Essays of a Biologist

by Julian Huxley

Readers of Bury’s interesting book on the Idea of Progress[2] will perhaps, with me, have been surprised at the modernity of that conception. He shows how, in antiquity, the idea was never a dominant one, and further that the adumbrations made of it all lacked some element without which it cannot be styled progress in the sense in which that word is used to-day.

Not indeed till the late Renaissance can we say that the idea of Progress became in any real sense incorporated with the common thought of Western civilization. From then to the present it has suffered many vicissitudes. Starting in the XVIIth century as little more than a consciousness of the superiority of the present over the past, in the XVIIIth it changed to a dogma, its adherents claiming that there existed a “Law of Progress” leading inevitably to the perfectioning of humanity. In the XIXth century the dogma was questioned, and thinkers began to put it to the test—the test of comparing theory with historical fact. A new lease of life, however, was given to the idea of a law of progress by the evolution theory; but finally, of late years, there has been a marked reaction, leading not only to a denial of any such inevitable law, but often to a questioning of the very existence of Progress in any shape or form.

It is the business of the philosopher and of the biologist to see whether this scepticism be justified, and to find out by a more scientific approach how much of the doctrine of Progress is valid. To the layman it would seem inevitable, once the validity of the evolution theory was granted, to concede the fact of Progress in some form or another. If we accept the doctrine of evolution, we are bound to believe that man has arisen from mammals, terrestrial from aquatic forms, vertebrates from invertebrates, multicellular from unicellular, and in general the larger and the more complex from the smaller and simpler. To the average man it will appear indisputable that a man is higher than a worm or a polyp, an insect higher than a protozoan, even if he cannot exactly define in what resides this highness or lowness of organic types.

It is, curiously enough, among the professional biologists that objectors to the notion of biological progress and to its corollary, the distinction of higher and lower forms of life, have chiefly been found. I say curiously enough, and yet to a dispassionate observer it is perhaps not so curious, but only one further instance of that common human failing, the inability to see woods because of the trees that compose them.

That is as it may be. Our best course will be to start by examining some of the chief objections to the idea of biological progress, in order to see if they involve errors of thought which we may then avoid.

The most widespread of all the objections raised may, I think, be fairly put as follows: “The fundamental attribute of living beings is adaptation to environment. A man is not better adapted to his environment than the flea which lives upon him as a parasite, or than the bacillus which kills him, nor is a bird better adapted to air than a jelly-fish to water; therefore we have no right to speak of one as higher than the other, or to regard the transition from one type to another as involving progress.”

A second class of objector is prepared to admit that there has been an increase of complexity, an increase in the degree of organization during evolution, but refuses to allow that increase of complexity has any value in itself, whether biological or philosophical, and accordingly refuses to dignify this trend towards greater complexity by the name of progress.

Yet a third difficulty is raised by those who ask us to fix our attention on forms of life like Lingula, the lamp-shell, which, though millions of years elapse, do not evolve. If there exists a Law of Progress, they say, how is it that such creatures are exempt from its operations?

Finally, a somewhat similar attitude is adopted by those who refuse to grant that evolution can involve progress when it has, as we know, brought about well-nigh innumerable degenerations. Granted, for instance, they would say, that the average Crustacean is in many ways an improvement upon the simple form of life from which we must suppose that it arose, yet we know that within the group of Crustacea there are several lines of descent which have led to the production of parasitic forms—animals in which the activity and complex organization of the ancestral type has been sacrificed, and as end-product we are presented with a hateful being, an almost shapeless mass consisting of little else but over-developed reproductive organs and mechanisms for sucking nutriment from its unfortunate host. Such a result is revealed to us in the Crustacean form Sacculina, and is paralleled by countless other examples in almost every class of animals. The degradation of parasites and sedentary types is equally a product of the evolutionary process with the genesis of the ant, the bird or the human being; how then can we call the evolutionary process progressive?

These are important objections. Can they be met? In the broadest way they can and must be met by the only possible method, the method of Science, which consists in examining facts objectively, and by drawing conclusions not a priori, but a posteriori. A law of Nature is not (and I wonder how often this fallacy has been exploded, only to reappear next day)—a law of Nature is not something revealed, not something absolute, not something imposed on phenomena from without or from above; it is no more and no less than a summing-up, in generalized form, of our own observations of phenomena; it is an epitome of fact from which we can draw several conclusions. By beginning in this way from the very beginning, by examining the basis of our mode of thinking in natural science, only thus are we enabled to see at one and the same moment how to investigate the question of progress on the constructive side, and how to neutralize the force of the objections to the idea.