The place of death in evolution

Preface

This volume is the first fruit of a further and larger purpose which the author has long had in mind, and which in some future season may possibly become ripe for its harvesting. It springs from a profound conviction that the one theological task which waits to be accomplished is a thorough and comprehensive demonstration of the fact, which the disciple of old perceived, that the Life was manifested in the Christ; and hence it will prove true that His essential words meet and match the great principles of life which have been hidden in nature's heart from the beginning. It will be shown how naturally, and as the appointed heir of all things, Christianity wins and wears the crown of life.

The next reconstruction of Christian theology will be a vital one; it will result from a deeper knowledge and a truer

Vlll PREFACE

interpretation of the sacred Scripture of Life, which the hand of God has written in nature. The coming theologian, therefore, — the next successful defender of the faith once given to the saints, — will be a trained and accomplished biologist. Not only will his thought, descending from the heights of solitary abstraction, and forsaking the cloistered shades of the schoolmen, ancient and modern, proceed like the wayfaring Son of man along the familiar paths of human life, in closest touch with the common heart of humanity; but also each organic form will tell to him the story of its origins, and the least living cell will unveil the secret chambers of its divinity. Partial and hurried efforts, indeed, have been made in recent years to set our primal faiths in their large vital connections; — Mr. Drummond's Natural Laiv in the Spiritual World, and Mr. Kidd's Social Evolution, are stimulating efforts in this direction; but the value of these first endeavors lies in their true apprehension of the work needing to be done, rather than in their

PREFACE IX

permanent contribution to its solution. The science of biology itself has been far too crude, and its theories are still too tentative, and even conflicting at many points, to warrant us as yet in building upon them over-confidently the higher conclusions of the Christian reason. Nevertheless, within the past thirty years, and since Darwin, some sure ground has been gained by evolutionary science, and biology in particular is opening fields of knowledge which invite fresh inquiry on the part of thoughtful believers.

The larger work, in this attractive field, to which the author looks forward, may never be brought by him to its accomplishment: it is so large and many-sided that it can be achieved only by the toil of many minds, and as the result of prolonged studies and discoveries of the laws and processes of life, from the marvel of the microscopic germ up to nature's highest miracle of the potency of human thought and love. Both that earlier wonder of the living cell, and the later marvel

X PREFACE

of the living soul, belong to the same continuous order, and are a revealing of the same divine mystery of life. All our science of nature and the history of man may come back at last to the Master's single word of interpretation: "It is the spirit that quickeneth."

One reason for the present publication of this portion of the author's work is the hope that it ma}^ stimulate other minds to enter, in the pursuit of similar inquiries, that field of evolutionary research which not long ago it was thought to be perilous for theologians to traverse, and past which devout believers were inclined to hasten, as though it were a forbidden region, haunted with destructive doubts; but which we now generally perceive to be a field of the Lord, fresh with fruits of wholesome knowledge, and bright with promise for Christian faith.

The author ventures also to hope that the line of thought which is pursued through the following pages may lead some readers to surer courage for daily life amid its trials and sorrows. It may bring

PREFACE XI

help especially to those who must receive inward renewal and cheer, if at all, not merely from the breath of spiritual fragrance which may be borne in occasionally through the soul's open windows — they hardly know from whence and how; but rather from their thoughtful entertainment of those serious truths which knock for entrance into our minds, as they come in plain and honest simplicity from the workshops of our sciences, and from the fields of laborious investigations. Only thus, through an open-minded and fearless hospitality towards all observed and reasoned truths, can our Christian faith escape the weakness of a pleasing but ineffectual desire, and continue to be our reasonable service.

Although the author's main purpose is still in the process of growth, suggestive circumstances and the warmth of friendships whose light is in part the joy of present life, and in part the influence of the unseen, have caused this single branch of his thought to come more quickly to its ripening; and because as a study it is

Xll

PREFACE complete in itself, it is now given to the public.

If the sustenance and comfort for our dearest and deathless hopes here offered, should seem at first taste to any readers to be enclosed in a too scientific rind, the author trusts that within the harder scientific reasonings much sweetness and strength may be found for our vital faiths. In order to render the matter of it more easy of access for the general reader, necessary technical scientific material and extended citations of authorities have been relegated to notes in an appendix. These notes, however, should not be overlooked in any critical review of the subject.

The pursuit for several years of such studies increases the conviction in which this volume has been written, that new light is breaking from evolutionary science, and that in that light we shall see coming out again more clearly and more surely the simple and immortal faiths of our human hearts and homes.

New Haven, April, 1897.

