According to De FraviÈre, Landois, and some other observers, bees have a number of different notes, or tones, whereby they communicate information to one another;[59] but there seems to be little doubt that the means chiefly employed are gestures made with the antennÆ. For example, Huber divided a hive into two chambers by means of a partition: great excitement prevailed in the half of the hive deprived of the queen, and the bees set to work to build royal cells for the creation of a new queen. Huber then divided a hive in exactly the same manner, with the difference only that the screen, or partition, was made of trellis work, through the openings of which the bees on either side could pass their antennÆ. Under these circumstances the bees in the queenless half of the hive exhibited no disturbance, nor did they construct any royal cells: the bees in the other, or separated, half of the hive were able to inform them that the queen was safe.

Turning now to ants, the extent to which the power of communicating by signs is here carried cannot fail to strike us as highly remarkable. In my work on Animal Intelligence I have given many observations by different naturalists on this head, the general results of which I will here render.

When we consider the high degree to which ants carry the principle of co-operation, it is evident that they must have some means of intercommunication. This is especially true of the Ecitons, which so strangely mimic the tactics of military organization. “The army marches in the form of a rather broad and regular column, hundreds of yards in length. The object of the march is the capture and plunder of other insects, &c., for food; and as the well-organized host advances, its devastating legions set all other terrestrial life at defiance. From the main column there are sent out smaller lateral columns, the component individuals of which play the part of scouts, branching off in various directions, and searching about with the utmost activity for insects, grubs, &c., over every log, under every fallen leaf, and in every nook and cranny where there is any chance of finding prey. When their errand is completed, they return into the main column. If the prey found is sufficiently small for the scouts themselves to manage, it is immediately seized, and carried back to the main column; but if the amount is too large for the scouts to deal with alone, messengers are sent back to the main column, whence there is immediately despatched a detachment large enough to cope with the requirements.... On either side of the main column there are constantly running up and down a few individuals of smaller size and lighter colour than the other ants, which seem to play the part of officers; for they never leave their stations, and while running up and down the outsides of the column, they every now and again stop to touch antennÆ with some member of the rank and file, as if to give instructions. When the scouts discover a wasps’-nest in a tree, a strong force is sent out from the main army, the nest is pulled to pieces, and all the larvÆ carried to the rear of the army, while the wasps fly around defenceless against the invading multitude. Or, if the nest of any other species of ant is found, a similarly strong force—or perhaps the whole army—is deflected towards it, and with the utmost energy the innumerable insects set to work to sink shafts and dig mines till the whole nest is rifled of its contents. In these mining operations the ants work with an extraordinary display of organized co-operation; for those low down in the shafts do not lose time by carrying up the earth which they excavate, but pass the pellets to those above; and the ants on the surface, when they receive the pellets, carry them—with an appearance of forethought which quite staggered Mr. Bates—only just far enough to insure that they shall not roll back again into the shaft, and, after depositing them, immediately hurry back for more. But there is not a rigid (or merely mechanical) division of labour: the work seems to be performed by intelligent co-operation amongst a host of eager little creatures; for some of them act at one time as carriers of pellets, and at another as miners, while all shortly afterwards assume the office of conveyers of the spoil.”[60]

Mr. Belt writes:—“The Ecitons and most other ants follow each other by scent, and I believe they can communicate the presence of danger, of booty, or other intelligence to a distance by the different intensity or qualities of the odours given off. I one day saw a column running along the foot of a nearly perpendicular tramway cutting, the side of which was about six feet high. At one point I noticed a sort of assembly of about a dozen individuals that appeared in consultation. Suddenly one ant left the conclave, and ran with great speed up the perpendicular face of the cutting without stopping.... On gaining the top of the cutting, the ants entered some brushwood suitable for hunting. In a very short time the information was communicated to the ants below, and a dense column rushed up in search of prey.”

Again, Mr. Bates writes:—“When I interfered with the column, or abstracted an individual from it, news of the disturbance was quickly communicated to a distance of several yards to the rear, and the column at that point commenced retreating.”

