Part 7

Chapter 72,892 wordsPublic domain

EVOLUTION OF MIND.

It seems hardly credible that there should exist people who profess to accept the Darwinian theory of development of species in all its fulness, and yet reject the idea of the human mind having been evolved by slow stages from the primitive sense-organ of our lowliest ancestors, the Protista. Such inconsistency seems almost puerile, and, were it not for the fact that the admission of this truth would be the final blow at the various faiths of the world, we should not be called upon to-day to defend a position so utterly impregnable as that assumed by Haeckel and others in regard to the evolution of the human mind. When education has advanced further there will, we must hope, be less of this shutting of the eyes to obvious truths for the mere sake of propping up for a little while longer the belief in a batch of fairy tales and preposterous legends. As we look around us upon the wonderful objects of nature we see everywhere animation and law; the heavens above are full of life—suns, planets, moons, and other celestial bodies incessantly moving to and fro, all bound in their courses by the immutable laws of nature; the vast ocean, teeming with myriads of living beings, is incessantly rolling and roaring like some great monster, but never exceeds the limits which nature has assigned to its action; and the whole face of the earth presents a constant scene of activity of some kind or other—volcanoes discharging their molten fluid, huge glaciers grinding along the ground, monster rivers rushing forward with incessant roar, and the vegetable and animal kingdoms increasing and multiplying at a marvellous pace. All this is life—in fact, everything we see around us, of whatever form or shape, is life of some sort. The very ground upon which we stand is full of life, each particle of dust being held to its fellow particles by mutual attraction; and there is not a single atom of the earth’s substance or of the whole universe that we can say is minus this property of life or activity; nothing in the universe that we know of ever remains for one moment in a state of rest; everything is constantly moving, and every particle of the whole contributes its own share to the general activity which we term motion or life. The whole universe is a huge manifestation of phenomena, which make up the sum-total of life or activity. The sun rotating on its axis is one form of life; the moon silently wandering round our planet is another form of life; the trees and animals growing and multiplying on the land are other forms; and every lump of ore taken out of the ground and every paving stone in our streets are other forms of life. Every particle of every substance whatever is in a state of continual motion, and therefore full of life. In fact, it is this very motion or life that sustains matter; for matter could not exist—that is, its particles could not hold together, and thus form substance—without the life, motion, activity, or whatever we like to term the property which operates upon them and produces mutual cohesion.

Life has always, therefore, been active in matter, and always will be, for life or motion cannot be separated from matter; and, just as matter has passed from a condition of homogeneity to one of heterogeneity, so has life done likewise. Life possesses infinite potentiality, and manifests itself in an infinite variety of ways by means of different combinations, which it brings about in the molecular atoms of universal matter. It acts, for instance, upon a planet by causing its particles to hold together in one mass apart from other bodies of a similar or dissimilar character; it also acts upon what we unscientifically call inanimate nature by causing its particles to hold together, forming in one case a stone, in another a metal, etc.; and it acts upon what we term animated nature by causing its molecules to combine and procreate. This power of attraction and cohesion of particles of universal matter is life, and it depends entirely upon what particular combination of the molecular atoms of universal matter takes place whether a sun, a moon, a planet, a stone, a crystal, a sponge, a tree, or a man be the result. This much is certain, however, that not one of these bodies can ever be produced except by an evolutionary process subject to the universal and unchangeable law which fixes the sequence.

Animal life, as distinct from all other life, is a comparatively late development or manifestation in the sequence of universal phenomena. This world on which we live had existed as a compact body for millions of ages before life assumed the character of animal life; and so gradual was the process of evolution from the primal condition of homogeneity, through all the manifold stages of life, until the condition of animal life was reached, that it is impossible to fix a particular moment when such life became manifest. So it is with every stage of the evolutionary process; there are no starting-places for particular species, the whole being one continuous unfolding of phenomena, without arrest of any kind.

