CHAPTER V. Birthplace and Early Beginnings of Man

BIRTHPLACE AND EARLY BEGINNINGS OF MAN

INFLUENCES OF FOREST AND PLAIN ON BRAIN DEVELOPMENT

The place of man’s origin is a matter of little significance if he came into being by a creative miracle. Any one of a hundred natal sites, chosen for reasons of local pride or racial prestige, might have served the purpose. Eden undoubtedly was most colourful, but otherwise it had no exceptional advantages. Once created and upon his feet, man had the world before him to conquer and possess. Such was the beginning and end of his story.

If, on the other hand, the human race came through evolution from lower forms of animals, then man’s homeland is of utmost significance. It must have exercised a strong influence not only upon his origin but also upon all his life and progressive development.

Africa, Europe, or Asia

Some students of this subject have regarded Africa as the most likely birthplace of man. According to this view the human form first appeared as certain Nilotic negroes. From this homeland man spread throughout the world. On the other hand, the accumulating fossil evidence of man’s existence seems to be strongly in favour of western Europe as a centre of human dispersal. Professor Osborn points out that between the years 1823 and 1925 there were discovered in this part of the world alone no less than 116 individuals belonging to the Old Stone Age or to the Dawn Stone Age. Two of these were members of the Piltdown race. Fossils of forty other individuals belong to the Neanderthal race. Seventy-four are accredited to the Cromagnon and other races that lived in late Stone Age times. Remains of 236 individuals belonging to races that lived between the end of the Old Stone Age and the beginning of the New Stone Age were also found. These fossil men, in all 352 individuals, have been discovered within the last hundred years. During the same period, a little more than a century, only one human fossil has been found in the entire continent of Asia, one in the Holy Land, and two in Africa. Such a great preponderance in numbers clearly favours Europe as the home of primitive man. Africa, Asia, and those parts of Oceania formerly connected with the Asiatic continent, have borne no such abundant evidence of man’s early presence. Both the northern and southern continents of the New World have revealed nothing as yet that may be accepted as representing man in his early prehistoric period. This survey of the globe seems to limit the first appearance of man to European regions. In this connection it should be borne in mind that the various countries of Europe have been carefully explored in the search for early human fossils, while in other parts of the world the search is little more than just begun.

Northern Asia has also been regarded as likely to contain the site of man’s birthplace. This has been the view of certain French authorities who consider the Eskimos as the most ancient northerly race of mankind. From this homeland there was a progressive southward migration of primitive tribes under the influence of the severe conditions imposed by northern glaciation. More recently attention is being directed to central Asia as the birthplace of man. This locality was suggested long ago by the great American scientist, Joseph Leidy, and this viewpoint has been supported by Professor Osborn. Dr. Matthews in considering the matter of climate and evolution discussed the origin and migratory history of man. He believes that Asia was the centre of dispersal for human migrations, which were among the last of great migratory movements of animals in the history of the world. It is his opinion that most scientists to-day would place this centre in or about the Great Plateau of central Asia. In this region, now barren and very sparsely inhabited, are probably the remains of civilizations more ancient than any yet recorded. Immediately around this region and lying upon its borders are the territories of the earliest civilizations known to man. Chaldea, Asia Minor, and Egypt lie to the west, India to the south, China to the east. From this central region came successive migrations, which overflowed into Europe during prehistoric, classical, and mediæval times. The history of India shows that similar invasions poured down upon it from the north. Toward the east, invasions in successive waves entered the Chinese Empire and North America by way of Alaska, spreading southward over the two continents of the New World.

