# Popular Science Monthly/Volume 34/April 1889/The Derivative Origin of the Human Mind

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* THE DERIVATIVE ORIGIN OF THE HUMAN MIND.
By G. J. ROMANES, F. R. S.
IF it is true that "the proper study of mankind is man," assuredly the study of nature has never before reached a territory of thought so important in all its aspects as that which in our own generation it is for the first time approaching. After centuries of intellectual conquest in all regions of the phenomenal universe, man has at last begun to find that he may apply in a new and most unexpected manner the adage of antiquity—Know thyself. For he has begun to perceive a strong probability, if not an actual certainty, that his own living nature is identical in kind with the nature of all other life, and that even the most amazing side of this his own nature—nay, the most amazing of all things within the reach of his knowledge—the human mind itself, is but the topmost inflorescence of one mighty growth, whose roots and stem and many branches are sunk in the abyss of planetary time. Therefore, with Prof. Huxley we may say: "The importance of such an inquiry is indeed intuitively manifest. Brought face to face with these blurred copies of himself, the least thoughtful of men is conscious of a certain shock, due perhaps not so much to disgust at the aspect of what looks like an insulting caricature, as to the awaking of a sudden and profound mistrust of time-honored theories and strongly rooted prejudices regarding his own position in nature, and his relations to the wider world of life; while that which remains a dim suspicion for the unthinking, becomes a vast argument, fraught with the deepest consequences, for all who are acquainted with the recent progress of anatomical and physiological sciences."
The problem, then, which in this generation has for the first time been presented to human thought, is the problem of how this thought itself has come to be. A question of the deepest importance to every system of philosophy has been raised by the study of biology; and it is the question whether the mind of man is essentially the same as the mind of the lower animals, or, having had, either wholly or in part, some other mode of origin, is essentially distinct—differing not only in degree but in kind from all other types of psychical being. And forasmuch as upon this great and deeply interesting question opinions are still much divided—even among those most eminent in the walks of science who agree in accepting the principles of evolution as applied to explain the mental constitution of the lower animals—it is evident that the ​question is neither a superficial nor an easy one. I shall, however, endeavor to examine it with as little obscurity as possible, and also, I need hardly say, with all the impartiality of which I am capable.
It will be remembered that in the introductory chapter of my previous work I have already briefly sketched the manner in which I propose to treat this question. Here, therefore, it is sufficient to remark that I began by assuming the truth of the general theory of descent so far as the animal kingdom is concerned, both with respect to bodily and to mental organization; but in doing this I expressly excluded the mental organization of man, as being a department of comparative psychology with reference to which I did not feel entitled to assume the principles of evolution. The reason why I made this special exception, I sufficiently explained; and I shall therefore now proceed, without further introduction, to a full consideration of the problem that is before us.
First, let us consider the question on purely a priori grounds. In accordance with our original hypothesis—upon which all naturalists of any standing are nowadays agreed—the process of organic and of mental evolution has been continuous throughout the whole region of life and of mind, with the one exception of the mind of man. On grounds of analogy, therefore, we should deem it antecedently improbable that the process of evolution, elsewhere so uniform and ubiquitous, should have been interrupted at its terminal phase. And looking to the very large extent of this analogy, the antecedent presumption which it raises is so considerable, that in my opinion it could only be counterbalanced by some very cogent and unmistakable facts, showing a difference between animal and human psychology so distinctive as to render it in the nature of the case virtually impossible that the one could ever have graduated into the other. This I posit as the first consideration.
Next, still restricting ourselves to an a priori view, it is unquestionable that human psychology, in the case of every individual human being, presents to actual observation a process of gradual development, or evolution, extending from infancy to manhood; and that in this process, which begins at a zero level of mental ​life and may culminate in genius, there is nowhere and never observable a sudden leap of progress, such as the passage from one order of psychical being to another might reasonably be expected to show. Therefore, it is a matter of observable fact that, whether or not human intelligence differs from animal in kind, it certainly does admit of gradual development from a zero level. This I posit as the second consideration.
Again, so long as it is passing through the lower phases of its development, the human mind assuredly ascends through a scale of mental faculties which are parallel with those that are permanently presented by the psychological species of the animal kingdom. A glance at the accompanying diagram will serve to show in how strikingly quantitative, as well as qualitative, a manner the development of an individual human mind follows the order of mental evolution in the animal kingdom. And when we remember that, at all events up to the level where this parallel ends, the diagram is not an expression of any psychological theory, but of well-observed and undeniable psychological fact, I think every reasonable man must allow that, whatever the explanation of this remarkable coincidence may be, it certainly must admit of some explanation—i.e., can not be ascribed to mere chance. But, if so, the only explanation available is that which is furnished by the theory of descent. These facts, which I present as a third consideration, tend still further—and, I think, most strongly—to increase the force of antecedent presumption against any hypothesis which supposes that the process of evolution can have been discontinuous in the region of mind.
