Lesson XIX EVOLUTION OF MAN

The following lessons, while they do not treat directly of either the chemistry of food or the chemistry of the body, are so closely allied to these subjects that this work would not be complete without them.

WHAT IS EVOLUTION?

If a resident of a city, who is not familiar with modern farm machinery, should see a grain-binder at work, he would be impressed with the skill and the ingenuity of man. In all probability he would think that the machine was the product of one inventive mind. In this, however, he would be mistaken. The reaper in its modern form is the result of gradual development or growth.

An example of evolution

The earliest method of gathering grain was pulling it up by the roots. Later, as cutting tools were invented, a rough knife was used to sever the stalks just above the ground. An improvement upon this method was the cycle; then came the scythe, then the cradle; and next came the mower which was operated by horse-power. From the mower was developed the self rake, which bunched the grain so that the hand-binders could work with greater facility. The next improvement was a self-binding machine. In the present machine we have all of these and many other improvements, which give greater speed with less waste of labor and time.

This development of the grain-binder is a process of evolution. In order to understand a machine so as to use it intelligently, or to make improvements upon it, it is necessary not only to know the machine as it actually is, but also to know the history of its development up to its present form.

To know man is to know evolution

The story of the evolution of a machine is, at best, but a crude illustration of the evolution of man. Nevertheless, the conclusion is the same. If we are to understand man, we must study not only his present physical and mental state, but also the history of his development. Yet those whose work is concerned directly with man—whether they be teachers, guiding the growth of the child; statesmen, formulating the laws and regulations by which men are to be controlled in their public actions; or physicians, who are supposed to instruct and to guide men in the care of their physical well-being—are often densely ignorant of the most rudimentary knowledge of the evolution of man as it is now known and understood by the leading scientists of the world.

Our entire system of education, our ideas of health and dis-ease, our social customs, the principles of our form of government; our ideas of right and wrong, of rewards and punishments, are all fundamentally concerned with the evolution of man, and when this knowledge is studied with as much application as are the ancient languages, we may expect to see humanity progress at a rate hitherto unknown.

Significance of the term "evolution"

The evolution of man has been very much misunderstood. The term "evolution" is a broad one. It may refer to the growth of the individual, or to the race. It may mean the development of strictly physical organs, or of mental habits, of social customs, or of material products of man's genius, as the great works of civilization in the form of recorded learning, and the wonderful products of man's building ingenuity as seen in modern cities.

The subject of the evolution of the human race may be grouped into three general kinds of development or growth:

The development of the physical man

The development of the mind

The development of custom and of external civilization

Evolution in these three directions has taken place simultaneously. The mind and the body depend upon each other for their life and actions; while customs are merely the product of many minds working together and communicating their ideas to each other.

The human race is but the sum of the individuals composing it. We cannot consider the development of the individual without considering him in his relation to the race, neither can we understand the development of the race without understanding the growth of the individual.

Difference between inherited and acquired characteristics

One distinction too often overlooked by those who are not familiar with physiological science is the difference between actual physical inheritance and external customs. I wish to dwell at length upon this distinction, because a lack of understanding upon this point has been the source of many errors of judgment on the part of those who have been interested in the subject of physical training and food science.

At birth the individual inherits an organism with certain tendencies, both physical and mental, but this inheritance should not be confused with the physical habits which the child acquires by training from its parents and its associates. Thus, the child may inherit a brilliant mind, a weak stomach, or a sixth finger, but the child does not inherit a liking for broiled lobster, or a fondness for golf, or for driving an aeroplane. These are acquired and developed as habits, the same as the child would learn English or French, or would cultivate a fancy for parting his hair in the middle, or on the left side.

THE THREE GREAT PROOFS OF THE EVOLUTION OF ANIMAL LIFE

At the present time scientists are agreed upon the general theory of the evolution of man. The discussions pro and con regarding this, which exist today, are either discussions of minor points which have not yet been clearly worked out, or are the discussions of people who have grasped only a portion of the idea of evolution, and who are ignorant of its broader conception and of the facts which science has brought to the light of day.

The three great proofs of evolution are:

The actual history of the past recorded as fossils in the rocks and in the relics of pre-historic races

The existence in the world today of a range of animals and plants which shows living examples of earlier types

The repetition of the development of man as found in the growth of the individual

These three separate records of the development of living beings are considered by scientists as a most conclusive proof of the truth of evolution. Recorded as fossils in the rocks, we find the story of the development of all life upon the earth, from its simplest to its highest forms of plants and animals that live today, among which is man.

