The facts of anatomy, at least, are all against us. Struggle as we may, be as snobbish as we will, we cannot shake off these poor relations of ours. Our adult anatomy at once betrays our ancestry, if we attempt to deny it. Read the first chapter of that remarkable book by Professor Drummond on the "Ascent of Man," the chapter on the ascent of the body, and the second chapter on the scaffolding left in the body. The tips of our ears and our rudimentary ear muscles, the hair on hand and arm, and the little plica semilunaris, or rudimentary third eyelid in the inner angle of our eyes, the vermiform appendage of the intestine, the coracoid process on our shoulder-blades, the atlas vertebra of our necks—to say nothing of the coccyx at the other end of the backbone—many malformations, and a host of minor characteristics all refute our denial.
If we appeal from adult anatomy to embryology the case becomes all the worse for us. Our ear is lodged in the gill-slit of a fish, our jaws are branchial arches, our hyoid bone the rudiment of this system of bones supporting the gills. Our circulation begins as a veritable fish circulation; our earliest skeleton is a notochord; Meckel's cartilage, from which our lower jaw and the bones of our middle ear develop, is a whole genealogical tree of disagreeable ancestors. Our glandula thyreoidea has, according to good authorities, an origin so slimy that it should never be mentioned in polite society. The origin of our kidneys appears decidedly vermian. Time fails me to read merely the name of the witnesses which could be summoned from our own bodies to witness against us.
Even if the testimony of some of these witnesses is not as strong as many think, and we have misunderstood several of them, they are too numerous and their stories hang too well together not to impress an intelligent and impartial jury. But what if it is all true? What if, as some think, our millionth cousin, the tiger or cat, is anatomically a better mammal than I? His teeth and claws and magnificent muscles are of small value compared with man's mental power.
What a comedy that man should work so hard to prove that his chief glory is his opposable thumb, or a few ounces of brain matter! Man's glory is his mind and will, his reason and moral powers, his vision of, and communion with, God. And supposing it be true, as I believe it is true, that the animal has the germ of these also, does that cloud my mind or obscure my vision or weaken my action? It bids me only strive the harder to be worthy of the noble ancestors who have raised me to my higher level and on whose buried shoulders I stand. Whatever may have been our origin, whoever our ancestors, we are men. Then let us play the man. If we will but play our part as well as our old ancestors played theirs, if we will but walk and act according to our light one-half as heroically and well as they groped in the darkness, we need not worry about the future. That will be assured.
Says Professor Huxley: "Man now stands as on a mountain-top far above the level of his humble fellows, and transfigured from his grosser nature by reflecting here and there a ray from the infinite source of truth. And thoughtful man, once escaped from the blinding influences of traditional prejudice, will find in the lowly stock whence man has sprung the best evidence of the splendor of his capacities, and will discern in his long progress through the past a reasonable ground of faith in his attainment of a nobler future."
We have sketched hastily and in rude outline the anatomical structure of the successive stages of man's ancestry; let us now, in a very brief recapitulation, condense this chronicle into a historical record of progress.
We began with the amoeba. This could not have been the beginning. In all its structure it tells us of something earlier and far simpler, but what this earlier ancestor was we do not know. Rather more highly organized relatives of the amoeba, the flagellata, have produced a membrane, and swim by means of vibratile, whiplash-like flagella. We must emphasize that these little animals correspond in all essential respects to the cells of our bodies; they are unicellular animals. And the cell once developed remains essentially the same structure, modified only in details, throughout higher animals. And these unicellular animals have the rudiments of all our functions. Their protoplasm and functions seem to differ from those of higher animals only in degree, not in kind. And the more we consider both these facts the more remarkable and suggestive do they become.
Cells with membranes can unite in colonies capable of division of labor and differentiation. And magosphaera is just such a little spheroidal colony. But the cells are still all alike, each one performs all functions equally well. But in volvox division of labor and differentiation of structure have taken place. Certain cells have become purely reproductive, while the rest gather nutriment for these, but are at the same time sensitive and locomotive, excretory and respiratory. The first function to have cells specially devoted to it is the reproductive; this is a function absolutely necessary for the maintenance of the species. For the nutritive cells die when they have brought the reproductive cells to their full development. These few nutritive cells represent the body of all higher animals in contrast with the reproductive elements. And with the development of a body, death, as a normal process, enters the world. The dominant function is here evidently the reproductive, and the whole body is subservient to this.
In hydra the union and differentiation of cells is carried further. But the cells are still much alike and only slowly lose their own individuality in that of the whole animal. This is shown in the fact that each entodermal cell digests its own particles of food, although the nutriment once digested diffuses to all parts of the body. Also almost any part of the animal containing both ectoderm and entoderm can be cut off and will develop into a new animal.
But beside the reproductive cells and tissues hydra has developed a very simple digestive system, in which the newly caught food at least macerates and begins to be dissolved. This is the second essential function. The animal can, and the plant as a rule does, exist with only the lowest rudiments of anything like nervous or muscular power; but no species can exist without good powers of digestion and reproduction. These essential organs must first develop and the higher must wait. And the inner, digestive, layer of cells persists in our bodies as the lining of the mid-intestine. We compared hydra therefore to a little patch of the lining of our intestine covered with a flake of epidermis; only these layers in hydra possess powers lost to the corresponding cells of our bodies in the process of differentiation. Notice, please, that when cell or organ has once been developed it persists, as a rule, modified, but not lost. Nature's experiments are not in vain; her progress is very slow but sure. But hydra has also the promise of better things, traces of muscular and nervous tissue. There are still no compact muscles, like our own, much less ganglion or brain or nerve-centre of individuality. The tissues are diffuse, but they are the materials out of which the organs of higher animals will crystallize, so to speak. Notice also that these higher muscles and nerves are here entirely subservient to, and exist for, digestion and reproduction.
In the turbellaria the reproductive system has reached a very high grade of development. It is a complex and beautifully constructed organ. The digestive system has also vastly improved; it has its own muscular layers, and often some means of grasping food. But it is slower in reaching its full development than the reproductive system. But all the muscles are no longer attached to the stomach; they are beginning to assert their independence, and, in a rude way, to build a body-wall. But they are in many layers, and run in almost all directions. Some of these layers will disappear, but the most important ones, consisting of longitudinal and transverse fibres, will persist in higher forms. Locomotion by means of these muscles is slowly coming into prominence. They are no longer merely slaves of digestion.
But a muscular fibril contracts only under the stimulus of a nervous impulse. More nerve-cells are necessary to control these more numerous muscular fibrils. The animal now moves with one end foremost, and that end first comes in contact with food, hindrances, or injurious surroundings. Here the sensory cells of feeling and their nerve fibrils multiply. Remember that these neuro-epithelial sensory cells are suited to respond not merely to pressure, but to a variety of the stimuli, chemical, molecular, and of vibration, which excite our organs of smell, taste, and hearing. Such organs and the directive eyes appear mainly at this anterior end. But a ganglion cell sends an impulse to a muscle because it has received one along a sensory nerve from one or more of these sensory cells. Hence the ganglion cells will increase in number. The old cobweb-like plexus condenses into a little knot, the supra-oesophageal ganglion. This ganglion cannot do much, if any, thinking; it is rather a steering organ to control the muscles and guide the animal. It is the servant of the locomotive system. Yet it is the beginning of the brain of higher animals, and probably still persists as an infinitesimal portion of our human brain. And all this is the prophecy of a head soon to be developed. An excretory system has appeared to carry off the waste of the muscles and nerves.
In the schematic worm and annelid the reproductive system is simpler, though perhaps equally effective. It takes the excess of nutriment of the body. The muscular system has taken the form of a sack composed of longitudinal and transverse fibres. The perivisceral cavity, formed perhaps by cutting off and enlarging the lateral pouches of the turbellarian digestive system, serves as a very simple but serviceable circulatory system. But in the annelid and all higher forms a special system of tubes has developed to carry the nutriment, and usually oxygen also, needed to keep up the combustion required to furnish the energy in these active organs. The digestive system has attained its definite form with the appearance of an anal opening and the accompanying division of labor and differentiation into fore-, mid-, and hind-intestine.
The digestive and reproductive systems have thus nearly attained their final form. From the higher worms upward the digestive system will improve greatly. Its lining will fold and flex and vastly increase the digestive and absorptive surfaces. The layer of cells which now secrete the digestive fluids will in part be replaced by massive glands. Far better means of grasping food than the horny teeth of annelids will yet appear. But all these changes are inconsiderable compared with the vast advance made by the muscular and nervous systems. Reproduction and digestion are losing their supremacy in the animal body. Their advance and improvement will require but little further attention.
In the annelid especially, and to some extent in the schematic worm, the supra-oesophageal ganglion is relieved in part of the direct control of the muscular fibrils and has become an organ of perception and the seat of government of lower nervous centres. In all higher forms it innervates directly only the principal sense-organs of the head. And at this stage the light-perceiving directive eye has developed into a form-perceiving, eidoscopic organ. The eye was short of range and its images were perhaps rude and imperfect, but it was a visual eye and had vast possibilities. The animal is taking cognizance of ever more subtle elements in its environment. Perhaps it is not too much to say that the eidoscopic eye first awakened the slumbering animal mind, for its reflex effect upon the supra-oesophageal ganglion cannot be over-estimated. The animal will very soon begin to think.
