A Multitude of Marvels
JUDGING from contemporary " best-sellers," it would appear t hat the branches of science which chiefly interest the layman are those which are richest in profound, and perhaps startling, philosophical implications. It is almost wholly for this reason that modern physics is the most popular of the sciences. By depriving space and time of their objective reality, by resolving matter into a cloud of mathematical symbols, and by hinting that something like free will lies at the basis of material phenomena, physics has profoundly stirred the popular imagination. It is evident that philosophy is still one of the ordinary man's chief preoccupations, whether or not he knows it under that name. Physics has usurped the place once occupied by biology in the public interest and chiefly, we may suppose, because of its greater philosophical interest.
But is this difference real or only apparent ? Is it true that biology is comparatively remote from the major human interests, or is it merely that it has lacked an expositor ? The present volume is a great help in answering this question. The Science of Life is, on the whole, extremely well written. It is immensely comprehensive. The sense of proportion displayed is remarkable, and the narrative flow and sweep of the book is throughout first-rate. It tells the layman what he wants to know in the most agreeable manner, and after reading its 880 double-column pages only the most exceptional layman would want to know any mon Ani what carries him through the 880 pages What is the reai interest of the book ?
The chief interest of this book, it seems to the present re- viewer, lies in the immense panorama, the multitude of marvels, that is here displayed. The amazing varieties of living forms, their varieties of behaviour, habitat, and re- sources ! The sheer profusion of nature's invention, as revealed in these pages, staggers the imagination The distances, ages, and temperatures of astronomy by their mere monotonous swelling accumulation, soot-. blunt the nerve of wonder, but here the marvels are infinitely various, inexhaus- tible in ingenuity.
The authors start their survey with the form of life we know best—our own—and then give us the first broad sketch of the various kinds of living things. We are now in a position to ask how it all came about, and the next section of the book treats of " The Incontrovertible Fact of Evolution." The authors make it clear that they are here discussing a fact, not a theory. Evolution, they inform us, has indubitably occurred. Complex forms of life have arisen, step by step, from simpler forms, until we get back to the microscopic specks that began it all. A very impressive array of evidence, from various sources, is brought forward to reinforce this conclusion. And what is the method of evolution ? How did it occur ? Before this question is answered we are given an account of the mechanism. of inheritance where, for the first time, we move in the -usual scientific atmosphere of a clear and definite theory suggested and controlled by clear and definite experiments. The Mendelian experiments, and the theory of chromosomes and genes, import an agreeable quantitative element into this highly descriptive science. Biology, in this
region at any rate, is approaching the ideals of the " exact " sciences.
We can hardly say as much about the central biological theory to which we are introduced in the next section—the theory of evolution. The authors describe three theories of the evolutionary process. Lamarckism, which supposes that animals develop by individual effort and then transmit the development to their progeny, conflicts with the generally accepted doctrine that acquired characteristics are not in- herited. The elan vital theory, which supposes that there is a mystical drive towards development in certain directions, is regarded as obscure and superfluous. We are left with the original Darwinian theory, that evolution occurs through the selective action of the environment on random variations. The authors are doubtful whether this theory can, at present, be made to account for everything, but they are hopeful that it will do so. But this theory, even as expounded here, is certainly obscure. The fundamental terms are not suffi- ciently clear. What, for instance, is the degree of random- ness of random variations ? And in some cases it appears that a " variation is really the resultant of the combination of a large number of elements. Such resultants, the authors explain, do not witness to miraculous coincidences, but are due to " functional differentiation," whereby an organism adapts its internal machinery to new stresses and strains. But is this adaptation to be taken as an irreducible fact about the organism ? When, for instance, the authors tell us that evolution " receives as natural an explanation as does the pressure of air through the impact of its myriad separate molecules, as envisaged by the kinetic theory of gases," we can only conclude that " functional differentiation " is to be taken as being an irreducible concept like " mass " in physics. It is one of the fundamental concepts in terms of which the explanation is to proceed. If we accept these terms as fundamental then the theory of natural selection is probably a self-consistent whole. But it is by no means a mechanical theory. To show that evolution is a mechanical process all these biological terms must be reduced to the terms of mechanics, as certain notions once peculiar to chemistry, for example, are now being reduced to the terms of physics.
The obscurity of its central theory reminds us that Biology is still predominantly a descriptive science, and the rest of this great book magnificently illustrates this cardinal charac- teristic. Such philosophical conclusions as can be drawn from this immense store-house of facts seem at present to be tentative and ambiguous. We may suspect that the human imagination must be considerably expanded before it can grapple with facts so numerous, so diverse, and so mysterious. When that expansion occurs it may well be that biology will prove to be, in all respects, the most important of the
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