It is equally impossible to fix a particular point or moment for the manifestation of the crystal life as it is for that of the animal or the vegetable life. All are but gradual unfoldings of the universal potentiality. Crystal life is the highest development of what is popularly but erroneously termed inanimate nature, and differs not one iota from Moneron life, which is the lowest form of animal life, in its constituent elements, the only difference between the two being in the mode of combination of the elementary particles composing each. The crystal elements combine in such proportions as to cause the mass to hold together like other solid bodies, its bulk being increased by the deposition of fresh particles upon its outer surface; while the Moneron elements combine in such a manner as to render the body soft and yielding, so that it can absorb nutriment from without to within and multiply by fission. The elements of both are identically the same: the manner of combination causes the differences between them. Many learned men declare that, if this were true, we ought to be able to take the five elements—viz., Oxygen, Hydrogen, Nitrogen, Carbon, and Sulphur—in the necessary proportions, and, by uniting them, form animal life. This, they say, has been attempted, and the result has been failure; therefore, animal life could not have been generated in that manner, but must have been specially created at some particular moment. This argument is absurdly unsound. These persons might just as well say that, to substantiate the assertion that crystals are formed of a combination of elementary molecules, we ought to be able to take the necessary quantity of these elements, and, by uniting them together, form a crystal; and that, if this cannot be done, then crystals also require a special creation. The same argument for a special creation will apply to every species of the animal, vegetable, and mineral kingdoms. Protoplasm is the lowest form of animal life, differing from the highest form of mineral life only in the mode of combination of its elementary particles; but this difference causes the manifestation of fresh phenomena, in this case as in every other modification of a previous state of nature, which gives it the appearance of possessing a property that had not been possessed by any substance previously, whereas, in truth, the apparently new property is but a further development of that previously possessed by inorganic bodies. In short, the power of absorption possessed by the Moneron is simply one of the many manifestations of that universal life or energy that is inherent in all matter, and has been so from all time; but it is a comparatively late development, occurring at a particular period in the world’s history, when the conditions necessary for such a development were present. Before this period no such combination of molecular atoms took place with the same result, simply because the necessary conditions of development were absent. In the same manner precisely there was a prior period when no such substance as a crystal existed, the conditions requisite for the peculiar combination of molecular atoms to result in the formation of a crystal having been absent.

When the world had undergone sufficient evolutionary development there came a time when such atmospheric and other conditions were present as to permit of a modification of the then existing substances and properties, which resulted in the formation of the crystal; and, precisely in the same manner, and for the same reason, a further and later modification resulted in the formation of Protoplasm, which is the earliest form of animal life. This little substance gradually differentiated into two distinct parts, by a nucleus being formed in the centre of the protoplasmic mass, and became possessed with a peculiar power of locomotion, which caused a still greater difference to exist between itself and its ancestral stock. This power of locomotion, again, is but a modification of that life-power of which we have spoken, and forms a stepping-stone between the molecular action of mineral substances and the mental wonders of the human being. The crystal, in common with all other bodies in the mineral kingdom, always possessed this power of locomotion to a limited extent; every one of the individual atoms which make up the whole substance has always had the power of locomotion, for they all attract and repel each other and effect cohesions by their mutual attraction. This locomotive power underwent such a modification when cell-life (Protozoa) was manifested that not only were the constituent molecular atoms individually possessed of this power, as before, but the whole mass of the cell became endowed with the same property, just as a whole continent of free people who have been in the habit of defending themselves singly against their enemies sometimes combine and co-operate with each other in the form of a republic, the function of the individual being assumed by the body as a whole. The little cellular organisms, which are called Amœbæ, possess this extended power of locomotion, and may be seen constantly moving about in the endeavour to locate themselves in the brightest part of their dwelling place, frequently a little pond. They are attracted by light, which clearly proves that they possess a degree of sensory perception, although special sense-organs are of course wanting, the whole mass of the body being nothing more than a single cell composed of protoplasm and nucleus. These little cellular organisms soon unite with each other, forming small bodies composed of several cells in a state of cohesion (Synamœbæ), and on the surface of these multicellular organisms are shortly afterwards thrown out minute threads or ciliae, the first attempt at separation of sense-organs from the surface of the body. In these tiny Protozoa, those organisms which consist of one single cell only, the Amœbæ, as well as those consisting of several cells in a state of union, the Synamœbæ, are able to perform all the functions of animal life—cohesion, sensation, motion, digestion, and reproduction; but, as the organism becomes more and more complex, these different functions are shared among several groups of cells. This differentiation proceeds steadily stage by stage, until at last different senses are located in different parts of the body, and we find animals possessing eyes, ears, noses, and mouths, one organ performing the function of sight, another that of hearing, and so on. All these organs of sense are but parts of the general nervous organisation of the body, which is _apparently_ absent in the Protista, but existing potentially in the protoplasmic substance, as it also does in every other substance in the universe.