Between the turbellarian and the annelid many aberrant lines diverged. Some of these attained a comparatively high level and then seemed to meet insuperable obstacles, while others came to an end or turned downward very early. Three of these demanded attention, those leading to mollusks, insects, and vertebrates. And it is interesting to notice that the fundamental difference between these three lines was the skeleton, or perhaps we ought to say it was the habit of life which led to the development of such a skeleton.
The mollusk took to a sluggish, creeping mode of life, under an external purely protective skeleton; the insect to a creeping mode of life, with an external but almost purely locomotive skeleton; the vertebrate kept on swimming and developed an internal locomotive skeleton. And it must already have become clear to you that the destiny of these different lines was fixed not so much directly by the skeleton itself as by its reflex effect in moulding the muscular, and ultimately the nervous, system.
The insects formed their skeleton by thickening the horny cuticle of the annelid. They transformed the annelid parapodia into legs and developed wings. They attained life in the air. They devoted the muscles of the body largely to the extremities and gained swift locomotion. They have a fair circulatory and an excellent respiratory system. Best of all, they developed a head and a brain by fusing the three anterior ganglia of the body. The insect could and does think. Such a structure ought to lead to great and high results. But actually their possibilities were very limited. They have not progressed markedly during the last geological period. Their external skeleton was easily attained and brought speedy advantages, which for a time placed them far above all competitors. But it limited their size and length of life and opportunities, and finally their intelligence. They remained largely the slaves of instinct. They followed an attractive and exceedingly promising path, but it led to the bottom of a cliff, not to the summit.
The mollusks, clams, and snails took an easier, down-hill road. They formed a shell, and it developed large enough to cover them. It hampered and almost destroyed locomotion and reduced nerve to a minimum. But nerves are nothing but a nuisance anyhow. And why should they move? Food was plenty down in the mud, and if danger threatened, they withdrew into the shell. They stayed down in the mud and let the world go its way. If grievously afflicted by a parasite they produced a pearl—to save themselves from further discomfort. They developed just enough muscle and nervous system to close the shell or drag it a little way; that was all. Digestion and reproduction retained the supremacy. They were fruitful and multiplied, and produced hosts of other clams and snails. The present was enough for them and they had that.
For if the winner in the struggle for existence is the one who gains the most food, the most entire protection against discomfort, danger from enemies or unfavorable surroundings, and the most fruitful and rapid reproduction—and these are all good—then the clam is the highest product of evolution. It never has been surpassed—I venture to say it never can be—except possibly by the tape-worms. I can never help thinking with what contempt these primitive oysters, if they had had brains enough, would have looked down upon the toiling, struggling, discontented, fighting, aspiring primitive vertebrates. How they would have wondered why God allowed such disagreeable, disturbing, unconventional creatures to exist, and thanked him that he had made the world for them, and heaven too, if there be such a place for mollusks. Their road led to the Slough of Contentment.
But even in molluscan history there was a tragic chapter. The squids and cuttle-fishes regained the swimming life, and in their latest forms gave up the protective shell. But its former presence had so modified their structure that any great advance was impossible. It was too late. The sins of the fathers were visited upon the children in the thousandth generation.
The vertebrate developed an internal skeleton. This was necessarily a slow growth, and the type came late to supremacy. The longitudinal muscles are arranged in heavy bands on each side of the back, and the animal swims rapidly. The sense-organs are keen. The brain contains the ganglia of several or many segments and is highly differentiated. It has a special centre of perception, thought, and will; it is an organ of mind. The vertebrate has the physical and mental advantages of large size.
First the definite form and mode of developing a vertebra is attained. Then the vertebral column is perfected. The fins are modified into legs. The lungs increase in size and the heart becomes double. The animal emerges on land; and, with a better supply of oxygen and less loss of heat, all the functions are performed with the highest possible efficiency. First, apparently, amphibia, then reptiles, and finally mammals of enormous size and strength appeared. It looked as if the earth were to be an arena where gigantic beasts fought a never-ending battle of brute force. But these great brutes reproduced slowly, had therefore little power of adaptation, were fitted to special conditions, and when the conditions changed they disappeared. The bird tried once more the experiment of developing the locomotive powers to the highest possible extent. It became a flying machine, and every organ was moulded to suit this life. Every ounce of spare weight was thrown aside, the muscles were wonderfully arranged and of the highest possible efficiency. The body temperature is higher than that of mammals. The whole organization is a physiological high-pressure engine. The sense-organs are perhaps the finest and keenest in the whole animal kingdom. The brain is inferior only to that of mammals. The experiment could not have been tried under more favorable conditions; it was not a failure, it certainly was not a success when compared with that of mammals.
The possibilities of every system except one had been practically exhausted. Only brain development remained as the last hope of success. Here was an untried line, and the mammals followed it. During the short tertiary period the brain in many of their genera seems to have increased tenfold. By the arboreal life of the highest forms the hand is developed as the instrument of the thinking brain. The battle is beginning to become one of wits, and the crown will soon pass from the strongest to the shrewdest. Mind, not muscle, much less digestion or reproduction, is the goal of the animal kingdom. And we shall see later that the mammalian mode of reproduction and of care of the young led to an almost purely mental and moral advance. For these could have but one logical outcome, family life. And the family is the foundation of society. And family and social life have been the school in which man has been compelled to learn the moral lessons, the application of which has made him what he is.
You must all, I think, have noticed that the different systems of organs succeed one another in a certain definite order; and that each stage from the lowest to the highest is characterized by the predominance of a certain function or group of functions. This sequence of functions is not a deduction but a fact. Place side by side all possible genealogical trees of the animal kingdom, whether founded on comparative anatomy, embryology, palaeontology, or all combined. They will all disclose this sequence of functions arranged in the same order. Let me call your attention to the fact that this order is not due to chance, but rests upon a physiological basis. We might almost claim that if the evolution of man from the single cell be granted, no other order of their occurrence is possible.
The protozoa are mostly, though not purely, nutritive and reproductive. These functions are essential to the existence of the species. Naturally in the early protozoan colonies, and in forms like hydra, these functions predominated. But mere digestive tissue is not enough for digestion. Muscles are needed to draw the food to the mouth, to keep the digestive sack in contact with it, and for other purposes. A little higher they are used to enable the animal to go in search of its food. They are still, however, more or less entirely subservient to digestion. But in the highest worms we are beginning to see signs that muscles are predominating in the body; and we feel that, while mutually helpful, the digestive system exists for the muscles, and these latter are becoming the aim of development. From worms upward there is a marked advance in physical activity and strength. The muscles thicken and are arranged in heavier bands. Skeleton and locomotive appendages and jaws follow in insects and vertebrates. The direct battle of animal against animal, and of strength opposed to strength or activity, becomes ever sharper. The strongest and most active are selected and survive.
And yet this is not the whole truth. Some power of perception is possessed by every animal. But until muscles had developed the nervous system could be of but little practical value. Knowledge of even a great emergency is of little use, if I can do nothing about it. But when the muscles appeared, nerves and ganglion cells were necessary to stimulate and control them. And this highest system holds for a long time a position subordinate to that of the lower muscular organ. Its development seems at first sight extraordinarily slow. Only in insects and vertebrates has it become a centre of instinct and thought. Through the sense-organs it is gaining an ever clearer, deeper, and wider knowledge of its environment. First it is affected only by the lower stimuli of touch, taste, and smell. Then with the development of ear and eye it takes cognizance of ever subtler forces and movements. Memory comes into activity very early. The animal begins to learn by experience. The brain is becoming not merely a steering but a thinking organ. More and more nervous material is crowded into it and detailed for its work. Wits and shrewdness are beginning to count for something in the battle. Not only the animal with the strongest muscles, but the one with the best brain survives. And thus at last the brain began to develop with a rapidity as remarkable as its long delay. Thus each higher function is called into activity by the next lower, serves this at first, and only later attains its supremacy.
And yet the advance of the different functions is not altogether successive. Muscle and nerve do not wait for digestion and reproduction to show signs of halting before they begin to advance. They all advance at once. But the progress of reproduction and digestion is most rapid at first, and it appears as if they would outrun the others. But in the ascending series the others follow after, and soon overtake and pass by them. And these lower functions, when out-marched, do not lag behind, but keep in touch with the others, forming the rear-guard and supply-train of the army. And notice that each organ holds the predominance about as long as it shows the power of rapid improvement. The length of its reign is pretty closely proportional to its capacity of development. The digestive system reaches that limit early, the muscular system is capable of indefinitely higher complexity, as we see in our hand. But the muscular system has nearly or quite reached its limit. The body had seen its day of dominance before man arrived on the globe.