Contents

THAPTEK PAGE

I. THE ENTRANCE AND USE OF DEATH IN

NATURE 1

Chapter I The Entrance And Use Of Death In Nature

IN recent years biological investigations have penetrated within the veil of microscopic cells, and learned secrets of life and death which were little dreamed of in our philosophy. Traces of an infinitesimal structure, which before had not been suspected, have been lately discovered within the least and simplest living cells; and arrangements of invisible molecules of matter in an orderly and organized service are now known to be provided in the contents of each cell in which life has its abode. One of the last wonders of modern science consists

B l

Z ENTRANCE AND USE OF DEATH

in the disclosure of the intricate mechanism of the nucleus of each cell, and in the revelation of regular processes of its marvellous development. Further explanation of the problem of heredity and the causes of variation, which Darwinism opened, but did not solve, is now eagerly sought by many keen-eyed biological students, equipped with the highest powers of the microscope, who peer into the structural texture, and observe the behavior of the vital units within the mystery of the egg. The living cell, that "long-expected child of time," "the precious nursling of the ages," as it has been called, has recently drawn to itself an immense amount of scientific attention; and doubtless upon the fascinating mystery of its origins, its aptitudes, and its growth, it will concentrate still more the interest of thoughtful observers who would interpret with definite knowledge nature's unceasing drama of life and death.

Neither of these familiar powers of life or death has disclosed to our most inquisitive biological science its last, innermost secret. The science which has entered so far within the cell, and which is observing with exact definition the last hiding-places of life, nevertheless does not hear the first creative word, and cannot tell the final cause of the origin of life. Probably it never will; for to see life revealed in its first truth might be to see the living God. Our science, which thus pursues life until it is lost from view in some mystery of godliness, has not succeeded any better in disclosing the ultimate nature or final cause of death. Yet the nearer approach of recent biological science to the origins of life brings knowledge closer also to the beginnings of death in the organic world. Some new light is thus thrown by recent science over the dark problem of mortality. By the scientific method, — that is, by reasoning which proceeds from a basis of observed facts, — we may now make a further and profitable study of the origin and function of death in nature, and thus be enabled to interpret more intelligibly its mission for life.

Until quite recently our evolutionary science was content either to pass by the place and work of death without exact observation of its uses in nature ; or else it has regarded the universal prevalence of death throughout the organic world as a necessary consequence of the struggle of life, and has dismissed it from further questioning as an incidental factor in evolution. Thus Mr. Spencer was satisfled with a philosophical determination and definition of the nature of vital processes, which included the possibility of death within the terms of the definition. More attention was called to this neglected factor in organic evolution by the publication in 1881, and again in 1883, by a German investigator, Weismann, of some results of his studies concerning heredity, in the course of which he discussed the nature of death, and the causes for the limitation in different species of the duration of life. About the same time another German zoologist, Biitschli, who had carried on extensive researches among the lowest organisms, began to entertain ideas somewhat similar to those which Weismann first published in his essays on Life and Death and the Duration of Life. Mr. Wallace, who shares with Darwin the honor of originating the modern conception of the part which has been played by natural selection in evolution, in a note to his volume on Darwinism (published in 1889) remarks that an idea similar to that advanced by Weismann, concerning the utility of natural death, had occurred to him some twenty years before, and been noted down, but subsequently forgotten.

Later investigations seem to require the modification in some particulars of the ideas originally advanced by Weismann, and to put back the first appearance of natural death nearer to the earliest manifestations of life than he had supposed. Much work of painstaking research in this direction remains to be accomplished ; and biological theories concerning the nature of heredity and the fundamental laws and processes of life and death are still too largely in the air, and b ENTRANCE AND USE OF DEATH

they will need to be anchored more securely to observed facts before we can trust entirely our faiths to them. Nevertheless, much knowledge has been gained concerning the origin and functions of death in the course of the development of life by the researches already undertaken; and the facts disclosed, as well as the theories advanced by some trained biologists, fairly open the new and interesting question whether death itself does not fall naturally under some principle of selection and law of utility for life. Enough ground, at least, has been won by our tentative science to give our philosophy further, and somewhat more advanced foothold in the path of inquiry, along which the reason of man makes ceaseless effort to surmount the hard inevitableness of death, and in clearer light to gain firmer hope of immortality.

These studies of life which our newer biologists, since Darwin, are carrying on, may be described in the graphic words of one of the oldest observers of nature and human life, who was also a tried and troubled theologian, " Man setteth an end to darkness, and searcheth out to the furthest bound the stones of thick darkness and of the shadow of death."* Like one who sets miners' lamps along the course which he would explore, so man in these more recent sciences searches to the furthest bound, and finds there the stones which mark for the present the end of his inquiry into the thick darkness and the shadow of death. Our science of life is reaching into the darkness, and farther and farther from the borders of the near, the tangible, and the visible, it is removing the bounds of knowledge out into the mystery of life and death.

