Scientists are reporting that the wide size variety in dogs is caused by variations in but one gene. From the story in the Telegraph:
Ranging from toy to giant, dogs have the biggest size variation of any mammal and the team of US and British experts believe it is due to variations in one gene.
After analysing DNA samples from 3,200 dogs, they pinpointed IGF-1, a gene that makes a hormone called insulin-like growth factor 1.Variants of the gene were very strongly associated with the different sizes of dogs and the scientists are now trying to determine the precise mutations occurring within the gene…The study is relevant to human medicine because a vast majority of the genes in the human genome can also be found in the dog genome.
And here’s the human exceptionalism angle: Dogs did not evolve. They were intelligently designed by the only species in the known universe capable of literally transforming some members of a species (wolf) into something substantially different (dog). And contrary to the beliefs of animal liberationists, both we and “man’s best friend” have benefited tremendously.
Post Script: Isn’t this typical about how science reporting is often incorrect in the popular press? It turns out, dog size may not be based on one gene after all. From the LA Times story:
Eventually, they accumulated and analyzed genetic samples from 3,241 dogs from 143 breeds. All the small dogs had the same altered regulatory sequence.
So, too, did the occasional big dog, such as a Rottweiler and a mastiff.
“There is something funny going on with Rottweilers,” Ostrander said. “That told us right away that that the whole story isn’t IGF-1. There are other genes that interact, and we are going after them right now.”
So, apparently the “one gene” story isn’t really a story. But human exceptionalism remains.