But where is the limit to man's mental or moral powers? Every upward step in knowledge, wisdom, and righteousness only opens our eyes to greater heights, before unperceived and still to be attained. These capacities, even to our dim vision, are evidently capable of an indefinite, perhaps infinite, development. What, as yet only partially developed, faculty remains to supersede them? As being capable of an endless development and without a rival, may we not, must we not, consider them as ends in themselves? They are evidently what we are here for. Everything points to a spiritual end in animal evolution. The line of development is from the predominantly material to the predominance of the non-material. Not that the material is to be crowded out. It is to reach its highest development in the service of the mind. The body must be sustained and perfected, but it is not the end. The goal is mind, the body is of subordinate importance.
But if this is true, we must study carefully the development of mind in the animal. The question presses upon us; if there is a sequence of physical functions in animal development, is there not perhaps also a sequence in the development of the mental faculties? What is the crowning faculty of the human mind and how is its fuller development to be attained? Let us pass therefore to the question of mind in the animal kingdom.
THE HISTORY OF MENTAL DEVELOPMENT AND ITS SEQUENCE OF FUNCTIONS
We have sketched hastily the development of the human body. This portion of our history is marked by the successive dominance of higher and higher functions. It is a history treating of successive eras. There is first the period of the dominance of reproduction and digestion, purely vegetative functions, characteristics of the plant just as truly as of the animal. This period extends from the beginning of life up to the time when the annelid was the highest living form yet developed. But in insects and lower vertebrates another system has risen to dominance. This is muscle. The vertebrate no longer devotes all, or the larger part, of its income to digestion and reproduction. If it did, it would degenerate or disappear. The stomach and intestine are improved, but only that they may furnish more abundant nutriment for building and supporting more powerful muscles better arranged. The history of vertebrates is a record of the struggle for supremacy between successive groups of continually greater and better applied muscular power. Here strength and activity seem to be the goal of animal development, and the prize falls to the strongest or most agile. The earth is peopled by huge reptiles, or mammals of enormous strength, and by birds of exceeding swiftness. This portion of our history covers the era of muscular activity.
But these huge brutes are mostly doomed to extinction, and the bird fails of supremacy in the animal kingdom. "The race is not to the swift, nor the battle to the strong." All the time another system has been slowly developing. The complicated nervous system has required ages for its construction and arrangement. Only in the highest mammals does the brain assert its right to supremacy. But once established on its throne the brain reigns supreme; its right is challenged by no other organ. The possibilities of all the other organs, as supreme rulers, have been exhausted. Each one has been thoroughly tested, and its inadequacy proven beyond doubt by actual experiment. These formerly supreme lower organs must serve the higher. The age of man's existence on the globe is, and must remain, the era of mind. For the mind alone has an inexhaustible store of possibilities.
The development of all these systems is simultaneous. From the very beginning all the functions have been represented, all the systems have been gradually advancing. Hydra has a nervous system just as really as man. It has no brain, but it has the potentiality and promise of one, and is taking the necessary steps toward its attainment. But while the development of all is simultaneous, their culmination and supremacy is successive, first stomach and muscle, then brain and mind. That was not first which is spiritual, but that which is natural; and afterward that which is spiritual. But now that the mind has once become supreme, man must live and work chiefly for its higher development. Thus alone is progress possible.
But the word mind calls up before us a long list of powers. And the questions arise, Is one mode and line of mental action just as much the goal of man's development as another? Is man to cultivate the appetite for food and sense gratification just as much as the hunger for righteousness? Or is appetite in the mind like digestion in the body, a function, necessary indeed and once dominant, but no longer fitted for supreme control? Is there in the development of the mental powers or functions just as really a sequence of dominance as in that of the bodily functions? Are there older and lower powers and modes of action, which, though once supreme, must now be rigidly kept down in their proper lower place? Are there lower motives, for which the very laws of evolution forbid us to live, just as truly as they forbid a man's living for stomach or brute strength instead of brain and mind? Are these lower powers merely the foundation on which the higher motives and powers are to rise in their transcendent glory? This is the question which we now must face, and it is of vital importance.
We have come to one of the most important and difficult subjects of zooelogy. Let us distinctly recognize that it is not our task to explain the origin of mind, or even of a single mental faculty. I shall take for granted what many of you will not admit, that the germs of all man's highest mental powers are present undeveloped in the mind, if you will call it so, of the amoeba. The limits of this course of lectures have required us to choose between alternatives, either to attempt to prove the truth of the theory of evolution, or taking this for granted, to attempt to find its bearings on our moral and religious beliefs. I have chosen the latter course, and here, as elsewhere, will abide by it. I should not have followed such a course if I did not thoroughly believe that man also, in mind as well as body, is the product of evolution. But this is no reason for your accepting these views. You are asked only to judge impartially of the tendencies of the theory. We take for granted, I repeat, that all man's mental faculties are germinally, potentially, present in protoplasm; we seek the history of their development.
We must remember, further, that the science of animal or comparative psychology is yet in its infancy. Even reliable facts are only slowly being sifted and recorded in sufficient numbers to make deductions at all safe. And even of these facts different writers give very different explanations. As Mr. Romanes has well said, "All our knowledge of mental faculties, other than our own, really consists of an inferential interpretation of bodily activities—this interpretation being founded on our subjective knowledge of our own mental activities. By inference we project, as it were, the human pattern of our own mental chromograph on what is to us the otherwise blank screen of another mind." The value and clearness of our inferences will be proportional to the similarity of the animal to ourselves. Thus we can educate many of our higher mammals by a system of rewards and punishments, and we seem therefore to have good reason to believe that fear and joy, anger and desire, certain powers of perception and inference, are in their minds similar to our own. But fear in a fish is certainly a much dimmer apprehension of danger than in us, even if it deserves the name of apprehension. And the mental state which we call "alarm" in a fly or any lower animal is very difficult to clearly imagine or at all express in terms of our own mind.
Some investigators have made the mistake of projecting into the animal mind all our emotions and complicated trains of thought. Thus Schwammerdam apparently credits the snail with remorse for the commission of excesses. Others go to the other extreme and make animals hardly more than mindless automata. We are warned, therefore, by our very mode of study, to be cautious, not too absolutely sure of our results, nor indignant at others who may take a very different view. And yet by moving cautiously and accepting only what seems fairly clear and evident we may arrive at very valuable and tolerably sure results.
The human mind, and the animal mind apparently, manifests itself in three states or functions. These are intelligence, the realm of knowledge; susceptibility, the realm or state of feelings or emotions; will, the power or state of choice. Let us trace first the development of intelligence or the intellect in the animal. Let us try to discover what kinds of knowledge are successively attained and the mode and sequence of their attainment. Hydra appears to be conscious of its food. It recognizes it partially by touch, perhaps also by feeling the waves caused by its approach. It seems also to recognize food at a little distance by a power comparable to our sense of smell. Stronger impacts cause it to contract. It neither sees nor hears; it probably does little or no thinking. Its knowledge is therefore limited to the recognition of objects either in contact with, or but slightly removed from, itself. And its recognition of the objects is very dim and incomplete, obtained through the sense of touch and smell.
A little higher in the animal world a rude ear has developed, first as a very delicate organ for feeling the waves caused by approaching food or enemies; only later as an organ of hearing. Meanwhile the eye has been developing, to perceive the subtle ether vibrations. The eye of the turbellaria distinguishes only light from darkness, that of the annelid is a true visual organ. Now the brain can begin to perceive the shape of objects at a little distance. Touch and smell, hearing, sight; such is sequence of sense perceptions. The sense-organs respond to continually more delicate and subtle impacts, and cover an ever-widening range of more and more distant objects. Up to this point intelligence has hardly included more than sense-perceptions.
But these sense-perceptions have been all the time spurring the mind to begin a higher work. At first it is conscious merely of objects, and its main effort is to gain a clearer and clearer perception of these.
Now it is led to undertake, so to speak, the work of a sense-organ of a higher grade. It begins to directly see invisible relations just as truly as through the eye it has perceived light. First perhaps it perceives that certain perceptions and experiences, agreeable or disagreeable, occur in a certain sequence. It begins to associate these. It learns thus to recognize the premonitory symptoms of nature's favor or disfavor, and thus gains food or avoids dangers. The bee learns to associate accessible nectar with a certain spot on the flower marked by bright dots or lines, "honey-guides," and the chimpanzee that when a hen cackles there is an egg in the nest. But association is only the first lesson; inference and understanding follow.
The child at kindergarten receives a few blocks. It admires and plays with them. Then it is taught to notice their form. After a time it arranges them in groups and learns the first elements of number. But when it has advanced to higher mathematics, the blocks, or figures on the blackboard, become only symbols or means of illustrating the great theorems and propositions of that science. Thus the animal has begun in the kindergarten way to dimly perceive that there are real, though intangible and invisible, relations between objects. But what is all human science but the clearer vision, and farther search into, and tracing of these same relations? And what is all advance of knowledge but a perception of ever subtler relations? What is even the knowledge of right but the perception of the subtlest and deepest and widest relations of man to his environment? The animal seems to be steadily advancing along the path toward the perception of abstract truth, though man alone really attains it.
