domination of the world by the Aryan race is said to have been largely due to their utilization of horse power. The conquest of Peru was made much easier because of horses. The Incas were terrified at the mounted soldiers; and, according to the records, horses were as effective in the conquest as superior weapons. Although in modern conditions of warfare cavalry is of less consequence than formerly, it is still valuable where fighting is in the open. And the employment of horses and mules behind the lines is still so advantageous that it is difficult to see how they can ever be entirely displaced. For scientific purposes. In recent years entirely new ways have been discovered for utilizing animals in the service of mankind. Through our observation and examination of them our knowledge of anatomy and of heredity has been greatly advanced; and in addition, through animal experimentation, great progress has been made in medicine and surgery. Some of the notable discoveries made or perfected through animal experimentation have been the anti-toxin of diphtheria, septic methods in surgery, methods of transfusion of blood, and the serum for cerebro-spinal meningitis. Where animals have been used for experimentation, they have in the great majority of cases been subjected to no pain; sometimes they have been inoculated with disease germs; and occasionally direct pain has been inflicted. But animals are after all less valuable than human beings, and the sacrifice of a few has been the means of restoring the health and preserving the lives of countless human beings. Dr. Flexner perfected his serum for meningitis by experiments upon twenty-five monkeys and one hundred guinea pigs, and this serum restores to health hundreds of human beings each year. After a discovery has once been made the gain to humanity is perpetual. The result has been regarded as so important that scientists have even offered themselves for experimentation for the good of humanity in cases where experiments upon animals would not suffice. Animals are used also for the production of the serums and vaccines used in the treatment of human diseases. For the destruction of pests. Another utilization of animal 1 W. W. Keen, Animal Experimentation and Medical Progress. life, gradually being extended, is the destruction of noxious animals through the introduction, or deliberate increase, of harmless varieties which feed upon them. From the earliest times domestic animals, such as the dog and the cat, and occasionally wild species, such as the snake and the toad, have been used to exterminate vermin; but the extensive employment of wild animals as pest exterminators had to wait more accurate knowledge of their life habits. At present birds are most commonly used in this way. Sufficient study has now been made to enable us to distinguish in most cases between the desirable and undesirable species; and we are beginning deliberately to protect and encourage the multiplication of those species which feed on destructive worms and insects. Large birds, such as hawks and owls, - more than fifty species in all, — feed on rodents; and smaller birds, such as cuckoos, woodpeckers, and flickers, feed on caterpillars and insects, including destructive ants. Bluejays destroy the nests of the brown tail moth. Vireos and many varieties of warblers protect the foliage of trees by consuming small insects. And tiny birds, such as chickadees and titmice, do their part by industriously hunting small insects, larvae, and eggs of insects. Birds which are definitely known to do more harm than good are comparatively few in numbers. They include seven kinds of hawks, several species of owls, and the golden eagle. The wanton killing of birds has resulted in enormous losses to crops through the spread of pests which birds ordinarily consume. A few reptiles are useful for the same purposes as are the birds, and it is even possible that harmless insects can more frequently be employed to destroy other species that are injurious to plant life. The introduction of a new animal into the environment is attended, however, with considerable risk for it sometimes destroys the balance of animal life, or the animal produces unfortunate results by developing unexpected feeding habits. The introduction of the English sparrow is an illustration of an undesirable addition to bird life. Other animals have been even more objectionable. The rabbit, after its introduction into Australia as a new food, multiplied so rapidly that it became a destructive pest, and much labor had to be expended conse quently to protect vegetation. In some sections it actually became a question whether the rabbits or the human inhabitants would survive. Another notable example is that of the introduction of the mongoose into Jamaica to rid the plantations of rats. It succeeded in its mission so quickly that soon it was forced to seek other kinds of food and began to exterminate useful animals and even to feed on the sugar cane itself which it was supposed to protect. In introducing an animal into a district to eliminate a pest, we seldom consider what that animal will feed upon if it is successful in its mission. Nor do we always realize that an animal apparently undesirable may after all be feeding on other animals or insects still more objectionable. The complete feeding habits of an animal must be known before sentence can be pronounced against it. With more adequate knowledge of the life habits of the lower animals, however, it is possible that we shall be able to create a balance of life among them more nearly in accord with our welfare. In this way we shall be utilizing the lower animals without being obliged to domesticate them. For aesthetic and social enjoyment. Finally it should be added that both plants and animals are used to contribute to our aesthetic enjoyment; and animals, and in a sense even plants also, are made to add to our social pleasures and to companionship. The cultivation of flowering and of other plants for decorative purposes has become a great industry. And the pleasure and healthful enjoyment which many people derive from the private cultivation of plants cannot be ignored. The use of animals and animal products for decorative purposes presents a more difficult problem. Of these products a few are obtained only through the cruel and inhuman destruction of animal life, - sacrifices which, by the way, are not followed by the priceless benefits that result from the sacrifice of animals for the advancement of science. Only those products which are obtained without inflicting injury are proper materials for aesthetic uses. The uses of animals for pets, for companionship, and even for protection, are of noteworthy importance to social life, and are open to few objections provided the animals selected are capable of undergoing the restraints of captivity, and also provided the animals themselves are kept in a healthy state. Most of the evil results come from neglected animals, although cats are ruthless destroyers of valuable birds unless they are more carefully confined than is usually the case. The use of the ordinary domestic animals for pets is so common as to need only a passing mention; but the possible use of wild animals for this purpose is not generally realized. Several birds, as for instance the chickadee, and a few wild animals as well, are really friendly by nature and may be partially tamed, especially in the season when their natural food supply is scarce. Mutual service can be rendered, and the acquaintance may be made the source of great pleasure and educational profit. Inasmuch as the bird is left in its natural environment, free to follow its natural habits, it does not become a care, nor does it suffer from the restraints of captivity. If this new method of making pets should be developed it would extend the sphere of association between man and animals to include many new species, would help to safeguard valuable species, and would also add the benefit to be derived from association on terms of equality. Association between man and domesticated animals is on the basis of superiority and subordination, the animal being molded to the will of the master. Friendship with wild animals would require study of their habits, exercise of patience, and a consideration of their likes and dislikes, which would open a new and wholesome chapter in the relationship of man with some of the humbler species that serve him. 1 REFERENCES FOR COLLATERAL READING to Man and CHAPTER X THE STRUGGLE OF GROUPS The Human Environment. Turning now to the third division of economic phenomena, the relation of man to the human environment, we enter the general province of social selection as distinct from natural selection. The same sharp distinction appears between the struggle phase and the utilization phase in the relationship to the human environment, but both are more complicated in their action. The struggle of men with one another is obviously of two kinds: the struggle between groups, and the struggle between individuals within a group. Both forms lead to a selective process, which Pearson calls autogeneric selection. In its less intensive forms this struggle leads to social gradations, and to the division of labor. The phenomena connected with group struggle will be considered first. Causes of Group Conflict. Group conflict has been almost universal, except with the few peoples who have been isolated from their neighbors by physical barriers. The explanation of group conflict is, briefly stated, that when groups realize that their interests are dissimilar they separate and make war, and when they feel that their interests are similar they coöperate or coalesce. Now the degree of unity in interests between peoples has ordinarily varied with economic organization and with means of communication. As economic life progresses in form and as means of communication improve, the attitude of nations towards one another changes, the lines of friendship and of enmity are shifted, and new alliances are formed. And the course of warfare itself has been from petty conflicts of small groups to organized struggles of large nations, or groups of nations. Eventual subsidence of all war will depend upon whether mankind can ever be made to feel a unity of interests |