The Fitness of the Environment

be of biological importance or which appear to be related to complexity, regulation, and metabolism. IX. There are no other compounds which share more than a small part of the qualities of fitness of water and carbonic acid; no other elements which share those of carbon, hydrogen, and oxygen. X. None of the characteristics of these substances is known to be unfit, or seriously inferior to the same characteristic in any other substance. XI. Therefore the fitness of the environ- ment is both real and unique.

In drawing this final conclusion I mean to assert the following propositions : — I. The fitness of the environment is one part of a reciprocal relationship of which the fitness of the organism is the other. This relationship is completely and perfectly recip- rocal ; ^ the one fitness is not less important ' This is not to be understood as an assertion that the rela- tionship is symmetrical. The fact is that each organism fits its particular environment, while the environment in its most general and universal characteristics fits the most general and universal characteristics of the organic mechanism.

than the other, nor less invariably a constitu- ent of a particular case of biological fitness; it is not less frequently evident in the char- acteristics of water, carbonic acid, and the compounds of carbon, hydrogen, and oxygen than is fitness from adaptation in the char- acteristics of the organism. II. The fitness of the environment results from characteristics which constitute a series of maxima — unique or nearly unique prop- erties of water, carbonic acid, the compounds of carbon, hydrogen, and oxygen and the ocean — so numerous, so varied, so nearly complete among all things which are concerned in the problem that together they form cer- tainly the greatest possible fitness. No other environment consisting of primary constitu- ents made up of other known elements, or lacking water and carbonic acid, could possess a like number of fit characteristics or such highly fit characteristics, or in any manner such great fitness to promote complexity, durability, and active metabolism in the organic mechanism which we call life.

It must not be forgotten that the possibility of such conclusions depends upon the universal character of physics and chemistry. Out of the properties of universal matter and the characteristics of universal energy has arisen mechanism, as the expression of physico- chemical activity and the instrument of physico- chemical performance. Given matter, energy, and the resulting necessity that life shall be a mechanism, the conclusion follows that the atmosphere of solid bodies does actually pro- vide the best of all possible environments for life.

A HALF century has passed since Darwin wrote "The Origin of Species," and once again, but with a new aspect, the relation between life and the environment presents itself as an unexplained phenomenon. The problem is now far different from what it was before, for adaptation has won a secure posi- tion among the greatest of natural processes, a position from which we may suppose it is certainly never to be dislodged; and natural selection is its instrument, even if, as many think, not the only one.^ Yet natural selec-

' Natural selection remains still a vera causa in the origin of species; but the function ascribed to it is practically reversed. It exchanges its former supremacy as the supposed sole determinant among practically indefinite possibilities of structure and function, for the more modest position of simply accelerating, retarding, or terminating the process of otherwise determined change. It furnishes the brake rather than the steam or the rails for the journey of life ; or in better

tion does but mold the organism ; the environ- ment it changes only secondarily, without truly altering the primary quality of environ- mental fitness. This latter component of fit- ness, antecedent to adaptations, a natural result of the properties of matter and the characteristics of energy in the course of cosmic evolution, is as yet nowise accounted for. It exists, however, and rtaust not be dismissed as gross contingency. The mind balks at such a view. Coincidences so nu- merous and so remarkable as those which we have met in examining the properties of matter as they are related to life, must be the

metaptor, instead of guiding the ramifications of the tree of life, it would, in Mivart's excellent phrase, do little more than apply the pruning knife to them. In other words, its functions are mainly those of the third Fate, not the first, of Siva, not of Brahma. — Patbick Geddes and J. Arthur Thomson, "Evolution." New York, Home University Li- brary, 1911, p. 248. "But as my conclusions have lately been much misrep- resented, and it has been stated that I attribute the modifica- tion of species exclusively to natural selection, I may be permitted to remark that in the first edition of this work, and subsequently, I placed in a most conspicuous position — ■ namely, at the close of the Introduction — the following words : 'I am convinced that natural selection has been the main but not the exclusive means of modification.' " — Chables Dabwin, "The Origin of Species by Means of Natural Selection." New York, reprinted from the Sixth London Edition, The Home Library, pp. 495-496.

orderly results of law, or else we shall have to turn them over to final causes ^ and the phi- losopher. There is, in truth, not one chance in count- less millions of millions that the many unique properties of carbon, hydrogen, and oxygen, and especially of their stable compounds water and carbonic acid, which chiefly make up the atmosphere of a new planet, should simultaneously occur in the three elements otherwise than through the operation of a natural law which somehow connects them together. There is no greater probability that these unique properties should be with- out due cause uniquely favorable to the organic mechanism. These are no mere acci- dents ; an explanation is to seek. It must be admitted, however, that no explanation is at hand.

