrees, can be traced to relatively few ancestors, and exhibits a variety of traits interesting to scientists.

Lark’s research team identified traits, such as bone size and shape, that vary along a continuum among different dogs of the breed.

The genes that influence these traits are part of a complex network: Some genes stimulate bone growth in one area while inhibiting it in another. To simplify things, Lark and his group considered the skeletal frame as a series of parts traits to be quantified and examined.

Each of these traits that govern skeletal form, Lark says, is composed of many smaller traits. “You could say that the trait of operating a car is composed of separate traits, like steering, operating the clutch, and checking the rearview mirror,” he says. A larger trait, like the overall ability to drive a car, might be something like jaw size. The smaller traits that make it up, in this case, would involve individual bone thickness and length.

In the genes

The genes that affect skeletal variations within the Portuguese water dog population may also help explain why different breeds of dogs can look so markedly different even though they are members of the same species. Relatively few genes, Lark suspects, may be responsible for the variation between vastly different breeds, such as the greyhound and the pit bull.

For example, these genes can enhance jaw size while reducing stature. In dogs like the pit bull, such a gene would be successful because as a powerful jaw and neck develop, a stockier body with thicker bones provides better support than a tall, lean frame like the greyhound’s.

Many of the same genes that affect bone development in dogs act in humans as well. New understanding of the relationships between these genes could provide insight into human evolution.

And the techniques used in the new study, Lark says, could advance knowledge about a host of human ailments, including hip dysplasia and retinitis pigmentosa.

As for Miller’s appeal, the researchers still don’t understand how Addison’s disease is passed through generations. But, Lark says, the matter is on the table for future research. In the meantime, the breeder has no complaints. Lark “was tenacious, and I was tenacious,” she says. “And we’re both getting what we want.”