CHAPTER VI
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.[1]
[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 appet.i.tes, 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 appet.i.tes, 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, appet.i.te 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 appet.i.te, 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 cla.s.sification 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 ill.u.s.tration where palaeontology can help us. The earth was at one time covered with marsupial mammals. Some advanced into placental forms. The great ma.s.s 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 c.u.mberers 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 compet.i.tion were its own brethren. Death, rarely commuted into life imprisonment, is the verdict p.r.o.nounced 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?
Notice once more that as we ascend in the scale of development natural selection selects more unsparingly and the path to life narrows. It is a very easy matter for the lowest forms to get food.
Indeed the plant sits still and its food comes to it. And the battle of brute force can be fought in a mult.i.tude of ways--by mere strength, by activity, by offensive or defensive armor, or even by running into the mud and skulking. It is harder to gain knowledge, and yet many roads lead to an education. Colleges are by no means the only seats of education. And many totally uneducated men have college diplomas. And life is, after all, the great university, and here the sluggard fails and the plucky man with the poor "fit" often carries off the honors.
"But where shall wisdom be found?
And where is the place of understanding?
The gold and the crystal cannot equal it: And the exchange of it shall not be for jewels of fine gold.
No mention shall be made of corals or of pearls: For the price of wisdom is above rubies."
And when it comes to righteousness there is only one right, and everything else is wrong. "Wide is the gate and broad is the way that leadeth to destruction, and many there be that go in thereat: Because strait is the gate and narrow is the way which leadeth unto life, and few there be that find it." Therefore "strive to enter in at the strait gate." And remember that "strive" means wrestle like one of the athletes in the old Olympic games.
"I saw also that the Interpreter took Christian again by the hand and led him into a pleasant place, where was built a stately palace beautiful to behold; at the sight of which Christian was greatly delighted. He saw also, upon the top thereof, certain persons walking, who were clothed all in gold. Then said Christian, May we go in thither?
"Then the Interpreter took him and led him up toward the door of the palace; and, behold, at the door stood a great company of men, as desirous to go in, but durst not. There also sat a man at a little distance from the door at a table-side, to take the name of him that should enter therein; he saw also that in the door-way stood many men in armour, to keep it, being resolved to do to the men that would enter what hurt and mischief they could.
Now was Christian somewhat in amaze. At last, when every man started back for fear of the armed men, Christian saw a man of a very stout countenance come up to the man that sat there to write, saying, Set down my name, Sir; the which when he had done, he saw the man draw his sword, and put an helmet upon his head, and rush toward the door upon the armed men, who laid upon him with deadly force; but the man, not at all discouraged, fell to cutting and hacking most fiercely. So after he had received and given many wounds to those that attempted to keep him out, he cut his way through them all, and pressed forward into the palace, at which there was a pleasant voice heard from those that were within, even of those that walked upon the top of the palace saying:
""Come in, come in; Eternal glory thou shalt win."
"So he went in, and was clothed in such garments as they.
"Then Christian smiled, and said, I think verily I know the meaning of this."--Bunyan"s, Pilgrim"s Progress, p. 44.
If you wish to climb the Matterhorn many paths lead up the lower slopes, and a stumble here may cost you only a sprain. And I suppose that several paths lead to the base of the cone. But thence to the summit there is but one path, and a misstep means death. Pardon these quotations and ill.u.s.trations. They are my only means of at all adequately presenting to you a scientific man"s conception of the meaning of the struggle for life. The laws of evolution are written in blood and bear the death penalty. For
"Life is not as idle ore, But iron dug from central gloom, And heated hot with burning fears, And dipt in baths of hissing tears, And battered with the shocks of doom To shape and use."
There would seem therefore to be going on a process of natural selection. Natural selection seems to select more unsparingly and the struggle for life--or even existence--to grow fiercer as we advance from lower forms to higher in the animal kingdom.
But the theory which we have agreed to accept teaches us that these survivors are those which or who have conformed to their environment and that they have survived because of their conformity. And what do we mean by environment? And does not man modify his environment?
Certainly he changes by irrigation a desert into a garden. He carries water against its tendency to the hill-top. But he has learned to do this only by studying the laws which govern the motions of fluids and rigorously obeying them. He must carry his water in strong pipes and take it from some higher point, or must use heat or some means to furnish the force to drive it to the higher point. He cannot change a single iota of the law, and gains control of the elements only by obedience to their laws. Electricity is man"s best servant as long as he respects its laws, but it kills him who disobeys them. But does not man make his own surroundings in social life? He merely enters upon a new mode of life; and if this new mode be in conformity with the eternal forces and laws of environment man prospers in this new mode of life and conforms still more closely.