The earliest forms of animal life

The first forms of animal life were, in all probability, minute one-celled organisms; these left no visible fossil remains. As soon as animals developed hard parts in their bodies, such as shells and bones, we find a record of their existence as fossils. The earliest recorded forms of life were various kinds of sea-creatures, of which the modern crustacea (lobsters, etc.), snails, clams, and various shell-fishes are types. Later were developed boneless fishes, on the order of skates. After these came true fishes; then amphibia (frogs, etc.); then reptiles, birds, and, last of all, mammals, including man.

The facts are the same, whether we take the history of the successive forms as recorded as fossils in the rocks, or the living representatives that remain to tell the story in another form.

The single cell is the nucleus

The third proof, which is the story of evolution recorded in the growth and development of the individual, is yet more interesting. As life developed from simpler forms, each individual animal or plant became more complex, or carried a little further the process of growth. But the method of reproduction of new individuals remained fundamentally the same. Each individual began, like its ancestors, as a single-cell being. By the process of nutrition these single cells in each case would grow, divide, and produce various tissues and organs, but always repeating the general story of the development of the race.

Gills in the human embryo

The growth of the human embryo offers many proofs of evolution, which are wholly unexplainable upon any other theory of the origin of man, and would in themselves prove the truth of this view of man's creation were the proofs of geology entirely lacking. A single example will serve as an illustration. The human embryo at a certain period develops gill slits in the neck, the same as the embryo of a fish. This formation of unused or rudimentary organs which are afterwards outgrown, is very common throughout the animal world. In the upper jaw of a calf there are formed at a certain period incisor teeth, which never grow through the gums, but are reabsorbed and disappear as the calf develops.

I will not go further into the proofs and facts of the general theory of the evolution of animal life, but will now consider the later period of the development of man, which will show us his relation to other animals, and from which we can derive much valuable information regarding his natural physiological requirements.

MAN'S ANIMAL KINSHIP

The conception of man being descended from a monkey has been the subject of much wit and mirth.

Man's relation to anthropoid apes

The scientist is not concerned with this theory; he only claims that man is very closely related to certain monkey-like forms known as anthropoid apes. The proofs of this assertion are abundant and conclusive. In fact, anthropoid apes, such as gorillas, chimpanzees and orang-outangs, are much more closely related to man than they are to other kinds of monkeys. This relation is shown by very close resemblance between the anatomy of man and apes, especially as to the teeth and digestive organs. Other facts are now known, of which Darwin and early investigators were ignorant, which prove this relation in a much more striking manner.

Comparison of blood from man and apes

Late studies upon the growth of the embryo of anthropoid apes have shown that they were at certain periods almost indistinguishable from human embryos. Another proof, quite striking and interesting, is in the similarity of the parasites and dis-eases of men and apes. Scientists have, within the past few years, made a series of comparative investigations upon the blood and serum of men and apes, which have resulted in most remarkable discoveries. There are certain accurate tests known to the physiological chemist by which human blood may be distinguished from the blood of all other animals, but the blood of these man-like apes is an exception to this, and cannot be distinguished from human blood.

Difference in the development of man and apes

From these facts it is clear that the earlier types of men were creatures whose physical development and whose habits were not very different from those of apes. The development that has taken place since that time is truly very wonderful and has resulted in a widening gap between man and apes that today seems very great. The truth remains, however, that this gap is not so much one of anatomy and physiology as it is one of mentality and of external habits and material aids to living that have resulted from man's greatly developed mental faculties.

Power of speech a factor in man's evolution

Thus, when the mind of man reached the stage of development in which the use of articulate speech became possible, the evolution of intelligence proceeded at a very much more rapid pace than had been possible before. He could communicate his ideas to his fellow-creatures; concerted action became possible, and the faculty of reason, or the ability to think was multiplied by the number of beings who could communicate with each other.

The power of reason and the ability to communicate ideas resulted in the formation of those habits which distinguish man from other animals. When one primitive man learned the use of a club as a weapon, found how to use sharp-edged stones as cutting tools, or discovered the wonders and power of fire, he communicated his new-found knowledge to the other members of his tribe, with the result that new ideas became common property.

Man's bad habits have kept pace with his progress

This spreading of habits or customs took place very rapidly among men and was the source of the various changes which distinguished civilized life from savage life. But we must here point out that not only good habits were so spread, but bad ones as well. The origin and the use of opium and of alcohol, the injuries of fashionable dress and the economic wrongs of tyrannical government originated along with the birth of language, art, science, and all that uplifts and benefits mankind.