On arriving at a stream of water, the marching column first endeavours to find some natural bridge whereby to cross it. Should no such bridge be found, “they travel along the bank of the river until they arrive at a flat sandy shore. Each ant now seizes a bit of dry wood, pulls it into the water and mounts thereon. The hinder rows push the front ones farther out, holding on to the wood with their feet and to their comrades with their jaws. In a short time the water is covered with ants, and when the raft has grown too large to be held together by the small creatures’ strength, a part breaks itself off, and begins the journey across, while the ants left on the bank pull the bits of wood into the water, and work at enlarging the ferry-boat until it breaks again. This is repeated as long as an ant remains on shore.”[61]

So much, then, to give a general idea of the extent to which co-operation is exhibited by Ecitons—a fact which must be taken to depend upon some system of signs. Turning next to still more definite evidence of communication, Mr. Hague, the geologist, writing to Mr. Darwin from South America, says that on the mantel-shelf of his sitting-room there were three vases habitually filled with fresh flowers. A nest of red ants discovered these flowers, and formed a line to them, constantly passing upwards and downwards between the mantel-shelf and the floor, and also between the mantel-shelf and the ceiling. For several days in succession Mr. Hague frequently brushed the ants in great numbers from the wall to the floor, but, as they were not killed, the line again reformed. One day, however, he killed with his finger some of the ants upon the mantel-shelf. “The effect of this was immediate and unexpected. As soon as those ants which were approaching arrived near to where their fellows lay dead and suffering, they turned and fled with all possible haste. In half an hour the wall above the mantel-shelf was cleared of ants. During the space of an hour or two the colony from below continued to ascend until reaching the lower bevelled edge of the shelf, at which point the more timid individuals, although unable to see the vase, somehow became aware of the trouble, and turned without further investigation; while the more daring advanced hesitatingly just to the upper edge of the shelf, when, extending their antennÆ and stretching their necks, they seemed to peep cautiously over the edge until they beheld their suffering companions, when they too turned and followed the others, expressing by their behaviour great excitement and terror. An hour or two later the path or trail leading from the lower colony to the vase was entirely free from ants.... A curious and invariable feature of their behaviour was that when an ant, returning in fright, met another approaching, the two would always communicate; but each would pursue its own way, the second ant continuing its journey to the spot where the first ant had turned about, and then following that example. For some days after this there were no ants visible on the wall, either above or below the shelf. Then a few ants from the lower colony began to reappear; but instead of visiting the vase, which had been the scene of the disaster, they avoided it altogether, and, following the lower front edge of the shelf to the tumbler standing near the middle, made their attack upon that with precisely the same result.”

Lastly, Sir John Lubbock made some experiments with the express purpose of testing the power of communication by ants. He found that if an ant discovered a deposit of larvÆ outside the nest, she would return to the nest, and, even though she might have no larvÆ to show, was able to communicate her need of assistance—a number of friends proceeding to follow her as a guide to the heap of larvÆ which she had found.

In one very instructive experiment Sir John arranged three parallel pieces of tape, each about two and a half feet long: one end of each piece of tape was attached to the nest, and the other dipped into a glass vessel. In the glass at the end of one of the tapes he placed a considerable number of larvÆ (300 to 600): in the glass at the end of another of the pieces he put only two or three larvÆ, while the third glass he left empty. The object of the empty glass was to see whether any of the ants would come to the glass under such circumstances by mere accident. He then took two ants, one of which he placed in the glass with the many larvÆ, and the other in the glass with the few. Each ant took a larva, carried it to the nest, then returned for more, and so on. After each journey he put another larva in the glass with the few larvÆ, in order to replace the one which had been removed. The result of the experiment was that during 47½ hours the ants which had gone to the glass containing numerous larvÆ brought 257 friends to their assistance, while during 53 hours those which had gone to the glass containing only two or three larvÆ brought only 82 friends; and no single ant came to the glass which contained no larva. Now, as all the glasses were exposed to similar conditions, and as the roads to the first two must, in the first instance at all events, have been equally scented by the passage of ants over them, these results appear very conclusive as proving some power of definite communication, not only that larvÆ are to be found, but even where the largest store is to be met with.

As to the means of communication, or method of sign-making, there can be no doubt that this in ants, as in bees, is mainly gestures made by the antennÆ; but that gestures of other kinds are also employed is sufficiently well proved by the following observation of the Rev. Dr. M’Cook. “I have seen an ant kneel down before another and thrust forward the head, drooping quite under in fact, and lie there motionless, thus expressing as plainly as sign-language could, her desire to be cleansed. I at once understood the gesture, and so did the supplicated ant, for she at once went to work.”

