Chapter 16

The complex lives of communal insects like ants and bees bring us to the level of mentality where an understanding of causes and effects seems to be the guide for conduct. Nevertheless the facts do not warrant the assumption that reason and intelligence play any part in the mental life of these creatures, as they do in the lives of man and the apes. Because we ourselves can see the utility of the definite and peculiar behavior of the queen and the worker, there is no logical necessity for assuming an identical form of knowledge as a possession of these insects. Many investigators have dealt with these fascinating subjects, and they are almost unanimous in the conclusion that the instinct of an insect is a mechanical and hereditary synthesis of combined reflex acts.

The lower orders of psychological processes play a far larger part in the lives of the higher animals than we are wont to believe. A pointer and sheep dog possess different qualifications in the way of instincts that make them useful to man in different ways. A bulldog or a game-cock does not reason out its course of action during a contest, but like a mechanism when the spring is released, it acts promptly and with effect. A ball flashing past the human eye causes the lids to close unconsciously, and it is not always possible to inhibit this instinctive mechanical act by the exercise of the will. An examination of the workings of the human body reveals manifold activities of an even lower or reflex nature, like the movements of the viscera and the adjustments in respect to the amount of supplies of blood sent to different parts of the body as local needs arise. Directed always by specific portions of the nervous system, such reflex actions play their part in human life without any effort on the part of reason and so-called will, and without coming into consciousness except indirectly and subsequently.

Passing by many interesting members of the psychological series of intergrading forms, we reach the familiar animals like the cat and dog and horse which display what is called intelligence. This is the power to learn by experience, and to improve the quality and promptitude of reactions to stimuli. In certain respects intelligence seems to differ from instinct, inasmuch as it involves a response to stimuli that may be altered and quickened by repeated experience, but in ultimate analysis the two forms of psychological processes are fundamentally alike. A single example chosen from Thorndike's extensive investigation will serve to bring out the primary characteristics of intelligence. A cat was placed in a latticed cage provided with a door that could be opened from within when a catch was pressed down, and meat was put in a dish outside the door where the cat could see it. At first, the animal escaped from the cage by freeing the door during its aimless scrambling about the catch, but as trial after trial was made, the time necessary for the cat to make its way out was shortened, until after seventy-five or one hundred trials, the animal immediately opened the door and seized the food. In mechanical terms, the connection between "scrambling about the door" and "freedom to get the meat" became established by numerous repetitions until the originally disconnected elements were physiologically associated and made inseparable. When animals like horses and seals and dogs are trained for the circus, it is by exactly the same method, for training consists merely in the establishment of a psychological sequence so that the performance of one series of acts leads mechanically to others. Thus we learn that the psychological property called intelligence is the ability to establish wide relations between numerous activities which are themselves of a more or less complex nature; and we find also that because these elements are ultimately nerve-cell and sense-cell reflexes, an intelligent response is quite as machine-like as any and all of its elements. A difference in degree of complexity and extent is the only thing that places intelligence apart from instinct and reflex action, for the units are the same in all cases,--so far as science knows.

The apes are of the greatest value in providing the transition from the grade of intelligence to the human level where reason is found. Whether or not a chimpanzee can reason at all is less important than the fact that its total "mental" powers are lower than those of man, and higher than those of inferior mammalia. Apes are far more susceptible to training than cats and dogs, because their improved nervous mechanism enables them to establish a psychological sequence with greater facility. If we are to judge by the facts at hand, these creatures possess a low order of mentality, like, but by no means equivalent to, that of man.

At the end of the comparative scale, we reach the human mind which is characterized by its ability to perceive and recognize far wider relations than those which are involved in intelligence. Human consciousness is the stream of thoughts and feelings which constitute the immediate contents of mind. In our own case, we know both the activities we perform and some of the internal phenomena with which such activities are connected. Then we are impelled to compare the objective phenomena of action with the behavior of other men and of lower organisms, and if their behavior does not coincide with our own we are justified in believing that its direction lacks some of the elements we know about in our own case. This is the method of comparative psychology, which establishes the conclusion that reason is the more complex term of a series to which reflex action, instinct, and intelligence directly lead.

