It is hardly needful to say that those mammals, which stand at the very top of the animal world and most approach man by their structure and intelligence, are eminently sociable. Evidently we must be prepared to meet with all varieties of character and habits in so great a division of the animal kingdom which includes hundreds of species. But, all things considered, it must be said that sociability, action in common, mutual protection, and a high development of those feelings which are the necessary outcome of social life, are characteristic of most monkeys and apes. From the smallest species to the biggest ones, sociability is a rule to which we know but a few exceptions. The nocturnal apes prefer isolated life; the capuchins (Cebus capucinus), the monos, and the howling monkeys live but in small families; and the orang-outans have never been seen by A.R. Wallace otherwise than either solitary or in very small groups of three or four individuals, while the gorillas seem never to join in bands. But all the remainder of the monkey tribe—the chimpanzees, the sajous, the sakis, the mandrills, the baboons, and so on—are sociable in the highest degree. They live in great bands, and even join with other species than their own. Most of them become quite unhappy when solitary. The cries of distress of each one of the band immediately bring together the whole of the band, and they boldly repulse the attacks of most carnivores and birds of prey. Even eagles do not dare attack them. They plunder our fields always in bands—the old ones taking care for the safety of the commonwealth. The little tee-tees, whose childish sweet faces so much struck Humboldt, embrace and protect one another when it rains, rolling their tails over the necks of their shivering comrades. Several species display the greatest solicitude for their wounded, and do not abandon a wounded comrade during a retreat till they have ascertained that it is dead and that they are helpless to restore it to life. Thus James Forbes narrated in his Oriental Memoirs a fact of such resistance in reclaiming from his hunting party the dead body of a female monkey that one fully understands why "the witnesses of this extraordinary scene resolved never again to fire at one of the monkey race."(22) In some species several individuals will combine to overturn a stone in order to search for ants' eggs under it. The hamadryas not only post sentries, but have been seen making a chain for the transmission of the spoil to a safe place; and their courage is well known. Brehm's description of the regular fight which his caravan had to sustain before the hamadryas would let it resume its journey in the valley of the Mensa, in Abyssinia, has become classical.(23) The playfulness of the tailed apes and the mutual attachment which reigns in the families of chimpanzees also are familiar to the general reader. And if we find among the highest apes two species, the orang-outan and the gorilla, which are not sociable, we must remember that both—limited as they are to very small areas, the one in the heart of Africa, and the other in the two islands of Borneo and Sumatra have all the appearance of being the last remnants of formerly much more numerous species. The gorilla at least seems to have been sociable in olden times, if the apes mentioned in the Periplus really were gorillas.
We thus see, even from the above brief review, that life in societies is no exception in the animal world; it is the rule, the law of Nature, and it reaches its fullest development with the higher vertebrates. Those species which live solitary, or in small families only, are relatively few, and their numbers are limited. Nay, it appears very probable that, apart from a few exceptions, those birds and mammals which are not gregarious now, were living in societies before man multiplied on the earth and waged a permanent war against them, or destroyed the sources from which they formerly derived food. "On ne s'associe pas pour mourir," was the sound remark of Espinas; and Houzeau, who knew the animal world of some parts of America when it was not yet affected by man, wrote to the same effect.
