Two Theories of Dog Domestication

I showed this video today as an intro to my 8-week "mini-course" on Canine Cognition.

In it, narrator John Lithgow presents two slightly different versions of the dog domestication story. The first version is essentially the Belyaev story: young wolves would be adopted into the camps of early humans. Only those who were most tame would breed with eachother, and over many generations, the domestic dog would emerge. The second is the version in which wolves "chose" to be domesticated - they noticed a lot of tasty trash around human encampments, and if they were unafraid enough to hang around, they got to eat lots of leftovers, and those individuals would mate, and over generations, the domestic dog would emerge.

The two stories have quite a bit of similarities, but still have a few critical differences.

Based on what you've read on this blog so far, and elsewhere, which do you think is the more likely scenario?

As a bonus, here's my favorite John Lithgow scene, ever (Third Rock from the Sun, Season 1, Episode 1).

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Have you read the original work by Tchernov on this?

Personally, I favor a process whereby the key feature of dog domestication (vast majority of typical individuals relate well to humans and tend to NOT eat them) happens in the "wild" population.

One of the pieces of evidence adduced in the film ... that HG';s are always taking in pets ... have two problems.

1) They don't randomly take in whatever animals are out there as pets, and the degree to which it is done varies widely, etc. and 2) If humans everywhere always took in lots of wild animals all the time, there would be lots of different origins of dogs (there are not) and more other domesticated species than there are (probably).

Coppinger is closer to Tchernov than the other guys. For Tchernov, the key feature is exclusion of competitors (con specifics and interspecies) as the main attractor for wolves to human settlement. Tchernov worked in the Natufian and documented the similarities between all the different commensals (including mice, etc.).

Commensal animals and human sedentism in the Middle East
E Tchernov, C Grigson, J. BAR International. 1978 - British Archaeological Reports.

Body size diminution under domestication: Unconscious selection in primeval domesticates. Eitan Tchernov and Liora Kolska Horwitz. Journal of Anthropological Archaeology. Volume 10, Issue 1, March 1991, Pages 54-75

ETwo New Dogs, and Other Natufian Dogs, from the Southern Levant. itan Tchernova and François F. Vallab. Journal of Archaeological Science. Volume 24, Issue 1, January 1997, Pages 65-95

I'm unclear why these two theories are mutually exclusive.

Before the first humans settled down to invent farming, it would have have paid off for wolves to loiter near their camps, hunting for food, and looking to pick up the scraps the humans left unprotected. The skittish wolves would select themselves out of the competition for hunting near humans, leaving the more comfortable wolves to hunt mice, rats, snakes, frogs, lizards, nestlings, rabbits, and whatever else didn't vacate due to the humans.

As early humans moved from place to place, leaving after firewood and game dwindled, and garbage piled up. There would be a payoff in following the nomads from camp to camp, hunting on the periphery, stealing food, and eating scraps.

When humans began farming, grain plants and stores would draw in rodents, making for tasty treats for canines (and felines as well). Farmers wouldn't mind the canines (or the felines) since the animals did eat grain.

I fail to see why we would expect the "domestication" of dogs - aka our mutual evolution into interspecific relationship - to have taken a path different from the domestication of E. coli or Mus musculus. Or anything else.

We should not overlook the fact that humans overwhelmingly gather animals as food sources; domesticated animals can be controlled and bred to produce more food animals, and the dog is raised as food and eaten by many people today. Perhaps dogs were also first domesticated as food items, but humans discovered they could be trained to do a lot more. Regarding dogs as human-like and off the menu is both culturally determined and very recent. Dogs will be eaten by most anyone facing starvation.

Roast wolf. Yuck. Nothing like as yummy as a nice tasty poi dog.

Seriously, why would humans raise large carnivores as meat sources? I mean, sure, once they were dogs, yeah. Most food dogs today are smallish and easy to fatten up. But big ol' stringy vicious wolves? Seems like there are way easier food sources to breed, like chickens and rabbits.

Against the "dogs first domesticated as food" theory, you can also put the fact that dogs were domesticated (or domesticated us) many thousands of years before any of the other domestic animals.