Were we to study in detail the psychology of adult human beings, we would find only more truly that instinct and intelligence play a large part in our everyday mental life, and more certainly that even the highest reasoning powers we possess are only more complex in nature than the nervous processes of lower mammals and invertebrates. Just as the nervous systems advance in physical or structural respects, so must their activities become more and more complex until the result is human faculty.

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We must now briefly consider what may be called the "comparative anthropology" of mind which deals with the various degrees of mental ability displayed by different human races; this subject follows inevitably upon the comparison of the human mind viewed as a single type with the psychological processes of lower animals. When we reviewed the diverse characteristics of human races--the protrusion of the jaws, greater or lesser stature, and the like--it appeared that so-called "lower" races could be distinguished which differed from the "higher" races in the direction of the apes; the question immediately arises whether similar distinctions and relations are discoverable on the basis of mental traits. But in the present case there are not so many well-substantiated differentia at the disposal of the student, and it does not appear so clearly that the "higher" races are furthest from the lower primates and lower mammalia as regards their mental processes. What facts there are, however, prove to be highly significant, and they materially amplify our conception of human faculty as a product of evolution. The essential point is that the intellectual attainments of various races are by no means the same. The calculus is a mental product of the white race only; gunpowder and printing from movable type were independently invented by the Caucasian and Mongolian races; but the American Indian and the Negro never originated them. Human faculty, to employ the most general term for all that distinguishes man from the brutes, proves to be a very varied thing when we draw comparisons between and among races with independent lines of ancestry and heredity occupying widely separated areas. Should we analyze it, we find it to be composed of three constituents; namely, the physical elements of the brain, the degree to which the observational or perceptual and higher elements cooperate in building up the conceptions peculiar to the type, and the materials with which the physical mechanism deals, in the way of environmental, educational, and social "grist for the mental mill." Many anthropologists accord too great an importance to the third constituent of human faculty, I believe, and they are therefore led to deny that races differ in mental respects to so large a degree as the thoroughgoing evolutionist would contend. They hold that differences in such things as powers of observation are due to training: that, for example, an American Indian or a South Sea Islander sees certain things in his environment more quickly than a white man only because these are the things which the experiences of his earlier life have accustomed him to look for and to find. This may be granted, and it may also be admitted that children of so-called "lower" races can be educated side by side with the youth of white races without noticeably falling behind, up to a certain point when, at the age of adolescence, in the classic case of the Australian natives, other factors prove to be obstacles to further progress. We must also recognize that the character of the environment of a race determines to a large extent the mode of life of the people; a forest-dwelling Indian of the interior is a hunter as well as a warrior, while a South Sea Islander is a navigator and a fisherman.

But the fact remains that the inhabitants of similar countries have reached markedly different grades of intellectual and cultural life. Anglo-Saxon dominance must be referred ultimately to Anglo-Saxon heredity and not to the peculiarities of the land. Although adaptation is no less necessary for men as individuals and as social groups than it is for all other living things, I believe that it is to diversity in constitutional endowments, however these may have arisen, that we must attribute the superiority of some races over others. The question is not whether a savage race can or cannot adopt the higher conceptions of a civilized people; the fact is that they have not actually become civilized by themselves. Thus, while evolution in mental respects has not resulted in the loss of plasticity in the case of the brain and the nervous system as a whole, wherefore the activities of these organs still remain capable of individual and racial modifications that are impossible in the case of the skeleton and in the color and shape of the eye, it remains true that races do differ intellectually, and that their differences are marks of a mental evolution quite as definite as their physical natural histories of change.

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In my own view the strongest and most impressive evidence bearing upon the great problem before us is provided by the series of transformations by which the human intellect develops during an individual life. Mind has an embryology no less significant than that of the skull or of any other element of the body; and its investigation leads to the evolutionary interpretation quite as surely as the study of the various grades of adult psychology constituting the anatomical sequence, which we have reviewed previously. When in the earlier part of the book we dealt with embryology in general, we learned how the changes which take place when an organism develops from an egg demonstrate the actuality of true organic transformation without the necessity of concluding or inferring that this process might occur. It is not superfluous to insist again that the essential fact in evolution is the alteration of one organic characteristic into another type; must we not recognize at the very outset that mental transformation is as real as physical development?