The Top of the World

Since his recent visit to Mongolia, Professor Osborn is strengthened in his conviction that central Asia will prove the homeland not only of man but of all the greater forms of mammal life. Here, he believes, in the Gobi Desert, were the ideal surroundings for the early development of Dawn men who were the direct ancestors of the human race. His belief in this part of the world as the birthplace of man depends upon certain characters in the terrain which are essential to racial development, concerning which he reasons as follows: Man’s earliest existence was mainly in the open either along river bottoms and river drifts or on uplands and plateaus. Such a life developed the finest physical qualities of the race. The earliest man could not have been a forest-living animal. Such parts of the human race as lived in forested lands have either been exceedingly slow in their development or have gone backward. Thus, the South American Indians, living in the forests, are much behind those who live in the open. Of the latter, those who live in the uplands are further advanced than those who lived in the river drifts. An alert, progressive race cannot develop in a forest, and it would be impossible for such country to serve as the centre of human radiation. Higher types of men do not develop in a lowland river bottom country, because food is plentiful and vegetation luxurious. It is upon the plateaus and the high uplands that life is most exacting and calls for exertions which are most beneficial for development. Mongolia was probably a region forested only in part, certainly not a country of dense forests. It was a most favourable upland country throughout the entire Age of Mammals. Here the conditions of life were apparently ideal, and since all other indications point to Asia as the place of man’s origin, Professor Osborn looks to Mongolia and Tibet, which he calls the top of the world, as the most favourable centre offered by nature for the birthplace of man. Here he has hopes of finding our remote human ancestors. He is, however, guarded in this view, which he feels must be treated merely as an opinion. It is not yet a theory, but is, however, an opinion sufficiently sound to warrant further extensive investigation. In consequence, several great Asiatic expeditions have been sent out by the American Museum of Natural History into the Gobi Desert. Under the leadership of Dr. Roy Chapman Andrews this exploration was undertaken in the search for fossil men. One of the explorers, Dr. Nels C. Nelson, soon made the remarkable discovery that in the wide expanse of this ancient desert there had lived, ages ago, certain people whom he called “dune dwellers of the Gobi.” His discovery included a great collection of flint implements of the Mousterian type, closely resembling those found in the cavern of Le Moustier in France, and thus belonging to the Old Stone Age. These newly discovered implements reveal the existence of man at a much earlier period in the Gobi Desert than the Mousterian period in Europe. Indications of an earlier Stone industry were also found in Mongolia. Some of these ancient implements show that long ago there were probably men living in this part of the world who belonged to the Dawn Stone Age.

The latest evidence in favour of Asia as the home of primitive man was supplied by a surprising fossil discovery made by Turville-Petre (August, 1925). This new find consists of a skull of Neanderthal type, discovered in Palestine and known as the “Galilee skull.” The rapidly accumulating discoveries of the past three years sustain Professor Osborn’s view that central Asia is the homeland of the human race. He concludes that “while the anthropoid apes were luxuriating in the forest and lowlands of Asia and Europe, the Dawn men were rising in the invigorating atmosphere of the relatively dry plateaus of central Asia.”

Home Surroundings Necessary to Human Evolution

If, as a result of evolution, man took origin from lower animals, these must of necessity have been mammals nearly like himself. They must have borne and nursed their young as he did. Mammals other than the primates differ so much from man that they could scarcely stand in the direct line of his origin. How different from him are all of the great races of hoofed animals, including the great varieties of cattle, horses, deer, camels, giraffes, and elephants. All of these are highly specialized and seem at once to exclude themselves even as remote relatives of man. So it is also with the pawed animals, the great families of dogs, cats, rats, and hares. These are definitely quadrupeds, clearly designed to meet the issues of life upon four legs. They fail to disclose anything resembling a near approach to man, either in form of body or mental capacity. The winged animals like the bats, strange specializations of the mammal kind, bear little resemblance to the human form and offer a poor beginning from which such a form might start. The swimming mammals, like seals, whales, and porpoises, also exclude themselves from direct connection with the line of man’s ancestry. In fact, all mammals must be put to one side in considering this question, except a single remarkable group. The apes and their kind alone bear an undeniable semblance to men both in body and in behaviour. Many of their parts are similar to the human, such as their hands and feet, fingers and toes all equipped with nails, as well as their thumbs which may be held against each finger in turn. The apes have acquired a more or less erect posture. Some of them, called manlike apes (anthropoids), possess so many characteristics in common with man that they alone of all animals might be regarded as connected with the direct line of origin. If this relationship be true, then the nature and location of man’s original homeland is of profound significance. Wherever this place may be, it should bring into combination two distinctly different types of home surroundings. It should provide this combination in order that the apes might supply the last long step by means of which man has ascended into humanity. These two different but essential types of abode are:

1. Home surroundings favourable for ape life.

2. Home surroundings favourable to human life.

A third condition must bring these two elements into final combination. These specialized surroundings must be relatively near together, so that transition from one to the other may readily take place. Does Mongolia and particularly the Gobi Desert fulfil all of these three conditions?