When Europeans first settled Australia, dingoes were observed to be semi-domesticated camp followers of Aboriginal people which used to accompany them on hunts, and were helpful in locating prey.

I have had exactly this relationship with a very unfriendly kelpie sheepdog (kelpies are believed to have been cross-bred from dingoes) - on a 'personal' level she had no interest in being friendly, she showed no affection or signs of being friendly at all (farmers discourage developing affectionate attachment to humans in sheepdogs they train because they think it distracts the dogs from their work), but she was a great working dog herding sheep, and whenever I went hunting kangaroos in the rapidly darkening twilight, she was right there, she knew what I was going out to do, and she would find the feeding kangaroo mobs for me, and then lead me to the kangaroo I had shot, even repeatedly looking back at me to make sure I was following her as she located the dead animal. That dog knew exactly what she was doing - it was a partnership, an equal partnership based on mutual benefit, and mutual affection had no part in it, it was strictly business.

The contract was that she helped me find the prey and then locate the animal I had killed, and she got a portion of the kill - I got the hind legs and tail, she and her pups got the rest.

So I go for Theory 2. The wolves chose humans as companions, not the other way round - but it wasn't just a case of wait and get the scraps, it was teamwork in hunting. There was no affection permitted, if I had tried to pat her she would have taken my hand off, but it seemed to me there was companionship and some kind of mutual respect. I could be anthropomorphising that last part, but whenever I picked up my rifle and walked out the door after sunset, she would look at me like "OK, here we go, I'm in on this, right?", when the rest of the time she avoided any kind of eye contact with me or looking at my face.

By Sandgroper (not verified) on 08 Oct 2010 #permalink

Nobody has mentioned the numerous societies in which dogs are regarded as unclean and either merely tolerated or actively discouraged, but in which they hang around and scavenge anyway.

Is that recent behaviour (on the part of humans, I mean)? Or old enough to be significant?

By Ian Kemmish (not verified) on 08 Oct 2010 #permalink

RE: Wolves / Dogs as food. I don't think our ancestors were at all picky; survival mode means that everything goes into the mouth and is swallowed regardless of the "ick" factor. We were cannibals, after all! How yucky does that seem to us today? It is a matter of fact that humans will eat anything if desperate: old shoes, newspapers, dirt, rats, insects, worms, and lice, and our ancestors were desperate much of the time.

Coyotes form hunting partnerships with badgers.

Forming partnerships with other animals, such as badgers as Aaron #13 points out, has also been observed in ravens and wolves, so it would seem that the capacity for wolves, at least those that weren't too afraid, to form a kind of natural partership with humans, sounds quite believable and yet the idea that humans facilitated these relationships is quite believable as well. As is sometimes said of particular kinds of relationships we have with our significant others; "it's complicated", and complexity implies multiple interacting factors the precise implications of which we may never fully understand. It would be 'interesting' to conduct some experiments similar to the 'siberain fox' breeding experiment using other animals such as coyotes, or maybe even some primates.

Nobody has mentioned the numerous societies in which dogs are regarded as unclean and either merely tolerated or actively discouraged, but in which they hang around and scavenge anyway.

Is that recent behaviour (on the part of humans, I mean)? Or old enough to be significant?

I think that you have the answer. The eat garbage just as pigs do.

And speaking about garbage and dogs, why not have a sequential hypothesis: dogs that hung around encampments for a long time became tame enough for their pups to be then adopted.

By natural cynic (not verified) on 10 Oct 2010 #permalink

After thinking about this for 5 min, I came up with another possibility.
Among the wolves that hang around a human camp, one runs off to chase a rabbit and brings it back. A human takes the rabbit and rewards the wolf with a steady supply of scraps. The wolf learns quickly, and others copy. A mutual benefit arises.

