Dog Sense (11 page)

The persistence of the dingo-keeping tradition in Australia suggests that, in the absence of (or sometimes in spite of) practical considerations, humans will keep puppies purely for their cuteness. Dingoes are clearly a drain on human resources—not an asset. Originally, scientists speculated that Aboriginal Australians kept dingoes to serve as hunting companions, but in fact dingoes interfere with hunting, to the point that Aboriginals bring home more meat if they leave their dingoes
behind. Furthermore, dingoes often outnumber the human inhabitants of a village and accordingly have to compete for food; their scavenging can be so intense that they have to be deliberately excluded from meal times. Nevertheless, the habit of taming large numbers of these animals has persisted for hundreds, probably thousands of years, so they must have some redeeming features in the eyes of their hosts. Indeed, dingoes feature more in the Aboriginals' art and spiritual narratives than any other animal, with the possible exception of snakes. Although respect for dingoes of all ages has long been encapsulated in Aboriginal culture, the habit of keeping young dingoes must surely have started as an exaggerated susceptibility to the cuteness of puppies.

It thus seems entirely possible that, in one or two locations, perhaps twenty thousand years ago, there were hunter-gatherer groups in which wolf cubs taken from the wild came to have a social significance similar to that of contemporary hunter-gatherer's pets. The feeding and care of the young wolves, so difficult to account for if their parents had been merely scavengers, would instead have been performed by the villagers, initially for their own enjoyment and subsequently to gain social esteem—much as, for example, the keeping of monkeys as pets brings status to women of the Guaja. Additionally, the intimate relationship between the cub and its carer would have enabled the cub to become socialized to people as well as to its own kind—provided, of course, that it had the capacity to do both.

There is one very important way in which the dog is different from other hunter-gatherer pets. Whereas the dog eventually became domesticated, these other “pets”—from rodents to parrots to monkeys—are really just tame animals, many of whom have been raised in isolation from their own kind and probably would not know how to breed even if given the opportunity: Hence the need for these “pets” to be continually replenished from young born in the wild. The wolf, however, became domesticated because it stayed near humans by choice, forming a reciprocal relationship. For domestication to begin, a wolf would need to be raised by humans from a cub, and then stay in (or return to, but that seems unlikely) the village to produce its own first young. (Village habitation would be necessary only for the females; the cubs could just
as well be fathered by wild wolves, but it would be essential for the females to be completely tame so that the cubs could be born in the village.)
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In fact, by comparing today's wolves and dogs, we can see that dogs have adapted to human presence in a remarkable way. Perhaps the most striking difference between dogs and wolves today, apart from their appearance, is the ease with which domestic dog puppies adopt a dual identity, something today's wolf cubs seem incapable of. This capacity for the dog to adopt a dual identity—part human and part wolf—is essential in accounting for the transition from primitive pet to truly domesticated animal. Perhaps it is the key attribute that singled out the grey wolf, from all the other possible candidates among the canids, for successful domestication. Perhaps its unique transformation to domestic animal has little to do with its ability to form packs or to communicate by body language (neither of which, as we have already seen, are traits unique to the grey wolf). Perhaps the grey wolf was simply able to form social bonds with humans, whereas other canids were not.

It is entirely possible that some accident of genetics—some sort of mutation—gave a few wolves the ability to socialize to two species simultaneously, to direct their social behavior to mankind
and
to other wolves, while their sexual preferences remained steadfastly directed at their own species. Until man came along, this hereditary change would have been of no advantage (or disadvantage) to the wolves that carried it. But as hunter-gatherer societies in places where there were also wolves developed to the point where the “pet”-keeping habit became established, those local wolves with the altered socialization mechanism would have been pre-adapted for coexistence with mankind. On the one hand, then, societies that serendipitously happened to adopt wolves in the locations where their socialization mechanisms had been altered were presented with animals that could breed successfully within a man-made environment. On the other hand, societies that fixed on canids such as the golden jackal as their prototype pet of choice could tame them as individuals but could never succeed in breeding them, because their socialization mechanisms were still suited only to their original wild lifestyle.

What evidence is there for the existence of these special, easily socialized wolves? Simple: It is all around us, in the form of modern dogs.
They are the only living descendants of the socializable wolves that, I suspect, existed twenty thousand years ago. Modern wolves are, of course, quite different from the earlier wolves I'm describing; today's grey wolves are very difficult to tame, let alone socialize to people. Even tame wolves do not seem to form specific attachments to individual humans. Modern wolves, however, are not the descendants of the wolves that became dogs.

Today's dogs are, if my hypothesis is correct, the descendants of a small fraction of the original wolf population, products of a mutation that separated these wolves from the majority of their species by allowing them to socialize with both humans and other wolves. While this small fraction of wolves went on to live among humans and eventually turned into dogs, most wolves could never follow this path, because they displayed a natural wariness of man. In essence, what I am suggesting is that this ability to socialize to humans is not, as it is usually assumed, a
consequence
of domestication. Instead, I conceive it as the crucial, if accidental, pre-adaptation that opened the door to domestication in the first place.

The key difference between a dog and a wolf is not what it looks like but how it behaves, and especially how it behaves toward people. DNA and bones cannot tell us how these early dogs behaved or what their everyday interactions with people were actually like. Domestication affects outward appearance, for sure, but at the very earliest stages this is incidental. What defines an animal such as a dog is what goes on under the skin—specifically, how the behavior of its ancestors has been altered to enable it to live comfortably in man-made environments.

