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My relationship with dogs is sometimes a bit split. One side of things is that I love them, for all the reasons everybody reading this understands so well. Another side of my relationship with dogs is my fascination with them—a true scientific interest, based on some of their extraordinary characteristics. And research about their genetics has continued to add to their appeal as creatures worthy of great attention, even beyond the fact that they are so lovable.
From the diversity of forms seen in the domestic dog, it’s easy to come to the conclusion that their genetics are unusual. Though other domestic animals including chickens, horses, cows, sheep and cats have many different breeds, dogs alone have the amount of physical variation that is represented by Great Danes, Dachshunds, Pugs and Borzois. Animal lovers are generally interested in that fact, but all scientists ought to be astounded by it, and I most definitely am.
The selective breeding that has led to the range of forms in this species is a fascinating genetics experiment. Geneticists are grateful to the “field work” done by countless breeders over many generations because the dogs that have resulted provide a way to understand things that can’t be learned elsewhere.
One of the most fascinating recent discoveries that makes use of the variation in dogs is that it’s only a few genes that are responsible for the huge range of differences in the appearance of different breeds  of dogs. The incredible variation in dog size, fur type, length and color, ear shape and position, and shape of the nose is controlled by just a few dozen gene regions.
In other species, the genetic control of traits such as size and shape is much more complex. For comparison, human height is controlled by around 200 gene regions. Until it was investigated, researchers assumed that underlying the incredible diversity of canine appearances was a corresponding genetic diversity, but it’s just not so. The more we learn about dogs, the more fascinating they become.