Part 2

“I see no reason for denying intelligence to animals ranking below Man in the scale. Both the lower animals and the human species possess what are called instincts, which are said to act spontaneously, without the aid of reasoning. No animal, indeed, possesses a greater number of instincts than Man.

“But if the distinction between instinct and intelligence is to be based on the employment of conscious reasoning or intelligence, this faculty cannot be denied to the lower animals, because I believe that many of them do exercise a power of reasoning, i. e., of drawing conclusions from observation.

“Natural history books are full of instances of exhibitions of intelligence by Dogs, Cats, Elephants, Horses and many other creatures. It is true that some naturalists insist that all of the apparently intentional and reasoned acts of such creatures are merely manifestations of instinct, or unconscious responses to external stimuli, but all naturalists are not of that opinion.”

No, they are not.

Prof. S. J. Holmes says: “Psychologists nowadays with comparatively few exceptions agree in regarding intelligence not as a faculty standing in sharp contrast to instinct, as was formerly taught, but as one resting on a foundation of instinct, and gradually growing out of behavior of the purely instinctive type. The term intelligence is used here in the wider sense as embracing all those forms of profiting by experience through the formation of associations. It therefore includes psychic activity ranging from simple associative memory to complex trains of reasoning.”

Paley, in his “Natural Theology,” defines instinct as “a propensity prior to experience and independent of instruction”; while Spencer (“Principles of Psychology”) states that instinct is a “compound reflex action,” which is terse, if not explanatory.

Hartmann’s “purposeful action without consciousness of the purpose” is a contradiction in terms. “Purpose” implies consciousness of end in view. One cannot readily believe that when an Orang-utan builds its platform or “nest” in the boughs of a tree in the jungle it does not purpose (intend) to rest and sleep on it; or that when a Beaver cuts down a tree in such wise that it invariably falls in the direction of its need it does not know that it is constructing a hut to live in that will meet the requirements of the situation in a running stream.

Dr. Wm. T. Hornaday, in his authoritative recent work, “The Minds and Manners of Wild Animals,” (1922) says:

“Instinct is the knowledge or impulse which animals or men derive from their ancestors by inheritance, and which they obey, either consciously or subconsciously in working out their own preservation, increase and betterment. Instinct often functions as a sixth sense.”

Again: “While avoiding the folly of idealism, we also must shun the ways of the narrow mind, and the eyes that refuse to see the truth. Wild animals are not superhuman demigods of wisdom; but neither are they idiots, unable to reason from cause to effect along the simple lines that vitally affect their existence.... Some animals have more intelligence than some men; and some have far better morals.”

Nevertheless, it is still “correct” to say: “Man alone possesses reason.” Fundamentalists, and even many scientists, find this phrase acceptable. The “Age of Reason” began with the appearance of Man on earth, according to orthodox views. “Instinctive behavior” explains--for many scientists--all acts even of such highly organized creatures as Ants, Bees and Wasps. Below this come “tropisms”--obligatory movements made by the organism as a whole in response to the varied stimuli of its environment.

Then we have the category of “purely reflex” actions of the organism--the definite but unconscious reaction of the organism to stimulation of certain nerve-cells.

In the higher microscopic organisms it is admitted that any one of several reactions to a given stimulus might occur, the organism “trying” (unconsciously) one reaction after another, on the hit or miss, or “trial and error” method. Man, of course, learns by some faculty other than “trial and error”--maybe.

Finally, and lowest in the scale of animal evolution, we come to the Amœba, a unicellular organism apparently lacking even in a rudimentary nervous system. But this microscopic speck of carnivorous protoplasm seeks and pursues its zigzagging prey!

While there is no proof that psychic life begins only with pluricellular animals, thus denying any sort of consciousness of purpose to even the highest groups (Ciliata) among unicellular organisms (Protozoa), it must be admitted that no conclusive evidence of the presence of mind in these lowly organisms has yet been presented. I shall therefore turn at once to the Metazoa (many-celled animals) for examples of the intelligence of Invertebrates; beginning with the lowest in which manifestations of mind are said to appear, namely, the Earthworm.

FOOTNOTES:

Cf. Loeb, Jacques, “Comparative Physiology of the Brain and Comparative Psychology,” New York, 1900.