Familiarity with the successes, and also with the failures, of evolutionary science since Darwin will serve to produce, in regard to all such inquiries, a reverent spirit, if not also an expectant attitude of faith. Men who have but slight acquaintance with the work needing to be done, which still lies before our biologists, may conjure lightly with the word * Job xxviii. 3.

evolution, as though it explained all mysteries, and dispensed with any necessity of faith; but men who have learned how knowledge as well as faith requires patience for its perfecting will understand the wisdom both of the caution and the hope which finds expression in this remark of one of our American biologists: "My last word is, that we are entering the threshold of the Evolution problem, instead of standing within the portals. The hardest tasks lie before us, not behind us, and their solution will carry us well into the twentieth century."*

While our biological science has thus, until quite lately, not ventured so far as it might into the darkness of the shadow of death over nature, our theology, on the other hand, has been and is still contented to regard the law of death as a law of sin, originally connected with man's fall, and as presenting chiefly a human problem to

* Osborn, The Hereditary Mechanism and the Search for the Unknoivn Factors of Evolution, in Biological Lectures, Wood's Holl, for 1894, p. 100.

our faith. The fact of the prevalence of death in nature before man's fall has been left vaguely in the background of theology. It has sometimes been ignored as a problem of evil with regard to which we have no clear word of revelation ; or, when the problem of natural evil has pressed like a burden upon the heart of faith, the entrance of death into the creation before man has been hesitatingly explained as a necessary anticipation of the curse which was predestined to fall, and which nature consequently must, from the beginning, make ready to let drop in due time upon the sin of man. Death, occurring in the natural order of life, has thus been regarded as a part of the preparation of the stage for the tragedy of man's sin and the victory of his redemption.

Our theology may be excused for not gaining any larger and more intelligent conception of the appearance of death in nature beneath man, so long as our biological science has had little or nothing to say as to the exact point in the evolution of life where death first entered, and while also it has been unable to offer anything better than a general conjecture concerning the natural function and possible service of death in the evolution of life. But our Christian theology would be worthy of blame, should it not be quick to take up into its conception of the divine order of benevolence any hints which recent biology may have to suggest with reference to the probable natural utilities of death. It is of religious concern, as well as of scientific interest, for us to learn, and to think out, as far as we possibly may, all the facts and suggestions which prolonged and microscopic researches may bring to our knowledge concerning the minute processes, or most intimate and hidden laws of life and death. For if we, children of an age of questioning and of change, are to keep a rational faith in spiritual reality, strong and genuine as was our fathers' faith according to their light, ours must be a faith that shall strike its roots down deep into all knowledge, although light from above alone may bring it to its perfect Christian trust and sweetness. If, then, our biological science is running the lines of its investigation deeper across familiar ground, as well as over fields of knowledge not hitherto upturned, our faiths should quickly follow, sowing again their seed of promise in the freshly worked soil. Nor should we despise any hints which biology may bring of larger utilities in nature than we have imagined, because such facts may seem at first thought to be slight and insignificant. The least facts of nature may be germinal with high spiritual significance and beauty.

Analogies indeed from natural laws are not proofs of spiritual processes ; and they should never be pressed beyond the probabilities of reason which may lie within them. The demonstration of the spiritual order cannot lie in the natural. Nevertheless, if the universe be framed in one divine thought, and its laws, in different realms of it, proceed from the same Intelligence, we should expect to find that knowledge, shining suddenly in any part of it, will throw revealing light also over other outlying regions, and especially over those dark spiritual places which may lie contiguous to the points which some science is lighting up; for the different spheres and orders of the cosmos, from the lowest to the highest, are not so many separate and closed spaces, but the universe is connected in all its parts, — its rooms are all openwindowed, and its successive chambers lead into one another; — there are many mansions and one house of the Father.

What is thus true in general of the value of any single science for the broader illumination of life, does not hold false of the service which biology is beginning to render to our conception of the law of death. If we may discover and carefully observe the working of a power favorable to life's best ends in the utilities of death in nature, we shall have thereby a light in our hands by means of which our reason may possibly find its way still farther through the mystery of death in our human life. It is true that under the existing limitations of our earthly experience we may not expect to reach a full explanation of any of the great laws of nature, and a final discovery of the one benevolence in them all; but partial explanations are better than none, — the child's imaginations may seize upon enough of the truth to satisfy the mind of the child, until it shall put away childish things, and know as it is known. We should not neglect therefore as insignificant the least divine hints which may have been dropped amid the silences of nature; for any such suggestions may prove a very present help to reason while faith waits for the final revelation.