In the first instance we might concern ourselves with the physical basis of mind and its history. In the earliest stages of human embryology no nervous system whatsoever is present, and it is unreasonable to suppose that there is anything going on which corresponds to human thought. A little later a cellular tube is established as a primitive nerve axis, which at first is nearly uniform throughout its entire length and displays no differentiation into brain and spinal cord. Before long an enlargement of the anterior end expands and develops into a primitive three-parted brain. It is not yet a real brain, however, and it is entirely incapable of functioning in such a way as to justify the use of the word _mental_ for the results of its operations. We know that it is only in the cerebral hemisphere of the adult brain that the processes of true human consciousness go on. But it is not until long after the three-parted stage that the cerebral hemispheres make their appearance therefore we cannot speak of mind as present when the cell and tissue basis of mind is not present. When, now, the cerebral hemispheres do appear, they are small bean-shaped structures no larger relatively than those of a fish. Later they enlarge so as to attain the relative size of the cerebral hemispheres of an amphibian, and still later they are like those of a reptilian brain. Continuing to enlarge, they begin to fold so that the total surface is increased without very much addition to their bulk. At this time the cerebral hemispheres of the brain of the human embryo are like those of an adult cat or dog. The process of general enlargement and of progressive convolution are continued, and stages are reached and passed which correspond with the monkey and ape conditions.

Nothing in human development is more impressive than the origin of the cerebrum and its development by passing through successive stages which are counterparts in the main of the adult brains of other and lower animals. The alteration of a tissue-mechanism constructed in one way into a tissue-mechanism of a more complex nature, provides the most conclusive evidence of the reality of brain evolution, because the process of transformation actually takes place.

But in the present connection we are more interested in the dynamic or functional aspects of mental evolution, which it must be remembered are inseparably bound up with the physical structures and their modifications. After a human infant is born its activities are reflex and mechanical like those of the adult members of lower groups. As it grows it performs instinctive acts because its inherited nervous system operates in the purely mechanical manner of a lower mammal's nervous system. For these reasons an eminent psychologist has said that the mental ability of an infant six months old is about that of a well-bred fox terrier. The same infant at nine months displays an intelligence of a higher order equal to that of a well-trained chimpanzee; it has become what it was not, and in so far it has truly evolved in mental respects. At two years of age the child is incapable of solving problems of the calculus, for its reasoning powers are elementary and restricted, but these same powers change and intensify so as to render the older mind quite capable of grasping the highest of human conceptions and ideas. In my judgment the unbroken transformation of a child's mind that exhibits only instinct and intelligence into an adult's mind with its power of reasoning, is far more conclusive as proof of mental evolution than the inference drawn from the comparisons we have made above of the adult psychological phenomena of man, ape, cat, and fish. It is surely natural for such mental transformations to take place, for they do take place in the vast majority of human beings; when they do not, in cases where the brain fails to mature, we speak of unnatural or diseased minds.

The third division of our evidence relating to mental evolution constitutes what we have called the palæontology of mind. By this term we mean the study of human minds of the past as we may know them through the many varied relics and documents which indicate their characters. It is only too obvious to every one that human knowledge has advanced in the course of time and that every department of human thought and mental activity has participated in this progress. No one would have the temerity to assert that we know nothing more than our ancestors of 5000 or even 1000 years ago. Our common-sense teaches us even before the man of science produces the full body of evidence at his disposal that human faculties have evolved. With regard to reasoning powers, which form one of the four distinguishing characteristics of the human species as contrasted with other animals, the case has already been reviewed, and we now turn to speech and language and other departments of human mentality. When we compare the attainments of present day men with the abilities and ideas of their ancestors we will do for mental phenomena precisely what was done when we compared the skeletons of modern animals with those of creatures belonging to bygone geological ages; in this reason is found the justification for the phrase employed in the present connection.

