THE MIND OF A GARDENING ANT.
ACOLONY of gardening ants has now been established for more than a year in the insect house at the Zoo. They came from Trinidad, originally in two colonies, bat the queen of one died. The two communities were then persuaded to join, and have fed up their queen to the dimensions of a house-spider. The rest of the society consists of small yellow working ants, and big policemen ants with large heads. The latter keep the others to their work, and act as foremen. If a ray of sunshine comes in on a cold day, and a dozen workers stop and " loaf " in the warmth, the foremen soon run up and send them about their business, if necessary carrying them some part of the way in their months.
The work in which these creatures are mainly occupied is cutting out circular discs of rose-leaf, about the size of the top of a pencil, and carrying them across a long bridge to the nest, to make their garden. As they carry these upright, or sloping over their heads, they have been called "parasol ants." But as they do this when there is no sun at all, it is clear that it is convenience, not shelter from sun, which suggests the ,position. Arrived at the nest, they go through the whole of the astonishing agricultural operations which Mr. Belt described in the "Naturalist in Nicaragua," and of which Herr Alfred Millen collected a number of similar examples among other South American ants. They pulp the rose-leaves, roll them into balls, and heap them in masses in the nest. On these " mushroom-beds " grows a fungus or inonld, and on this the ants live. The mushroom-bed, and the process of preparation and growth, may be seen through the glass top of the box. Mr. Belt, after clearly describing the object of these labours, reserves his opinion as to the intelligence which directs them. "Many of these actions," he writes, "such as those of two relays of workmen to carry out the ant-food, can scarcely be blind instinct ; " and he gives instances of the mistakes made by the ante and of their correction. But he prefers to state the facts, which can now be seen in concrete form at the Z0, rather than to hazard a theory to account for them.
The interesting question suggested by the activities of the gardener ant is whether it consciously uses its intelligence, or, if not, how far " instinct " and reason are working side by side. In endeavouring to solve it, we are confronted at the outset with this difficulty, that the insect mind works on lines remote from our own experience, and exhibits its methods by indications very hard for us to interpret. The aloofness of the insect mind from apprehension by vertebrates' brains per- plexes all inquirers. We can range ourselves side by side with the constructive bird, or the engineering beaver. There is sympathy between us and them both in intelligence and feelings. But the mute and expressionless being which animates the metallic shell of some social insect lives out of re- lation to our lines of thought. Man and dog may take common action on the same grounds but we cannot see practical problems eye to eye with an ant. Our sympathy and common share in the emotions of birds and beasts has very largely helped us to infer their intellectual processes. The border line where love, fear, wants, and desires originate action is common to us with them ; and we know that many animals also share with us the aesthetic sense. In endeavouring to under- stand the process of thought in insects we have to subtract the whole of this common ground, and to approach the subject almost—not quite—as if it were working in a different medium. What we do know of their senses seems in some instances to keep us at this impossible distance. Physical inquiry accentuates these differences. We know, for instance, that the compound eyes of many insects must present objects to them in a different form from that in which we see them. Some ants have no eyes at all, yet go about their daily business quite as well as if they saw. Sir John Lubbock's experiments show that they can smell; but, on the other hand, they cannot hear,—or, rather, do not hear the sounds which we hear. They are also mute ; but it is quite likely that they utter sounds which we cannot hear. Thus the human world of sounds is non-existent for the ant, and very pro- bably the ant brain is busy with sounds which are non- existent for us. At the same time they have a different quality of sight, which, if transferred to us, would make us unable to find the Nelson Column in Trafalgar Square. The result of the gap between the mind of the man who observe% and the mind of the insect whose activities he watches, has always tended to produce one of two contradictory forms of in- terpretation. The first was to assume that, because social bees or ants were engaged in exactly the same activities as human communities, their minds were practically the same as our own ; that, in fact, there was something equivalent to human intelligence of a very high order, with necessarily corre- sponding moral qualities, in the bee, and that for the purposes of this life there was, in fact, a tiny " soul " in each working member of the hive. This soul, if the conclusions of the early naturalists