So much, then, for the power of sign-making displayed by the Hymenoptera. As I have not much evidence of sign-making in any of the other Invertebrata,[62] I shall pass on at once to the Vertebrata.

Ray observed the different tones used by the common hen, and found them uniformly significant of different ideas, or emotional states; therefore we may properly regard this as a system of language, though of a very rudimentary form. He distinguishes altogether nine or ten distinct tones, which are severally significant of as many distinct emotions and ideas—namely, brooding, leading forth the brood, finding food, alarm, seeking shelter, anger, pain, fear, joy or pride in having laid an egg. Houzeau, who independently observed this matter, says that the hen utters at least twelve significant sounds.[63]

Many other cases could be given among Birds, and a still greater number among Mammals, of vocal tones being used as intentionally significant of states of feeling and of definite ideas; but to save space I will only render a few facts in a condensed form.

“In Paraguay, the Cebus azarÆ when excited utters at least six distinct sounds, which excite in other monkeys similar emotions (Rengger).... It is a more remarkable fact that the dog, since being domesticated, has learned to bark in at least four or five distinct tones: ... the bark of eagerness, as in the chase; that of anger, as well as growling; the yelp, or howl of despair, when shut up; the baying at night; the bark of joy when starting on a walk with his master; and the very distinct one of demand or supplication, as when wishing for a door or window to be opened.”[64]

I may next briefly add allusions to those instances of the use of signs by mammals which are fully detailed in Animal Intelligence.

Mr. S. Goodbehere tells me of a pony which used to push back the inside bolt of a gate in its paddock, and neigh for an ass which was loose in the yard beyond; the ass would then come and push up the outside latch, thus opening the gate and releasing the pony (p. 333).

With respect to gestures, Mrs. K. Addison wrote me of her jackdaw—which lived in a garden, and which she usually supplied with a bath—reminding her that she had forgotten to place the bath, by coming before her and going through the movements of ablution upon the ground (p. 316).

Youatt gives the case of a pig which was trained to point game with great precision (pp. 339, 340), and this, as in the case of the dog, implies a high development of the sign-making faculty. Every sportsman must know how well a setter understands its own pointing, and also the pointing of other dogs, as gesture-signs. As regards its own pointing, if at any distance from the sportsman, the animal will look back to see if the “point” has been noticed; and, if it has, the point will be much more “steady” and prolonged than if the animal sees that it has not been observed. As regards the pointing of other dogs, the “backing” of one by another means that as soon as one dog sees another dog point he also stands and points, whether or not he is in a position to scent the game. In my previous work, while treating of artificial instincts, I have shown (as Mr. Darwin had previously remarked) that in well-bred sporting dogs a tendency to “back,” more or less pronounced, is intuitive. But I have also observed among my own setters that even in cases where a young dog does not show any innate disposition to “back,” by working him with other dogs for a short time he soon acquires the habit, without any other instruction than that which is supplied by his own observation. I have also noticed that all sporting dogs are liable to be deceived by the attitude which their companions strike when defÆcating; but this is probably due to their line of sight being so much lower than that of a man, that slight differences of attitude are not so perceptible to them as to ourselves.

Major Skinner writes of a large wild elephant which he saw on a moonlight night coming out of a wood that skirted some water. Cautiously advancing across the open ground to within a hundred yards of the water, the animal stood perfectly motionless—the rest of the herd, still concealed in the wood, being all the while so quiet and motionless that not the least sound proceeded from them. Gradually, after three successive advances, halting some minutes after each, he moved up to the water’s edge, in which however he did not think proper to quench his thirst, but remained for several minutes listening in perfect stillness. He then returned cautiously and slowly to the point at which he had issued from the wood, whence he came back with five other elephants, with which he proceeded, somewhat less slowly than before, to within a few yards of the tank, where he posted them as patrols. He then re-entered the wood and collected the whole herd, which must have amounted to between eighty and a hundred, and led them across the open ground, with the most extraordinary composure and quiet, till they came up to the five sentinels, when he left them for a moment and again made a reconnaissance at the edge of the tank. At last, being apparently satisfied that all was safe, he turned back, and obviously gave the order to advance; “for in a moment,” says Major Skinner, “the whole herd rushed to the water, with a degree of unreserved confidence so opposite to the caution and timidity which had marked their previous movements, that nothing will ever persuade me that there was not rational and preconcerted co-operation throughout the whole party”—and so, of course, some definite communication by signs (p. 401).