Association is found in the animal world at all degrees of evolution; and, according to the grand idea of Herbert Spencer, so brilliantly developed in Perrier's Colonies Animales, colonies are at the very origin of evolution in the animal kingdom. But, in proportion as we ascend the scale of evolution, we see association growing more and more conscious. It loses its purely physical character, it ceases to be simply instinctive, it becomes reasoned. With the higher vertebrates it is periodical, or is resorted to for the satisfaction of a given want—propagation of the species, migration, hunting, or mutual defence. It even becomes occasional, when birds associate against a robber, or mammals combine, under the pressure of exceptional circumstances, to emigrate. In this last case, it becomes a voluntary deviation from habitual moods of life. The combination sometimes appears in two or more degrees—the family first, then the group, and finally the association of groups, habitually scattered, but uniting in case of need, as we saw it with the bisons and other ruminants. It also takes higher forms, guaranteeing more independence to the individual without depriving it of the benefits of social life. With most rodents the individual has its own dwelling, which it can retire to when it prefers being left alone; but the dwellings are laid out in villages and cities, so as to guarantee to all inhabitants the benefits and joys of social life. And finally, in several species, such as rats, marmots, hares, etc., sociable life is maintained notwithstanding the quarrelsome or otherwise egotistic inclinations of the isolated individual. Thus it is not imposed, as is the case with ants and bees, by the very physiological structure of the individuals; it is cultivated for the benefits of mutual aid, or for the sake of its pleasures. And this, of course, appears with all possible gradations and with the greatest variety of individual and specific characters—the very variety of aspects taken by social life being a consequence, and for us a further proof, of its generality.(24)
Sociability—that is, the need of the animal of associating with its like—the love of society for society's sake, combined with the "joy of life," only now begins to receive due attention from the zoologists.(25) We know at the present time that all animals, beginning with the ants, going on to the birds, and ending with the highest mammals, are fond of plays, wrestling, running after each other, trying to capture each other, teasing each other, and so on. And while many plays are, so to speak, a school for the proper behaviour of the young in mature life, there are others, which, apart from their utilitarian purposes, are, together with dancing and singing, mere manifestations of an excess of forces—"the joy of life," and a desire to communicate in some way or another with other individuals of the same or of other species—in short, a manifestation of sociability proper, which is a distinctive feature of all the animal world.(26) Whether the feeling be fear, experienced at the appearance of a bird of prey, or "a fit of gladness" which bursts out when the animals are in good health and especially when young, or merely the desire of giving play to an excess of impressions and of vital power—the necessity of communicating impressions, of playing, of chattering, or of simply feeling the proximity of other kindred living beings pervades Nature, and is, as much as any other physiological function, a distinctive feature of life and impressionability. This need takes a higher development and attains a more beautiful expression in mammals, especially amidst their young, and still more among the birds; but it pervades all Nature, and has been fully observed by the best naturalists, including Pierre Huber, even amongst the ants, and it is evidently the same instinct which brings together the big columns of butterflies which have been referred to already.
The habit of coming together for dancing and of decorating the places where the birds habitually perform their dances is, of course, well known from the pages that Darwin gave to this subject in The Descent of Man (ch. xiii). Visitors of the London Zoological Gardens also know the bower of the satin bower-bird. But this habit of dancing seems to be much more widely spread than was formerly believed, and Mr. W. Hudson gives in his master-work on La Plata the most interesting description, which must be read in the original, of complicated dances, performed by quite a number of birds: rails, jacanas, lapwings, and so on.
The habit of singing in concert, which exists in several species of birds, belongs to the same category of social instincts. It is most strikingly developed with the chakar (Chauna chavarris), to which the English have given the most unimaginative misnomer of "crested screamer." These birds sometimes assemble in immense flocks, and in such cases they frequently sing all in concert. W.H. Hudson found them once in countless numbers, ranged all round a pampas lake in well-defined flocks, of about 500 birds in each flock.
"Presently," he writes, "one flock near me began singing, and continued their powerful chant for three or four minutes; when they ceased the next flock took up the strains, and after it the next, and so on, until once more the notes of the flocks on the opposite shore came floating strong and clear across the water—then passed away, growing fainter and fainter, until once more the sound approached me travelling round to my side again."
On another occasion the same writer saw a whole plain covered with an endless flock of chakars, not in close order, but scattered in pairs and small groups. About nine o'clock in the evening, "suddenly the entire multitude of birds covering the marsh for miles around burst forth in a tremendous evening song…. It was a concert well worth riding a hundred miles to hear."(27) It may be added that like all sociable animals, the chakar easily becomes tame and grows very attached to man. "They are mild-tempered birds, and very rarely quarrel"—we are told—although they are well provided with formidable weapons. Life in societies renders these weapons useless.
