How centuries of breeding altered dogs' DNA

          Joey apparently thinks Madge was bred to provide him with a pillow.



Sometimes when look at Madge, I start to wonder about what her parents looked like. (Which one was the pit bull, and which one was the basset hound?) But I also think about her odd mix of traits, and how those traits originally were developed. Somebody, somewhere in the distant past must have liked the idea of having a dog with a super-long body and stubby legs, and tried to breed to accentuate those characteristics. Similarly, someone in the past must have found brindle coloring attractive (even though Madge's original owners didn't, and actually abandoned her at the dog pound because of it).

Anyway, I was fascinated to see this Washington Post article about scientists' quest to unravel the genetic past of  400 different breeds of dogs. So far, they've identified 150 or so gene locations, containing more than 1,600 genes, that have been altered by human-orchestrated breeding. Variations in the genes IGF1 and FGF5, for example, influence dogs' size and limb length, respectively. Another interesting tidbit: while dogs have been bred domestically for 14,000 years, most dog breeds have only been around for 500 to 1,000 years at most. In terms of evolution, that's barely the wink of an eye. That makes it all the more fascinating that human tinkering with dog genes has managed to create a creature as unusual as Madge.