By James Raymond (not verified) on 11 Oct 2010 #permalink

I'm confused by the dating. In the video they refer to earliest dates of canine domestication at about 10,000 to 20,000 years ago. This bothers me because it seems too short a time to explain the dramatic changes we have seen in dogs. IIRC, it takes roughly 30,000 generations for speciation to occur (rule of thumb only). Dogs can still breed with wolves, so the 30K generations rule of thumb presents an upper limit on the age of first domestication. Still, it seems obvious to me that they're getting close to that point, hence I'd expect that at least 20K generations have passed since first domestication. 20K years is therefore the absolute lower limit on first domestication -- wolves don't become sexually mature for a year after birth, and it would take some time longer for a wolf to get high enough in the social hierarchy to be able to breed, so I'd prefer a number between, say, 20K years and 50K years.

But this raises a new issue: humans were hunter-gatherers right up until the end of the ice age 10K years ago. Canine domestication took place either as part of the agrarian lifestyle or as part of the hunter-gatherer lifestyle. If canine domestication was part of the agrarian lifestyle, then it could not have begun until 10K years ago -- way too short a time period, IMO, to explain the dramatic changes in the dog's conformation. On the other hand, if it took place as part of the hunter-gatherer lifestyle, why did it wait until 20K years ago? Hominids were hunter-gatherers for a couple of million years -- what was the difference between hominid hunter-gatherers 500K years ago and hominid hunter-gatherers 20K years ago? Not much, I would think. So why did it take so long?

By Chris Crawford (not verified) on 12 Oct 2010 #permalink

Both theories make good points, and both have their drawbacks, so I doubt it's an "either/or" scenario. It's most likely a mixture of both theories. I doubt prehistoric man simply thought one day that they could use wolves as hunting partners and then raided a wild wolf den looking for submissive pups. However, Ray Coppinger's theory of wolves choosing to be domesticated and taming themselves is flawed.

First off, he talks about the difficulty of training a dog. Well, to what extent? If you want to train a dog to not jump on or chew furniture, to not pee inside, to search for narcotics or herd sheep, yeah, dog training is hard. But I doubt stone-age humans were concerned with any of that. Even the most novice dog owner can teach a puppy basics like sit and stay in a relatively short amount of time. The skills that would have interested hunter humans were already instilled into the wolves by instinct: Tracking, chasing, and killing. Humans just needed a way to have wolves do the same exact things they would do in a normal wild pack, only for humans. In this way, humans did not train wolves in the modern way we think of training. They simply took over the role of alpha for these animals and let the wolves' instincts take over. The tame wolf saw humans as its pack, therefore it hunted with its pack and it did not attack its pack. The question is then how did wolves start seeing humans as its pack instead of its competition?

A second mistake that Coppinger makes is that just because a wild animal does not run off when a human approaches it, does NOT mean it is tame. It means it does not FEAR humans, which is totally different. There are plenty of wild bears that have learned to associate humans with easy food, that don't care about coming into human territory looking for garbage and they aren't even close to tame. Humans have to charge at them with barking dogs and guns to instill fear of humans into these still dangerous and aggressive animals.

For another modern example look at present day wolves vs. wolf-dogs. Modern wolves tend to be naturally wary of humans and thus avoid them unless desperate and starving. However, wolf-dog hybrids, having been raised by humans, do not fear people, but are not necessarily as docile as domestic dogs. There is a higher rate of stray wolf-dog on human and dog attacks than among regular stray dogs simply because hybrids retain some wildness but lost their fear. And because some still retain an incredibly high prey drive, they view human children as prey, a trait that no early (or modern) human would want around. It's the reason that such hybrids are banned in some states and those people who own them have to be very experienced and extra vigilant to keep them under control. So just because the wolves weren't afraid to hang around the outskirts of human camps for leftover garbage, doesn't mean they wouldn't bite or attack a human that came too close. Maybe just the opposite since they didn't fear humans. Couldn't a lack of fear of humans over time just as easily breed fearless wolves that would venture closer to humans looking for easy food like slow and helpless human children? Just wait until the all men are out hunting and presto! Buffet time at the camp site! So clearly, there needed to be another force actively choosing for docility and tameness in these scavenger wolves.

Most likely, while hanging around for scraps, humans were able to observe their competition much closer and learned which ones would attack humans if they ventured too close. Early humans not only saw up close how well these wolves hunted and tracked, but also came to learn of their personalities: The mean ones vs the nurturing ones, the dominate ones vs the submissive ones etc. Human beings also would have appreciated how the wolves alerted them to danger approaching the area with their keener senses, so the humans had an incentive to have them hang around.