And the higher power of association and inference which we call understanding, aided by memory, results in the power of learning by experience, so characteristic of higher vertebrates. The hunted bird or mammal very quickly becomes wary. A new trap catches more than a better old one until the animals have learned to understand it, and young animals are trapped more easily than old. Cases showing the limitations of mammalian intelligence are interesting in this connection. A cat which wished to look out and find the cause of a noise outside, when all the windows were closed by wooden blinds, jumped upon a stand and looked into a mirror. Her inference as to the general use of glass was correct; all its uses had not yet come within the range of her experience. A monkey used to stop a hole in the side of a cage with straw. The keeper, to tease him, used to pull this out. But one day the monkey tugged at a nail in the side of his cage until he had pulled it out, and thrust it into the hole. But when it was pushed back he fell into a rage. His inference that the nail-head could not be pulled through was entirely correct; he had failed to foresee that it could be pushed back. Many such instances have probably come within the range of your observation, if you have noticed them. But many of the facts which Mr. Romanes gives us concerning the intelligence of monkeys, apes, and baboons would not disgrace the intelligence of children or men.
Mr. Romanes relates the following account of a little capuchin monkey from Brazil:
"To-day he obtained possession of a hearth-brush, one of the kind which has the handle screwed into the brush. He soon found the way to unscrew the handle, and having done that he immediately began to try to find out the way to screw it in again. This he in time accomplished. At first he put the wrong end of the handle into the hole, but turned it round and round the right way for screwing. Finding it did not hold he turned the other end of the handle and carefully stuck it into the hole, and began again to turn it the right way. It was of course a difficult feat for him to perform, for he required both his hands in order to screw it in, and the long bristles of the brush prevented it from remaining steady or with the right side up. He held the brush with his hind hand, but even so it was very difficult for him to get the first turn of the screw to fit into the thread; he worked at it, however, with the most unwearying perseverance until he got the first turn of the screw to catch, and he then quickly turned it round and round until it was screwed up to the end. The most remarkable thing was, that however often he was disappointed in the beginning, he never was induced to try turning the handle the wrong way; he always screwed it from right to left. As soon as he had accomplished his wish he unscrewed it again, and then screwed it in again the second time rather more easily than the first, and so on many times. When he had become by practice tolerably perfect in screwing and unscrewing, he gave it up and took to some other amusement. One remarkable thing is that he should take so much trouble to do that which is no material benefit to him. The desire to accomplish a chosen task seems a sufficient inducement to lead him to take any amount of trouble. This seems a very human feeling, such as is not shown, I believe, by any other animal. It is not the desire of praise, as he never notices people looking on; it is simply the desire to achieve an object for the sake of achieving an object, and he never rests nor allows his attention to be distracted until it is done....
"As my sister once observed while we were watching him conducting some of his researches, in oblivion to his food and all his other surroundings—'When a monkey behaves like this it is no wonder that man is a scientific animal!'"[A]
[Footnote A: Romanes: Animal Intelligence, pp. 490, 498.]
In the highest mammals we find also different degrees of attention and concentration of thought and observation. This difference can easily be noticed in young hunting dogs. A trainer of monkeys said that he could easily select those which could most easily be taught, by noticing in the first lesson whether he could easily gain and hold their attention. This was easy with some, while others were diverted by every passing fly; and the latter, like heedless students, made but slow progress.
It is interesting to notice that one of the perceptions which we class among the highest is apparently developed comparatively early. I refer to the aesthetic perception of the beautiful. Now, the perception of beauty is generally considered as not very far below or removed from the perception of truth and right. But some insects and birds apparently possess this perception and the corresponding emotion in no low degree. The colors of flowers seem to exist mainly for the attraction of insects to insure cross-fertilization, and certain insects seem to prefer certain colors. But you may say that these afford merely sense gratification like that which green affords to our eyes or sugar to our tastes.
But does not the grouping of colors in the flower appeal to some aesthetic standard in the mind of the insect? What of the tail of the peacock? Its iridescent rings and eyes evidently appeal to something in the mind of the female. Do form and grouping minister to pure sense gratification? What of the song of the thrush? Does not the orderly and harmonious arrangement of notes and cadences appeal to some standard of order of arrangement, and hence idea of harmony, in the mind of the bird's mate?
Now, I grant you readily that the A B C of this training is mere sense gratification at the sight of bright colors. Most insects and birds have probably not advanced much beyond this first lesson. Savages have generally stopped there or reverted to it. But any appreciation of form and harmonious arrangement of cadence and colors seems to me at least to demand some perception which we must call aesthetic, or dangerously near it. But here you must judge carefully for yourselves lest you be misled. For remember, please, that those schemes of psychology farthest removed from, and least readily reconcilable to, the theory of evolution maintain that perception of beauty is the work of the rational faculty, which also perceives truth and right in much the same way that it perceives and recognizes beauty. If the animal has the aesthetic perception, it has the faculty which, at the next higher stage of development, will perceive, and recognize as such, both truth and right. We are considering no unimportant question; for on our answer to this depends our answer to questions of far greater importance.
Does it look as if the animal had begun to learn the first rudiments of the great science of rights, of his own rights and those of others? This is an exceedingly difficult question, though often answered unhesitatingly in the negative. But what of the division of territory by the dogs in oriental cities, a division evidently depending upon something outside of mere brute strength and power to maintain, and their respect of boundaries? The female is allowed, I am told by an eye-witness long resident in Constantinople, to distribute her puppies in unoccupied spots through the city without interference. But when she has once located them, she is not allowed to return and visit them, or pass that way again. So the account by Dr. Washburn of platoons of dogs coming in turn, and peaceably, to feed on a dead donkey in the streets of Constantinople, would seem to be most naturally explained by some dim recognition of rights. Rook communities have not received the attention and investigation which they deserve, but their actions are certainly worthy of attention. Concerning the sense of ownership in dogs and other mammals opinions differ, and yet many facts are most naturally explained on such a supposition.
Just one more question in this connection, for we are in the borderland or twilightland where it is much safer to ask questions than to attempt to answer them. How do you explain the "instinctive" fear of man on the part of wild and fierce animals? They certainly do not quail before his brute strength, for a blow at such a time breaks the charm and insures an attack. They quail before his eye and look. Is not this the answering of a personality in the animal to the personality in man; a recognition of something deeper than bone and muscle? And may not, as Mr. Darwin has urged, this fear in the presence of a higher personality be the dim foreshadowing of an awe which promises indefinitely better things? Is, after all, the attachment of a dog to his master something far deeper than an appetite for bones or pats, or a fear of kicks?
A host of other and similar questions throng upon us here, to no one of which we can give a definite answer. We need more investigation, more light. We must not rest contented with old prejudices or accept with too great certainty new explanations. The questions are worthy of careful and patient investigation. The study of comparative anatomy has thrown a flood of light on the structure and working of the human body in health and disease. We shall never fully understand the mind of man until we know more of the working of the mind of the animal.
It would seem to be clear that there is a sequence of dominance in the faculties of the intellect. First, the only means of acquiring knowledge is through sense-perception. But memory dawns far down in the animal kingdom. And thus the animal begins to associate past experience with present objects. The bee remembers the gaining of honey in the past, associated with the color of the flower which she now sees, and knows that honey is to be attained again. Thus in time association leads to inference, and understanding has dawned. But the highest faculty of the intellect is the rational intelligence, which perceives beauty, truth, and goodness. This is the last to develop. Traces of its working may be perhaps discovered below man, but only in man does it become dominant. Through it I perceive my rights and duties, and come to the consciousness of my own personality as a moral agent. This tells me of the relation of my own personality to other persons and things. And these are evidently the most important objects of human study. The attainment of this knowledge and the development of this faculty are evidently the goal of human intellectual development. This it is which has insured progress and raised man ever higher above the brutes.
Before we can proceed to the study of the will we must clearly recognize and define certain modes of mental and nervous action, which sooner or later manifest themselves in muscular activity. For, while certain of our bodily activities are clearly voluntary, others take place wholly, or in part independently, of the individual will. Between these different modes of bodily action we must distinguish as clearly as may be possible.
1. Reflex Action. I touch something cold or hot in the dark, suddenly and unexpectedly. I draw back my hand involuntarily and before I have perceived the sensation of cold or heat. You tell me to keep my eyes open while you make a sudden pass at them with your hand. I try hard to do so, but my eyes shut for all that. I shut them unconsciously and against my own will. I say, "They shut of themselves." Now, this is not true, but the explanation is not difficult. These and similar actions are entirely possible, although the continuity between spinal marrow and brain may have been so interrupted by some accident that sensation in the reflexly active part fails altogether. A bird flaps its wings after its head is cut off, and yet the seat of consciousness and will is certainly in the brain. A patient with a "broken back," and paralyzed in his legs, will draw up his feet if they are tickled, although he is entirely unable to move them by any effort of his will and has no consciousness of the irritation.
The physiological action is in this case clear. The vibration of the nerve caused by the tickling travels from the foot to the appropriate centre in the spinal marrow, and here gives rise to, or is switched off as, a motor impulse travelling back to the muscles of the leg, causing them to contract. In the injured patient the nervous impulse cannot reach the brain, the seat of consciousness, and hence this is not awakened. Normally consciousness does result in a majority of such cases, but only after the beginning or completion of the appropriate action. Yet the movements of our internal organs, intestine and heart, go on continually, and in health we remain entirely unconscious of their action.