That life in societies is the most powerful weapon in the struggle for life, taken in its widest sense, has been illustrated by several examples on the foregoing pages, and could be illustrated by any amount of evidence, if further evidence were required. Life in societies enables the feeblest insects, the feeblest birds, and the feeblest mammals to resist, or to protect themselves from, the most terrible birds and beasts of prey; it permits longevity; it enables the species to rear its progeny with the least waste of energy and to maintain its numbers albeit a very slow birth-rate; it enables the gregarious animals to migrate in search of new abodes. Therefore, while fully admitting that force, swiftness, protective colours, cunningness, and endurance to hunger and cold, which are mentioned by Darwin and Wallace, are so many qualities making the individual, or the species, the fittest under certain circumstances, we maintain that under any circumstances sociability is the greatest advantage in the struggle for life. Those species which willingly or unwillingly abandon it are doomed to decay; while those animals which know best how to combine, have the greatest chances of survival and of further evolution, although they may be inferior to others in each of the faculties enumerated by Darwin and Wallace, save the intellectual faculty. The highest vertebrates, and especially mankind, are the best proof of this assertion. As to the intellectual faculty, while every Darwinist will agree with Darwin that it is the most powerful arm in the struggle for life, and the most powerful factor of further evolution, he also will admit that intelligence is an eminently social faculty. Language, imitation, and accumulated experience are so many elements of growing intelligence of which the unsociable animal is deprived. Therefore we find, at the top of each class of animals, the ants, the parrots, and the monkeys, all combining the greatest sociability with the highest development of intelligence. The fittest are thus the most sociable animals, and sociability appears as the chief factor of evolution, both directly, by securing the well-being of the species while diminishing the waste of energy, and indirectly, by favouring the growth of intelligence.
Moreover, it is evident that life in societies would be utterly impossible without a corresponding development of social feelings, and, especially, of a certain collective sense of justice growing to become a habit. If every individual were constantly abusing its personal advantages without the others interfering in favour of the wronged, no society—life would be possible. And feelings of justice develop, more or less, with all gregarious animals. Whatever the distance from which the swallows or the cranes come, each one returns to the nest it has built or repaired last year. If a lazy sparrow intends appropriating the nest which a comrade is building, or even steals from it a few sprays of straw, the group interferes against the lazy comrade; and it is evident that without such interference being the rule, no nesting associations of birds could exist. Separate groups of penguins have separate resting-places and separate fishing abodes, and do not fight for them. The droves of cattle in Australia have particular spots to which each group repairs to rest, and from which it never deviates; and so on.(28) We have any numbers of direct observations of the peace that prevails in the nesting associations of birds, the villages of the rodents, and the herds of grass-eaters; while, on the other side, we know of few sociable animals which so continually quarrel as the rats in our cellars do, or as the morses, which fight for the possession of a sunny place on the shore. Sociability thus puts a limit to physical struggle, and leaves room for the development of better moral feelings. The high development of parental love in all classes of animals, even with lions and tigers, is generally known. As to the young birds and mammals whom we continually see associating, sympathy—not love—attains a further development in their associations. Leaving aside the really touching facts of mutual attachment and compassion which have been recorded as regards domesticated animals and with animals kept in captivity, we have a number of well certified facts of compassion between wild animals at liberty. Max Perty and L. Buchner have given a number of such facts.(29) J.C. Wood's narrative of a weasel which came to pick up and to carry away an injured comrade enjoys a well-merited popularity.(30) So also the observation of Captain Stansbury on his journey to Utah which is quoted by Darwin; he saw a blind pelican which was fed, and well fed, by other pelicans upon fishes which had to be brought from a distance of thirty miles.(31) And when a herd of vicunas was hotly pursued by hunters, H.A. Weddell saw more than once during his journey to Bolivia and Peru, the strong males covering the retreat of the herd and lagging behind in order to protect the retreat. As to facts of compassion with wounded comrades, they are continually mentioned by all field zoologists. Such facts are quite natural. Compassion is a necessary outcome of social life. But compassion also means a considerable advance in general intelligence and sensibility. It is the first step towards the development of higher moral sentiments. It is, in its turn, a powerful factor of further evolution.