With regard to the use of gesture-signs by cats, I have given such cases as those of their imitating the begging of a terrier on observing that the terrier received food in answer to this gesture (p. 414); making a peculiar noise on desiring to have a door opened, which, if not attended to, was followed up by “pulling one’s dress with its claws, and then, having succeeded in attracting the desired attention, it would walk to the street door and stop there, making the same cry until let out” (p. 414); also of a cat which, on seeing her friend the parrot “flapping its wings and struggling violently up to its knees in dough,” ran upstairs after the cook to inform her of the catastrophe—“mewing and making what signs she could for her to go down,” till at last “she jumped up, seized her apron, and tried to drag her down,” so that the cook did go down in time to save the bird from being smothered. This gesture-sign of pulling at clothing, in order to induce one to visit a scene of catastrophe, is of frequent occurrence both in cats and dogs. Several instances are likewise given of cats jumping on chairs and looking at bells when they want milk (this being intended as a sign that they desire the bell pulled to call the servant who brings the milk), placing their paws upon the bell as a still more emphatic sign, or even themselves ringing the bell (p. 416).

Concerning gesture-signs made by dogs (other than pointing), I may allude to a terrier which I had, and which when thirsty used to signify his desire for water by begging before a wash-stand, or any other object where he knew that water was habitually kept. And Sir John Lefroy, F.R.S., gave me a similar, though still more striking, case of his terrier, which it was the duty of a maid-servant to supply with milk. One morning this servant was engaged on some needlework, and did not supply the milk. “The dog endeavoured in every possible way to attract her attention and draw her forth, and at last pushed aside the curtain of a closet, and, although never having been taught to fetch or carry, took between his teeth the cup she habitually used, and brought it to her feet” (p. 466). Another case somewhat similar is given on the same page.

Again, Mr. A. H. Browning wrote me:—“My attention was called to my dog appearing in a great state of excitement, not barking (he seldom barks) but whining, and performing all sorts of antics (in a human subject I should have said gesticulating). The herdmen and myself returned to the sty; we caught but one pig, and put him back; no sooner had we done so, than the dog ran after each pig in succession, brought him back to the sty by the ear, and then went after another, until the whole number were again housed” (p. 450).

Further, I give an observation of my own (p. 445) on one terrier making a gesture-sign to another. Terrier A being asleep in my house, and terrier B lying on a wall outside, a strange dog, C, ran along below the wall on the public road following a dog-cart. Immediately on seeing C, B jumped off the wall, ran upstairs to where A was asleep, woke him up by poking him with his nose in a determined and suggestive manner, which A at once understood as a sign: he jumped over the wall and pursued the dog C, although C was by that time far out of sight, round a bend in the road.

On page 447 I give, on the authority of Dr. Beattie, the case of a dog which saved his master’s life (who had fallen through the ice, and was supporting himself with a gun placed across the opening), by running into a neighbouring village, and pulling a man by the coat in so significant a manner that he followed the animal and rescued the gentleman. Many cases more or less similar to this one are recorded in the anecdote books.

Concerning the use of gesture-signs by monkeys, I give on page 472 the remarkable case recorded by James Forbes, F.R.S., of a male monkey begging the body of a female which had just been shot. “The animal,” says Forbes, “came to the door of the tent, and, finding threats of no avail, began a lamentable moaning, and by the most expressive gestures seemed to beg for the dead body. It was given him; he took it sorrowfully in his arms and bore it away to his expecting companions. They who were witnesses of this extraordinary scene resolved never again to fire at one of the monkey race.”

Again, Captain Johnson writes of a monkey which he shot upon a tree, and which then, as he says, “instantly ran down to the lowest branch of a tree, as if he were going to fly at me, stopped suddenly, and coolly put his paw to the part wounded, covered with blood, and held it out for me to see. I was so much hurt at the time that it has left an impression never to be effaced, and I have never since fired a gun at any of the tribe. Almost immediately on my return to the party, before I had fully described what had passed, a Syer came to inform us that the monkey was dead. We ordered the Syer to bring it to us; but by the time he returned the other monkeys had carried the dead one off, and none of them could anywhere be seen” (p. 475).

