It seems most likely that for ages the principal use of the dog which dwelt about the camps of the primitive people was found in the reserve food supply which they afforded their thriftless masters. When the hunting was successful the poor brutes had a chance to wax fat, and even in times of scarcity they managed to pick up enough food to keep them alive. When their masters were brought to a state of famine they were doubtless accustomed, as are many savages at the present time, to eat a portion of their pack. In the early conditions of humanity there was no other beast which could be made to serve so well this simple need in the way of provender. The dog is, in fact, the only animal ever domesticated which can be trusted through his own affections alone to abide with his master in the endless changes of camp and the rapid movements of flight and chase which characterized men before their housed state began. In a certain curious way the use of dogs for food has served greatly to advance the development of these captives. When the savage was driven to feed upon his dogs he was naturally more willing to sacrifice the least intelligent and affectionate of them, delaying, to the point of extremity, the time when he would kill those which had endeared themselves to him. In this way for ages a careful though unintended process of selection was applied to these creatures, and to it we may fairly attribute, as many considerate naturalists have done, a large part of the intellectual--indeed, we may say moral--elevation to which they have attained. When the place of the dog as the first and most intimate companion of man was affirmed in the rude way above described--when the savagery to which he was at first made free gradually enlarged to civilization, a number of special uses were found for the peculiar capacities of the creature. These varied in the different parts of the world, according to the peculiarities in the conditions of the masters. In high latitudes, where the ground is snow-covered during the winter season, dogs were used, as they are to this day, in dragging sleds. They were, indeed, perhaps the first animals which were harnessed to vehicles. When they were brought to serve this definite end, we may well believe that the stronger and more enduring individuals were spared in times of dearth for the reason that they were almost indispensable to their masters, and even the little forethought which we find among primitive peoples would lead to their preservation. Here again, doubtless, came in the process of unintended selection which has made the Esquimau sled-dog one of the most remarkable varieties of his kind.