These facts lead one to refer to the familiar circumstance that the native dogs of all regions approximate closely in size, coloration, form, and habit to the native wolf of those regions.  Of this most important circumstance there are far too many instances to allow of its being looked upon as a mere coincidence.  Sir John Richardson, writing in 1829, observed that “the resemblance between the North American wolves and the domestic dog of the Indians is so great that the size and strength of the wolf seems to be the only difference.  I have more than once mistaken a band of wolves for the dogs of a party of Indians; and the howl of the animals of both species is prolonged so exactly in the same key that even the practised ear of the Indian fails at times to discriminate between them.”

As the Eskimo and Indian dogs resemble the North American wolf, so the dog of the Hare Indians, a very different breed, resembles the prairie wolf.  Except in the matter of barking, there is no difference whatever between the black wolf-dog of the Indians of Florida and the wolves of the same country.  The same phenomenon is seen in many kinds of European dogs.  The Shepherd Dog of the plains of Hungary is white or reddish-brown, has a sharp nose, short erect ears, shaggy coat, and bushy tail, and so much resembles a wolf that Mr. Paget, who gives the description, says he has known a Hungarian mistake a wolf for one of his own dogs.  Many of the dogs of Russia, Lapland, and Finland are comparable with the wolves of those countries.  Some of the domestic dogs of Egypt, both at the present day and in the condition of mummies, are wolf-like in type, and the dogs of Nubia have the closest relation to a wild species of the same region, which is only a form of the common jackal.  Dogs, it may again be noted, cross with the jackal as well as with wolves, and this is frequently the case in Africa, as, for example, in Bosjesmans, where the dogs have a marked resemblance to the black-backed jackal, which is a South African variety.

It has been suggested that the one incontrovertible argument against the lupine relationship of the dog is the fact that all domestic dogs bark, while all wild Canidae express their feelings only by howls.  But the difficulty here is not so great as it seems, since we know that jackals, wild dogs, and wolf pups reared by bitches readily acquire the habit.  On the other hand, domestic dogs allowed to run wild forget how to bark, while there are some which have not yet learned so to express themselves.

The presence or absence of the habit of barking cannot, then, be regarded as an argument in deciding the question concerning the origin of the dog.  This stumbling block consequently disappears, leaving us in the position of agreeing with Darwin, whose final hypothesis was that “it is highly probable that the domestic dogs of the world have descended from two good species of wolf (C. 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 jackal; and perhaps from one or more extinct species”; and that the blood of these, in some cases mingled together, flows in the veins of our domestic breeds.