We shall seek, therefore, to gather up such knowledge as recent biological science may have to offer concerning the place and function of death in the order of nature; and then we shall proceed to inquire whether such knowledge has any further interpretative value in relation to the law of our human subjection to death, and its attendant suffering.

What has been from the first the r61e appointed for death to play in the unfolding drama of life in nature? Looking down through the history of ever-advancing life on the earth, looking back to the first appearance and working of death, do we discover any signs which indicate that death, contrary to our common judgment of it, has had appointed to it all the while a benevolent part, that it has not been the natural enemy, but in reality a servant of life, — a helpmeet for ever more abounding, higher, and happier life on the earth?

The first fact which has been observed is, that natural death does not appear immediately at the beginning of the history of life on the earth. There was no such thing as death, or at least nothing like a dead body, when life first stirred, and for some indefinite period after life began to increase and multiply in earthly matter.

The earliest and the simplest organism consists of a single cell. That unicellular organism is now known to be not completely homogeneous, or without beginnings of distinctions between its parts; but within the divine simplicity of a single cell, the infinitesimal tracing of whose marvellous structure may be detected by our microscopes, while its perfect discrimination defies their powers, life begins its work, never henceforth to cease, of organizing matter for increasing sentience, for developing function and faculty, and for final aptitude and service for self-conscious thought and love. Our human interest in the problem of the origin and the destiny of life may be concentrated in the study of this earliest and simplest living organism, composed of a single cell. What Tennyson sang of the "Flower in the crannied wall" would be now more true of the efflorescence of life in the little cell which the biologist plucks " out of the crannies " : —

" I hold you here, root and all, in my hand, Little flower — but if I could understand What you are, root and all, and all in all, I should know what God and man is."

If we could read the whole secret of that living cell, we might know the mystery of our origin and our destiny. Before it or within it, is there any trace to be discovered of a pre-existing life, or any hint to be found of life's coming glory? Does life in its earliest known beginnings contain any revelation of a Spirit that was before it, or disclose any mystery of Messianic promise of its coming divinity?

These questions, however, concerning the ultimate origin and possible spiritual direction of life, we hold in reserve for a later place in our present plan of discussion; we are content to begin with a strictly biological conception of life as a peculiar property of matter, or, as it has been tersely stated, "as matter in a peculiar state or condition." Whatever may have been the origin of life, we may read with scientific eye its story, after it has come to write upon the records of the earth its history and its prophecy. We may notice the point where, so far as known, death first enters the course of life.

That which actually occurs, after life has come far enough out of the unseen for us to see and to touch it, and to keep its growth under the eye of our science, may be summarily described as follows: The first one-celled organism does not exist for a season, produce another like itself, and then decay, and die, and totally disappear; it does nothing of the sort; the one thing it does is, not to die, but to live on. It succeeds in living on, and on, by a very simple yet persistent process ; for after a while it divides itself into two cells, each like itself, and thus it continues to exist, living in these cells a double life; and this process of simple division and multiplication is carried on for a number of successive generations without the appearance of any dead ancestor, or of anything like that which we mean when we speak of a dead body. The simplest forms of life, if left to themselves, if left under favorable conditions, and without accident, to follow their natural course, do not die; they bud and divide, they increase and multiply.

This process of cell-division and multiplication, it was supposed by Weismann, might naturally continue in an endless succession among the unicellular organisms; hence he held that such organisms are potentially immortal. As the entire substance of each cell passes into the cells into which it divides, the process leaves behind it no trace of anything resembling a dead and decaying animal form, and hence it has been said of these lowest organisms that "no Amoeba has ever lost an ancestor by death."

In the multicellular organisms, — those composed of several cells, or groups of cells, — life grows more complex. The germinal cells — those which bear the hereditary matter and the continuous reproductive power of life — are distinguished, according to Weismann's theory, from the somatic cells, — those forming the body, which support, while they are themselves fashioned by, the germ-cells. These latter cells, Weismann supposed, in their differentiation from the former, lost the power of indefinite multiplication ; and probably for the benefit of the other germinal cells, which contain the undying germ-plasm, or continuous, hereditary matter of life, the somatic (body) cells became limited in the number of their possible divisions ; that is, they acquired mortality, and acquired it as an advantageous adaptation to the ends of life. Hence death first appeared among the multicellular organisms (Metazoa), and it appeared on account of its utility. 1