According to Professor Osborn’s theory, the uplands and plateaus are the most favourable places for human development. Such being the case, we must also agree, then, that the forests are equally essential to the life of apes. Only a few of these animals have adjusted themselves to life outside of wooded country. Living in the trees, therefore, is the existence that favours the life of the subhuman primates (lemurs, monkeys, and apes). The forest provides the home surroundings favourable for ape life, just as the plains afford those conditions favourable to human life. Does such proximity of these two essentials exist in the region of the Gobi Desert? Mongolia is not a densely wooded country. It is a territory forested only in parts. In this light it does not seem to be an ideal locality for the final transition from ape to man. To explain this defect, Professor Osborn at present holds that man in evolving had but a brief and very distant phase of tree life. He believes that the quadrumanous arboreal stage was extremely remote in geologic time. It was never a profound or exclusive mode of life. There are those, on the other hand, who firmly maintain that in this ape to man transition a long intermediate period of tree living was necessary in order to bring about those changes in the primate stock which laid the foundations for human existence. This life in the trees was essential to determine the erect posture of man, to free his hands ultimately for purposes other than locomotion; in fact, to free them so that they might become the chief incentives in the further development of the human brain. Even from this viewpoint, Mongolia may still be considered the homeland of mankind. The forested lands throughout its extent and upon its borders might well serve as adequate surroundings for the development of life during that critical intermediate phase when the first ancestors of men had parted company with the apes and had at length become humans.

With many animals there has been a strong tendency to take refuge in the trees. The chief object of this tendency was to make life more secure either by escaping danger or by obtaining food. But with the coming of the ape kind this arboreal habit took a somewhat new turn. It furnished the early members of the monkey kind a permanent abode. Such a change to a more or less fixed dwelling in the trees produced marked modifications in the animals themselves. It created a new type of home and developed a new kind of thoroughfare over highways in the tree tops. In order to acquire a proper equipment for such transportation, both fore and hind paws became grasping organs. In consequence these animals developed four hands. They gradually gave up the older pattern of paw and claw, and by developing a new instrument connected with the arms and legs they acquired a supreme facility for grasping the branches of the trees. The tail also, in some cases, acquired similar grasping powers. Thus, as the trees became the home and the highways of these animals, their four grasping hands and their grasping tails gave them a mastery over the forest which they used to their own peculiar advantages.

The forest background of their lives played an important rôle in the molding of their behaviour. The perpetual semidarkness of their home surroundings exerted a subtle influence upon them. It might be that the forest in which they lived stood on the edge of a wide plain with a clear opening from which to look into the farther distances outside. Undoubtedly there must have been an alluring temptation in the green plains and their inviting freedom. Yet for these tree-living animals to venture into this open space was a hazardous undertaking. There were many dangers lurking in the plain and over it. Fierce creatures of every kind were there. Reptiles, mammals, and birds, all of them beasts of prey, were lying in wait for just such an adventuresome excursion. So for the time at least, and until they were better prepared to cope with the enemies outside, the semidarkness was safer, even though the view were limited and many interesting things were left unexplored.

