The Biology, Physiology and Sociology of Reproduction - Winfield Scott Hall (ebooks that read to you TXT) 📗

years—sometimes progressively increasing to the last. These sacrifices take the form, for the most part, of support and protection, and begin soon after conception on the part of the mother—as the pregnant woman usually requires much greater solicitude and care on the part of the husband than she does on other occasions.

The normal father, like the normal mother, holds himself in readiness to watch by the bedside of the sick child should the occasion arise, and to make other sacrifices incident to the protection and support of the child.

It is shown above that sacrifices incident to the egoistic activities receive their compensation. The question next demanding our attention is—do the sacrifices which are made incident to our phyletic activities receive a compensation? The most striking solution of this question would be a personal solution. Let any young man ask his parents if they have been compensated for all the sacrifices they have made for him. If this son is such a one as brings pride and satisfaction to the parents it is very evident what their unhesitating answer would be, viz., that they have been compensated many times over for all the sacrifices they have made. In what does such compensation consist? It can be expressed most briefly: LOVE OF OFFSPRING. This principle of love of offspring seems to be a more or less general one in the whole realm of conscious living nature. That a tree could possess this no one would suggest; that a sea urchin could possess it no one would be likely to contend. It is probably possessed by all of those animals that are conscious of sacrifices; that is, if an animal is conscious of sacrifice he is capable of being conscious of this compensation which we term, love of offspring. For organisms too low in the scale of life to be conscious of either sacrifice or love of offspring, nature seems to have arranged another scale of sacrifices and compensations—sacrifice taking the form of contention for possession of females and sacrifice in their support and protection, the recompense being the gratification incident to sexual intercourse.

That this last factor may enter, to a certain extent, as a determining factor among the higher animals cannot be questioned. The higher we get in the scale of animal life the less the part played by sexual gratification and the greater the part played by love of offspring. In some of the higher animals, especially those in which the family circle is maintained or the community life highly developed, there is frequently at work still another consideration that may play no small part in ameliorating or compensating the sacrifice incident to reproduction. Reference is here made to the expectation on the part of the parents that support and protection will be provided for them in their old age when they are unable to support or protect themselves. That this plays any great part in determining the procreation in the first place is not probable; but that it later becomes a matter of consideration is not to be doubted. However, in so far as these considerations of personal welfare enter into the compensation of the parents for the sacrifices that they have made for their offspring, in just so far do we remove these considerations from the realm of the phyletic and place them within the realm of the egoistic.

Reverting again to a discussion of the lower organisms—we have yet to consider the character and extent of the compensation which these organisms, which are unconscious of sacrifice, receive. The conscious sacrifice of higher animals receives a conscious compensation; similarly the unconscious sacrifice of lower organisms receives an unconscious compensation.

It will be remembered that the amoeba did not die, but that it was rejuvenated in its offspring. In the next and every succeeding generation there is no death, but a rejuvenation. It thus transpires that these lowly organisms enjoy immortality; or perhaps it may be better stated, that the protoplasm of these organisms enjoys immortality and this immortality is the compensation for the sacrifice which each successive individual makes unconsciously in the division of its protoplasm. This principle of biology was first discovered and formulated by the great German Biologist, Weissmann.

Summary of Principles.

a. The propagation of offspring and the protection and support of the young and defenseless always involve sacrifice on the part of the parents and the stronger members of the race.

b. Sacrifice made consciously for the race is, in the natural order of things, compensated.

CHAPTER II ADOLESCENCE IN THE MALE

ADOLESCENCE IN THE MALE.ToC

The period of a young man's life from about fifteen to twenty-five years, when he is growing from boyhood to mature adult life, is called the period of adolescence. The period of adolescence is ushered in by a series of physical and psychical changes which make a well defined initial period called puberty. The period of puberty is about two years in length, and in the average case among American boys, covers the period between the fifteenth and seventeenth years, and is completed when the youth can produce fertile semen capable of fertilizing the human ovum. It is now universally recognized, however, that when the youth reaches this point in his development, while he may be called a man, he represents manhood in its lowest terms. He has not reached either a physical or mental development or maturity which justifies him in undertaking the responsibilities incident to procreating his kind. It requires in the average case a period of eight more years to develop the young man to the full stature of adult manhood, possessing his full physical and mental powers and the strength required of one who should assume the responsibilities of parenthood, so that at the age of twenty-five in the average case the young man may be said to have reached this period of complete development and to have finished the adolescent period. We may profitably now consider more in detail some of the changes incident to this most important period.

