|A re-post from January 2012.|
A reader writes to ask about the putative origin of dogs.
It seems she was listening to Science Friday and they referenced this story from PlosOne: Evidence of the Earliest Domestication Disrupted by the Last Glacial Maximum
She wonders how the transformation from wolf to dog could have occurred in so many diverse geographical areas. If one wolf pup was taken in by humans in Nome, Alaska another in Brittany, France, and another in the Fertile Crescent of Iraq, wouldn't they have a lot of genetic differences?
Here's an interesting question!
Let's start with a simple point: DNA and mDNA are not as good as a license plate. DNA can tell you if this blood or hair came from that animal, but population DNA is a little more complex and a little less clear, and that is especially true for animals that routinely make 1,000 mile migrations and which can jump human-constructed taxonomic fences as if they were little more than chalk lines on a black board.
So what are all these papers about that are proclaiming some scientist or another has just discovered "the first dog"?
What is going on here, is that some underfunded and overlooked dirt scraper in some God-forsaken location has come across a canid skull in a cave.
But, of course, there has to be more, and so measurements are taken, tests are run, and speculation runs rampant as people desperate for more funding look for a headline, a first, a discovery, a whole new way of looking at the world.
Carbon dating will be done, of course, and in the paper they will note the presence of a possible fire pit nearby, the bones of dozens of other animals, and maybe a few cut marks on a few bones. The scientists will measure the teeth and claim the animal they found has teeth ever so slightly different from some putative "norm" for wolves, and they may also say the muzzle was ever so slightly shorter than some other putative norm.
This "study" has been done again and again, all over the world, with only slightly different wording. So far scientists have boldly proclaimed that the first dogs came from China, the Middle East, France, Ethiopia, Oregon, and ... wherever.
It is all nonsense. They have no idea, and in fact the folks making these claims have no real understanding of wolves, dogs, species or even evolution. Hard to believe, but absolutely true.
Let's start with the basics: The differences between wolves, dogs, Coyotes, and Golden Jackals are so slight that they can ALL interbreed and produce fertile young.
Let's take a look at a few pictures:
|New Guinea Singing Dog|
|Negev Desert wolf|
|Egyptian stray dogs|
|Greenland sled dogs|
|Chinese village dog|
|Philippines Village Dog|
Shave these animals down to account for coat differences due to climate variance, and color them all the same, and there is not a biologist in the world that can reliably say which is dog, wolf, jackal or coyote based on simply looking at them. There are differences in size, but those differences are arrayed on a continuum and there is no obvious break moving from one animal to another.
This is not to say dogs, Coyotes, Golden Jackals, and wolves are not different.
Wolves and coyotes howl and almost never bark, while dogs bark and almost never howl.
Male and female alpha wolves lift their legs to pee, while all other wolf pack members squat to pee. With dogs, almost all males lift their legs, and almost all females squat.
With wolves, estrus occurs only once a year in January or February, while with most non-primitive dogs, estrus occurs twice a year, and can occur at any time.
There are other differences too -- physical differences. Wolves have a pre-caudal gland while dogs do not, and there is also a very small bone difference in the feet of one wolf sub-species.
But can a scientist, anywhere, pick up the skull of an ancient canid and definitely and reliably say this one is a coyote, and this one is a red wolf, and this one is an Arabian wolf, and this one is a dog, and this one is a Golden Jackal and nothing has ever been crossed?
The morphology and biology of dogs, wolves, coyotes, and Golden Jackals is simply too plastic for that kind of facile work based on single skull samples.
In fact, the very nature of the claim being made is flawed at its core.
The assumption is that dogs were created from wolves. It's far more accurate to say dogs ARE being created from wolves. The world of canids is one in which speciation is occurring and has not yet fully occurred. It is still a process, not an event.
And it is a process in which man is still very much stirring the pot.
In Alaska, Kazakhstan, Spain and Romania, there are still wolf pups being snatched from the wild and raised as dogs. These animals are so unreliable as pets that there are laws in almost every country prohibiting their ownership, but their ownership is so common that there's also a entire lexicon of language where the dogs are described as "Malamutes." In fact, many of the animals bought as wolves are Malamutes! Such is the plastic nature of dogs and wolves.
In Italy, Alaska, Minnesota, Spain, Ethiopia and the Middle East, wolves are occasionally crossing with dogs to create small unstable hybrids with the result being mostly wolf, but with sizable doses of dog coursing through the bloodstream.
Here in the U.S. no one knows what to make of the giant coyotes that have appeared in New York and Maine. They appear to be mostly wolf, but there's a little dog in there too.
And, of course, there is the Red Wolf, which has always been nothing more than a stable and self-replicating hybrid of a wolf and a coyote.
The point here is that the world needs to stop saluting this notion that there was a "magic moment" when a wolf became a dog, or that there is even a bright-line morphological difference between Wolves, Dogs, Coyotes, and Golden Jackals.
Bones, by themselves, do not actually tell us all that that much in this instance.
|Malaysian feral dog|
|Native American dog, Sioux|
|Leonhard Sepalla and his sled dogs|