For the coincidence of properties itself a rational explanation based upon known laws of nature is perhaps conceivable. Attention has already been called to the interconnection of such properties as latent heat of vaporiza- tion, thermal conductivity, molecular vol- ume, the value of the van der Waals constant a, * Bacon compared final causes to vestal virgins. "Like them," he says, "they are dedicated to God, and are barren." — "The Advancement of Learning," Book IE, p. 142.

the dielectric constant, and ionizing power. Further, it is of course most probable that numerous other properties are necessarily associated with these; and finally it is not surprising that elements of low atomic weight, which become concentrated in the atmos- phere on account of the small specific gravity of their gases, should possess unusual proper- ties, like high specific heat, or if one property leads to another, many unusual properties. Be that as it may, chemical science is still a very long way from accounting for the simul- taneous occurrence of the various character- istics of water, especially if we include such things as heat of formation, solvent power, the process of hydrolytic cleavage, the degree of solubility of carbon dioxide, the anomalous expansion on cooling near the freezing point, etc.

There is, in fact, exceedingly little ground for hope that any single explanation of these coincidences can arise from current hypotheses and laws. But if to the coincidence of the unique properties of water we add that of the chemical properties of the three elements, a problem results under which the science of to-day must surely break down. If these taken as a whole are ever to be understood, it will be in the future, when research has pene- trated far deeper into the riddle of the prop- erties of matter. Nevertheless an explana- tion cognate with known laws is conceivable, and in the light of experience it would be folly to think it impossible or even improbable.

Such an explanation once attained might, however, avail the biologist little; for a further problem, apparently more difficult, re- mains. How does it come about that each and all of these many unique properties should be favorable to the organic mechanism, should fit the universe for life ? And for the answer to this question existing knowledge provides, I believe, no clew.^ Thus regarded, our new form of the old riddle appears twofold, and, on that account, for the present the more unanswerable. There is but one immediate compensation for this complexity; a proof that somehow, beneath adaptations, peculiar and unsuspected relation- ships exist between the properties of matter and the phenomena of life; that the process of cosmic evolution is indissolubly linked with the fundamental characteristics of the organism; that logically, in some obscure

* The great difficulty appears to be that there is here no possibility of iateraction. In our solar system, at least, the fitness of the environment far precedes the existence of the living organisms. manner, cosmic and biological evolution are one. In short, we appear to be led to the assumption that the genetic or evolutionary processes, both cosmic and biological, when considered in certain aspects, constitute a single orderly development that yields results not merely contingent, but resembling those which in human action we recognize as pur- poseful. For, undeniably, two things which are related together in a complex manner by reciprocal fitness make up in a very real sense a unit, — something quite different from the two alone, or the sum of the two, or the re- lationship between the two.^ In human af- fairs such a unit arises only from the effective , operation of purpose.

Now it is most clearly evident from the experience of centuries that ordinary teleology is dangerous doctrine in science, and in the past, accidents apart, it has been invariably sterile.'^ A statement that the legs have been formed for the purpose of locomotion, no doubt possesses scientific validity, if it be properly interpreted. But the real scientific concern is for the bones and muscles, the 1 This appears logically to correspond with the "achop- ferische Synthase" of Wundt.

^ Interesting discussions bearing upon this subject will be found in Pearson's well-known "Grammar of Science." tendons and ligaments which are employed in walking, and for the evolutionary process by which they have been adapted to their use. Nevertheless, biological science has not been able to escape the recognition of a natural formative tendency, which Darwin identified as the result of natural selection. And now it appears to be necessary to postulate a like tendency in the evolution of inorganic nature. We have found that the properties of the environment, biologically considered, present the same fitness as the properties of life. In each case the fitness results, at least in part, from an evolutionary process. Through the main lines of later development these are both known, though in both cases we stop short, perhaps far short, of the origins — the origin of life and the origin of the universe — if indeed they have ever originated.^ Can we then deny that in the one as in the other process there is a tendency, a bent, a direc- tion of flow or development ? ^ I think not,

* It is hardly necessary to point out that the properties of the elements are themselves quite free from variation of any sort. ^ "Alike in the external and the internal worlds, the man of science sees himself in the midst of perpetual changes of which he can discover neither the beginning nor the end. If, trac- ing back the evolution of things, he allows himself to enter- tain the hypothesis that the universe once existed in a dif- and it seems clear that the facts of physical science call for an explanation of the tend- ency to fitness of the environment in the same way that formerly the facts of biologi- cal science called for an explanation of the tendency to fitness of the organism.

