Henry Edward Crampton - The Doctrine of Evolution

H >> Henry Edward Crampton >> The Doctrine of Evolution

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The conclusion that the human brain has made mankind is thus established
as one of fundamental importance. Proceeding further, we learn that this
organ proves to be essentially the same as the brain of lower primates; it
does not gain its greater size and efficiency by the origination of wholly
new and unique parts, but solely by the further elaboration of the ones
present in lower forms. In a word, it is only a difference in _degree_ and
not in essential _kind_ that separates man from the apes and other
primates. Human nature is animal nature, and human structure is animal
structure, for nowhere can final and absolute differences be found. This
does not mean that no differences appear, for it would be absurd to
contend that man and the apes are identical in every respect; but it does
mean that the resemblances are fundamental and comprehensive, and any
details of dissimilarity are in the degree of complexity only. The supreme
place in nature attained by man is therefore due to progressive evolution
in the nervous system. The other systems have degenerated to a greater or
less degree, but such regressive changes are more than compensated for by
the superior control exerted by the improved brain. In purely physical and
mechanical respects, the human body is a degenerate as compared with a
gorilla; the arm of the latter is more powerful than the lower limb of the
former, while the gorilla's chest is more than twice as broad as the
human, and more than four times as capacious. It is not through superior
physique, but by superior ability to direct the activities of his body,
that man excels in the struggle for existence with the lower animals.

* * * * *

Moreover, the human body is a veritable museum of rare and interesting
relics of antiquity. This characterization is justified by those vestigial
and rudimentary structures that represent organs of value to human
relatives among the lower animals, though they play a less active part at
the present time in human economy. There is scarcely a single system that
does not exhibit many or fewer of these rudimentary structures, but only a
few need be specified. As compared with those of the apes, the human
wisdom teeth are degenerate; in the gorilla they are cut at the same time
as the other molars; and in the lower human races they come through the
gums in early youth, while in the more advanced Caucasic races they are
cut only in later life or not at all. The reduced vermiform appendix of
man, a source of much ill health, is another structure that is a
counterpart of a relatively larger and useful part of the digestive tract
in the lower primates and other animals. Furthermore, the human tail is a
reality, not a fiction. Now and then an individual is born with a tail
that may reach a length in later life of eight or ten inches; such
structures are, of course, abnormal. But in every normal human being there
is a series of little bones at the lower end of the vertebral column,
constituting the coccyx, and this is just where the abbreviated tail of
the ape and the still longer prehensile tail of the monkey arises from the
body. Unless the coccyx is a tail, what can it be? And if it does not
represent a reduced counterpart of the tails of other mammals, what does
it represent?

Many of the vestigial structures of man appear more clearly in infancy and
in embryonic development. The human embryo possesses a complete coat of
hair, called the lanugo, which usually disappears before birth. This hair
cannot be regarded as any less significant than the coat of hair which the
infant whale possesses; it means a completely haired ancestor. The
elements of this coat are arranged precisely as they are in the apes; upon
the arm, for example, they point from shoulder to elbow and from wrist to
elbow. Unless the anterior limb of the hairy human ancestor was held in
the position of the climbing ape's, this arrangement would be
disadvantageous, for the hair as a rain-shedding thatch would be effective
only upon the upper arm, while the hairs upon the forearm would catch the
rain. In a word, this vestigial coat indicates in the clearest possible
manner that the ancestor of the human species was not only hairy, but also
arboreal in its mode of life.

Every human infant is bow-legged at birth, and the natural position of its
curved limbs is like that of the gorilla's, for the soles of the feet are
turned toward one another. Again, the so-called great toe is at first
shorter than the others, and for a time it retains the power of free
movement that indicates a handlike character of the lower limb in the
ancestor. Many savage human races, however, whose feet remain unshod, make
use of the primitive grasping power of the foot which the higher races
lose completely. An Australian and Polynesian can pick up small objects
with the foot very much as we may with the hand.

Among the wonderful reminiscent characters displayed by the human infant
is the firm clasping power of the hand, which it possesses for a time
after birth and which enables it to hang suspended for several minutes
from a stick placed in its grasp. The muscles which enable the infant to
do this gradually dwindle, so that the two-year-old child can hang
suspended for only a few seconds. This grasping muscle is a heritage from
the ape, where there is an obvious necessity for the newborn individual to
have a firm hold upon the hairy coat of its tree-climbing mother. When the
newborn child hangs in this way, it bends its curved lower limbs so that
the soles of the feet are turned toward one another, thus increasing its
resemblance to the ape.

