The Master of Destiny

CHAPTER I. Primitive Ancestors

PRIMITIVE ANCESTORS

ORIGIN AND EARLY DAYS OF THE BRAIN

Since every well-arranged biography should start at the beginning, we may first inquire into the origin of the brain. The early history of such an important organ must be closely interwoven with the genesis of man. If man were the result of a separate creative miracle, so also was his brain.

But we are not obliged to accept this view which attributes the universe and all living things to creative miracles. There is another and equally reasonable possibility. We may, for example, assume that man and all else came into existence by that process of continuous change and progressive development called evolution. We have excellent grounds for accepting such an assumption. Astronomy, geology, biology, chemistry, and all of the sciences relating to mankind have revealed the essential facts. Any other interpretation must disregard or repudiate this convincing record. With such a record as this to guide us we may turn our attention to the origin of the brain.

Earliest Forms of Animal Life

The inception of life on our planet was simple in the extreme. The earliest animals, although well organized, possessed no special organs in the strict sense. In the beginning there was nothing which could be specifically called a stomach or a heart, a lung or a kidney. Certainly there was nothing even remotely resembling a brain. The business of living was transacted within a single cell. This cell was so small that it could not be seen by the naked eye. Each of these cells was sufficient unto itself. Each played its own separate part with a simple programme of existence. Each was required to get its own food, to carry on its own chemical activities of digestion and elimination. Finally, after it had been successful in this remarkable process, it was called upon to produce offspring, to perpetuate its species. This last act was the crown and climax of its life, for in this way it conferred a material immortality upon its kind.

The amœba, among living animals, is a good example of this simple life. It is wholly intent upon carrying on within itself the earliest traditions of existence. All of its life is conducted within a single microscopic cell, which is at once its office and workshop. It has nothing in its make-up that could in the ordinary sense be called an organ. In such amœban animals as these there seems to be nothing progressive, nothing to suggest the possibilities of further advancement. Each amœba might, if such a thing were possible, look back over a long line of ancestors exactly like itself. In looking forward it might see no great possibility of progress. Perhaps it might reach the more specialized conditions of its present-day relatives with contractile threads in their substance and vibrating hairs by which to move themselves about. At best the outlook of the amœba for progress was restricted within very narrow limits.

Familiar Animals of Earliest Type

Certain events in the long history of these little animals have acquired much human interest. At times some of these simple lives become strikingly dramatic. Their monotonous existence is changed and they pass through certain exciting phases. Such a drama is often enacted when certain amœbæ gain entrance into the body of another animal and there become parasites. The other animal may be some huge beast or even man himself. One unpretentious amœba (Amœba histolytica), if it gains entrance into the intestinal tract of man, may cause amœbic dysentery and abscess of the liver. Another single cell animal (Trypanosome Gambiense) living in the blood of certain cattle is often conveyed by the tsetse fly to human blood where it produces the fatal disease known as “African sleeping sickness.” This small animal claims hundreds of thousands of victims a year. In tropical Africa its devastations go on unchecked over an area of more than a million square miles. In this region sleeping sickness kills as many persons as all other diseases combined. From five to seventy per cent. of the inhabitants in different localities are stricken. Cattle, horses, and other domestic animals cannot be kept because of this disease. On this account, and also because the area in which the sickness rages is extremely fertile, it has been said that the conquering of this malignant protozoan would be equivalent to the discovery of a new continent.

Even better known are the several acts in the cycle of the plasmodium malaria. This protozoan animal is often borne by the Anopheles mosquito and injected into the blood of man. Then follows the familiar series of pathological events consisting of chill, fever, and sweat, called malaria. In certain respects it seems like retributive justice when this animal is injected into the body of man to cure the effects produced by another microörganism. The other organism is the spirochæte which causes syphilis. It often produces changes which destroy the human brain in consequence of a disease known as paresis. Many other protozoan animals are parasites, but in the main they live and have lived simple, unobtrusive lives.

Notwithstanding their apparent simplicity of structure and action, these minute animals, like all other things, have been subject to the influence of continuous change. They have responded to this influence in different ways. In many instances, through generations of reproduction, they have effected combinations and recombinations of their essential constituents out of which have emerged modifications of their original structure. Often these changes have proved progressive and contributed to more complex modes of living. Often they have been regressive or non-progressive. It was the progressive modifications in these earliest animals that were of utmost importance to the origin of the brain. This organ was not yet in sight, but adaptations working toward it were soon to appear.

Critical Changes in Animal Existence

In the course of time certain critical changes took place in the lowly scheme of animal existence. These were distinctly progressive changes. Some of the single-cell animals began to live in colonies. Circumstances thus conferred upon them a community life. They began to exist in close contact with others like themselves and were compelled to forego their simple, independent habits. They were, in fact, actually joined to each other by rather slender bonds of their own vital substance--protoplasm. This was an epochal stride forward. It was the first step which led to progress. In some instances it brought about entirely new relations between these animals and the world in which they lived. Now, since these small cells were grouped together as colonies, each individual cell lost much of its own independence. Its interests became, in some degree at least, the interests of the group. If, as a single cell by itself, it had been thoroughly self-contained, now it was necessary for it to follow the needs and inclinations of its neighbours. It was forced to observe the conventions and habits of its colony. This condition of affairs exists in what are known as the colonized protozoans. In addition to the advantages of community life there was another and far more important reason why this new kind of existence was a critical step. It introduced for the first time the principle of differentiation or class distinction. A division of labour was thus made possible. Some of the cells in each group were forced to take up positions on the outer surface of the colony. Others occupied places inside of the group. This arrangement immediately created a distinction between “outer cells” and “inner cells.” It was destined to have far-reaching consequences because it established a difference in the responsibilities of two great classes. The outer cells made an immediate and direct contact with the world. They were nearest to the water, to the light, and to all of the outer chemical substances necessary for living. They were like guards and outposts about a camp, defending the colony from adverse influences. They might be likened to the first line of battle in the aggressive struggles for life, acting as foragers and procurers of food. The rôle of the inner cells was different. Their contacts with the world were more indirect and established largely through the outer cells. Their offices were especially confined to the inner workings of the colony. They became the germ cells whose function it was to insure the immortality of the species. This arrangement was a momentous advance in the direction of progress. It was particularly momentous because it laid the foundations upon which all of the great developments in the animal world were to be built. In a certain way, it was also a prophecy, for it foretold the coming of animals that were to follow the protozoans. These newcomers, the metazoans (animals which came after the first forms of animal life), were to possess a body with outer cells engaged chiefly in the efforts of life, while the inner cells would be particularly concerned with the essence of living, such, for example, as digestion, assimilation, and circulation.

This remarkable process of class distinction among cells developed new and useful methods in living. It brought about a division of labour in the business of life. Different parts of the animal now had different obligations to fulfil. Some parts served to move the body about, some were employed in digesting food, some in eliminating waste, some in breathing and circulation, some in reproduction. In the end, this division of labour resulted in the formation of a body made up of many different organs, each having its own particular responsibilities. We may find an excellent example of the very earliest stages of this division of labour in Volvox, one of the colony-forming protozoans. Most of the colonized cells of this minute animal are on the outside, forming a hollow sphere. These cells are equipped with minute hairs or flagellæ which, by their constant motion, keep the animal rolling around in the water like a hollow rubber ball. In this manner it seeks and finds its food, and thus also it may escape when threatened. But all of the cells of Volvox are not on the outside. A number of them are tucked away from the actual surface of the animal. These are the sex cells to which is entrusted the important duty of reproduction.

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