Effects of Tree Life

The lemurs were probably the first of these new tree-living animals. Their bodies were still slender and furry, their heads long and fox-like, their eyes widely separated, and their tails long and bushy. But in their hands and in their feet they showed the real beginning of fingers and toes. This stage marks the transition from some lower form of mammal to the primates (lemurs, monkeys, apes, and man). It was a profound change, and in it the new order of primates had its origin. The steps preceding this important one we shall consider subsequently. But with this advance there began a period of tree living which influenced all of these animals as they and their successors passed through their many stages upward. The little animal known as Tarsius, perhaps even more than the lemurs, shows the effects of these new influences caused by tree-living habits. The monkeys of South America reveal the manner in which the next step forward was taken. The effects of it appear in the shape of the head, in the almost human expression of the face, in the closer relation of the eyes to each other, and in the shape of the nose and the position of the mouth. All of these features prophesy the coming of the still more manlike apes. Above everything else, these South American monkeys are conspicuous in the history of development because of their almost human hands, and also because of their hand-like feet. Most of the members of this group acquired prehensile or grasping tails. With the appearance of the Old World monkeys, this tail began to wane in importance. It lost all of its grasping power and was reduced to much the same condition as in other animals not of the monkey tribe. Some of the Old World apes, such as the gibbons, developed the ability to stand and walk upright. In addition to this erect posture these apes had passed through another phase that brought them nearer to man. They had lost their tails. This had come about, doubtless, from their habit of sitting upright. The erect posture of the gibbons, however, was most important as a forerunner of further developments in the great manlike apes, the orang-outang, the chimpanzee, and the gorilla. These animals had grown so large that for most of them living in the trees was a matter of some inconvenience. It was necessary for them to come to the ground at times, because they found it difficult to swing from tree to tree like the smaller monkeys. Of the great manlike apes, the orang-outang still adheres rather closely to the forest. The chimpanzee, which has developed even greater cleverness in climbing, seeks the ground oftener. He has learned to walk upon all fours, using the knuckles of his hands as a support in this act. Like the orang-outang, he can stand up quite erect and walk like a man. Finally the gorilla, the largest of the manlike apes, often attains the size of nearly four hundred pounds in adult life, and standing erect may reach the height of nearly six feet. He also is able to walk upright. But the influences of tree living are so strong even with the gorilla that he has not yet made a good adjustment for life upon the ground. If it were not for the prodigious strength in his great arms it would be difficult for him to take to the trees, and he thus shows a betwixt and between specialization, not entirely suitable for the ground and too large for security among the trees.

All of the manlike apes are capable of standing and walking in the upright posture, but in this posture they are awkward and inefficient. Their awkwardness is due to the fact that the foot in all three of them retains many characters of a hand. None of them has a good foot for effective heel and toe walking on the ground. Yet in spite of the handicaps in their poor feet, in spite also of their long, ungainly arms, these apes are able to venture beyond the limits of their forest home. Some of them live in the plains or on the mountain sides. By their great strength they are equipped to cope with many of the dreaded enemies outside of the forest. The orang-outang seems to have no natural enemies because of its own great offensive power. Only two of the larger reptiles presume even to attack it--the crocodile and the python. According to the natives of Borneo, the orang always succeeds in killing the crocodile through main strength by standing upon its back and opening its jaws until he is able to tear out its throat. It is reported that if attacked by the python, the orang seizes the reptile with both hands, squeezing it with such force and biting it so ferociously that the outcome of the combat is soon decided in favour of the anthropoid. The gorilla also has conquered most of its antagonists in the animal world, and is regarded as the most powerful and the most dangerous brute enemy of man. All of these apes have acquired a certain freedom in using their hands, which are thus made available for acts of self-defense and even for a considerable degree of exploring their surroundings.

Progress in the direction of mankind had its beginning when the tree-living tendency of the apes began to recede. The recession of such tree life paved the way for those first indecisive but promising steps which took the great apes out of their ancient forest homes into the inviting plain. Finally with the complete passing of tree life there began that long and adventurous journey which was to lead over every sea and into every land, until no region of the earth remained for further conquest, until the full development of the hand and the upright posture had more and more bent the forces of nature to the designs of the races of man.

Stages in Developing the Erect Posture

The advances made toward mankind through the intermediate stepping stones of the great apes and smaller monkey kind may be traced through successive stages of tree life up to the time when the fully erect posture became an accomplished fact. These stages have been recognized as a result of exhaustive studies made by Professors Gregory and Morton. They consist of gradual changes which finally gave rise to the human foot. This structure permitted man at length to stand upright and thus gave him the free use of his hands for constructive purposes.

The first stage came in the Eocene (beginning of the Age of Mammals, about 65,000,000 years ago). At this time certain four-footed land-living animals began to live in the trees. This arboreal life had profound effects upon the fore and hind paws. In order to climb among the branches a clinging grip was necessary. Long, sharp claws developed in consequence of this requirement. The digits of the paw were short and the palms well padded. The thumb also was short but not opposable. As yet there was no squatting or half-sitting posture. The toes were likewise short and clawed. The heel was lifted off the ground. The sole was well padded and the great toe large. These four-footed animals made only an imperfect adjustment to tree life. Their movements were slow and their range of action correspondingly limited. The tree shrew is a good living example of such animals, while certain fossils of the Eocene belonging to this type have been described by Professors Matthews and Gregory.

