In order to set forth the evidence on which is based the conclusion that the present juncture of affairs is not merely, as it very obviously is, a meeting-place of epochs in the historical series, but also marks a stage in the biological series which will prove to have been a moment of destiny in the evolution of the human species, it will be necessary to inquire somewhat closely into the biological meaning of the social habit in animals. In an earlier essay certain speculations in the same subject were indulged, and a certain amount of repetition will be necessary. The point of view then taken up, however, was different from that from which I shall now attempt to review the facts. Then the main {102} interest lay in an examination of the meaning of gre­gar­i­ous­ness for the individual mind, and although reasons enough were found for uneasiness at the course of events, and at the instability of civilization which any radical examination displayed, the inquiry was not pursued under any immediate imminence of disaster to the social fabric as it must be now. Naturally, therefore, at the present time certain aspects of the subject which before were of no special relevance become of great importance and demand close examination.

In a general view of the social habit in animals certain outstanding facts are readily to be observed. It is of wide distribution and sporadic occurrence, it varies much in the completeness of its development, and there seems to be an inverse relation between its completeness and the brain power of the animal concerned.

From the wideness of its distribution the social habit may be supposed to represent a forward step in complexity which comes about readily. It has the appearance of being upon a path which species have a natural tendency to follow, a line of evolution which is perhaps rendered possible by constantly occurring small variations common to all animals and taken advantage of only under certain circumstances of pressure or increase. It seems not to depend on any sudden large variation of type, and such is not necessary to account for it. It differs from many other modifications which we know animal life to have undergone in being immediately useful to the species from its very beginning and in its least perfect forms. Once started, however imperfectly, the new habit will have a natural tendency to progress towards fuller forms of sociality by reason of special selective forces which it inevitably sets going. The fact that it is valuable to the species in which it develops even in its most larval forms, {103} combined with its tendency to progress, no doubt accounts for the wonderful series of all degrees of gre­gar­i­ous­ness which the field of natural history presents.

I have pointed out elsewhere that the fundamental biological meaning of gre­gar­i­ous­ness is that it allows of an indefinite enlargement of the unit upon which the undifferentiated influence of natural selection is allowed to act, so that the individual merged in the larger unit is shielded from the immediate effects of natural selection and is exposed directly only to the special form of selection which obtains within the new unit.

There seems little doubt that this sheltering of the individual allows him to vary and to undergo modifications with a freedom which would have been dangerous to him as an isolated being, but is safe under the new conditions and valuable to the new unit of which he now is a part.

In essence the significance of the passage from the solitary to the gregarious seems to be closely similar to that of the passage from the unicellular to the multicellular organism—an enlargement of the unit exposed to natural selection, a shielding of the individual cell from that pressure, an endowment of it with freedom to vary and specialize in safety.

Nature has thus made two great experiments of the same type, and if one be reasonably careful to avoid arguing from analogy, it is possible to use one case to illuminate the other by furnishing hints as to what mechanisms may be looked for and in what directions inquiry may profitably be pursued.

The sporadic occurrence of gre­gar­i­ous­ness at widely separated points of the animal field—in man and sheep, in ant and elephant—inclines one to suppose that multi­cel­lu­lar­ity must have arisen also at multiple points, and that the metazoa did not arise from the protozoa by a single line of descent. It {104} suggests also that there is some inherent property in mobile living organisms that makes combination of individuals into larger units a more or less inevitable course of development under certain circumstances and without any gross variation being necessary to initiate it. The complex evolution which multi­cel­lu­lar­ity made possible, and perhaps enforced, can scarcely fail to make one wonder whether the gregarious animal has not entered upon a path which must of necessity lead to increasing complexity and co-ordination, to a more and more stringent intensity of integration or to extinction.

The varying degrees to which the social habit has developed among different animals provide a very interesting branch of study. The class of insects is remarkable in furnishing an almost inexhaustible variety of stages to which the instinct is developed. Of these that reached by the humble bee, with its small, weak families, is a familiar example of a low grade; that of the wasp, with its colonies large and strong, but unable to survive the winter, is another of more developed type; while that of the honey bee represents a very high grade of development in which the instinct seems to have completed its cycle and yielded to the hive the maximum advantages of which it is capable. In the honey bee, then, the social instinct may be said to be complete.

It is necessary to examine somewhat closely into what is denoted by the completeness or otherwise of the social habit in a given species.

To return for a moment to the case of the change from the unicellular to the multicellular, it is obvious that in the new unit, to get the full advantage of the change there must be specialization involving both loss and gain to the individual cell; one loses power of digestion and gains a special sensitiveness to stimulation, another loses locomotion {105} to gain digestion, and so forth in innumerable series as the new unit becomes more complex. Inherent, however, in the new mechanism is the need for co-ordination if the advantages of specialization are to be obtained. The necessity of a nervous system—if progress is to be maintained—early becomes obvious, and it is equally clear that the primary function of the nervous system is to facilitate co-ordination. Thus it would seem that the individual cell incorporated in a larger unit must possess a capacity for specialization, the ability to originate new methods of activity, and a capacity for response—that is, the ability to limit itself to action co-ordinated suitably to the interests of the new unit rather than to those that would have been its own if it had been a free unit in itself. Specialization and co-ordination will be the two necessary conditions for success of the larger unit, and advance in complexity will be possible as long only as these two are unexhausted. Neither, of course, will be of avail without the other. The richest specialization will be of no good if it cannot be controlled to the uses of the whole organism, and the most perfect control of the individual cells will be incapable of ensuring progress if it has no material of original variation to work on.