But reflex actions may be anything but simple. We walk and talk, and write or play the piano without ever thinking of a single muscle or organ. Yet we had once to learn with much effort to take each step or frame each letter. Thus actions, originally conscious and intended, easily become reflex; often repeated the brain leaves their control to the lower centres. We often say, "I did not intend to do that; I could not help it." We forget that this excuse is our worst condemnation. It is a confession that we have allowed or encouraged a habit to wear a groove from which the wheels of our life cannot escape. The essential characteristic of reflex action is therefore that from beginning to completion it goes on independently of consciousness.
2. Instinct. This is a much-abused word. It is frequently applied to all the mental actions of animals without much thought or care as to its meaning. Let us gain a definition from the study of a typical case lest we use the word as a cloak for ignorance or negligent thoughtlessness. Watch a spider building its wonderful geometrical web. The web is a work of art, and every motion of the spider beautifully adapted to its purpose. But the spider is not therefore necessarily an artist. Let us see of how much the spider is probably conscious, remembering that our best judgment is but an inference. We have good reason to believe that she is conscious of the stimulus to action, hunger. She may be, probably is, conscious of the end to be attained—to catch a fly for her dinner. She seems conscious of what she is doing. In all these respects this differs from reflex action. But she is probably unconscious of the exact fitness of the means to the end. We do not believe that she has adopted the geometrical pattern, because she has discovered or calculated that this will make the closest and largest net for the smallest outlay of labor and material. Furthermore the young spider builds practically as good a web as the old one. She has inherited the power, not developed or gained it by experience or observation. And all the members of the species have inherited it in much the same degree of perfection.
Concerning the origin of instincts there are several theories. Some instincts would seem to be the result of non-intelligent, perhaps unconscious, habits becoming fixed by heredity and improved by natural selection; others would appear to be modifications of actions originally due to intelligence. Instinct is therefore characterized by consciousness of the stimulus to act, of the means and end, without the knowledge of the exact adaptation of means to end. It is hereditary and characterizes species or large groups.
3. Intelligent Action. You come in cold and sit down before an open fire. You push the brands together to make the fire burn. Applying once more the criterion of consciousness to this action we notice that you are conscious of the stimulus to act, of the steps of the action, and of the end to be attained, exactly as in instinctive action. But finally, and this is the essential characteristic of intelligent action, you are aware to a certain extent of the fitness of the means to the attainment of the end. This piece of knowledge you had to acquire for yourself. Erasmus Darwin defined a fool as a man who had never tried an experiment. Experience and observation, not heredity, are the sources of intelligence. Intelligence is power to think, and a man may be very learned—for do we not have learned pigs?—and yet have very little real intelligence. Hence this is possessed by different individuals in very varying degrees.
We may now briefly compare these three kinds of nervous action.
Reflex action is involuntary and unconscious. The actor may, and usually does, become conscious of the action after it has been commenced or completed, but this is not at all necessary or universal.
Instinctive action is to a certain extent voluntary and conscious. The actor is conscious of the stimulus, the means and mode, and the end or purpose of the action. Of the exact fitness or adaptation of the means to the end the actor is unconscious.
Intelligent action is conscious and voluntary. The actor is conscious of the stimulus to act, of the means and mode, and to a certain extent of the adaptation of the means to the end. This last item of knowledge, lacking in instinctive action, is acquired by experience or observation.
Reflex action may be regarded as a comparatively mechanical, though often very complex, process; the reflex ganglia appear to be hardly more than switch-boards. There is stimulus of the sense-organs, and thus what Mr. Romanes has called "unfelt sensation," unfelt as far as the completion of the action is concerned. But in instinct the sensation no longer remains unfelt; perception is necessary, consciousness plays a part. And this consciousness is a vastly more subtle element, differing as much apparently from the vibration of brain, or nervous, molecules as the Geni from the rubbing of Aladdin's lamp, to borrow an illustration.
But this element of consciousness is one which it is exceedingly difficult to detect in our analysis, and yet upon it our classification and the psychic position of an animal must to a great extent depend. The amoeba contracts when pricked, jelly-fishes swim toward the light, the earthworm, "alarmed" by the tread of your foot, withdraws into its hole. Are these and similar actions reflex or instinctive? A grain of consciousness preceding an action which before has been reflex changes it into instinct. Mr. Romanes, probably correctly, regards them as purely reflex. We must, I think, believe that these actions result in consciousness even in the lowest forms. The selection and attainment of food certainly looks like conscious action. Probably all nerve-cells or nervous material were originally, even in the lowest forms, dimly conscious; then by division of labor some became purely conductive, others more highly perceptive. The important thing for us to remember in our present ignorance is not to be dogmatic.
Furthermore, the gain of a grain of consciousness of the adaptation of certain means to special ends changes instinctive action into intelligent, and its loss may reverse the process. Fortunately we have found that in so far as actions, even instinctive, are modified by experience, they are becoming to that extent intelligent. This criterion of intelligence seems easily applied. But this profiting by experience must manifest itself within the lifetime of the individual, or in lines outside of circumstances to which its ordinary instincts are adapted, or we may give to individual intelligence the credit due really to natural selection. We must be cautious in our judgments.
These reflex actions are performed independently of consciousness or will. Consciousness may, probably does, attend the selection and grasping of food; but most of the actions of the body will go on better without its interference. It is not yet sufficiently developed, or, so to speak, wise enough to be intrusted with much control of the animal.
Among higher worms cases of instinct seem proven. Traces of it will almost certainly be yet found much lower down. Fresh-water mussels migrate into deeper water at the approach of cold weather. And if the clam has instincts, there is no reason why the turbellaria should not also possess them. But all higher powers develop gradually, and their beginnings usually elude our search. Along the line leading from annelids to insects instinct is becoming dominant. A supraoesophageal ganglion has developed, and has been relieved of most of the direct control of the muscles. Very good sense-organs are also present. From this time on consciousness becomes clearer, and the brain is beginning to assert its right to at least know what is going on in the body, and to have something to say about it. Still, as long as the actions remain purely instinctive the brain, while conscious, is governed by heredity. The animal does as its ancestors always have. It does not occur to it to ask why it should do thus or otherwise, or whether other means would be better fitted to the end in view. It acts exactly like most of the members of our great political and theological parties. And until the animal has a better brain this is its best course and is favored by natural selection.
But the hand of even the best dead ancestors cannot always be allowed to hold the helm. The brain is still enlarging, the sense-organs bring in fuller and more definite reports of a wider environment. Greater freedom of action by means of a stronger locomotive system is bringing continually new and varied experiences. And if, as in vertebrates, longer life be added, frequent repetition of the experience deepens the impression. Slowly, as if tentatively, the animal begins to modify some of its instincts, at first only in slight details, or to adopt new lines of action not included in its old instincts, but suited to the new emergencies. This is the dawn of intelligence. Its beginnings still remain undiscovered. Mr. Darwin believes that traces of it can be found in earthworms and other annelids. He also tells us that oysters taken from a depth never uncovered by the sea, and transported inland, open their shells, lose the contained water, and die; but that left in reservoirs, where they are occasionally left uncovered for a short time, they learn to keep their shells shut, and live for a much longer time when removed from the water. If oysters can learn by experience, lower worms probably can do the same.
Certain experiments made on sea-anemones, actinae animals a little more highly organized than hydra, demand repetition under careful observation.[A] The observer placed on one of the tentacles of a sea-anemone a bit of paper which had been dipped in beef-juice. It was seized and carried to the mouth and here discarded. This tentacle after one or two experiments refused to have anything more to do with it. But other tentacles could be successively cheated. The nerve-cells governing each tentacle appear to have been able to learn by experience, but each group in the diffuse nervous system had to learn separately. The dawn of this much of intelligence far down in the animal kingdom would not be surprising, for the selection and grasping of food has always involved higher mental power than most of the actions of these lowest animals. Memory goes far down in the animal kingdom. Perhaps, as Professor Haeckel has urged, it is an ultimate mental property of protoplasm. And the memory of past experience would continually tend to modify habit or instinct.
[Footnote A: These experiments have been continued with most interesting and valuable results by Dr. G.H. Parker, of Harvard University.]
It is unsafe, therefore, to say just where intelligence begins. At a certain point we find dim traces of it; below that we have failed to find them. But that they will not be found, we dare not affirm. In the highest insects instinct predominates, but marks of intelligence are fairly abundant. Ants and wasps modify their habits to suit emergencies which instinct alone could hardly cope with. Bees learn to use grafting wax instead of propolis to stop the chinks in their hives, and soon cease to store up honey in a warm climate.
Our knowledge of vertebrate psychology is not yet sufficient to give a history of the struggle for supremacy between instinct and intelligence, between inherited tendency and the consciousness of the individual. But the outcome is evident; intelligence prevails, instinct wanes. The actions of the young may be purely instinctive; it is better that they should be. But instinct in the adult is more and more modified by intelligence gained by experience. There is perhaps no more characteristic instinct than the habit of nest-building in birds. And yet there are numerous instances where the structure and position of nests have been completely changed to suit new circumstances. And the view that this habit is a pure instinct, unmodified by intelligence, has been disproved by Mr. Wallace. But while size of brain, keenness of sense-organs, and length of life may be rightly emphasized as the most important elements in the development of vertebrate intelligence, the importance of the appendages should never be forgotten. Cats seem to have acquired certain accomplishments—opening doors, ringing door-bells, etc.—never attained by the more intelligent dog, mainly because of the greater mobility and better powers of grasping of the forepaws. The elephant has its trunk and the ape its hand. The power of handling and the increased size of the brain aided each other in a common advance.