Clearly, then, that man is misinformed who defends a wrong by referring to its age and reasons that, if certain things were harmful, they would not have survived. To the young thinker the existence of harmful ideas and habits among mankind may at first seem inconsistent with the principles of the survival of the fittest, but this difficulty will disappear upon further investigation.

Factors that determine the survival of races

Since the beginning of recorded history many factors have helped to determine what kind of individuals and races should survive. War, economic wealth and poverty, intellectual beliefs, religions, and social institutions have all been potent factors in determining who should survive. With wealth and conquest came the opportunity to gratify tastes and passions of which the poor individuals of weaker races could not avail themselves.

Many habits and customs detrimental to life and health

Many of the habits and customs which man has developed are not necessary to life, and may be positively detrimental to health and longevity. They have been handed down from generation to generation, not because of their benefit to man, but in spite of their detriment.

Such condition of affairs would not be possible if man were not the dominant animal. Man's intellectual supremacy has given him power over the rest of nature, which has resulted in making his struggle for existence much less severe. His use of weapons and of artificial protection from natural destructive forces, as severe heat or cold, has made it possible for him to live and to produce offspring in spite of wrong habits and wrong methods of living, and the natural resistance of life.

Man's organs have a limited power of adaptation

A prevalent error that is due to an incomplete knowledge of the facts of evolution is the belief that organs readily change or adapt themselves to the habits or environment of the individual. This is not true to the extent that it is ordinarily believed. Each individual has a certain limited power of adaptation. He may develop his lungs to a greater breathing capacity, or train his hand for certain skilled work, but these particular acquired habits of the individual are not inherited.

Evolution of the race proceeds by the law of natural selection. Thus, if those who are born with great vigor and strong lungs are enabled to live where their weak-lunged neighbors will die, the result will be that their offspring, having greater lung capacity, will form a race with increased lung capacity. But the individual training of the lungs, or of the hand, or of any other organ of the body, will not of itself change the inherited tendency, or, to use a common term of the scientist, the germ-plasm of the race.

Organs and functions will change or become evolved by natural selections; that is, where it is a matter of life and death. But where the selective agencies depend upon other things, an organ may be used or abused for thousands of successive generations, and yet the natural inherited organ of the new-born child will be identical in development and function to that of the remote ancestor.

Acquired characteristics are not inherited

There are abundant proofs that so called "acquired characteristics" are not inherited. Were acquired characteristics inherited, Chinese women would be born with small feet and the babies of the Flathead Indians would inherit the flat head which has for generations been produced by binding a flat stone on the soft skull of the new-born infant.

In the light of this fact we may understand how it has been possible for man to live through the varying dietetic habits and customs that the constantly changing ideas and tastes of civilization have thrust upon his physical organism. Each individual has transmitted to his offspring the same type of digestive organs and functions that he himself inherited from his remote anthropoid ancestors.

Meaning of expression "natural" diet

Thus, such terms as "back to nature," "natural diet," etc., only mean to the food scientist the habits of life or the dietary which is most suited to the unperverted physical organism of man. They do not imply the meaning that is popularly given to the term, of casting aside all the habits and customs of civilized man, but only the adapting of these customs to the inherited physiological organism of man.

Indeed, science may actually improve upon primitive conditions, and still not be inconsistent with the requirements of the inherited physiological machine. No intelligent man will dispute the advantage of a house in a snowstorm. Yet the house is artificial. It is not "natural" in the sense that the term is commonly used.

Or, again, man has by the aid of civilization rendered it possible for us to use foods far removed from their source of production, or, by preservation, to have them at seasons of the year when nature does not provide them. These artificial results of civilization are good. They are a part of the story of evolution, the benefit of which no one can question.

Man's dietetic development

But the great majority of the dietetic "frills" of modern man are actually unsuited to his physiological make-up, and exceedingly harmful. They have been developed as have habits of drink or personal adornment and may be in direct antagonism to the ultimate well-being of the human race.

I have briefly reviewed the history of the evolution of man. The facts to be remembered are:

That men are descended from earlier and more primitive types of beings and are governed by the same general laws of heredity and nutrition as are other forms of animals

Man, being a distinct species of animal, has particular laws that apply only to him, and therefore we should be careful not to judge him too closely by facts regarding other forms of animal life

Man has changed very materially in the few thousand years of his civilization, in his external habits and customs, but very little in his fundamental physiological processes; therefore we should be able to judge what will be best suited for his needs by studying the process of the development of his organs during the millions of years that preceded the historic period. This plane of life is best seen today in the case of savages unacquainted with fire, and in the case of anthropoid apes.

With this general survey of evolution, and a clear understanding of the principles involved, I trust the reader will consider the facts here presented in the unprejudicial spirit of the true scientist.