The analogy is helpful in the consideration of the mechanisms brought into play by the social habit. The community of the honey bee bears a close resemblance to the body of a complex animal. The capacity for actual structural specialization of the individuals in the interests of the hive has been remarkable and has gone far, while at the same time co-ordination has been stringently enforced, so that each individual is actually absorbed into the community, expends all its activities therein, and when excluded from it is almost as helpless as a part of the naked flesh of an animal {106} detached from its body. The hive may, in fact, without any very undue stretch of fantasy, be described as an animal of which all the individual cells have retained the power of locomotion. When one watches the flight of a swarm of bees its unanimity and directness very easily produce the illusion that one is witnessing the migration of a single animal usually sedentary but at times capable of undertaking journeys with a formidable and successful energy. This new animal differs from the other animals of the metazoa which it has outdistanced in the race of evolution, not merely in its immense power, energy, and flexibility, but also in the almost startling fact that it has recovered the gift of immortality which seemed to have been lost with its protozoal ancestors.

The extent to which the hive makes use of the powers of its individuals is the measure of the completeness with which the social habit is developed in it. The worker bee has practically no activities which are not directly devoted to the hive, and yet she goes about her ceaseless tasks in a way that never fails to impress the observer with its exuberant energy and even its appearance of joyfulness. It is thought that the average worker bee works herself to death in about two months. That is a fact which can scarcely fail to arouse, even in the least imaginative, at any rate a moment of profound contemplation.

If we could suppose her to be conscious in the human sense, we must imagine the bee to be possessed by an enthusiasm for the hive more intense than a mother’s devotion to her son, without personal ambitions, or doubts or fears, and if we are to judge by the imperfect experience man has yet had of the same lofty passion, we must think of her consciousness, insignificant spark as it is, as a little fire ablaze with altruistic feeling. Doubtless, such {107} an attribution of emotion to the bee is a quite unjustified fallacy of an­thro­po­mor­phism. Nevertheless, it is not altogether valueless as a hint of what social unity might effect in an animal of larger mental life. There can be little doubt that the perfection to which the communal life of the bee has attained is dependent on the very smallness of the mental development of which the individuals are capable. Their capacity to assimilate experience is necessarily from their structure, and is known by experience to be, small and their path is marked out so plainly by actual physical modifications that the almost miraculous absorption of the worker in the hive is after all perhaps natural enough. If she were able to assimilate general experience on a larger scale, to react freely and appropriately to stimuli external to the hive, there can be little doubt that the community would show a less concentrated efficiency than it does to-day. The standing miracle of the bee—her sensitiveness to the voice of the hive and her capacity to communicate with her fellows—would undoubtedly be less marvellously perfect if she were not at the same time deaf to all other voices.

When we come to consider animals in which the anatomist can recognize a brain and the psychologist an individual mind, the types of gre­gar­i­ous­ness we meet with are found to have lost the magnificent intensity of the bee. This decline in intensity seems to be due to the greatly increased variety of reaction of which the individual is capable. The gregarious mammalia are most of them relatively intelligent, they are capable of assimilating experience to a certain extent and have a definite capacity for individual existence. In them the social habit shows comparatively little tendency to a gradual intensification, but is a more static condition. Doubtless, there are other conditions {108} which also limit it. For example, the slowness of multiplication and fixity of structure in the mammalia obviously deprive them of the possibility of undergoing a continuous social integration as the insects have. Be this as it may, we find in them the social habit but little or scarcely at all expressed in physical specialization but shown as a deeply ingrained mental character which profoundly influences their habits and their modes of reaction to bodily and external impressions. Among the mammalia other than man and possibly apes and monkeys, gre­gar­i­ous­ness is found in two broadly distinguishable types according to the function it subserves. It may be either protective as in the sheep, the deer, the ox, and the horse, or aggressive as in the wolf and allied animals. In both forms it will involve certain common types of capacity, while the distinguishing characteristic of each will be a special kind of reaction to certain stimuli. It is important to understand that these peculiarities are possessed by each individual of the larger unit, and will be displayed by him in a characteristic way whether he is in the company of his fellows or not. It is not necessary to repeat here in any detail the characters of the gregarious mammal. They have been dealt with in an earlier essay, but it is desirable to emphasize here certain features of exceptional importance and some which were but little discussed before.