And Sir William Hoste records a closely similar case. One of his officers, coming home after a long day’s shooting, saw a female monkey running along the rocks, with her young one in her arms. He immediately fired, and the animal fell. On his coming up, she grasped her little one close to her breast, and with her other hand pointed to the wound which the ball had made, and which had entered above her breast. Dipping her finger in the blood and holding it up, she seemed to reproach him with having been the cause of her pain, and also of that of the young one, to which she frequently pointed. “I never,” says Sir William, “felt so much as when I heard the story, and I determined never to shoot one of these animals as long as I lived” (p. 476).

Lastly, as proof that the more intelligent of the lower animals admit of being taught the use of signs of the most conventional character (or most remote from any natural expression of their feelings and ideas), I may allude to the recent experiments by Sir John Lubbock on “teaching animals to converse.” These experiments consisted in writing on separate and similar cards such words as “bone,” “water,” “out,” “pet me,” &c., and teaching a dog to bring a card bearing the word expressive of his want at the time of bringing it. In this way an association of ideas was established between the appearance of a certain number and form of written signs, and the meaning which they severally betokened. Sir John Lubbock found that his dog learnt the correct use of those signs.[65] Of course in these experiments marks of any other kind would have served as well as written words; for it clearly would be absurd to suppose that the dog could read the letters, so as mentally to construct them into the equivalent of a spoken word, in any such way as a child would spell b-o-n-e, bone. But, all the same, these experiments are of great interest as showing that it falls within the mental capacity of the more intelligent animals to appreciate the use of signs so conventional as those which constitute a stage of writing above the drawing of pictures, and below the employment of an alphabet.

Enough has now been said to prove incontestably that animals present what I have called the germ of the sign-making faculty. As the main object of these chapters is to estimate the probability of human language having arisen by way of a continuous development from this germ, we may next turn to take a general survey of human language in its largest sense, or as comprising all the manifestations of the sign-making faculty.

Referring again to the schema (page 88), it is needless to consider cases 1 and 2, for evidently these are on a psychological level in man and animals. Case 3, also, especially in the direction of its branch 4, is to a large extent psychologically equivalent in men and animals: so far as there is any difference it depends on the higher psychical nature of man being much more rich in ideas which find their natural expression in gestures or tones, and which, therefore, are impossible in brutes. But it will be conceded that here there is nothing to explain. The fact that man has a mind more richly endowed with ideas carries with it, as a matter of course, the fact that their natural expression is more multiplex.

The case, however, is different when we arrive at conventional signs; for these attain so enormous a development in man as compared with animals, that the question whether they do not really depend on some additional mental faculty, distinct in kind, becomes fully admissible.

The first thing, then, we have to notice with regard to conventional signs as used by man is, that no line of strict demarcation can be drawn between them and natural signs; the latter shade off into the former by gradations, which it becomes impossible to detect over large numbers of individual cases. With respect to tones, for example, it cannot be said, in many instances, whether this and that modulation, which is now recognized as expressive of a certain state of feeling, has always been thus expressive, or has only become so by conventional habit; although, if we consider the different tones by which different races of mankind express some of their similar feelings, we may be sure that in these cases one or other of the differences must be due to conventional habit—just as in the converse cases, in which all mankind use the same tones to express the same feelings, we may be sure that this mode of expression is natural. And so with gestures. Many which at first sight we should, judging from our own feelings alone, suppose to be natural—such, for instance, as kissing—are shown by observation of primitive races to be conventional; while others which we should probably regard as conventional—such, for instance, as shrugging the shoulders—are shown by the same means to be natural.[66]

But for our present purposes it is clearly a matter of no consequence that we should be able to classify all signs as natural or conventional. For it is certain that animals employ both; and hence no distinction between the brute and the man can be raised on the question of the kind of signs which they severally employ as natural or conventional. This distinction, therefore, may in future be disregarded, and natural and conventional signs, if made intentionally as signs, I shall consider as identical. For the sake of method, however, I shall treat the sign-making faculty as exhibited by man in the order of its probable evolution; and this means that I shall begin with the most natural, or least conventional, of the systems. This is the language of tone and gesture.