1. PHYSICAL CHANGES. General Changes in the Body.

a. Pilosity.—The human being belongs to the vertebrate class, mammalia, and as a member of that class he possesses over the cutaneous surface of the body, excepting the palms of the hands and soles of the feet, hair follicles which produce the hairy covering typical of mammals. A careful study of the distribution of the hair on the surface of the human body, comparing it with that of the anthropoid apes, demonstrates that the distribution is identical; and the "lay" of the hair in any one region of the human body corresponds exactly with that of the same region in the ape. For example—the hair on the forearm points outward and upward; on the upper arm down-ward and outward and so on throughout in the human and simian types. Every child comes into the world with a coat of rudimentary hair which is shed at once. Aside from the growth of hair on the head, including the brows and the lashes, the skin is quite free from any noticeable growth of hair for months or even years. Beginning at the age of puberty, however, the growth of hair is very much accelerated over the whole pilous surface of the body, particularly upon the face, in the axilla and over the pubic region. It is a generally recognized law of biology, that, at the period of sexual development, the hairy mammalian character becomes accentuated. The increase in the growth of hair at this time can have only one interpretation, viz., that the ancestors of man represented a very much higher degree of pilosity than is the case with man at the present time. It is interesting to note in this connection the almost universal attempt of men to rid the face of this hairy growth by various devices, either pulling the beard or shaving it. The origin of this custom of depilation probably dates back to the remote past and has been observed as a custom among both savages and civilized peoples.

b. The Voice.—In all animals the voice plays an important part in sexual and social relations. In many animals the voice seems to have almost no other function than as a sex call, or a communication between mates and between parents and young. The human subject illustrates this general biological principle in the profound changes which the voice undergoes at the time of puberty. These changes in the male subject consist in increasing the depth of the larynx, thereby increasing the length of the vocal cords which in turn modifies the pitch of the voice, usually about an octave, making it not only lower but much more pleasing in quality and greatly increased in volume.

c. Bone, Muscle and Gland.—Of incalculably greater importance than the changes described above though perhaps less noticeable to the casual observer, are those physical changes which the body undergoes during the first half of the period of adolescence. I refer to the growth of bone, of muscles and of those internal organs associated with nutrition.

The first step in these profound physical changes is a rapid growth in height that makes itself manifest about the fifteenth year. It is not at all unusual for a boy to grow from four to six inches in a year. This increase in height is very largely due to a lengthening of the thigh and leg bones. In serial homology with the thigh and leg are the bones of the arm and we find that these are undergoing an increase in length commensurate with the increase of the legs. So the boy outgrows his clothes; his coat sleeves are drawn up half way to his elbows and his trousers half way to his knees. The muscles scarcely keep pace with the bones in their growth, and tend to be flabby and to lack usual tonicity. It is difficult for the youth to hold his back straight and his shoulders back; he is awkward and ungainly in his movements and becomes easily fatigued because of the condition of his muscles. But the muscles follow immediately in their development and rapidly gain volume and tonicity, filling out the arms, legs, back and shoulders with large masses of firm muscular tissue. The growth of these muscle masses changes the dimensions of the youth and he fills out in his girths as rapidly as, in the previous period, he increased in length measurements.

All of this increase in bulk can only be accomplished by increased activity of all the nutritive processes. The appetite is practically insatiable; the boy can eat three square meals in the day and lunches between meals. If he wakes up in the night he is hungry. To accomplish the digestion and absorption of this food material, the alimentary tract throughout, and particularly the stomach is greatly increased in size. To accomplish the distribution of the food (blood) the heart also is increased in size and strength. With increased bulk of muscle and increased quantity of food we have increased oxidation in the tissues. This requires increased respiration, which demand is satisfied by rapid development of the respiratory system. The thorax increases in dimensions in all directions; it becomes deeper, broader and longer. Not only does the thorax become more capacious but also more mobile and more responsive to the varying requirements of the system.

If we are interested in the biology of all these changes, we need not go far to discover the natural causes at work to produce them. Nature is preparing in the youth a home builder; it is preparing an individual who can support and protect not only himself, but also a family. This equipment in the case of primitive man must necessarily be one of bone and brawn. While under the conditions of modern