The second stage in developing transportation came with certain light, lemur-like animals. They were still slow and cautious in getting about and depended upon a clutch-like grip. This new kind of grasping produced long digits like fingers. The toes were changed in the same manner, so that the feet began to look more like hands. (Living examples of this stage, Loris and Lemur potto.)

The third stage was a more decisive advance since transportation through the trees now combined the advantages of climbing and leaping. Locomotion was swifter and more effective. A tendency to a partially erect posture developed, and squatting or sitting up was tentatively established. All of the fingers became much longer. Most of them had finger nails, so that these animals at last possessed what might be called a hand. Changes of the same type took place in the toes. The thumb and the great toe became more powerful and both were opposable. They could be brought in contact with each of the other fingers or toes in turn. In these animals the hands were now well formed and the feet looked much like hands. It is for these reasons that such animals are called quadrumanous (four-handed). (Representative animals of this stage, Lepidolemur and Notharctus.)

The fourth stage was but a short step from leaping and climbing to swinging from branch to branch or running along the branches. This swinging by the hands is called brachiation. It had far-reaching influences upon all subsequent stages. Such swinging naturally lengthened and strengthened the arms. It produced a better grasping grip around the branches and caused the fingers to grow longer. The thumb did not participate in this increase of size. It actually was reduced in strength and prominence. This is true in most of the New World monkeys. In some of these, like the spider monkey, the thumb has disappeared altogether. It should be remembered that most of these animals had a prehensile tail which they used much like a fifth hand. The foot also developed a grasping grip and looked if anything even more like a hand than before. All of the South American monkeys, besides their ability to swing from the limbs of trees, can run along on the top of the branches in what is known as “pronograde” locomotion. But their swinging propensity probably had the greatest influence upon the final developments of transportation. It tended to bring the body in a close approach to the upright position. Many of the Old World monkeys sat in a semi-erect sitting posture, and from their habit of squatting developed thick pads (ischial callosities) over their buttocks. The leg became lengthened but was yet too much flexed at the hip to permit of the most complete erect posture. This stage is represented both by the New World and Old World monkeys, with the exception of the baboons. These latter animals are an interesting variation. They more or less deserted the old custom of living in the trees. Their bodies and heads assumed many dog-like characters, and they returned to a four-footed ground-living type of locomotion. In consequence their limbs became shortened, as was also true of their fingers and toes. All of these important changes took place in the early part of the Oligocene (second period in the Age of Mammals, probably 30,000,000 years ago).

The fifth stage occurred much later in this period when another decisive advance was introduced. For one thing, the tail entirely disappeared. The legs became more extended at the hip. Swinging from branch to branch was the chief means of getting about. This produced extremely long arms and hands, and because this swinging mode of transportation was predominant it kept the trunk more and more in the upright position. Such straightening up of the body introduced the most positive influence toward standing erect up to this time. The legs did not grow in proportion to the arms, and the feet retained a close resemblance to hands. On the ground such animals as these could make their way with considerable speed, standing upright and running much as man runs. The only difference between this kind of gait and that of the human was due to the great length of the arms and the poor feet.

This stage in the development of the upright posture is often seen in motion pictures of those animals which portray this particular phase of locomotive advance. These are the remarkable apes known as gibbons. Those familiar with them in the zoölogical gardens, or in moving pictures, will remember the peculiar way in which they run upright, holding their long arms stretched out much like balancing poles. Thus erect, they speed about in getting their food or playing with other monkeys. Their upright gait is awkward but extremely interesting. Once, however, they get into the trees their locomotion has all the grace of a bird in flight. This gibbon stage of development was one of extreme importance, since it gave the primates preceding man their first chance to stand upon two feet and to run about in something like human fashion. It is this stage that many authorities consider indispensable in the final working out of the human erect posture and human locomotion. Many students of this question also believe that the upright posture could never have been attained unless animal life had passed through that particular phase in the development of transportation called brachiation. It seems certain that this stage itself was dependent upon a preceding and extremely long period of life in the trees.

