I think that this article, suggesting that dogs may have evolved from the wolves who were “able to scavenge and digest the food waste of early farmers”, isn’t quite as satisfying an explanation as others I’ve read for how dogs are different from wolves. However, I think it does explain why the domestication of dogs is so much more ancient than the domestication of cats. Dogs—socially, behaviorally, ecologically, and physiologically more similar to us than cats—were just easier to domesticate.
A completely domesticated cat wouldn’t be of much utility anyway. I didn’t appreciate this until the neighborhood started emptying out. I’ve got four empty houses next to mine, and there are many more around within a two minute walk. Some are well maintained by investors who think the houses are going to suddenly be worth five times their current worth some time soon. (We’ve lost 80% of our property value in this neighborhood in the last few years.) They’re delusional, but they probably won’t lose their shirts because they all picked the houses up extremely cheap.
Anyway, some of these houses aren’t maintained at all. They’ve had windows and doors smashed in – and now the neighborhood has rats. Not a lot, not yet, but we’ve got some. I feed a group of feral cats around my house for just such a reason. The steady food keeps them near me, but their instincts all say “HUNT!” So every now and then I step out the door or come home from somewhere and one of them is eating a nice juicy rat in the front yard. Nicely done, kittens! If they were completely domestic I just don’t think they’d bother with the hunt with a steady supply of food. Note that I only feed them when they show up, I don’t leave food out. They have to come to me to get the free food.
I’ll also note that dogs are completely useless in this regard. My neighbor has pitbulls, and complained that he had rats in his shed. He almost – ALMOST – thanked me the other day because my cats got the rats. But he’s scared of cats, so he couldn’t quite bring himself to do it. But his dogs didn’t do anything about the rats. They’ll eat cats though. Or children. But those are other stories.
(And yes, I’ve seen enough of the carcasses to know they’re rats, clearly not squirrels because of the tails, and not possums either.)
Razib Khan blogged on this, pointing out that the study appears to be oriented towards Western breeds, and that there is evidence that the American Indians domesticated dogs before agriculture. It may be a romantic notion, but its easy to imagine dog-wolves forming hunting partnerships with man, particularly if either became isolated from their own group.
I have never been satisfied with the garbage dump theory. Wolves are pack animals. There would be a pack of wolves around the garbage dump, and a pack of wolves would not limit themselves to garbage.
I think the genes are due to living around humans. It probably started with wolf puppies being captured for entertainment, and it evolved from there.
At this point the estimated timeframe for the domestication of dogs is something like 15,000-20,000 years ago. Not only does that predate agriculture, it probably predates the ancestors of today’s American Indians coming to North America.
However, even that doesn’t rule out the hypothesis. The practice of horticulture goes back much farther than the practice of agriculture. Hunting and gathering bands even today scatter seeds in the expectation that when they return to the area later in the season there’ll be a crop to harvest. There’s evidence of that practice going back long before systematic agriculture.
” they were completely domestic I just don’t think they’d bother with the hunt with a steady supply of food. ”
The cats I had in the past still hunted even though they had a steady supply. So do the two dogs I have now. Dogs vary widely in how strong is their hunting instinct.
One thing about this study that interests me but the article does not mention: If dogs have the genes to digest starch is the advice to use pet food made of meat instead of grains still valid?
Dave, I was going to argue that such early horticulture surely would not have entailed what we would commonly consider “starchy” foods, particularly wheat. But in checking my timelines, I ran across this gated article that identifies a site in Israel where grain flour appeared to be baked in an oven-like hearth, 12,000 years before wheat and barley were domesticated:
http://www.nature.com/nature/journal/v430/n7000/full/nature02734.html
So the timeline might be reasonable, but the notion of dogs scavenging still seems far fetched. The gathering and processing of these plants into a food source would seem to be extremely energy intensive for there to be much waste; more likely biscuits were taken on the hunt and shared with the dog/wolf.
It’s been quite a few years since I read the Braidwoods’ books on early horticulture and agriculture but the gist of what they found was that horticulture goes way back.
Look at all the more-or-less modern people using stone age technologies. Rice, corn, and others all utilized on a pre-agricultural basis.
I believe I’m stuck on the specific reference to “wheat” in the linked article though the gated study refers to adaptation to a “starch rich” diet. The words “wheat” and “starch-rich” all imply agriculture to me and thus after the neolithic revolution, whenever it occurred in a given location. Otherwise, it wouldn’t seem at all likely that wolf/dogs or humans would be producing enough “wheat” or having a “starch-rich” diet to have a transformative effect on DNA. I understand hunter/gatherers would have engaged in planting seeds (either knowingly or unknowingly) that would have enhanced the gathering of fruits and vegetables. Maybe the claim is to starch-rich nuts and tubers?
I’m not disputing the science of the article I’ve not read. I just wonder if the dietary transformation is simply a later consequence of much earlier social adaptations.
Emmer and einkorn wheat are known to have been items in the diet of humans for at least 75,000 years, long before the development of agriculture. For those of you who are wondering, that’s the date of the earliest coprolites (fossilized feces) found to date.