In "Darwinism" (1889), Wallace advocates Weismann's theory of heredity. With regard to instinct, he uses arguments similar to those of his earlier work. He says of the hunting instincts of dogs: "At first sight it appears as if the acquired habits of our trained dogs—pointers, retrievers, etc.—are certainly inherited; but this need not be the case, because there must be some structural or physical peculiarities, such as modifications in the attachments of muscles, increased delicacy of smell or sight, or peculiar likes and dislikes, which are inherited; and from these, peculiar habits follow as a natural consequence, or are easily acquired." So that he thus defines instinct, by implication, as he does also in his former book, as inherited habit which has no correlative in physical organization, and is unconnected with feelings of liking or disliking. He further says: "Again, much of the perfection of instinct is due to the extreme severity of the selection, any failure involving destruction"; and adds that, even if we admit the inheritance of the effects of the direct action of the environment on the individual, the effects are so small in comparison with the amount of spontaneous variation of every part of the organism, that they must be quite overshadowed by the latter.[30] In his theory of a higher intelligence guiding human development, Wallace seems, in this book, to have abandoned all his former arguments except those from the mental and moral faculties, and it is perhaps due to a perception of the inconsistencies of his former utterances on the subject of the moral sense that he barely touches upon it in this book. On the other hand, he has elaborated his arguments from the mathematical and artistic faculties, and added an argument from wit and humor, none of which are found, he urges, among savages, except in their very rudiments, and none of which could have been developed by natural selection, since none could have been a cause of man's conquest in his struggles with wild beasts or with other tribes or nations. In answer to the objection that the law of Continuity, which he has quoted as favoring the belief in the existence of grades of supernatural beings between man and the Deity, tells against the introduction of new causes in man's development, Wallace maintains that there are certainly two other points in evolution where such new causes come into play,—namely, at the beginning of life and at the beginning of consciousness. "Increase of complexity in chemical compounds, with consequent instability, even if we admit that it may have produced protoplasm as a chemical compound, could certainly not have produced living protoplasm,—protoplasm which has the power of growth and reproduction, and of that continuous process of development which has resulted in the marvellous variety and complex organization of the whole vegetable kingdom, or, that is, vitality."[31] "All idea of mere complication of structure producing" consciousness is "out of the question." "Because man's physical structure has been developed from an animal form by natural selection, it does not follow that his mental nature, even though developed pari passu with it, has been developed by the same causes only."[32] Yet, in assuming Weismann's theory, Wallace asserts: "Whatever other causes have been at work, Natural Selection is supreme, to an extent which even Darwin himself hesitated to claim for it." "While admitting, as Darwin always admitted, the coöperation of the fundamental laws of growth and variation, of correlation and heredity, in determining the direction of lines of variation, or in the initiation of peculiar organs, we find that variation and natural selection are ever-present agencies which take possession, as it were, of every minute change originated by these fundamental causes, check or favor their further development, or modify them in countless ways according to the varying needs of the organism."[33]
In the opening portions of this book Wallace introduces a teleological argument to the effect that the pain which we ordinarily conceive as connected with the struggle for existence among lower species is mostly a figment of our imagination. Periods of suffering are comparatively short, since death speedily and without anticipation puts an end to those animals in any way incapacitated. Livingstone describes how, when seized by a lion, a sort of stupor succeeded the first shock, so that he felt neither fear nor pain; it is probable that terror induces this same condition in animals seized by beasts of prey, and that their end is therefore painless after the first shock. Cold is generally severest at night and tends to produce sleep and painless extinction. Hunger is scarcely felt during periods of excitement, "and when food is scarce, the excitement of seeking it is at its greatest." Nor is the gradual exhaustion and weakness of slow starvation necessarily painful.
FOOTNOTES:
[24] For criticism of these arguments, see Romanes, "Mental Evolution in Animals," p. 225, etc.; also "Animal Intelligence." In his second edition of this book (1891), Wallace notices a few of the instances cited by Romanes in objection to his theory: such as the recognition of the hen's call by a chicken hatched in an incubator, the fear shown, on the other hand, at the note of a hawk, and the fear exhibited by most young animals at the voice or presence of their natural enemies. Of these he says, however: "But in all these cases we have comparatively simple motions or acts induced by feelings of liking or disliking, and we can see that they may be due to definite nervous and muscular coördinations which are essential to the existence of the species. That a chicken should feel pleasure at the sound of a hen's voice, and pain or fear at that of a hawk, and should move towards the one and away from the other, is a fact of the same nature as the liking of an infant for milk and its dislike of beer, with the motion of the head towards the one and away from the other when offered to it." Of two authentic cases of the building of a nest by young birds, without instruction, he says that, in one case (that of ring-doves), the nest is a very simple one, and that the birds also received some assistance; and in the other case the nest was not built with the neatness ordinarily characteristic of the species. (See "Natural Selection and Tropical Nature," pp. 108-112.) The most of Romanes' instances and arguments he does not notice or answer.
[25] In his second edition, Wallace writes "not only innate ideas, but innate knowledge."
[26] In the second edition of this book, Wallace maintains the same position with regard to skull-measurement as a criterion of mental capacity. Nor does he notice distinctions in skull-form or the proportions of different parts of the brain to each other, except in the one case of the Eyzies.
[27] See Wallace on "Miracles and Modern Spiritualism," "The Psycho-physiological Sciences and their Assailants," and "The Scientific Aspect of the Supernatural."
[28] Wallace omits this particular clause in his second edition.
[29] The second edition reads "is, or pertains to."
[30] Pp. 442, 443.