To postulate such a tendency is, however, in itself rather a philosophical than a scientific act, and so, too, must be conjecture regarding the origin of fitness. It is open to any one who may be so minded speculatively to enrich this tendency with characteristics of any sort. He may follow the lead of M, Bergson and call it impetus, with all which that term now implies, or he may turn to natural theology and regard it as proof of supernatural purpose and design, or he may find a model for teleolog- ical views in many other quarters. But one thing is certain, no such discussion, be it ever so important to the philosopher or the theo- logian, can directly contribute to scientific knowledge and comprehension of the under- lying phenomena, which are the sole positive and certain knowledge of the subject that

fused form, he finds it utterly impossible to conceive how this came to be so ; and equally, if he speculates on the future, he can assign no limit to the grand succession of phenomena ever unfolding themselves before him." — Herbert Spencer, "First Principles." New York, reprinted from the Fifth London Edition, 1880. The Home Library, p. 57. we possess. For these facts an explanation of a different sort would be necessary, some- thing logically resembling natural selection, a natural process acting automatically through the properties of matter and energy, and never overstepping the limits of matter and energy, space and time; neither supernatural nor metaphysical, but purely mechanistic. Lacking any indication of what such an expla- nation may be, or how it is to be sought, we shall do well to turn to other considerations.

All the skill of trained biologists, multi- plying and refining our knowledge of the forms of life, has even yet not availed to make clear the fundamental ideas of the science. Complexity exists here in the very nature of the case, and here, if at all, the complete subjugation of natural phenomena to physi- cal science may be expected to fail. In an earlier chapter the painful advance of physics and chemistry into the domain of biology has been sketched, and it was then shown how progress is beset with well-nigh insuperable obstacles. Thus it is that bio- logical thought has never attained to that

finality which appears, at least by contrast, to characterize the greater body of opinions in physical science. In particular two extreme views, though often commingled, have continually striven for the mastery. The one of these, purely scientific and wholly positive, declares the phenomena of life to be, while partly unknown, ultimately knowable as manifestations of matter and energy. According to this view life is a mechanism and nothing more, in its positive scientific aspects at least. Without necessarily denying such assertions, the other view sees the unique properties of life to be dependent upon an equally unique force or tendency, operating in or through its physico-chemical organization. Either there is a peculiar vital force; or there is manifest in the organism a peculiar tendency ; or at any rate life patently follows the path into which it was propelled by an original impetus, peculiar to life, unknown in other phenomena. All such views inherently par- take of metaphysics, and have, therefore, ever aroused most determined opposition among the more orthodox devotees of science. Descartes appears to have been the first person to adopt the modern scientific attitude toward life, and from him a very large pro-

portion of French biologists, as well as those of other nations like Huxley and DuBois- Reymond, derive their philosophical views concerning their science. Descartes per- ceived, apparently the first among the mod- erns, that the scientific explanation of vital phenomena must be a physical one, in terms of matter and motion. Far in advance of his time he applied such ideas to the nervous system, thereby establishing the nature of reflex action and invading the very citadel of animism. Outside natural science, how- ever, Descartes was far from being a mechan- ist. Since the early seventeenth century the conflict between vitalism and mechanism has ranged over the whole field of biology, and its history is most complicated. After Des- cartes, Lavoisier, by his studies of combustion within and without the body, made the next very important step. He was then followed by Liebig, Wbhler, and a host of later chem- ists.

In the main the growth of exact science has steadily delivered over one vitalistic strong- hold after another to the mechanists. And though in the first flush of triumph mechan- ism has sometimes seemed to gain more in a particular engagement than later proved to be the case, vitalism has perhaps not had a positive success in three centuries. Such a history no doubt depends upon the very na- ture of the situation; upon the inherent and inevitable weakness, within the domain of science, of vitalistic views.

Experience seems to show that the only kind of hypothesis which can find conclusive scien- tific support, or sound basis in the phenomena of matter and energy, is a mechanistic hy- pothesis. Exact and positive knowledge can demonstrate scientifically the truth of no other hypothesis with the finality which char- acterizes its proof of a mechanistic theory. Hence, so far as it ventures into the field of science at all, a vitalistic theory, when attacked by science, cannot effectually avail itself of the weapons of the assailant, and can never make a powerful counter attack. Its only method consists in a determined resistance, yielding little by little before the advance of positive knowledge and never gaining new territory, nor, except by accident, regaining what it has lost. Where this process is to end ; in what respect and how far life is des- tined ever to remain a scientific riddle, can only be surmised.

