Here’s a question for those folks who get to put Latin-sounding genus and species names on animals. Why is that two almost identical little brown birds, identical other than one has a beige dot on the wingtip while the other does not, why is that those are considered two different species, when everything from a six-pound hairless Chihuahua to a ginormous, wooly Newfoundland are all Canis familiaris? Whether or not there is a good answer to that question, it does point to the fact that dogs come in a remarkably broad range of looks for a single species.
The term “plastic” is used to describe this aspect of doginess: like plastic, dogs are relatively moldable, able to be shaped by breeding over generations to meet various and changing human needs (everything from baby-surrogate to fierce soldier-guardian). Some of that was coincidental, like when the biggest and strongest dogs successfully grabbed the most food and were therefore able to produce the most offspring who then carried those big-strong genes forward, or when a doe-eyed adorable fluffball was hand-fed the most nutritious food, protected and lavished to the extreme, and given the chance to breed like bunnies. On the other hand, much of that plastic molding has been quite purposeful, with people intentionally breeding in the effort to give greater emphasis to one set of traits over another.
A team of geneticists just uncovered evidence of the most ancient example of our ancestors’ success in breeding dogs with such a goal in mind: a Neolithic Age selective breeding project which produced the Arctic Sled Dog more than 9,500 years ago. 9,500 years is a long time, but domesticated dogs had been part of our lives for at least 5,000 years before that. The current thinking is that our ancestors came to realize that potential “plasticity,” and that sled dogs were the first canines bred for a specific role, in this case to haul heavy loads in brutal winter conditions. The proof is found in the genetic material of ancient bone fragments. Just as interesting, that ten-millennia-old decision has left its mark as DNA still found in today’s Alaskan Malamutes, Siberian Huskies and other similar breeds, but in no others.