The teachableness of mammals is also a sign of high intelligence. The young are often taught by the parent, a dim foreshadowing of the human family relation. And we notice this capacity in domestic animals because of its practical value to man. And here, too, we notice the difference between individuals, which fails in instinct. All spiders of the same species build and hunt alike, although differences caused by the moulding influence of intelligence will probably be here discovered. But among individual dogs and horses we find all degrees of intelligence from absolute stupidity to high intelligence. And many mammals are slandered grievously by man. The pig is not stupid, far from it.
Still only in man does intelligence reign supreme and clearly show its innate powers. But even in man certain realms, like those of the internal organs, are rarely invaded by consciousness, but are normally left to the control of reflex action. These actions go on better without the interference of consciousness.
But other lines of action are relegated as rapidly as possible to the same control. We learn to walk by a conscious effort to take each step; afterward we take each step automatically, and think only whither we wish to go. We learn by conscious effort to talk and write, to sing, or play the piano. Afterward we frame each letter or note automatically, and think only of the idea and its expression.
So also in our moral and spiritual nature.[A]
[Footnote A: Mr. James Freeman Clarke has stated this better than I can. "We may state the law thus: 'Any habitual course of conduct changes voluntary actions into automatic or involuntary (i.e., reflex) actions.' By practice man forms habits, and habitual action is automatic action, requiring no exercise of will except at the beginning of the series of acts. The law of association does the rest. As voluntary acts are transformed into automatic, the will is set free to devote itself to higher efforts and larger attainments. After telling the truth a while by an effort, we tell the truth naturally, necessarily, automatically. After giving to good objects for a while from principle, we give as a matter of course. Honesty becomes automatic; self-control becomes automatic. We rule over our spirit, repress ill-temper, keep down bad feelings, first by an effort, afterwards as a matter of course.
"Possibly these virtues really become incarnate in the bodily organization. Possibly goodness is made flesh and becomes consolidate in the fibres of the brain. Vices, beginning in the soul, seem to become at last bodily diseases; why may not virtues follow the same law? If it were not for some such law of accumulation as this, the work of life would have to be begun forever anew. Formation of character would be impossible. We should be incapable of progress, our whole strength being always employed in battling with our first enemies, learning evermore anew our earliest lessons. But by our present constitution he who has taken one step can take another, and life may become a perpetual advance from good to better. And the highest graces of all—Faith, Hope, and Love—obey the same law." See James Freeman Clarke, Every-Day Religion, p. 122.]
There has been therefore in the successive forms and stages of animal life a clear sequence of dominant nervous actions. The actions of all animals below the annelid are mainly reflex or automatic, unconscious and involuntary. But in insects and lower vertebrates the highest actions at least are instinctive. Consciousness plays a continually more important part. Still the actions are controlled by hereditary tendency far more than by the will of the individual. But in man instinct has been almost entirely replaced by conscious, voluntary, intelligent action. And yet in man, as rapidly as possible, actions which at first require conscious effort become, through repetition and habit, reflex and automatic. All our conscious effort and the energy of the will, being no longer required for these oft-repeated actions, are set free for higher attainments. The territory which had to be conquered by hard battles has become an integral part of the realm. It now hardly requires even a garrison, but has become a source of supplies for a new advance and march of conquest.
But all this time we have been talking about action and have not given a thought to the will. And we have spoken as if conscious perception and intelligence directly controlled will and action. But this is of course incorrect. Will is practically power of choice. You ask me whether I prefer this or that, and I answer perhaps that I do not care. Until I "care" I shall never choose. The perception must arouse some feeling, if it is to result in choice. I see a diamond in the road and think it is merely a piece of glass. I do not stop. But as I am passing on; I remember that there was a remarkable brilliancy in its flash. It must have been, after all, a gem. My feelings are aroused. How proud I shall feel to wear it. Or how much money I can get for it. Or how glad the owner will be when it is returned to her. I turn back and search eagerly. Perception is necessary, but it is only the first step. The perception must excite some feeling, if choice or exertion of the will is to follow. This is a truism.
Now reflex action takes place independently of consciousness or will. Instinctive action may be voluntary, but it is, after all, not so much the result of individual purpose as of hereditary tendency. Is there then no will in the animal until it has become intelligent? I think there has been a sort of voluntary action all the time. Even the amoeba selects or chooses, if I may use the word, its food among the sand grains. And the will is stimulated to act by the appetite. Hunger is the first teacher. And how did appetite develop? Why does the animal hunger for just the food suited to its digestion and needs? We do not know. And the reproductive appetite soon follows. One of these results from the condition of the digestive, the other from that of the reproductive, cells or protoplasm. These appetites are due to some condition in a part of the organism and can be felt. They are in a sense not of the mind but of the body. And the response to them on the part of the mind is in some respects almost comparable to reflex action. But the mode of the response is, to a certain extent at least, within the control of consciousness. They train and spur the will as pure reflex action never could. But the will is as yet hardly more than the expression of these appetites. It expresses not so much its own decision as that of the stomach. It is the body's slave and mouthpiece. And once again it is best and safest for the animal that it should be so.
And these appetites are at first comparatively feeble. There is but little muscle or nerve and but little food is required. But these continually strengthen and spur the will harder and more frequently. And the will stirs up the weary and flagging muscles. The will may be a poor slave and the appetites hard taskmasters. But under their stern discipline it is growing stronger and more completely subjugating the body. Better slavery to hard taskmasters than rottenness from inertia. The first requirement is power, activity, and then this power can be directed to ever higher ends. You cannot steer the vessel until she has sails or an engine; with no "way on" she will not mind the helm, she only drifts. But the condition of the animal at this stage certainly looks very unpromising. Can the will emancipate itself from appetite and control it? Or is it to remain the slave of the body?
In time an emotion appears which marks the influence not directly of the body but of the individual consciousness. This is fear; it is for the body, but not, like hunger, directly of it. It arises in the mind. It results from experience and memory. The first animal which feared took a long step upward. But when and where was the dawn of fear? I touch a sea-anemone and it contracts. Has it felt fear? I think not. The action certainly may be purely reflex. Natural selection, not mind, deserves the credit of that action. But I am sure that the cat fears the dog, or the dog the cat, as the case may be. I have little or no doubt that the bird fears the cat. I am inclined to believe that the insect fears the bird and the spider the wasp. But does the highest worm fear? I do not know. I do not see how there can have been any fear until there was a nerve-centre highly enough developed to remember past experiences of danger and fair sense-organs to report the present risk.
Other emotions soon follow. Anger appears early. The order of appearance of these emotions or motives I shall not attempt to give to you. Indeed this is to us of relatively slight importance. The important point to notice is that a host of these have appeared in mammals and birds, and that each one of these is a new spur to the will. And the will of a horse or dog, to say nothing of a pig, is by no means feeble. And these are slowly emancipating the animal from the tyranny of appetite. But how slow the progress is! Has the emancipation yet become complete in man? I need not answer.
The will has in part, at least, escaped from abject slavery to appetite; it sometimes rises superior to fear. But it is evidently self-centred. The animal may have forgotten the claims of his dead ancestors, he is certainly fully alive to his own interests. Can he even partially rise superior to prudential considerations, as he has to some extent to the claims of appetite? Is it possible to develop the unselfish out of the purely selfish? And if so, how is this to be accomplished? It is not accomplished in the animal; it is but very incompletely accomplished in man. It will be accomplished one day.
In action, at least, the animal is not purely selfish. As Mr. Drummond has shown, reproduction, that old function and first to gain an organ, is not primarily for the benefit of self, but for the species. And not only the storing up of material in the egg, but care for the young after birth, is found in some fish and insects, and increases from fish upward. I readily grant you that this in its beginnings may be purely instinctive, and that not a particle of genuine affection for the young may as yet be present in the mind of the parent. But beneficial habits may, under the fostering care of selection, develop into instincts. The animal may at first be unconscious of these, and yet they may grow continually stronger. But one day the animal awakens to its actions, and from that time on what had been done blindly and unconsciously is continued consciously, intelligently, and from set purpose. This story is repeated over and over again in the history of the animal-kingdom. The care for the young once started as an instinct, affection will follow from the very association of parent with young. Certainly in birds and mammals there seems to be a very genuine love of the parents for their young. This is at first short lived, and the young are and have to be driven away, often by harsh treatment, to shift for themselves. But while it lasts it certainly seems entirely real and genuine. And how strong it is. "A bear robbed of her whelps" is no meaningless expression. And even the weak and timid bird or mammal becomes strong and fierce in defence of her young. In the presence of this emotion appetite and fear are alike forgotten.
