DOG, a name common to several species of Canidae -- a family of Carnivorous Mammals widely distributed over nearly every part of the globe.
Many of the species belonging to this family, as the wolf and the jackal, are social animals, hunting in packs, and are readily tamed; while in confinement they show little or no repugnance to breeding. In a group thus eminently capable of domestication, it is not surprising that in the earliest times one or more species should have been brought under the dominion of man, or that under human care the domestic dog should have become, as Baron Cuvier calls it, "the completest, the most singular, and the most useful conquest ever made by man."
There is sufficient evidence to show that the dog existed in the domesticated state during prehistoric times; consequently neither history nor tradition is available to solve the question of its origin. That must be decided, if at all, by the naturalist, and the variety of opinion existing on this point at the present time renders it exceedingly improbable that the parentage of the dog will ever be ascertained with certainly.
Some suppose that all our breeds have sprung from a single wild source, others that they are the product of the blending of several distinct species. Of the former, the majority regard the wolf as the parent form, others favour the claims of the jackal, while a few regard them as the descendants of an extinct species, and point to the fossil remains of a large dog, found in the later Tertiary deposits, as the probable wild stock.
The prevalent belief at the present day is probably that which regards the domestic dog as the product of the crossing of several species, living and extinct. This opinion is founded on such considerations as the presence in the earliest historic time of many breeds (totally distinct from each other, and nearly resembling existing forms), the existence of wild species of dogs in all quarters of the globe, the fondness of savage man for taming wild animals, and the extreme improbability that among so many presumably equally tameable canine species only one should have been chosen for domestication.
Nor is it to be forgotten, as Darwin has well shown, that fear of man in most wild animals is a gradually acquired instinct, and that before its acquirement a wild species would have been much more readily tamed than after. Thus the wild dog of the Falkland Islands (Canis antarchicus), when these were first visited by man, approached him without sign either of fear or of aversion.
The weightiest reason for this opinion, however, lies in the fact that many of the breed of domestic dogs, found in different countries, bear a more or less striking resemblance to the wild species still existing in those countries. The Esquimaux dogs of North America so closely resemble the wolf of the same regions, both in appearance and in voice, that Sir J. Richardson on one occasion mistook a pack of those wild animals for a troop of Indian dogs; and the Indians are said to take the young of wolves in order to improve their canine breed, which would seem to prove that the dog and wolf are sufficiently fertile inter se. The Hare Indian or Mackenzie River Dog, although somewhat smaller in size than the prairie wolf (Canis latrans) occurring in the same regions, so resembles the latter that Richardson could detect no decided differences in form. It seems, in fact, to bear the same relation to the prairie wolf that the Esquimaux dog does to the great grey wolf already mentioned.
The wolf certainly exhibits few peculiarly dog-like qualities, being both ferocious and cowardly, and showing no attachment to man; but instances, nevertheless, are on record of tamed wolves which is their gentleness, in love for their masters, and in intelligence, showed true dog-like capacity. The Esquimaux dogs are likewise decidedly wolfish in disposition, showing little as no attachment to their owners an sometimes it, is said even attacking them when pressed by hunger. Distinct varieties of the wolf occur in Europe and in India, and such European breeds as the shepherd dog of Hungary so closely resemble the wolf that an Hungarian has been known to mistake that animal for one of his own dogs; while certain of the Hindu pariah dogs are said by Blyth to resemble the Indian variety of wolf. The large semi-domesticated dogs of the northern parts of both hemispheres may thus be regarded as principally derived form the various species and varieties of wolves still existing there. The period of gestation in the wolf and dog is the same, being 63 days in both.
In the tropical regions of the Old World the wolf disappears, and with it the prevalence of wolf-like dogs, their places being taken by smaller breeds, such as certain of the pariah dogs of India and of Egypt, between which and the jackals abounding in those countries no structural difference can, according to Geoffroy Saint-Hilaire, be pointed out. Their period of gestation agrees with that of the dog and wolf, and like dogs, tamed jackals when caressed "will," says Darwin, "jump about for joy, wag their tails, lower their ears, lick their masters hands, couch down and even throw themselves on the ground belly upwards;" when frightened, also, they carry their tails between their legs. Jackals associate readily with dogs, and their hybrid offspring are not sterile; there is also an instance on record of one of these which barked like an ordinary dog.
The habit of barking, so characteristic of dogs, is not, however, universal among them, the domestic dogs of Guinea and certain Mexican breeds being described as dumb. This faculty appears to be readily lost and to be capable of reacquirement. The domestic dogs which ran wild on the island of Juan Fernandez are said to have lost the power of barking in 33 years, and to have gradually reacquired it on removal from the island. The Hare Indian Dog makes an attempt at barking, which usually ends in a howl, but the young of this breed born in the Zoological Gardens seem to possess this faculty to the full extent.
In tropical America, where jackals are unknown, there are several wild species of dogs to which the domestic breeds of those regions bear a considerable resemblance, and at the present day the Arawak Indians cross their dogs with an aboriginal wild species for the purposed of improving the breed. In Australia the Dingo, regarded by many as constituting a distinct species indigenous to that country, its remains having been found in caves associated with those of other extinct mammals, occurs both in the wild state and domesticated at the present day.
Darwin, after reviewing this question, concludes that "it is highly probable that the domestic dogs of the world have descended from two good species of wolves (Canis lupus and C. latrans), and from two or three other doubtful species of wolves, namely, the European, Indian, and North African forms, from at least one or two South American canine species, from several races or species of the jackal, and perhaps from one or more extinct species."
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