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.