More evidence of shared genetic history. Genes in the same location on mouse, human, and dog genomes have similar functions. Mutations in these genes yield similar phenotypic results. A mutation of a gene involved in skin appearance gives the shar-pei wrinkly skin. A mutation in that same gene in humans yields excessively wrinkly skin. Fascinating.
The "evolution" of dog breeds provides an interesting study of evolutionary concepts. It's amazing to think how much breeds have diverged in 10,000 years, while maintaining their cohesion as a single species. A Great Dane and a chihuahua are the same species! That means they can reproduce and yield viable offspring.
Different breeds come from selective breeding of dogs by humans for certain traits. These traits allowed dog to specific jobs. Having worked in a pet store, I can say that more people need to pay attention to the history of their favorite breed before purchasing a puppy. Australian cattle dogs are cute, but make poor pets for city-dwellers because they were bred to be on the move herding every day. When I was in middle school, my family helped round up and brand calves on a ranch in norther New Mexico. The ranch had a pair of ACD's named Ding and Dong that helped herd. Watching those dogs do their job was a pleasure - they were all business. I think the same can be said for watching for watching any herding, working or hunting breed do its job.
However, to achieve consistent breed characteristics (coat length, coat thickness, pointing, tracking, size, temperament, etc., etc.) dogs have to be inbred. This means fathers bred to daughters, mothers to sons, brothers to sisters, etc. This process emphasizes and accentuates both positive and negative genetic characteristics. This is why purebred dogs have higher incidences of genetic disorders and predispositions toward certain health problems (hip displasia, eye problems, etc.)
That's all for now. I love thinking about domestic animals and evolution (as did Darwin, by the way) so I'll talk more about this in the future, I'm sure.
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