You know how it is when someone says that they won’t believe in evolution because you can’t show it happening? That really drives me nuts! There is so much evidence out there, you know they really mean that they don’t want to believe in evolution no matter what. Very well, there is nothing I can do for you.
But, for those who are interested, I find the domestication of the dog a fascinating example. It really is evolution happening practically before our eyes. Ok, over the last tens of thousands of years, but that’s just the blink of an eye. So dogs as we know them, in all their variety evolved from wolves. It’s probably more correct to say that modern dogs and wolves share a common ancestor but I’m not an evolutionary biologist so I’m going to simplify things and say they evolved from wolves. And that recent experiments by some very clever geneticists have shown that dog domestication and the human diet are closely related.
It isn’t clear exactly when dogs as we know them came to be. There have been bones found, of dog like creatures as old as 30,000 years. Genetics tell us they have been around for at least 10,000 years and remains of dogs and humans together have been found and aged in this timeframe also.
There are a couple of theories of how dogs began. There must have been a strong driving force to drive this evolution from wolf to puggle. One possibility is that early humans captured wolf pups and used them for guarding and hunting. It would figure that the humans would get on best with the friendlier of these captured wolves (rather them than me) and if the friendlier more docile wolves were encouraged to breed then you have the beginnings of a new wolf breed which has a better temperament than it’s ancestors. Another theory (I like this one best but should stress this is not my area of expertise) is that when humans changed there lifestyle from a hunter-gatherer nomad to settling in permanent sites, wolves would have had an extra, previously unheard of food source…the dump.
At this time, the dawn of the agricultural revolution, humans had a diet change which involved eating more starch, from the veggies and grains we were learning to grow. Some of these would find their way to the community dump and some smart wolves would be there with open mouths. Hanging out at the dump would after all be much more fun than catching dinner yourselves. It is possible that these ‘scavenger wolves’ are the ancestors of modern dogs, again, the less aggressive and more able to live with humans they were, the better off they would be. Driving the selection of all the features of Fido that we love so much.
Back to those clever scientists. They were able to study the entire genetic code for 14 different dog breeds and compare this with the code from wolves. This is no mean feat because wolves and dogs are genetically speaking, so similar. Remember we are 97% genetically similar to mice*. They found some pretty remarkable things. First, that dogs and wolves differ in the genes responsible for behavior and thinking. I know that sound obvious, but to actually see it in the genes is amazing, at least in my humble opinion. Second and most important, they found that genes responsible for the ability to digest starch is only present in domestic dogs and not in wolves. Which seems to support the idea that domestication and the agricultural revolution are linked. It’s also very interesting that human and dogs both had a parallel genetic change or evolution when starchy foods became more available. We go back a long way, us and the mutts.
* I made this number up, but I’m sure it’s something like this
Reference: Axelsson et al., Nature. 495. 360. 201