Written history furnishes a wealth of material for interpreting the mental conditions of ancient peoples, but beside documentary evidence the anthropologist learns to use inscriptions of prehistoric times, the primitive graphic representations on tombs and monuments, and even the characteristics of crude implements like axes and arrow-heads. The layman finds it difficult at first to regard such relics as indications of the mental stature of the people who made and possessed them; but a little thought will show that a man who used a rough stone ax in the time of the ancient Celts could not possibly have had a mind which included the conception of a finished iron tool or modern mechanism. So in all departments of human culture, the evolution of material objects may be justly employed in interpreting and estimating the mental abilities of ancient peoples.

Language is undoubtedly the most important single intellectual possession of mankind, for it constitutes, as it were, the very framework of social organization. Without a ready means of communication the myriad human units who perform the varied tasks necessary for the economic well-being of a body-politic would be unable to coordinate their manifold activities with success, and the structure of civilized societies at least would collapse. It needs no legend of a Tower of Babel to make this plain. So fundamental is this truth that although we may not have recognized it explicitly, we unconsciously form the belief that speech and language are exclusive properties of the human species, and even more characteristic of man alone than the power of reason itself. While organized language is clearly something that as such we do not share with the lower animals, nevertheless we cannot regard the communication of ideas or states of feeling by sound as an exclusive property of mankind. All are familiar with the difference between the whine and the bark of a dog and with the widely different feelings that are expressed by these contrasted sounds. And we know too that dogs can understand what many of their master's words signify, as when a shepherd gives directions to his collie. We could even go further down in the scale and find in the shrill chirping of the katydid at the mating season a still more elementary combination of significant instinctive sound elements. To the comparative student the speech of man differs from these lower modes of communication only in its greater complexity, and in its employment of more numerous and varied sounds,--in a word, only in the higher degree of its evolution. And it is even more evident that the diverse forms of speech employed by various races have gradually grown to be what they now are.

At the outset it is well to distinguish between writing, as the conventional mode of symbolizing words, and spoken language itself; the two have been more independent in their evolution than we may be wont to believe. Speech came first in historical development, just as a child now learns to talk before it can understand and use printed or written letters. Furthermore, many races still exist who have a well-developed form of language without any concrete way of recording it. It is true, of course, that back of the conventions of speech and writing are the ideas themselves that find expression in the one way or the other, or even by the still more primitive use of signs and gestures. But it is not with these ultimate elements of thought that we are now concerned; our task is to learn, first, what evidences are discoverable which show that the property of human language in general has originated by evolution, and then, in the second place, to perceive how this development proves an evolution of one group of ultimate ideas, namely, human concepts of the modal value of words and symbols as expressions of ideas themselves.

A simple common-sense treatment of obvious facts will greatly facilitate our progress. We know very well that the English we speak to-day differs in many ways from the language of Elizabethan times, and that the former is a direct descendant of the other. The latter, in turn, was a product of Norman French and Anglo-Saxon,--a combination of certain elements of both, but identical with neither of its immediate parents. The Saxon tongue itself has a history that leads back to King Alfred's time and earlier. Thus we are already aware of the fact that our speech has truly evolved, like the physical structure of the men who employ it; and we know, too, how readily new words are adopted into current English, like _tabu_ from Polynesia, or _garage_ from the French, showing that language is even now in process of evolution.

The sounds that make up spoken words can be resolved into a single element with its modifications; this basic element is the brute-like call or shout made with the mouth and throat opened wide--a sound we may have heard uttered by men under the stress of pain or terror. All of the various vowels are simply modifications of this element by altering the shape of the mouth cavity and orifice, while the consonants are produced by interrupting the sound-waves with the palate or lips or tongue. Like the cell as a unit of structure throughout the organic world, this elemental utterance proves to be the basic unit of all human languages, which vary so widely among races of to-day no less than they have in the history of any single people.

One of the first steps in the making of spoken words was taken by human beings when they imitated the calls or other sounds produced by living things, and tacitly agreed to recognize the imitation as a symbol of the creature making it. Thus the names for the cuckoo and the crow in many languages besides our own are simply copies of the calls uttered by these birds; a Tahitian calls a cat _mimi_; the name for a snake almost invariably includes the hissing attributed to that creature. After a time words which were at first simply imitations and which referred only to the things that made these sounds came to refer to certain qualities of the things imitated, so that the naming of other than natural objects, such as qualities, began, leading ultimately to the use of words for qualities belonging to many and different objects in the way of abstractions.