Lastly, it is likewise a matter of observation, as I shall fully show in the next installment of this work, that in the history of our race—as recorded in documents, traditions, antiquarian remains, and flint implements—the intelligence of the race has been subject to a steady process of gradual development. The force of this consideration lies in its proving that, if the process of mental evolution was suspended between the anthropoid apes and primitive man, it was again resumed with primitive man, and has since continued as uninterruptedly in the human species as it previously did in the animal species. Now, upon the face of these facts, or from a merely antecedent point of view, such appears to me, to say the least, a highly improbable supposition. At all events, it certainly is not the kind of supposition which men of science are disposed to regard with favor elsewhere; for a long and arduous experience has taught us that the most paying kind of supposition which we can bring with us into our study of nature, is that which recognizes in nature the principle of continuity.
Taking, then, these several a priori considerations together, they must, in my opinion, be fairly held to make out a very strong ​prima facie case in favor of the view that there has been no interruption of the developmental process in the course of psychological history; but that the mind of man, like the mind of animals—and, indeed, like everything else in the domain of living nature—has been evolved. For these considerations show, not only that on analogical grounds any such interruption must be held as in itself improbable; but also that there is nothing in the constitution of the human mind incompatible with the supposition of its having been slowly evolved, seeing that not only in the case of every individual life, but also during the whole history of our species, the human mind actually does undergo, and has undergone, the process in question.
In order to overturn so immense a presumption as is thus erected on a priori grounds, the psychologist must fairly be called upon to supply some very powerful considerations of an a posteriori kind, tending to show that there is something in the constitution of the human mind which renders it virtually impossible—or at all events exceedingly difficult to imagine—that it can have proceeded by way of genetic descent from mind of lower orders. I shall therefore proceed to consider, as carefully and as impartially as I can, the arguments which have been adduced in support of this thesis.
In the introductory chapter of my previous work I observed that the question whether or not human intelligence has been evolved from animal intelligence can only be dealt with scientifically by comparing the one with the other, in order to ascertain the points wherein they agree and the points wherein they differ. I shall, therefore, here begin by briefly stating the points of agreement, and then proceed more carefully to consider all the more important views which have hitherto been propounded concerning the points of difference.
If we have regard to emotions as these occur in the brute, we can not fail to be struck by the broad fact that the area of psychology which they cover is so nearly coextensive with that which is covered by the emotional faculties of man. In my previous works I have given what I consider unquestionable evidence of all the following emotions, which I here name in the order of their appearance through the psychological scale—fear, surprise, affection, pugnacity, curiosity, jealousy, anger, play, sympathy, emulation, pride, resentment, emotion of the beautiful, grief, hate, cruelty, benevolence, revenge, rage, shame, regret, deceitfulness, emotion of the ludicrous.
Now, this list exhausts all the human emotions, with the exception of those which refer to religion, moral sense, and perception ​of the sublime. Therefore I think we are fully entitled to conclude that, so far as emotions are concerned, it can not be said that the facts of animal psychology raise any difficulties against the theory of descent. On the contrary, the emotional life of animals is so strikingly similar to the emotional life of man—and especially of young children—that I think the similarity ought fairly to be taken as direct evidence of a genetic continuity between them.
And so it is with regard to instinct. Understanding this term in the sense previously defined, it is unquestionably true that in man—especially during the periods of infancy and youth—sundry well-marked instincts are presented, which have reference chiefly to nutrition, self-preservation, reproduction, and the rearing of progeny. No one has ventured to dispute that all these instincts are identical with those which we observe in the lower animals; nor, on the other hand, has any one ventured to suggest that there is any instinct which can be said to be peculiar to man, unless the moral and religious sentiments are taken to be of the nature of instincts. And although it is true that instinct plays a larger part in the psychology of many animals than it does in the psychology of man, this fact is plainly of no importance in the present connection, where we are concerned only with identity of principle. If any one were childish enough to argue that the mind of a man differs in kind from that of a brute because it does not display any particular instinct—such, for example, as the spinning of webs, the building of nests, or the incubation of eggs—the answer of course would be that, by parity of reasoning, the mind of a spider must be held to differ in kind from that of a bird. So far, then, as instincts and emotions are concerned, the parallel before us is much too close to admit of any argument on the opposite side.
