Pedagogical Anthropology, Maria Montessori [online e book reader TXT] 📗

There are other theories of evolution less familiar than that of Darwin. Naegeli, for instance, attributes the variability of species to internal, rather than external causes—namely, to a spontaneous activity, implanted in life itself, and analogous to that which is witnessed in the development of an individual organism, from the primitive cell up to the final complete development; without, however, attributing to the progressive alterations in species that predestined final goal which heredity determines in the development of individual organisms.

The internal factor, namely life, is the primary cause of progress and the perfectionment of living creatures—while environment assumes a secondary importance, such as that of directing evolution, acting at one time as a stimulus toward certain determined directions of development; at another, permanently establishing certain useful characteristics; and still again, effacing such forms as are unfit.

In this way the external causes are associated with evolution, but with very different effects from those attributed to them by Darwin, who endowed them with the creative power to produce new organs and new forms of life.

Naegeli compared the internal forces to invested capital; it will draw a higher or lower rate of interest, according as its environment proves to be more or less favourable to earning a profit.

The most modern theory of evolution is that of De Vries, who, after having witnessed the spontaneous and unforeseen transformations of a certain plant, the Œnohtera Lamarckiana, without the intervention of any external phenomenon, admitted the possibility of the unexpected occurrence of other new forms, from a preexistent parent form—and to such phenomena he gave the name of mutations.

It is these mutations that create new species; the latter, although apparently unheralded, were already latent in the germ before they definitely burst into life. Consequently, new species are formed potentially in the germinating cells, through spontaneous activity.

The characteristics established by mutations are hereditary, and the species which result from them persist, provided their environment affords favourable conditions, better suited to them than to the preexisting parent form.

Accordingly new species are created unexpectedly. De Vries draws a distinction between mutations and variations, holding that the latter are dependent upon environment, and that in any case they constitute simple oscillations of form around the normal type determined in each species by mutation.

Species, therefore, cannot be transformed by external causes or environments, and the mechanism of transformation is not that of a succession of very gradual variations, which have given rise to the familiar saying: natura non facit saltus. On the contrary, what produces stable characteristics is a revolution prepared in a latent state, but unannounced in its final disclosure. A parallel to this is to be found, for example, in the phenomena of puberty in its relation to the evolution of the individual.

Now, when a species has once reached a fixed stability as regards its characteristics, it is immutable, after the analogy of an individual organism that has completed its development; henceforth its further evolution is ended. In such a case, the oscillations of variability are exceedingly limited, and adaptation to new environments is difficult; and while a species may offer the appearance of great strength (e.g., certain species of gigantic extinct animals), it runs the risk of dying out, because of a lower potentiality of adaptability; or, according to the theory of Rosa, it may even become extinct spontaneously.

Accordingly it is not the fixed species that continue the process of evolution. If we compare the tree of life to a plant, we may imagine evolution as soaring upward, sustained by roots far below; the new branches are not put forth by the old branches, but draw their sustenance from the original sources, from which the whole tree draws its life. When a branch matures and flowers, it may survive or it may wither but it cannot extend the growth of the tree.

Furthermore, the new branches are always higher up than the old ones; that which comes last is the highest of all.

Thus, the species which are the latest in acquiring a stable form are the highest up in the biological scale, because the privilege of carrying forward the process of evolution belongs to those species which have not yet become fixed. An apparent weakness, instability, an active capacity for adaptation, are consequently so many signs of superiority, as regards a potential power of evolution—just as the nudity and sensibility of animal cells, for example, are signs of superiority, as compared with vegetable cells—and of man, as compared with the lower animals.

In order to show that the inferiority of a species is in proportion to its precocity in attaining fixed characteristics, Rosa conceived the following striking comparison. Two animals are fleeing, along the same road, before an advancing flood. One of the two climbs to the top of a neighboring tree, the other continues in its flight toward a mountain. As the level of the water rises, it threatens to isolate and engulf the animal now stalled upon the tree; the other animal, still fleeing toward the heights, reaches, on the contrary, a higher and more secure position.

The animal on the tree stands for an inferior species that has earlier attained a fixed form; the other represents a higher species that has continued to evolve; but the animal upon the mountain never was on the tree at all, because, if he had mounted it and become caught there, he would have lost his chance of continuing on his way. In other words, the higher species never was the lower species, since the characteristics of the latter are already fixed.