The chief definitive triumphs of the mech- anistic view are two : the elimination of vital force and of a belief in peculiarity of chemical composition from organic chemistry, through the actual successes of the laboratory in new syntheses; and the final recognition, based upon understanding of the principle of the conservation of energy, that, whatever else "vital force" may be, it is certainly not force, — a form of energy. Thus limited, vitalism has been obliged to take refuge in a more restricted belief; namely, that the organ- ism is somehow governed by a directive tendency which, like an architect, presides over its development ; but that meanwhile the manifold processes of life and evolution go on within the world of physical science just as the work of the builder conforms to the laws of mechanics, though following the plan of the architect.

This view has been well stated by another great Frenchman, Claude Bernard: "Life is the directive idea or evolutive force of the being ; . . . but it would be an error to believe that this metaphysical force operates after the manner of a physical force. . . . The metaphysical evolutive force by which we may characterize life is useless to science, because, existing apart from physical forces, it can exercise no influence upon them. Hence we must here separate the world of meta- physics from the world of positive phenomena

which serves it as foundation, but which has nothing to contribute to it. . . . Summariz- ing, if we can define life with the help of a special metaphysical conception, it is none the less true that mechanical, physical, and chemical forces are the sole eflFective agents of the living organism, and that the physiologist has to take account of their action alone. We shall say with Descartes, 'One thinks meta- physically, but one lives and acts physically.' " ^ Thus restricted, vitalism can apply only to formative processes and the like, though the vitalist still sees in the state of the organism

* "Claude Bernard, 'La Science Exp6rimentale,' 3me ed., p. 211 : 'La vie est I'idee directrice ou la force evolutive de I'fitre ; . . . mais I'erreur serait de croire que cette force meta- physique est active a la fa^on d'une force physique. . . . La force metaphysique evolutive par laquelle nous pouvons caract6riser la vie est inutile a la science, parce qu'etant en dehors des forces physiques elle ne peut exercer aucune in- fluence sur elles. H faut done ici separer le monde metaphy- sique du monde physique phenomenal qui lui sert de base, mais qui n'a rien k lui emprunter. . . . En resume, si nous pouvons definir la vie El I'aide d'une conception metaphysique sp6ciale, U n'en reste pas moins vrai que les forces meca- niques, physiques, et chimiques, sont seules les agents effectifs de I'organisme vivant et que le physiologiste ne peut avoir k tenir compte que de leur action. Nous dirons avec Descartes : on pense metaphysiquement, mais on vit et on agit physique- ment.' " — Mehz, "A History of European Thought in the Nineteenth Century." Edinburgh and London, 1903, Vol. n, pp. 379-380.

effects of vitalistie control of its evolution, just as we perceive in a house not only the material structure, but the idea of the archi- tect. Further, the origin of life itself remains shrouded in mystery. Meanwhile, for most men physiology has become merely biophys- ics and biochemistry, and mechanism is un- doubtedly firmly established throughout every department of the science. Such limitations of the vitalistie hypothesis, damaging though they may be, do not de- stroy its claim to consideration as a controlling factor of the processes of evolution, embry- ology, repair, etc., in spite of the fact that even here it has suffered serious though less complete reverses. In 1859 Darwin's natural selection offered itself as a possible substi- tute for vitalism in a part or the whole of this field, and soon gained very general accept- ance. The survival of the fittest has now become in the judgment of all biologists an unquestioned force in the molding of life. Therefore, at best, but a restricted scope within its restricted field remains to vital- ism.

From the earliest days of the new hypothesis it has been widely recognized that to accept the survival of the fittest as one factor in the adaptation of life to its environment is quite a different matter from proving it to be the only force which directs evolution. An early eulogy by Du Bois-Reymond upon the work of Darwin clearly discloses the nature of the situation: "Here is the knot, here the great difficulty that tortures the intellect which would understand the world. Whoever does not place all activity wholesale under the sway of Epicurean chance, whoever gives only his little finger to teleology, will inevitably arrive at Paley's discarded 'Natural Theology,' and so much the more necessarily, the more clearly he thinks and the more independent his judgment . . . the physiologist may define his science as a doctrine of the changes which take place in organisms from internal causes. . . . No sooner has he, so to speak, turned his back on himself than he discovers himself talking again of functions, performances, ac- tions, and purposes of the organs. The possi- bility, ever so distant, of banishing from na- ture its seeming purpose, and putting a blind necessity everywhere in the place of final' causes, appears, therefore, as one of the greatest advances in the world of thought, from which a new era will be dated in the treatment of these problems. To have some- what eased the torture of the intellect which ponders over the world-problem will, as long