With regard to volition more will be said in a future installment of this work. Here, therefore, it is enough to say, in general terms, that no one has seriously questioned the identity of kind between the animal and the human will, up to the point at which so-called freedom is supposed by some dissentients to supervene and characterize the latter. Now, of course, if the human will differs from the animal will in any important feature or attribute such as this, the fact must be duly taken into account during the course of our subsequent analysis. At present, however, we are only engaged upon a preliminary sketch of the points of ​resemblance between animal and human psychology. So far, therefore, as we are now concerned with the will, we have only to note that up to the point where the volitions of a man begin to surpass those of a brute in respect of complexity, refinement, and foresight, no one disputes identity of kind.
Lastly, the same remark applies to the faculties of intellect. Enormous as the difference undoubtedly is between these faculties in the two cases, the difference is conceded not to be one of kind ab initio. On the contrary, it is conceded that up to a certain point—namely, as far as the highest degree of intelligence to which an animal attains—there is not merely a similarity of kind but an identity of correspondence. In other words, the parallel between animal and human intelligence which is presented in the diagram is not disputed. The question, therefore, only arises with reference to those superadded faculties which are represented above the level marked twenty-eight, where the upward growth of animal intelligence ends, and the growth of distinctively human intelligence begins. But even at level twenty-eight the human mind is already in possession of many of its most useful faculties, and these it does not afterward shed, but carries them upward with it in the course of its further development—as we well know by observing the psychogenesis of every child. Now, it belongs to the very essence of evolution, considered as a process, that when one order of existence passes on to higher grades of excellence, it does so upon the foundation already laid by the previous course of its progress; so that when compared with any allied order of existence which has not been carried so far in this upward course, a more or less close parallel admits of being traced between the two, up to the point at which the one begins to distance the other, where all further comparison admittedly ends. Therefore, upon the face of them, the facts of comparative psychology now before us are, to say the least, strongly suggestive of the superadded powers of the human intellect having been due to a process of evolution.
Lest it should be thought that in this preliminary sketch of the resemblances between human and brute psychology I have been endeavoring to draw the lines with a biased hand, I will here quote a short passage to show that I have not misrepresented the extent to which agreement prevails among adherents of otherwise ​opposite opinions. And for this purpose I select as spokesman a distinguished naturalist, who is also an able psychologist, and to whom, therefore, I shall afterward have occasion frequently to refer, as on both these accounts the most competent as well as the most representative of my opponents. In his presidential address before the Biological Section of the British Association in 1879, Mr. Mivart is reported to have said:
"I have no wish to ignore the marvelous powers of animals, or the resemblance of their actions to those of man. No one can reasonably deny that many of them have feelings, emotions, and sense-perceptions similar to our own; that they exercise voluntary motion, and perform actions grouped in complex ways for definite ends; that they to a certain extent learn by experience, and combine perceptions and reminiscences so as to draw practical inferences, directly apprehending objects standing in different relations one to another, so that, in a sense, they may be said to apprehend relations. They will show hesitation, ending apparently, after a conflict of desires, with what looks like choice or volition; and such animals as the dog will not only exhibit the most marvelous fidelity and affection, but will also manifest evident signs of shame, which may seem the outcome of incipient moral perceptions. It is no great wonder, then, that so many persons, little given to patient and careful introspection, should fail to perceive any radical distinction between a nature thus gifted and the intellectual nature of man."
* ↑ From "Mental Evolution in Man." By George John Romanes, LL.D., F.R.S. New York: D. Appleton & Co., 1889.
* ↑ "Man's Place in Nature," p. 59.
* ↑ It is perhaps desirable to explain from the first that by the words "difference of kind," as used in the above paragraph and elsewhere throughout this treatise, I mean difference of origin. This is the only real distinction that can be drawn between the terms "difference of kind" and "difference of degree"; and I should scarcely have deemed it worth while to give the definition, had it not been for the confused manner in which the terms are used by some writers—e. g., Prof. Sayce, who says, while speaking of the development of languages from a common source, "differences of degree become in time differences of kind" ("Introduction to the Science of Language," ii, 309).
* ↑ "Mental Evolution in Animals."
* ↑ "Mental Evolution in Animals."
* ↑ See "Mental Evolution in Animals," chapter on the Emotions.
* ↑ "Mental Evolution in Animals," p. 159. "The term is a generic one, comprising all the faculties of mind which are concerned in conscious and adaptive action, antecedent to individual experience, without necessary knowledge of the relation between means employed and ends attained, but similarly performed under similar and frequently recurring circumstances by all individuals of the same species."
* ↑ Of course, my opponents will not allow that this word can be properly applied to the psychology of any brute. But I am not now using it in a question-begging sense: I am using it only to avoid the otherwise necessary expedient of coining a new term. Whatever view we may take as to the relations between human and animal psychology, we must in some way distinguish between the different ingredients of each, and so between the instinct, the emotion, and the intelligence of an animal. (See "Mental Evolution in Animals," p. 335 et seq.)