The sixth stage developed early in the Miocene (third period of the Age of Mammals, about 15,000,000 years ago). One of its chief factors was a great increase in the body weight of the apes. This greater weight caused the animals to come nearer to the ground, as is the case of the chimpanzee and the gorilla. These animals actually spend much time upon the ground. In consequence, it was necessary for them to make certain transportation adjustments. Their locomotion in the trees was still of the brachiating type--that is, they depended largely upon their arms for swinging. The arms thus became long and powerful. When the gorilla stands erect his hands hang below his knees. The legs are relatively short, but the feet in consequence of living so much on the ground look less like hands than in the lower apes. They have well-recognized broad heels, but flat soles without much of an arch. The lesser toes are human in appearance. They are much shortened and have little resemblance to the fingers of a hand. The great toe is shorter and only in a slight degree opposable. This is especially so in the mountain gorilla, in which the great toe bears a striking likeness to the same part in man. The flexion of the leg at the hip is somewhat decreased and as a result the gorilla is able to stand upright in almost human fashion. All of these changes appear, to a less degree, in the chimpanzee also. Both gorilla and chimpanzee are able to stand erect, to walk, and even run in this posture. Their gait, however, is awkward. They are greatly hampered in their locomotion by the extreme length of their arms. Usually in getting about on the ground they run upon all fours, using their arms somewhat like crutches and coming down at each step on the knuckles of the flexed hand. When aroused or charging to the attack, the adult male gorilla usually stands upright and beats its fists upon its chest, at the same time emitting a terrifying growl. When it is necessary for the animal to make speed in flight or for other purpose, it usually comes down upon all fours. Arboreal locomotion in all of the three great apes still retains much of the brachiating type. It thus requires the retention of the hands as part of the locomotor apparatus. Tree life in the chimpanzee and the gorilla, combined with partial use of the ground, did much to develop the essentials of the erect posture. It did not, however, free the hands to that extent which permitted their exclusive use for purposes more constructive than transportation. However strong the inclination toward life upon the ground may have been in the manlike apes, they were committed long ago by their predecessors to a life in the trees. This commitment still kept them true to their kind and to their simian inheritance. If they were to be more than apes, it was necessary for them to shed the stigma that tree life stamped upon them. This the modern apes were never able to accomplish.

The Parting of the Ways

At length, however, in spite of many obstacles, the tendency toward the erect posture found a new opening. It was the foot that led the way to this great opportunity. It provided an efficient supporting structure with a well-developed heel, a non-opposable great toe, and a sole containing an effective longitudinal arch. Man could at last stand upright and be secure upon a capable pair of feet. At some period late in the Miocene two branches from the stock of those animals, which had managed to get into something approaching the upright posture, parted company. This was a critical juncture. Thenceforth one branch proceeded one way and the other followed an entirely different course. The apes accepted the trees as their lot. Man, because of his two human feet and what they supported above them, acquired the earth and all it contains. Thus with tree life a thing of the past, with a true ground-gripping foot, with longer legs, with an actual erect posture, the hands were finally liberated for the purposes of human success.

The development of the human foot, which must have been in progress through vast periods of time, marks the decisive parting of the ways between the apes and the races of men. It is doubtless true that the specialization of the hand has been a potent influence affecting the expansion of the brain and of brain power. The hand itself, however, was ultimately dependent for its free and unhampered use upon the development of the foot. This great factor was the forerunner of all those elements in structural organization which finally brought about the erect posture, which set the head upon the shoulders so that the eyes might look forward and upward, and at length made it possible for the eyes to guide the actions of the hands.

Step by step, the brain has kept pace with these progressive alterations. Old and new parts of it alike bear the imprint of adaptive change. The combinations determined by life in the trees and by the development of four hands have been worked out through graded stages, from the humblest of the monkey kind up to man. Beginning with the lowly tarsius and lemurs, this advance may be traced through intermediate phases to its ultimate goal in the human brain. Mongolia, as many authorities agree, may have been the land that saw man’s earliest beginnings. Whatever his homeland, a long period of tree life was necessary to develop in his predecessors those specializations by which he rose to his allotted position. It is in the tree-life part of man’s history that we see the dawn of the primate brain; for it was then there occurred the earliest exploits of that great order of mammals, the primates, to which all the monkeys, the great apes, and man belong.