For it must be remembered that a drug which should destroy some one part at an early embryonic stage, and thus prevent it from development, would prevent the creature from recognising the surroundings which affected that part when he was last alive and unmutilated, as being the same as his present surroundings. He would be puzzled, for he would be viewing the position from a different standpoint. If any important item in a number of associated ideas disappears, the plot fails; and a great internal change is an exceedingly important item. Life and things to a creature so treated at an early embryonic stage would not be life and things as he last remembered them; hence he would not be able to do the same now as he did then; that is to say, he would vary both in structure and instinct; but if the creature were tolerably uniform to start with, and were treated in a tolerably uniform way, we might expect the effect produced to be much the same in all ordinary cases.
We see, also, that any important change in treatment and surroundings, if not sufficient to kill, would and does tend to produce not only variability but sterility, as part of the same story and for the same reason—namely, default of memory; this default will be of every degree of intensity, from total failure, to a slight disturbance of memory as affecting some one particular organ only; that is to say, from total sterility, to a slight variation in an unimportant part. So that even the slightest conceivable variations should be referred to changed conditions, external or internal, and to their disturbing effects upon the memory; and sterility, without any apparent disease of the reproductive system, may be referred not so much to special delicacy or susceptibility of the organs of reproduction as to inability on the part of the creature to know where it is, and to recognise itself as the same creature which it has been accustomed to reproduce.
Mr. Darwin thinks that the comparison of habit with instinct gives “an accurate notion of the frame of mind under which an instinctive action is performed, but not,” he thinks, “of its origin.”
“How unconsciously,” Mr. Darwin continues, “many habitual actions are performed, indeed not rarely in direct opposition to our conscious will! Yet they may be modified by the will or by reason. Habits easily become associated with other habits, with certain periods of time and states of body. When once acquired, they often remain constant throughout life. Several other points of resemblance between instincts and habits could be pointed out. As in repeating a well-known song, so in instincts, one action follows another by a sort of rhythm. If a person be interrupted in a song or in repeating anything by rote, he is generally forced to go back to recover the habitual train of thought; so P. Huber found it was with a caterpillar, which makes a very complicated hammock. For if he took a caterpillar which had completed its hammock up to, say, the sixth stage of construction, and put it into a hammock completed up only to the third stage, the caterpillar simply re-performed the fourth, fifth, and sixth stages of construction. If, however, a caterpillar were taken out of a hammock made up, for instance, to the third stage, and were put into one finished up to the sixth stage, so that much of its work was already done for it, far from deriving any benefit from this, it was much embarrassed, and in order to complete its hammock, seemed forced to start from the third stage, where it had left off, and thus tried to complete the already finished work.”
I see I must have unconsciously taken my first chapter from this passage, but it is immaterial. I owe Mr. Darwin much more than this. I owe it to him that I believe in evolution at all. I owe him for almost all the facts which have led me to differ from him, and which I feel absolutely safe in taking for granted, if he has advanced them. Nevertheless, I believe that the conclusion arrived at in the passage which I will next quote is a mistaken one, and that not a little only, but fundamentally. I shall therefore venture to dispute it.
The passage runs:—
“If we suppose any habitual action to become inherited—and it can be shown that this does sometimes happen—then the resemblance between what originally was a habit and an instinct becomes so close as not to be distinguished. . . . But it would be a serious error to suppose that the greater number of instincts have been acquired by habit in one generation, and then transmitted by inheritance to succeeding generations. It can be clearly shown that the most wonderful instincts with which we are acquainted—namely, those of the hive-bee and of many ants, could not possibly have been acquired by habit.” (“Origin of Species,” p. 206, ed. 1876.) The italics in this passage are mine.
No difficulty is opposed to my view (as I call it, for the sake of brevity) by such an instinct as that of ants to milk aphids. Such instincts may be supposed to have been acquired in much the same way as the instinct of a farmer to keep a cow. Accidental discovery of the fact that the excretion was good, with “a little dose of judgement or reason” from time to time appearing in an exceptionally clever ant, and by him communicated to his fellows, till the habit was so confirmed as to be capable of transmission in full unself-consciousness (if indeed the instinct be unself-conscious in this case), would, I think, explain this as readily as the slow and gradual accumulations of instincts which had never passed through the intelligent and self-conscious stage, but had always prompted action without any idea of a why or a wherefore on the part of the creature itself.
For it must be remembered, as I am afraid I have already perhaps too often said, that even when we have got a slight variation of instinct, due to some cause which we know nothing about, but which I will not even for a moment call “spontaneous”—a word that should be cut out of every dictionary, or in some way branded as perhaps the most misleading in the language—we cannot see how it comes to be repeated in successive generations, so as to be capable of being acted upon by “natural selection” and accumulated, unless it be also capable of being remembered by the offspring of the varying creature. It may be answered that we cannot know anything about this, but that “like father like son” is an ultimate fact in nature. I can only answer that I never observe any “like father like son” without the son’s both having had every opportunity of remembering, and showing every symptom of having remembered, in which case I decline to go further than memory (whatever memory may be) as the cause of the phenomenon.
But besides inheritance, teaching must be admitted as a means of at any rate modifying an instinct. We observe this in our own case; and we know that animals have great powers of communicating their ideas to one another, though their manner of doing this is as incomprehensible by us as a plant’s knowledge of chemistry, or the manner in which an amœba makes its test, or a spider its web, without having gone through a long course of mathematics. I think most readers will allow that our early training and the theological systems of the last eighteen hundred years are likely to have made us involuntarily under-estimate the powers of animals low in the scale of life, both as regards intelligence and the power of communicating their ideas to one another; but even now we admit that ants have great powers in this respect.