Although we know a great deal about the behavior of today's American timber wolves and an increasing amount about the relict wolf populations of Europe, this information gives us little insight into the behavior of the first domestic dogs. Modern wolves are only very distantly related to the domestic dog, and they have been under intensive selection pressure, especially over the past few hundred years, from those who wished to exterminate them. It is therefore unsurprising that today's wolves are very difficult to socialize, and that tame wolves tend to remain unpredictable and potentially aggressive toward people throughout their
lives. By persecuting wolves, we have selected those individuals that are naturally wary of us; it is therefore very difficult to derive any knowledge about early dogs from what we know about contemporary wolves. Moreover, we cannot even replicate domestication, by taking wolves out of the wild and selectively breeding them to become more like dogs. Since the wolves that were the direct ancestor of domestic dogs are, in their original form, extinct, that would be impossible.

One recent modification of a canid is widely held to provide pointers as to how wolves might have changed into dogs. This is the silver fox, a color variety of the wild red fox that is bred in fur-farms. Silver foxes are usually kept in cages and are barely tame, let alone domesticated, but in the 1950s a group of Russian scientists began to breed them selectively, using only the tamest individuals in each generation.
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At first, few of the foxes could be handled, even by a person offering a tasty food treat. After a few generations of breeding only from individuals that would tolerate handling, however, some individuals emerged that would actively seek contact from people. Indeed, after thirty-five generations, most of the foxes were behaving in a remarkably dog-like way—wagging their tails, whimpering to attract attention, sniffing and licking their handlers' hands and faces. Some were even taken home as pets by the staff, who reported that these animals could be as obedient and loyal as domestic dogs. The geneticists' objective of producing a fox that was easier to handle seemed to have improved its welfare too. Freed from the relentless fear and anxiety of having to encounter an alien species (us!) every day of their lives, the new “tame” farm-foxes exhibit levels of stress hormones four times lower than those in the original “wild” version. A similar reduction in reactivity, and susceptibility to stress, is evident when dogs are compared with wolves—a reduction traceable to changes in the hypothalamus, a part of the brain that is, among several functions, concerned with emotional reactivity. Such changes are probably a direct consequence of selection for tameness, so in this respect the tame farm-foxes may well be similar to the wolves that adapted to living near, and scavenging from, human settlements.

The most interesting finding of the Siberian fox experiment was that the farm-foxes became easier to tame because the period before they became frightened of new experiences was effectively lengthened.
Most young mammals go through a period of their lives in which they are naturally inquisitive and trusting. And it's usually during this stage that they're still being looked after by their parents, who are on hand to make sure that these characteristics don't get them into trouble. As they get older and more independent, the offspring become much more suspicious of anything unusual and much more likely to run away after an initial inspection. In the farm-foxes, selection for tameness corresponded with an extension of this “trusting” phase, which ends when wild foxes are about six weeks old but lasts for about nine weeks in the “tame” variety. That extra three weeks is enough to allow regular handling to take effect, producing a fox that trusts, rather than fears, the people who look after it.

Another finding of the Siberian experiment has been used to posit the effect of domestication upon canids' appearance, though this is largely unsubstantiated. The appearance of some of the tame foxes produced in the experiment is different from that of the wild variety; a few, though by no means all, of the tame foxes have unusual dog-like features, such as curly tails, floppy ears, and white patches on their coats. Some authorities have claimed that such features are part and parcel of domestication, that selection for tameness inevitably brings with it all these changes in appearance. Unfortunately the data don't support this idea. True, more “tame” foxes have floppy ears than do the “wild” ones, but they are still in a tiny minority—fewer than a quarter of 1 percent. Fewer than one in ten of the tame foxes have a curly tail. Fewer than 15 percent have a white “star” on their forehead. Exactly how these changes became slightly more common in the “tame” foxes is still something of a mystery, but they are still rare, and probably tell us little or nothing about domestication.

While the Siberian experiment produced tame foxes, there is a significant difference between these foxes and domestic dogs in terms of the extent to which they are—or, it seems, can be—“domesticated.” In dogs, the process of acclimatizing to humans does not disrupt normal social relations with other dogs. By contrast, when the foxes develop a relationship with humans they seem to lose interest in socializing with other foxes. Red foxes—the same species as the farm-fox—are rather sociable animals, often living in groups of four to six animals. Yet the
tame farm-foxes are solitary animals—as devoted as dogs but as independent as cats. This contrasts with both the domestic dog (and the domestic cat), whose social relationships can and indeed normally do develop simultaneously with humans and with members of their own species (and perhaps other species as well).

Thus if the tame foxes can tell us anything useful about the dog, it is that tameness, while a useful first step, is not the same thing as full domestication. Tameness permits the replacement of one set of social responses—directed at members of the same species—with another—directed at humans. Dogs, by contrast, need to retain both, in order to continue functioning as members of their own species while simultaneously establishing and maintaining relationships with their human owners. Nothing in the farm-fox experiment sheds any light on how this capacity might have come about during the domestication of the dog.

The farm-fox experiment does show that selection for tameness can be extremely rapid—indeed, it seems to be fast enough to suggest a plausible first stage in the domestication of the wolf. The key difference between the two animals is, of course, that the foxes were a captive, isolated population that was deliberately selected for tameness. The wolves that were sufficiently tolerant of humans, on the other hand, selected themselves to be the ancestors of domestic dogs: Those that were easily tamed could start breeding in the proximity of humans; those that could not rejoined the wild population. The appearance of dog-like behavior in the tame foxes, such as licking of humans' faces and hands, and whimpering, also supports the idea that the dog's social repertoire is drawn not from that of the wolf exclusively but, rather, from an ancestral palette of possibilities inherited from the canids as a whole.