are examined, is clearly a human intelli- gence metamorphosed. This assumption would explain quite logically the astonishing and incredible perfection of the material aide of the life of social insects. It also accounted for the apparently moral ideas of subordination, self-sacrifice, and devotion to duty which their life exhibits. The difficulty in its acceptance was the limitation of this intelligence to a narrow class of actions, outside which this astonishingly brilliant intellect ceased to work at all, and the absence of any evidence beyond that set of acts to show the processes of thought. This absence of evidence of any thought originating and directing the work of social insects led also to an exactly opposite conclusion. The actions performed demanded so much mental power, and the evidence of mental action was so slight, and our powers of apprehending functions so aloof from our sensations so limited, that the whole of their complicated life and actions was set down as purely automatic. Every action ascribable to reason, from the making of the hexagonal cell of the honey-bee, in which the utmost carrying capacity is obtained with the least expenditure of material, to the making of "mushroom-beds" by the parasol ants, is thus ascribed to blind obedience to inherited instinct, or knowledge "prior to experience." In the light of this conclusion, the ants which make such admirable dwellings and storehouses that they arrest the germination of seeds, or, when needed, permit them to sprout and undergo the exact chemical change needed to turn them into ants' food, and arrest this again at the proper stage, and whose cities are peopled with dependants living on the "crumbs which fall from their table "—there are three hundred species of such ant parasites in Germany alone—are to-day as brainless as the newly hatched cuckoo, which, when still blind and naked, at once addresses itself to the task of ejecting its fellow-nestlings.
Both the one and the other of these extreme views are, we think, due mainly to the initial difficulty of apprehend- ing the mental processes of insects in the absence of the signs and tokens by which we understand the working of the brain of vertebrates. It is as if we were trying to receive a message in aerial telegraphy on a sensitive plate wrongly set. That we can see no evidence of conscious organisation, or of the transmission of ideas, is not the slightest evidence that work undertaken jointly is not concerted. In the case of bees and ants there is evidence of communication by contact and touch ; but many of the more important acts of the com- munity are done without visible communication. There is not the slightest reason to conclude from this that they do not communicate. Two wrens are building a nest in a bank. They settle, without conversation of any kind, that they will make the whole of the outside of dead leaves, to match other masses of dead leaves which have been drifted into corners of the bank. The same pair of wrens next year make their neat in a haystack, and decide to make the whole exterior of hay, to match the surroundings. It is an intellectual process, understood by both, carried into action jointly, and without visible communication. Two years ago some bees swarmed near Holkham Park. The whole swarm took flight, and traversed the park at a considerable height, followed by their owner, who kept them well in sight. They flew on, over the tree-tops, until they came over a certain oak, when the whole flight dropped like a flock of starlings, and entered a small hole leading into a hollow in this tree. They went "in a bee-line" for the tree from the hive in the garden whence they came. No one could possibly credit that there was not some bee to take them there, who had been there before, or that the swarm did not know what they were doing. This was one of the very rare instances in which our senses suggest what was probably in the minds of the insects. But what of the thousand instances in which this is at present hidden from us ? Another source of error, which supports the theory that insects are machines "wound up to go of themselves," is the fictitious appearance of mechanism, and the likeness to automata which well-organised industrial work usually presents, whether carried on by men or insects. When the object is purely material—and this is the case in a bee-hive as much as in an engineering shop or a pin factory—the more perfect the organisation the more automatic it appears to be. A dozen men, at similar machines, going through the same movements, or thirty girls rolling cigarettes, if seen through a diminishing glass reducing them to the size of white ants, would look very mechanical crea- tures indeed. An enlarged ant, with a pair of unimproved eyes, looking down on thousands of acres of Indian paddy fields, with brown-skinned creatures creeping about all day mending little banks, and going at night into little huts on bigger banks, might easily conceive them mere unintelligent insects, working successfully, on some inherited but now per- fectly unintelligent system, to prolong their existence, increase, and multiply.
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