The ciliated multiple cell-organism, in course of time, becomes transformed into a hollow body, having a wall composed of a single layer of cells, and this again, by invagination, or folding of itself within itself, forms a double-walled cavity, or Gastrula, having an external opening like a mouth. These little animals, the Gastrœada, having an inner layer of cells (the endoderm), which carries on the nutritive and assimilative functions of the organism, and an outer layer (the ectoderm), which forms the general motor and sense-organ of the body, are the first animal organisms to possess a real sense-organ separate and distinct from other parts of the body. From this epidermal organ of sense are developed, as higher forms of animal life make their appearance, the nerve-cells and sense-cells which form the whole nervous system.

In the fresh-water polyp, or Hydra, which is wanting in distinct organs of sense and nervous system, we find a remarkable sensitiveness to touch, warmth, and light, individual ectodermic neuro-muscular cells performing these functions, but a far greater sensibility being exhibited in the circle of fine prehensible tentacles surrounding the mouth than elsewhere. Here we have a marked attempt at localisation of sense-organs, and a manifestation of instinct, which makes the little animal shrink from the touch.

From the Hydræ evolved the Medusæ, which, instead of being dependent entirely on neuro-muscular cells like the parent forms, developed minute sets of nerves and muscles, by the use of which they became enabled to swim about easily and at their own will and pleasure. We get in this little animal the first appearance of real nerve function, or conductibility of stimulus along the nervous fibre to a muscle which it causes to contract—a totally different function to the contraction of the whole body upon a stimulus being applied to it, as in the case of the Hydræ.

In the worm forms, which evolve from the Gastrœada, we come across the first attempt at special sense-organ formation, in the shape of depressions on the integument of the body. The Himatega, or sack-worms, possess a rudimentary spinal cord, and were the parents of the first true vertebrates, organisms without skulls or brains, but with a true vertebral cord. These little vermiform animals, in addition to their rudimentary spinal cords, exhibited upon the surface of the body several small depressions, which answered the purpose of a set of special sense-organs, one tiny depression being set apart especially for the perception of light waves, another for the perception of sound waves, another for the perception of odours, etc.; and thus gradually came about that wonderful evolutionary process by which bodies became endowed with more or less perfect special sense-organs.

As the animal kingdom developed into higher and higher forms of life, and skulls and brains became the order of the day, the special sense-organs became possessed of larger powers, at the same time that the whole nervous organisation assumed higher and more complex functions, resulting eventually in a very gradual unfolding of the most wonderful of all the latent potentialities of universal life—the marvel of consciousness. This is the present climax of Nature’s evolution, the grandest and most awful achievement of that hidden and mysterious force which baffles comprehension, and beside which all things seen, heard, or felt pale into insignificance.

To point out the precise method of the evolution of mind, step by step, until the final climax of consciousness was reached, would require an abler pen than mine; therefore I shall be content to briefly notice the different products of intellectual development in the order in which they are unfolded, showing the analogy between ontogenesis, or the life-history of the individual, and phylogenesis, or that of the whole race, not now as regards bodily, but only mental, evolution. We must ever remember that the biogenetic law insists that the process of development in the race is reflected in miniature in the embryonic history of every individual. In other words, it is, beyond doubt, an accepted article of faith with biologists that the development of the individual from the embryo _in utero_ to the full-grown man is an exact counterpart of the development of the whole race from the primitive protoplasmic atom, the lowly Moneron, to _homo sapiens_, equally in regard to mental as to bodily evolution.