When fire was invented or discovered, no doubt such dogs shared with man its comforts and its protection, and this may have strengthened their determination to throw in their lot with the mysterious beings who could create such comfort and protection for them.

While the soldier in the world war was actuated by motives of patriotism, the mainspring of the dog's service in the great conflict was dauntless fidelity to its master. Neither hazards of terrain nor of battle could stop the dumb courier when bearing a message from the front-line trenches to the keeper in the rear. The illustration shows a British war messenger dog in the front area swimming across a canal to reach his master and deliver a message.

Sooner or later man would discover that certain individual dogs were swifter or stronger than their fellows and therefore more useful in the hunt. These would be encouraged to accompany him; the others would be left at home. The less useful dogs would gradually be eliminated - driven away from the home or killed - and the swifter, stronger dogs retained. We can imagine that this process of weeding out might continue until a distinct breed of hunting dogs was developed.

As dogs were required for other purposes - for guarding property, or even for household pets - other qualities might be encouraged and other breeds evolved.

The varieties produced in different regions would be likely to differ from one another partly by reason of the difference in the wild forms from which they sprang, partly because of the difference in the lines along which they were developed.

In the inevitable intercourse between peoples from different regions there would surely be an exchange of dogs, accidental or otherwise, and the result would be new varieties which in the course of ages and under widely varying conditions, including finally selective breeding, might eventually produce the many widely differing breeds we see today.