The quite fundamental characteristic of the social mammal, as of the bee, is sensitiveness to the voice of his fellows. He must have the capacity to react fatally and without hesitation to an impression coming to him from the herd, and he must react in a totally different way to impressions coming to him from without. In the presence of danger his first motion must be, not to fly or to attack as the case may be, but to notify the herd. This characteristic is beautifully demonstrated in the low {109} growl a dog will give at the approach of a stranger. This is obviously in no way part of the dog’s programme of attack upon his enemy—when his object is intimidation he bursts into barking—but his first duty is to put the pack on its guard. Similarly the start of the sheep is a notification and precedes any motion of flight.

In order that the individual shall be sensitive in a special degree to the voice of the herd, he must have developed in him an infallible capacity for recognizing his fellow-members. In the lower mammalia this seems almost exclusively a function of the sense of smell, as is natural enough since that sense is as a general rule highly developed in them. The domestic dog shows admirably the importance of the function of recognition in his species. Comparatively few recognize even their masters at any distance by sight or sound, while obviously with their fellows they are practically dependent on smell. The extent to which the ceremonial of recognition has developed in the dog is, of course, very familiar to every one. It shows unmistakable evidence of the rudiments of social organization, and is not the less illuminating to the student of human society for having a bodily orientation and technique which at first sight obscures its resemblance to similar, and it is supposed more dignified, mechanisms in man.

Specialization fitting the animal for social life is obviously in certain directions restrictive; that is, it denies him certain capacities and immunities which the solitary animal possesses; equally obviously is it in certain directions expansive and does it confer qualities on the social which the solitary does not possess. Among qualities of restrictive specialization are inability to live satisfactorily apart from the herd or some substitute for it, the liability to loneliness, a dependence on leadership, custom, and tradition, a {110} credulity towards the dogmas of the herd and an unbelief towards external experience, a standard of conduct no longer determined by personal needs but influenced by a power outside the ego—a conscience, in fact, and a sense of sin—a weakness of personal initiative and a distrust of its promptings. Expansive specialization, on the other hand, gives the gregarious animal the sense of power and security in the herd, the capacity to respond to the call of the herd with a maximum output of energy and endurance, a deep-seated mental satisfaction in unity with the herd, and a solution in it of personal doubts and fears.

All these characters can be traced in an animal such as the dog. The mere statement of them, necessarily in mental terms, involves the liability to a certain inexactitude if it is not recognized that no hypothesis as to the consciousness of the dog is assumed but that the description in mental terms is given because of its convenient brevity. An objective description of the actual conduct on which such summarized statements are founded would be impossibly voluminous.

The advantage the new unit obtains by aggressive gre­gar­i­ous­ness is chiefly its immense accession of strength as a hunting and fighting organism. Protective gre­gar­i­ous­ness confers on the flock or herd advantages perhaps less obvious but certainly not less important. A very valuable gain is the increased efficiency of vigilance which is possible. Such efficiency depends on the available number of actual watchers and the exquisite sensitiveness of the herd and all its members to the signals of such sentries. No one can have watched a herd of sheep for long without being impressed with the delicacy with which a supposed danger is detected, transmitted throughout the herd, and met {111} by an appropriate movement. Another advantage enjoyed by the new unit is a practical solution of the difficulties incident upon the emotion of fear. Fear is essentially an enfeebling passion, yet in the sheep and such animals it is necessarily developed to a high degree in the interests of safety. The danger of this specialization is neutralized by the implication of so large a part of the individual’s personality in the herd and outside of himself. Alarm becomes a passion, as it were, of the herd rather than of the individual, and the appropriate response by the individual is to an impulse received from the herd and not directly from the actual object of alarm. It seems to be in this way that the paralysing emotion of fear is held back from the individual, while its effect can reach him only as the active and formidable passion of panic. The gregarious herbivora are in fact timid but not fearful animals. All the various mechanisms in which the social habit shows itself apparently have as their general function a maximal sensitiveness to danger of the herd as a whole, combined with maintaining with as little interruption as possible an atmosphere of calm within the herd, so that the individual members can occupy themselves in the serious business of grazing. It must be doubted whether a truly herbivorous animal of a solitary habit could ever flourish when we remember how incessant must be his industry in feeding if he is to be properly nourished, and how much such an occupation will be interfered with by the constant alarms he must be subject to if he is to escape the attacks of carnivorous enemies. The evidence suggests that protective gre­gar­i­ous­ness is a more elaborate manifestation of the social habit than the aggressive form. It is clear that the security of the higher herbivora, such as the ox and especially the horse and their allies, is considerable in relation to the carnivora. One may {112} permissibly perhaps indulge the speculation that in the absence of man the horse possibly might have developed a greater complexity of organization than it has actually been able to attain; that the facts should seem to contain this hint is a curious testimony to the wonderful constructive imagination of Swift.

Setting aside such guesses and confining ourselves to the facts, we may say in summary that we find the infrahuman mammalia to present two distinctly separable strains of the social habit. Both are of great value to the species in which they appear, and both are associated with certain fundamentally similar types of reactive capacity which give a general resemblance of character to all gregarious animals. Of the two forms the protective is perhaps capable of absorbing more fully the personality of the individual than is the aggressive, but both seem to have reached the limit of their intensification at a grade far lower than that which has been attained in the insects.