But this affection or love once started does not remain limited to parent and offspring. Mammals, especially the higher forms, are social. They frequently go in herds and troops, and appear to have a genuine affection for each other. You all know how in herds of cattle or wild horses the males form a circle around the females and young at the approach of wolves. A troop of orangs were surprised by dogs at a little distance from their shelter. The old male orangs formed a ring and beat off the dogs until the females and young could escape, and then retreated. But as they were now in comparative safety a cry came from one young one, who had been unable to keep up in the scramble over the rocks, and was left on a bowlder surrounded by the dogs. Then one old orang turned back, fought his way through the dogs, tucked the little fellow under one arm, fought his way out with the other, and brought the young one to safety. I call that old orang a hero, but I am prejudiced and may easily be mistaken.
In a cage in a European zooelogical garden there were kept together a little American monkey and a large baboon of which the former was greatly afraid. The keeper, to whom the little monkey was strongly attached, was one day attacked and thrown down by the baboon and in danger of being killed. Then the little monkey ran to his help, and bit and beat his tyrant companion until he allowed the keeper to escape. We are all proud that the little monkey was an American.
Instances of disinterested actions are so common among dogs and horses that farther illustrations are entirely unnecessary. And disinterested action is limited to fewer cases because the environment is rarely suited to its development in the animal world. But do you answer that the affection of the dog is never really disinterested, but a very refined form of selfishness. Possibly. But it were to be greatly desired that selfishness would more frequently take that same refined form among men. But I cannot see how selfishness can ever become so refined as to lead an animal to die of grief over its master's grave.
And if refined selfishness were all, I for one cannot help believing that the dog would long ago have been asleep on a full stomach before the kitchen fire. Has no attempt been made to prove that all human actions are due to selfishness more or less refined? It is very unwise to apply tests and use arguments concerning animals which, if applied with equal strictness to human conduct, would prove human society irrational and purely selfish.
Mammals may be self-centred. But the highest forms have set their faces away from self and toward the non-self; some have at least started on the road which leads to unselfishness.
And man is governed to a certain extent by prudential considerations. If he entirely disregarded these he would not be wise. But the development of the rational faculty has brought before his mind a series of motives higher than these, which are slowly but surely superseding them. Truth, right, and duty are motives of a different order. With regard to these there can be no question of profit or loss. Here the mind cannot stop to ask, Will it pay? Self must be left out of account.
"When duty whispers low, Thou must, The soul replies, I can."
And thus man rises above appetite, above prudential considerations, and becomes a free and moral agent. And family and social life bring him into new relations, press home upon him new duties and responsibilities, every one of which is a new motive compelling him to rise above self. And thus the unselfish, altruistic emotions have made man what he is, and are in him, ever advancing toward their future supremacy. But some one will say, This is a very pretty theory; it is not history. But the perception of truth and right is certainly a fact, the result of ages of development. And the very highest which the intellect can perceive is bound to become the controlling motive of the will. It always has been so. It must be so, if evolution is not to be purely degeneration. Thus only has man become what he is. And the voice of the people demanding truth and justice, whenever and wherever they see them, is the voice of God promising the future triumph of righteousness. For it is proof positive that man's face is resolutely set toward these, as his ancestors have always marched steadily toward that which was the highest possible attainment.
We find thus that there is a sequence in the motives which control the will. The first and lowest motives are the appetites, and here the will is the mouthpiece of the bodily organs. Then fear and a host of other prudential considerations appear. The lowest of these tend purely to the gratification of the senses or to the avoidance of bodily discomfort. But they originate in the mind, and that is a great gain. But the higher prudential considerations take into account something higher than mere bodily comfort or discomfort. Approbation and disapprobation are motives which weigh heavily with the higher mammals. The lower prudential considerations are purely selfish. The higher ones, which stimulate to action for fellow-animals or men, show at least the dawn of unselfishness. And the altruistic motives, which stimulate to action for the happiness and welfare of others, predominate in, and are characteristic of, man. The human will is slowly rising above the dominance of selfishness. With the dawn of the rational perception of truth, right, and duty, the very highest motives begin to gain control. And the will becomes more and more powerful as the motives become higher. It is almost a mis-use of language to speak of the will of a slave of appetite. He is governed by the body, not at all by the mind.
The man who is governed by prudential considerations, and is always asking, Will it pay? is the incarnation of fickleness, instability, and feebleness. The apparent strength of the selfish will is usually a hollow sham. But truth, right, and love are motives stronger than death. And the will, dominated by these, gives the body to be burned. The man of the future will have an iron will, because he will keep these highest motives constantly before his mind.
In the preceding lectures we have traced the sequence of functions and have found that brain and mind, not digestion and muscle, are the goal of animal development. In this lecture we have attempted to trace a corresponding series of functions in the realm of mind. We have found, I think, that there has been an orderly and logical development of perceptions, modes of action, and finally of motives in the animal mind. Let us now briefly review this history and see whether it throws any light on the path of man's future progress.
Most of the sensory cells of the animal minister at first to reflex action, and there is thus little true perception. The stimuli which have called forth the reflex action may result afterward in consciousness; but until brain and muscle have reached a higher grade, this could be of but slight benefit to the animal. Perception and consciousness are exercised mainly in the recognition and attainment of food. When the animal begins to show fear, we may feel tolerably certain that it has been conscious of past experience of danger and remembers these experiences. But the sense-organs are all the time improving, whether as servants of conscious perception or of reflex action, and the development of the higher sense-organs, especially of the eyes, has called forth a higher development of the brain. The brain continually develops both through constant exercise and through natural selection. Through the higher and more delicate sense-organs it perceives a continually wider range of more subtile elements in its environment. And the higher the sense-organ the more directly and purely does it minister to consciousness. The eye, when capable of forming an image, is almost never concerned in a purely reflex action.
From the constant recurrence of perceptions and experiences in a constant order the animal begins to associate these, and when he has perceived the one to expect the other. Out of this grows, in time, inference and understanding. The mind is beginning to turn its attention not merely to objects and qualities, but to perceive relations. And thus it has taken the first step toward the perception of abstract truth. And if it has the aesthetic perception and can perceive beauty, we have every reason to believe that the same faculty will one day perceive truth and right. But on the purely animal plane of existence these powers could be of but little service, and we can expect to find them developed only very slightly and under peculiar surroundings. And in this connection it is interesting to notice the great results of man's training and education in the dog. For the wolf and the jackal, the dog's nearest relatives, if not his actual ancestors, are not especially intelligent mammals. Compared with them the dog is a sage and a saint.
The earliest form of action is the reflex. This is independent of both consciousness and will. The only conscious voluntary action of the animal is limited mainly or entirely to the recognition and attainment of food. The motive for the exertion of the will is the appetite, and the will is the slave or mouthpiece of the body. Far higher than this is the stage of instinct. Here the animal is conscious of its actions and new motives begin to appear. But the animal is guided by tendencies inherited from its ancestors. The will has, so to speak, advisory power; it is by no means supreme. But with a wider and deeper knowledge of its environment, with the memory of past experiences, carried by the higher locomotive powers into new surroundings, brought face to face with new emergencies outside of the range of its old instincts, it is compelled to try some experiments of its own. It begins to modify these instincts, and in time altogether does away with many of them. It has risen a little above its old abject slavery to the appetites, it is slowly throwing off the bondage to heredity. New emotions or motives have arisen appealing directly to the individual will. The heir has been long enough under guardians and regents, it assumes the government and can rightly say, "L'etat, c'est moi."
But a greater problem confronts it; can it rise above self? The animal often seems absolutely selfish. Can the unselfish be developed out of the selfish? This seems at first sight impossible. And the first lessons are so easy, the first steps so short, that we do not notice them. Reproduction comes to the aid of mind. The young are born more and more immature. They begin to receive the care of the parent. The love of the parent for the young is at first short lived and feeble. But it is the genuine article, and, like the mustard-seed planted in good soil, must grow. It strengthens and deepens. Soon it begins to widen also. Social life, very rude and imperfect, appears. And the members of this social group support, help, and defend one another. And doing for one another and helping each other, however slightly and imperfectly, strengthens their affection for one another. The animal is still selfish, so is man frequently, but it is in a fair way to become unselfish, and this is all we can reasonably expect of it.
For these are vast revolutions from reflex action to instinct, and from instinct to the reign of the individual will, and from appetite to selfishness on the ground of higher motives, and from immediate gratification to prudential considerations. And the crowning change of all is from selfishness to love. And each one of them takes time. Remember that the Old Testament history is the record of how God taught one little people that there is but one God, Jehovah. Think of the struggles, defeats, and captivities which the Israelites had to undergo before they learned this lesson, and even then only a fraction of the people ever learned it at all. As the prophet foretold, so it came to pass. Though Israel was as the sand by the sea-shore, but a remnant was saved.
But while we seek to do full justice to the animal, let us not underestimate the vast differences between it and man. The true evolutionist takes no low view of man's present actual attainments; in his possibilities he has a larger faith than that of the disbeliever in evolution. In intelligence and thought, in will power and freedom of choice, in one word, in all that makes up character and personality, man is immeasurably superior to the animal. These powers raise him to a new plane of being, give him an indefinitely higher and broader life, and his appearance marks a new era. He alone is a moral, responsible being, to a certain extent the former of his own destiny and recorder of his doom, if he fails. This gives to all his actions a peculiar stamp of a dignity only his. What he is and is to be we must attempt to trace in another lecture. But to one or two characteristic results of his progress we must call attention here.