Some eloquent comparisons might be drawn from the social life of to-day. We are all of us spurred on to choose as early as possible some form of employment that will place us in a secure and definite place at the great banquet of existence. The idea of continuing to follow an indefinite and uncertain path, leading upward toward the heights is far less attractive than the safe and comfortable shelter of the shady tree that rises by the wayside. The same law of inertia applies to every form of life. Biological evolution bears witness to it, in the forms of the different species; social evolution, in the forms of the professions and trades; the evolution of thought, in the forms of the different faiths. And whoever first halts in any path of life, the path of study, for instance, occupies a lower place than he who continues on his road.

The salaried clerk, armed only with his high-school certificate, has an assured income and the pleasures of family life, at a time when the physician, with an independent profession, is still struggling to establish a practice. But the obscure clerk will eventually hold a social position below that of the physician; his income will always be limited, while the physician may acquire a fortune. Now, the clerk, by adapting himself to his bureaucratic environment, has acquired certain well-defined characteristics; we might even say that he has become a representative type of the species, clerk. And the same will be true of the physician in his independent and brilliant life as high priest of humanity, scientist and man of wealth. Both men were high-school students, and now they are two widely different social types; but the physician never represented the type of clerk; or, in other words, he did not have to be a clerk before he could be a physician; on the contrary, if he had been a clerk, he never could have become a physician. It is somewhat after this fashion that we must conceive of the sequence of species in evolution. It follows that man never was an anthropoid ape, nor any other animal now living around us. Nor was the man of the white race ever at any time a negroid or a mongolian. Consequently, the theory is untenable which tries to explain certain morphological or psychic malformations of man, on the principle of atavism—because no one can inherit if he is not a descendant.

So, for example, reverting to our previous comparisons, if the animal on the mountain should climb a tree, or if the physician should become pedantic, this would not prove that the animal from the mountain was once upon a time the animal in the tree, nor that the physician recalled, by his eventual pedantry, certain bygone days when he was a clerk.

The theories of evolution seemed for a time to illumine and definitely indicate the origin of man. But this illusion has so far resulted only in relegating to still deeper darkness the truth that the biologists are seeking. We do not know of whom man is the son.

Even the earlier conceptions regarding the mechanics of evolution are essentially altered. The mystery of the origin of species, like that of the mutability of forms, has withdrawn from the forms that are already developed, and taken refuge in the germinal cells; these cells in which no differentiation is revealed, yet in which the future organism, in all its details, exists in a potential state; in which, we may even say, life exists independent of matter, are the real laboratorium vitæ. The individual, in developing, does nothing more than obey, by fulfilling the potentiality of the germs.

The direction of research has shifted from the individual to its germs. And just as the early Darwinian theories evolved a social ethics, seemingly based upon the facts of life, to serve as a guide in the struggle for existence, so in the same way, to-day, there has arisen from the modern theories a new sexual ethics, founded upon a biologic basis.

The Phenomena of Heredity.—The most interesting biological researches of to-day are in regard to the hereditary transmission of characteristics.

To-day the phenomena of heredity are no longer absolutely obscure, thanks to the studies of Mendel, who discovered some of its laws, which seemed to open up new lines of research prolific in results. Yet even now, although this field has been invaded by the most illustrious biologists of our time, among others, De Vries, Correns, Tschermack, Hurst, Russell, it is still in the state of investigation. Nevertheless, the general trend of researches relative to Mendel's laws is too important to permit of their enlightening first steps being neglected by Anthropology.

The first phenomena observed by Mendel, and the ones which led him to the discovery of the laws of heredity which bear his name, were revealed by a series of experiments conducted with peas.

Exposition of the Phenomena of Hybridism.—If two strains of peas are crossed, one of them having red flowers and the other white flowers, the result in the first generation is, that all the plants will have red flowers, precisely similar to those of one of the parent plants.

Accordingly, in hybridism, the characteristic of one of the parents completely hides that which is antagonistic to it in the other parent. We call this characteristic (in the case cited, the red flowers), dominant; in distinction to the other characteristic which is antagonistic to the first and overcome by it; namely, the recessive characteristic (in the present case, the white flowers). This is the law of prevalence, and constitutes Mendel's first law, which is stated as follows:

Mendel's First Law: "When antagonistic varieties or characteristics are crossed with each other, the products of the first generation are all uniform and equal to one of the two parents."

This result has been repeatedly reached in a host of researches, which have experimentally established this phenomenon as a law.

Thus, for example, if we cross a nettle having leaves with an indented margin, with a nettle having leaves with a smooth margin, the product of the first generation will all have leaves with indented margins, and apparently identical with the parent plant having indented margins, in other words, having the characteristic that has proved itself the dominant one (Russell).

These phenomena