Although certain species of insects, particularly the ants, have the well-developed habit of subjugating certain creatures of their own family, man is the only vertebrate that has ever adopted the plan of domesticating a variety of animals and plants. The beginnings of this custom were made in a very remote time, and for long ages the profit which was thereby gained appears to have been but slight. Gradually, however, races, owing to their masterful quality and to the opportunities which were offered by the wild life about their dwelling places, obtained flocks and herds. In the group of continents commonly termed the old world, where there were several ancient primitive peoples of innate ability, and where there were many species of larger mammals which were well fitted for domestication, the advance in social development went on rapidly. In the new world, though the primitive races contained tribes of much ability, there was practically no chance for the people to add to their strength by the subjugation of beasts of burden, or to their food resources by the adoption of various animals which could be used for the needs of food or raiment. The advance of men when they have obtained valuable domesticated animals, and their failure to win a high station where the surrounding nature denied such opportunities, go far to prove the bearing of this accomplishment in the development of peoples. A little consideration makes it evident to us that the advance of mankind above the original savage state is in several ways favored by the possession of domesticated animals. In the first place, each creature which is adopted into the household or the fields usually brings as its tribute a substantial contribution to the resources which tend to make the society commercially successful. When we consider the enlargements of resources and the diversification of industries which rest upon the adoption of any one of these animals--as, for instance, the horse--we see in a way what the possession of domesticated animals and plants really means, and are in a position to conceive, though at best but dimly, what the scores of these captive species have done for us. We recognize the fact that while, under almost any conditions, a certain manner of advance above the most primitive savagery is possible to a naturally able people, this on-going cannot lead any distance unless the folk have other help than their own weak bodies can give them. It is hardly too much to say that civilization has intimately depended on the subjugation of a great range of useful species.