This supposition, however, of the potential immortality of the lowest organisms through an endless process of cell-division must be modified by the results of later experiments which were conducted with much painstaking by the French biologist, Maupas. 2 His investigations consisted of the careful culture and observation of successive generations of several species of the unicellular animals (the Ciliated Infusoria). He was able to follow in different cultures the history of from two to over six hundred successive generations of these minute organisms. Two methods of reproduction had previously been observed among these organisms, the one by fission, — an asexual method ; and the other by something resembling fertilization, through the meeting and partial blending of the contents of two cells, — a conjugation of cells, — after which each of them continued to multiply by dividing into daughter cells. These researches of Maupas showed that among these higher Protozoa the preservation of the species is maintained by occasional intervention of this higher method of conjugation, and that without it the power of cell-division and multiplication becomes enfeebled and in time is completely lost. " The evident result," remarks Maupas, "after long and fatiguing experiments, is that the life of the species with the Cities is divided into evolutionary cycles, having each for its point of departure an individual regenerated, and its youth renewed by a sexual completion."*

By isolating individual Infusoria, and

thus preventing them from renewing their

power of reproduction by meeting other

more distantly related forms of their own species, Maupas discovered among the descendants of the isolated individual increasing signs of enfeebled life, senescence, and loss of the power to multiply; and finally the succession of their generations came to a complete pause, and a dead cell was left at the end of it.* At this point natural death, so far as now known, first appears. In the light of these investigations, life is seen to continue through a rudimental form of sexual rejuvenescence reaching on towards further and still more highly organized forms ; while life in its primitive method of multiplication by simple cell-division begins to droop, and at last to die. A double line of life is thus observed: the one, that composed of the sexually reinforced cells, branching up, and bringing forth more fruit; the other, that composed of the isolated, unreinforced cells, continuing for a while, but at length, as though overshadowed by the more fruitful branch, and as no longer

* " In nature, however, this limit is probably seldom if ever reached." — Sedgwick and Wilson, General Biology, p. 170.

22 ENTBANCE AND USE OF DEATH

advantageous for nature's end of a more abundant life, left to wither, and because no longer useful to come at length to an end. This end of this less advantageous method of the propagation of life is death ; thus nature produces and abandons the first known body of death in the history of life.

These researches of Maupas show that death may have entered into the course of life, earlier than Weismann had at first supposed, among the simpler unicellular organisms. If their universal validity should be admitted, they would compel us to modify the supposition of the immortality of the Protozoa by limiting it, among the Infusoria, to such organisms as are kept in the cycle of an ever self-rejuvenating life. Death would overtake those (if there are in nature any such) who fall out of this improved cyclic method of selfreproducing life. Some doubt, however, seems to be thrown over the universal validity of these experiments; and even if we admit that they indicate a general law of the continuation of life among the higher classes of the Infusoria, they do not necessarily prove, as Maupas himself was careful to observe, that a similar cyclic rejuvenescence obtains among still lower and simpler organisms. Simpler forms may (upon Weismann's theory of the continuous germ-plasm they must) possess indefinite power of cell-division without any interruption by death.* But these investigations, however they may modify the original supposition of the immortality of all the Protozoa, serve to determine more exactly the point in nature where death enters ; and they also throw new light over the earliest working and use of death among the simplest organisms. 3

An important fact of far-reaching significance, which these microscopic researches reveal, is the connection between the first observed occurrence of death and the earliest observed occurrence of sex, or something resembling sexuality in nature.

* "It is not known whether or not the Amoeba ever dies of old age." — Sedgwick and Wilson, General Biology, p. 166.

Their intimate connection in the time of their appearance does not show that the one is the cause of the other ; but it does show that both are introduced together in the process of life as co-operative factors for the furtherance of life's mission on the earth. Death enters, so far as now known, in connection with the alternation between two methods of reproduction and multiplication of life ; it occurs naturally in the course of the change from the asexual method of simple cell-division to the method of fertilization, which in time comes to be nature's dominant method not only of preserving life, but also of giving it variety, richness, and plastic power of adaptation to different environments. 4 With the rudiments of sex appear also the beginnings of death. With the entrance of the new method for the enrichment and diversification of selected life through sex, enters also the law of decay and death for that remainder of life which is not caught up into this higher potency of nature's fertilization. In this first discrimination of nature between the reinforced cells, destined to live, and the unrejuvenated cells, destined to die, there is seen to be a resemblance to the last judgment of life, as the Scripture describes it: "Then shall two be in the field ; the one shall be taken, and the other left." So death in the earliest judgment of life signifies that which is left, and left as the least available organ for life.