Then probably came the idea of taking in and adopting the wolves or just the pups of the wolves they had grown fond of watching as pets (again, modern humans tend to do this a lot). Favorite DOCILE adults could have gotten tossed scraps straight to them, conditioning the wolves that humans could be a direct source of good food as well, not just leftover bones. I look at stray dogs in places like Puerto Rico. While none of the strays are fearful (they won't run off if approached) not all of them are tame or voluntarily approach humans (which if Coppinger's theory was completely true, shouldn't be the case since generations of natural selection should have bred dogs that naturally trust humans). Such strays will avoid humans when possible and only venture close enough to raid garbage bins. If approached too closely by a person, they might snap instead of run. In the exact same neighborhood, other strays will walk right up to humans or hang out incredibly close to them while they eat because they are so used to getting handouts.

So some wolves that were accustomed to getting meat tossed to them would eventually learn to avoid attacking humans to keep the direct line of food coming instead of relying on hunting or picking at the bones left behind. By gaining the trust of these docile wolves, humans would have had easier access to their pups. Pups would have been adopted straight into the camp since they are easier to care for and influence. Those that were submissive to people, stayed in the camp and were bred together while those who grew up more wild or aggressive were probably culled,(since these adopted pups were probably kept separate from wild packs, there was a limited number of potential mates, and all wolves still possess the drive to reproduce; it's just that in the wild, the alphas actively discourage others from breeding). Breeding for temperament would not be an incredibly hard science for ancient humans. In this manner humans began the true domestication process by luring in the wolves in closer than they probably would have ventured in naturally and then bred for traits they wanted: docility and submissiveness. Only when docility was actively bred for would we have seen the transformation from wolf to dog. There had to be a reasonable amount of trust among the humans that a tame wolf would see a human - even a child- as a packmate. Then anything else could be viewed as prey. Once humans had their proto-dog living among them, they could point their hunting partners at an animal and let instincts take over. But none of that probably would have happened had wolves not made the first move by becoming scavengers.

I'd like to point out that so far everyone has been discussing the personality traits of the canines as determinant to which process/mix of processes happened. The personality of the primates involved was at least as determinative and still is, some folks are animal lovers & some aren't.

Most likely it was the more personable of each that actually worked on developing the relationships that evolved.

That still doesn't really explain cats but nothing ever will.

Rob Jase | October 13, 2010 2:52 PM

Heh. My guess with cats is they were attracted to small prey that raided human food stores and then hung around to breed. Kids love playing with kittens and the mature animals remembered that benign "friendship of equals" rather than forming any cooperative coalition with humans.

As for dogs the common idea that "humans domesticated dogs" sometimes seems a little off the mark to me, as strange as that might sound. Maybe stating "dogs domesticated humans" or "dogs and humans domesticated each other" might offer a useful insight into the process.

Ive lost count of the number of times I've seen a young working dog instinctively trying to "eye" humans

My two cents worth

In evolution, the internal past is eternally present. For wolves, and humans, this meant that behaviors from way back in the instinctual past could resurface, and do so quickly. The same DNA that contains the ferocity of the wolf also contains the cowering of the little mammals that scurried around the feet of dinosaurs. The rekindling of these more docile instincts may have happened quite suddenly. In other words, a wolf may have given birth to a fully formed dog.

By popdarwin (not verified) on 21 Oct 2010 #permalink

I'm with Coppinger on this. His scenario depicts a population of animals evolving; Serpell's scenario depicts a tiny number of individuals, separated by time and geography, evolving. I believe that the former is more likely.

I think, probably, the second theory is more accurate. Based on my own observations on campus cats I can easily say that the cats who are not afraid of humans are mostly the "winner"s. They have the best areas like the areas in which there are lots of restaurants. So they can eat more food. They can easily sleep inside the dormitories because people love them and let them in. They are the fattest cats I've ever seen. The cats that are afraid of humans are mostly quite skinny.
Maybe the same thing was happened to wolfves too.