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.