There is, indeed, but one environment, but the lower animal comes in contact with, and is affected by, but a small portion of its elements. Form and color were in the world before the animal had developed an eye, but up to this time these could have but little effect on animal life. Light vibrations were present in ether long before the animal by responding to them made them any part of its own true environment. There is vastly more in environment than man has yet discovered, and he will discover these elements only by obedience to their laws.
Environment includes ultimately all the forces and elements which go to make up our world or universe. It is an exceedingly general term.
I might say that under the environment of certain wheels, springs, and spindles, which we call a Jacquard loom, silk threads become a ribbon worthy of a queen. Is Nature and environment only a huge divine loom to weave man and something higher yet? One great difference is evident. Under normal conditions the silk must become a ribbon. But protoplasm can fail to conform and become waste.
Environment is a very hard word to define, and our views concerning it may differ.
One thing, however, seems to me clear and evident. If each successive stage in the ascending series is selected or survives on account of its conformity to environment there must be some element or power, something or somewhat in environment specially corresponding in some way to, or suited to drawing out, the characteristic of this ascending stage on account of which it survives. The forces and elements of environment make and work against those at each stage who wander from the right path, and for those who follow it. And thus natural selection arises as the total result of the combined working of all these forces. They all unite in one resultant working along a certain line, and natural selection is the effect of this resultant. In the stage represented by hydra the forces of environment combine in a resultant which works for digestion and reproduction and the best development of their organs.
But as the animal changes he comes into a new relation or occupies a new position in respect to these forces. New elements in the old environment are beginning to press upon him. And the resultant changes accordingly. He may be compared to a steamer at sea which raises a sail. The wind has been blowing for hours, but the sail gives it a new hold on the ship. Steam and wind now combine in a new resultant of forces. From worms upward environment manifests itself through natural selection as a power working for muscular force and brute strength or activity.
But soon natural selection ceases to select on the ground of brute force. After a time environment proves to be a power making for shrewdness. And when the mammal has appeared the resultant of the forces of environment impels more and more toward unselfishness, and when man has appeared environment proves to be a "power, not ourselves, that makes for righteousness." But what shall we say of an environment which unmasks itself at last as a power making for intelligence, unselfishness, and righteousness? Someone may answer it is a host of chemical and physical forces bringing about very high ends. That is very true, but is it the whole truth? The thinking man must ask, How did it come about, and why is it that all these forces work together for such high moral and intelligent ends?
We face, therefore, the question, Can an environment which proves finally and ultimately to be a power not ourselves making for righteousness and unselfishness be purely material and mechanical?
Or must there be in or behind it something spiritual? Shall we best call environment, in its highest manifestation, "it" or "him?"
The old argument of Socrates, as on the last day of his life he sits discoursing with his friends, still holds good. He is discussing the same old question, whether there is anything more than force, material, mechanism in the world. He says that one might a.s.sign as "the cause why I am sitting here that my body is composed of bones and muscles; that the bones are solid and separate, and that the muscles can be contracted and extended, and are all inclosed in the flesh and skin; and that the bones, being jointed, can be drawn by the muscles, and so I can move my legs as you see; and that this is the reason why I am sitting here. But by the dog, these bones and muscles would long ago have carried me to Megara or Booetia, moved by my opinion of what was best, if I had not thought it more right and honorable to submit to the sentence p.r.o.nounced by the state than to run away from it. To call such things causes is absurd. For there is a great difference between the cause and that without which the cause would not produce its effect."
If there is no intelligence or love of truth in the cause, how can there be anything higher in the effect? And if Socrates had been only bone and muscle, he ought to have run away.
Our problem stands somewhat as follows: We have given protoplasm, a strange substance of marvellous capacities, which we call functions, and possessing a power of developing into beings of ever higher grades of organization. Environment proves to be a combination of forces working for the higher development of functions in a certain orderly sequence. And every lower function in the ascending line demands the development of the next higher. Digestion demands muscle, and muscle nerve, and nerve brain. We shall soon see that mammalian structure had to culminate in the family, and the family demands unselfishness and obedience. Environment therefore proves from the beginning to have been unceasingly working for the highest end; never, even temporarily, merely for the lower. For we have seen that environment works most unsparingly against those who, having taken certain of the steps in the ascending path, fail to continue therein.
But in order to attain this highest end for which it has always been working, an immense number of subsidiary ends have had to be attained. These are not merely digestion and brain, but a host of others: _e.g._, in vertebrates, vertebrae of the right substance, position, form, arrangement, and union. And in the ascending line, for whose highest forms it has continually worked, the difficulties of attaining each subsidiary end have been successively solved, and through this host of subsidiary ends the animal kingdom has advanced straight to its goal of intelligence and righteousness. Now the whole process is a grand argument for design. But I would not emphasize the process so much as the end attained. This especially, when attained by conformity to that environment, demands more than mere mindless atoms in or behind that environment. Can we call the ultimate power which makes for righteousness "it?" Can we call it less than "Him, in whom we live and move and have our being?"