The principal subject of man's study is not so much the things which surround him as his relation to them and theirs to each other. His environment has become really one, not so much one of tangible and visible objects as of invisible relations. And these will demand endless investigation. The more he studies them the more wonderful do they become. The vein broadens and grows indefinitely richer the deeper he searches into it. We find thus the purpose of the intellect; it is to study environment.
And now a little about motives. The animal begins with appetite, and some animals and men never get any farther. And yet how easily this appetite for food is satiated! We all remember our experiences as children around the Thanksgiving or Christmas table. What a disappointment it was to us to find how soon our appetite had forsaken us, and that we had lost the power of enjoying the delicacies which we had most anticipated. And over-indulgence often brought sad results and was followed by a period of penitential fasting. And the appetites for sense gratification must always lead to this result. They not only crave things which "perish with the using;" temporarily at least, often permanently, the appetite itself perishes with the gratification.
But what of the appetite, if you will pardon the expression, for truth and right? All attainment only strengthens it; and, instead of enslaving, it makes men ever more free. And yet what a power there is in the appetite for truth and righteousness? In obedience to it man gives his body to be burned, or pours out his life-blood drop by drop for its attainment, and rejoices in the sacrifice. There are victims to appetite: there are only martyrs to truth. This soul hunger for truth and right, growing more intense as the soul is filled with the object of desire, is the only one capable of indefinite development and dominance of the will. This must be and is the mental goal of animal development, if man has a future corresponding in length at all to his past. Otherwise the history of life becomes a "story told by an idiot." For its satisfaction is the only one which never causes satiety, and of which over-indulgence is impossible. All others lead only to a slough of despond, or the deeper and more treacherous slough of contentment, beyond which rise no delectable mountains or golden city.
And now in closing let me call your attention to one thought of practical vital importance.
According to the theory which we have agreed to adopt, higher species have arisen through a process of natural selection, those species surviving which are best conformed to their environment. And this applies to man as well as to lower animals. All knowledge is in man, therefore, primarily, a means by which he may conform to environment, survive, and progress. But conformity includes more than mere knowledge of environment. A man might have all knowledge, and yet refuse to conform; and then his knowledge could not save him from destruction. For conformity alone gives survival. Conformity in man requires an effort of the will. It is intelligent, but it is also voluntary action. And knowledge is a necessary means of conformity because through it we see how we may conform, and because it furnishes the motives which stimulate the will to the necessary effort.
Now, that faculty of the intellect which is dominant in man, and which has raised him immeasurably above the animal, and made him man, is the rational intelligence. If there is any such thing as a law of history or as continuity in evolution, man's future progress must depend upon his clearer vision and recognition of the perceptions of this faculty. Through it man perceives beauty, truth, and goodness, and attains knowledge of himself as a person and moral agent, and recognizes his rights and duties. Of all this the animal is and remains unconscious; indeed he is not yet a moral being and person in any proper sense of the word.
Inasmuch as the rational perception is the dominant faculty in man, it must perceive the lines along which he is to conform. Truth, right, and duty must be his watchwords. These are to be the rules and motives of all his actions. He cannot live for the body, but for something higher, the mind. This was proven before man appeared on the globe. He is to be a mental, intelligent being. But he is not to be governed by appetite or mere prudential considerations. These are animal, not human motives. These are not to be disregarded any more than digestion can be safely disregarded by man. But they are not to be his chief motives. He must subordinate these to the higher motives furnished by right and duty. Man is not merely a mental but a moral being. If he sinks below this plane of life he is not following the path marked out for him in all his past development. In order to progress, the higher vertebrate had to subordinate everything to mental development. In order to become man it had to develop the rational intelligence. In order to become higher man, present man must subordinate everything to moral development. This is the great law of animal and human development clearly revealed in the sequence of physical and mental functions.
Must man be a religious being also? This question we must try to answer in a future lecture.
NATURAL SELECTION AND ENVIRONMENT
I have attempted to show that animal development has not been an aimless drifting. Functions developed and organs arose and were perfected in a certain order. First the purely vegetative organs appeared, and the animal lived for digestion and reproduction; then came muscle and it brought with it nerve. But these were not enough; the brain had all the time been gradually improving, and now it becomes the dominant function to which all others are subordinated. The experiment was fairly tried. Mere digestion and reproduction are carried to about the highest perfection which can be expected of them in worms and mollusks. The bird tried what could be done with digestion ministering to locomotion guided by the very keenest sense-organs and controlled by no mean brain. Even this experiment was not a success. But one organ remained, the brain, and on its mental possibilities depend the future of the animal kingdom. Vegetative organs and muscle have been tried and found wanting.
[Footnote 1: See chart, p. 310.]
We have followed hastily the development of mind. The mind began its career as the servant of digestion, recognizing and aiding to attain food. Action is at first mainly reflex. But conscious perception plays an ever more important part. The animal is at first guided by natural selection through the survival of the most suitable reflex actions, then by inherited tendencies, finally by its own conscious intelligence and will. The first motives are the appetites, but these are succeeded by ever higher motives as the perceptions become clearer and more subtile relations in environment are taken into account. Governed first purely by appetites, the will is ever more influenced by prudential considerations, and finally shows well-developed "natural affections." It has set its face toward unselfishness.
Digestion and muscle, as well as mind, have persisted in man. He is not, cannot be, disembodied spirit. And in his mental life reflex action and instinct, appetite and prudence, are still of great importance. But the higher and supreme development of these powers could never have resulted in man. They might alone have produced a superior animal, never man. His mammalian structure found its logical and natural goal in family and social life. And even the lowest goal of family life is incompatible with pure selfishness, and as family life advanced to an ever higher grade it became the school of unselfishness and love. And social life had a similar effect.
Moreover, man as a social being early began to learn that he could claim something from his fellows, and that he owed something to them. If he refused to help others, they would refuse to help him. This was his first, very rude lesson in rights and duties. Love, duty, and right have ever since been the watchwords of his development and progress. We have not yet considered, and must for the present disregard, the value and efficiency of religion in aiding his advance. At present we emphasize only the historical fact that man has not become what he is by a higher development of the body, nor by giving free rein to appetite, nor yet by making the dictates of selfish prudence supreme. And if there is any such thing as continuity in history, such modes and aims of life, if now followed, would surely only brutalize him and plunge him headlong in degeneration. He must live for right, truth, love, and duty. In just so far as he makes any other aim in life supreme, or allows it to even rival these, he is sinking into brutality. This is the clear, unmistakable verdict of history, and we shall do well to heed it.
But granting all that can be claimed for this sequence, have not the lower forms whose anatomy we have sketched—worm, fish, and bird—halted at various points along this line of march? Yet they have evidently survived. And if they have found safe resting-places, cannot higher forms turn back and join them? In other words, is not degeneration easier than advance and just as safe? What is the result if an animal tries to return to a lower plane of life or refuses to take the next upward step? Generally extermination. The very classification of worms in a number of small isolated groups, which must once have been connected by a host of intermediate forms, is indisputable proof of most terrible extermination. They did not go forward, and the survivors are but an infinitesimal fraction of those which perished. Let us take an illustration where palaeontology can help us. The earth was at one time covered with marsupial mammals. Some advanced into placental forms. The great mass remained behind. And outside of Australia the opossums are the only survivors of them all. And this is only one example where a thousand could be given. Place is not long reserved for mere cumberers of the ground. There are so few exceptions to this statement that we might almost call it a law of biology.
Let us see how it fares with an animal which retreats to a lower plane of life. A worm, rather than seek its own food, becomes a parasite. It degenerates, but still is easily recognized as a worm. A crustacean tries the same experiment, though living outside of its host instead of in it. It sinks to a place even lower, if possible, than that of the parasitic worm. A locomotive form becomes sessile. It loses most of its muscles and the larger part of its nervous system; and even the digestive system, which it has made the goal of its existence, is inferior to that of its locomotive ancestors and relatives. But to the vertebrate these lowest depths of stagnation and degeneration are, as a rule, impossible. From true fish upward parasitism and sessile life are practically impossible. Here stagnation and degeneration mean, as a rule, extinction. Of all the relatives of vertebrates back to worms only the very aberrant lines of amphioxus and of the tunicata remain. Of the rest not a single survivor has yet been discovered. And yet what hosts of species must have peopled the sea. The primitive round-mouthed fishes have practically disappeared. The ganoids survive in a few species out of thousands. The amphibia of the carboniferous and the next period and the reptiles of the mesozoic have disappeared; only a few feeble degenerate remnants persist. And this was necessarily so. Each advancing form crowded hardest on those which occupied the same place and sought the same food, that is, the members of the same species. And the first to suffer from its competition were its own brethren. Death, rarely commuted into life imprisonment, is the verdict pronounced on all forms which will not advance. And does not the same law of advance or extinction apply to man? What is the record of successive civilizations but its verification?