For an excellent discussion of this problem see Holmes, Prof. S. J., “The Evolution of Animal Intelligence,” Pages 63-89, New York, 1911; and Jennings, Prof. H. S., “Behavior of Lower Organisms,” New York, 1906. See also, Day and Bentley, “A Note on Learning in Paramœcium,” Journal of Animal Behavior, 1, 67, 1911; and Watkins, G. P., “Psychical Life in Protozoa,” American Journal of Psychology, 11, 166, 1900.

Italics mine.

EARTHWORMS

In the preceding introduction it was stated that a certain degree of intelligence had been attributed to animals as low in the scale of evolution as Earthworms. No less an authority than Charles Darwin was responsible for this conclusion. This great naturalist had observed that these lowly creatures had developed the peculiar habit of plugging up their burrows with dead leaves. He noted that leaves were drawn into the burrows by methods best suited to their particular shape. For example, linden leaves were drawn in by their tips, while no attempt was made to pull in leaves of the rhododendron by this method, these leaves being larger at the tip than at their base. On the other hand, pine needles, which frequently occur in pairs, with a common base, were never seized by the small end, since the separated ends of the needles would cause trouble. They were invariably attacked at the compact basal end, which is smaller than the mouth of the burrow.

“Instinct” may guide Worms in this nice discrimination. But Darwin tested them with materials unknown to them or to their ancestors. He cut up paper into triangular forms and placed it at the disposal of the Worms. To his astonishment the brainless creatures almost invariably seized the bits of paper by the most acute angle in carrying them to their burrows. Darwin therefore concluded that an intelligent choice of means to end had been made. Similar experiments were later made by Hanel, and Darwin’s results were verified; but the apparently intelligent reactions of the Worms were interpreted as “more or less complex reflexes in relation to the form and chemical nature of the objects drawn in.” As to which of these two interpretations is more in harmony with the observations, I leave to the reader’s own judgment.

Generally speaking, it is probably best to accept the guiding principle formulated by Prof. Lloyd Morgan, namely, “In no case may we interpret an action as the outcome of the exercise of a higher psychical faculty, if it can be interpreted as the outcome of one which stands lower in the psychological scale.”

Darwin’s conclusion seems to be justified by some experiments quite recently carried out by Professor Heck of the University of Prague, who gathered together for his purpose some five hundred Worms. The Worms were introduced into a passage shaped like a capital T, carved from a block of wood, and covered with a glass plate so that the movements of the animals might be watched. When they came to the junction, about half of them turned one way and half the other. Then the apparatus was arranged so that those Worms which took the left-hand passage received a mild but probably disagreeable shock. At first they did not seem to know what to make of this; but after they had all been through the experience about 200 times, they nearly all took the right-hand turn. When the electrodes were then moved to the right-hand passage, the Worms learned to shift to the left-hand after only 65 trials--evidently showing something beyond the operation of mere chance.

Commenting on this attitude of Earthworms to learn by experience, a writer in The Scientific American (April, 1924) remarks:

“In the human sense, Earthworms have no brains; their nervous systems consist of a series of little ganglions, or nerve centers, on the under side of the Worms and connected with each other by nerve fibers. If the Worms were cut in two, the fragments still showed the ability to distinguish between the safe and the unpleasant road to travel, indicating that the Earthworm remembers in every one of its ganglions, and that it is able to learn and profit by experience.”

In other words, the phenomena of associative memory, hence the capacity to learn by experience, seems to occur not only in animals devoid of cerebral hemispheres--long regarded as the sole seat of intelligence--but in organisms possessing no cerebro-spinal nervous system. In Invertebrates the mechanisms which allow associative memory “will probably be found in the supra-œsophageal ganglion” (Loeb).

“The Earthworm has no specialized sense organs, it has neither eyes to see, nor nose to smell, nor ears to hear with. Still, although it is apparently deaf, it is not devoid of the power of appreciating those stimuli which in us excite the sensation of sight or smell. A strong light suddenly turned on the anterior end of the body will cause the Worm instantaneously to withdraw into its burrow, and Worms readily recognize the presence of such favorite food as onions and raw meat. Their sense of touch is well developed and they are very sensitive to vibrations; for instance, a stamp of the foot on the ground will cause all those in a certain radius to disappear into their burrows. It is further possible that Earthworms possess other senses with which we are totally unacquainted.”