The history of life is a grand drama. "Paradise Lost" and Shakespeare"s plays are but fragments of it. But without intelligence they could never have been composed; without a choice of means and ends they could never have been placed upon the stage.
Does the plot of this grander drama of evolution demand no intelligence in its ultimate cause and producer? Is the succession of steps, each succeeding the other in such order as to lead to truth and right and continual progress toward a spiritual goal, is this plot possible without a great composer who has seen the end from the beginning? Could it ever have been executed upon the stage of the world, and perhaps of the universe, without an executing will?
Now I freely grant you that this is no mathematical demonstration.
Natural science does not deal in demonstrations, it rests upon the doctrine of probabilities; just as we have to order our whole lives according to this doctrine. Its solution of a problem is never the only conceivable answer, but the one which best fits and explains all the facts and meets the fewest objections. The arguments for the existence of a personal G.o.d are far stronger than those in favor of any theory of evolution. But we very rightly test the former arguments, indefinitely more rigidly and severely, just because our very life hangs on them. On the other hand, we should not reject them as useless, because they are not of an entirely different kind from those on which all the actions and beliefs of our common daily life are based. There is a scepticism which is merely a credulity of negations. This also we should avoid.
We have considered a few of the reasons for thinking that, with the material, there must be something spiritual in environment, that if the woof is material the warp is G.o.d. Here we need not delay long.
Blank atheism seems to be at present unpopular and generally regarded as unscientific. The so-called philosophic materialism of the present day seems to be in general far nearer to pantheism than to the old form of materialism which recognized only atoms and mechanism. Atheism as a power to deform the lives of men has, for the present, lost its hold, and even agnosticism is respectful. The materialism against which we have to struggle is not that of the school, but of the shop, of society, of life. There are comparatively few now who avow a system of philosophy making mindless atoms their first cause.
But there is a far grosser, more deadly materialism of the heart and will. It sits unrebuked in the front pews of our churches and controls alike church and parish, caucus and legislature. It calls on us all to fall down and worship, promising the world if we obey, the cross if we refuse. And we bow to it; and that is all it asks, for a nod on our part makes us its slaves. It is the idolatry of money, position, shrewdness, learning--in one word, of success. It takes all the strength out of our morality, loyalty and obedience to G.o.d out of our religion, and makes cowards and liars of us, who should be heroes. It makes our religion a byword with honest unbelievers. And if they are honest scientific minds, waiting for evidence of the practical value of our religion, why should they believe, when we live so successfully down to the religion which we would scorn to openly profess? Our fathers may have been narrow or straight-laced; they were not cross-eyed from trying to keep one eye on G.o.d and the other on the main chance. What is the use of whispering, "Lord, Lord," Sundays, if we shout, "Oh, Baal, hear us,"
all the rest of the week. Let us at least be honest, and "if Baal be G.o.d, follow him," and avow it. And worst, and most hideous, of all, we are not so much hypocrites as self-deceived. Let us not forget the old Greek doctrine of Ate, G.o.ddess of judicial blindness, sent down only upon those who were living the unpardonable sin of indifference.
But supposing that there is in environment something more and other than material, can we possibly know anything about it?
I am in a boat near the mouth of a river. The boat is tossed by the waves, driven by currents of wind, and now and then temporarily turned by eddies. I seem to look out upon a chaos of apparently conflicting forces. But all the time the wind and tide are sweeping me homeward. Now the wind, which sometimes indeed does shift, and the great tidal wave are steadily bearing me in a certain direction, though wave and eddy and gust may often make this appear doubtful to me. So, underneath all waves and eddies of environment, there is a great tidal wave, bearing man steadily onward; and I gain a certain amount of valid knowledge of environment from the direction in which it is bearing me.
Let us change the ill.u.s.tration. Man survives as all his ancestors have survived before him, through conformity to environment.
Environment has therefore during ages past been continually making impressions upon him. And he can draw valid inferences concerning the one power, which must underlie the apparent host of forces of environment, from the impressions which these have left upon the structure of his mind and character. By studying himself he gains valid knowledge of what is deepest in environment. For man is the most completely and closely conformed thereto of all living beings.
But man _is_ a religious being. This is a fact which demands explanation just as much as bone and muscle. Now no evolutionist would believe that the eye could ever have developed without the stimulus of light acting upon the cells of the skin. Place the animal in darkness and the eye becomes rudimentary and disappears.
Could a visual organ for seeing moral and religious truth have ever originated in the mind of man had there been no corresponding pulsation and thrill of a corresponding reality in environment? Is not the one development just as improbable or inconceivable as the other?