Let us realize that these curious relics found in so many places in the
framework of man are not unique, and that they are reduced counterparts of
larger and more valuable structures in the ape. Unless evolution is true,
they have absolutely no sensible reasons for existence. Science prefers
the evolutionary explanation of their occurrence because this explanation
is more in harmony with the facts known about other organisms, and it is
more reasonable than any other.

* * * * *

When we dealt with the general doctrine of natural transformation, it
appeared that the evidence of embryology was in many respects more cogent
and conclusive than that derived from the comparative study of animal
structures. In the case of man, as before, no one could demand any surer
or more convincing proof that an organic mechanism with one structure can
change into an organic mechanism with a different structure, than the
obvious facts of development. The embryo, which is not an infant or an
adult, becomes an infant which must work its way onward by the gradual
accumulation of slight changes here and there and everywhere in its
anatomy, until it becomes mature. Each and every one of us has actually
undergone the process of organic change in becoming what we are, and we
cannot deny the reality of such a process without challenging the evidence
of our senses.

When the full import of this history is realized, and when we look further
into the nature of these preliminary conditions through which the human
organism passes in development, we are forcibly impressed by other facts
than the one to which I have directed your attention, for not only do we
find natural transformation, as in the other mammals, but the embryonic
stages are marvelously similar to the earlier conditions in other mammals.
Not very long before birth the human embryo is strikingly similar to the
embryo of the ape; still earlier, it presents an appearance very like that
of the embryos of other mammals lower in the scale, like the cat and the
rabbit,--forms which comparative anatomy independently holds to be more
remote relatives of the human species. Indeed, as we trace back the still
earlier history, more and more characters are found which are the common
properties of wider and wider arrays of organisms, for at one time the
embryo exhibits gill-slits in the sides of its throat which in all
essential respects are just like those of the embryos of birds and
reptiles and amphibia, as well as of other embryo mammals and these
gill-slits are furthermore like those of the fishes which use them
throughout life. All the other organic systems exhibit everywhere the
common characteristics in which the embryos of the so-called higher animals
agree with one another and with the adult forms among lower creatures; the
human embryo possesses a fishlike heart and brain and primitive backbone,
fishlike muscles and alimentary tract. Can we reasonably regard these
resemblances as indications of anything else but a community of ancestry
of the forms that exhibit them?

Yet a still more wonderful fact is revealed by the study of the very
earliest stages of individual development. The human embryo begins its
very existence as a single cell,--nothing more and nothing less; in
general structure the human egg, like the eggs of all other many-celled
organisms, is just one of the unitary building blocks of the entire
organic world. And yet the egg may ultimately become the adult man. Does
this mean that man and all the other higher forms have evolved from
protozoa in the course of long ages? Science asks if it can mean anything
else. When the comparative anatomist bids us look upon the wide and varied
series of adult animals lower than man as his relatives, because they
display similar structural plans beneath their minor differences, it may
be difficult at first to obey him. But in the brief time necessary for the
human egg to develop into an adult, the entire range is compassed from the
single cell to the highest adult we know. There are no breaks in the
series of embryonic stages like those between the diverse adult animals of
the comparative array. I do not think we could ask nature for more
complete proof that human beings have evolved from one-cell ancestors as
simple as modern protozoa beyond the obvious facts of human transformation
during development. They at least are real and not the logical deductions
of reason; yet their very reality and familiarity render us blind to the
deeper meaning revealed to us only when science places the facts in
intelligible order.

* * * * *

And now, in the third place, we may look to nature for fossil evidence
regarding the ancestry of our species. Much is known about the remains of
many kinds of men who lived in prehistoric times, but we need consider
here only one form which lived long before the glacial period in the
so-called Tertiary times. In 1894 a scientist named Dubois discovered in
Java some of the remains of an animal which was partly ape and partly man.
So well did these remains exhibit the characters of Haeckel's hypothetical
ape-man, _Pithecanthropus_, that the name fitted the creature like a
glove. Specifically, the cranium presents an arch which is intermediate
between that of the average ape and of the lowest human beings. It
possessed protruding brows like those of the gorilla. The estimated brain
capacity was about one thousand cubic centimeters, four hundred more than
that of any known ape, and much less than the average of the lower human
races. Even without other characters, these would indicate that the animal
was actually a "missing link" in the scientific sense,--that is, a form
which is near the common progenitors of the modern species of apes and of
man. We would not expect to find a missing link that was actually
intermediate in all respects between modern apes and modern men, any more
than we should look for actual connecting bands of tissue between any two
leaves upon a tree. A missing link, in the true sense, is like a bud of
earlier years which stood near the point from which two twigs of the
present day now diverge. So _Pithecanthropus_ is a part of the chain
leading to man, not far from the place where the human line sprang from a
lower primate ancestor.

Of the fossil remains of true prehistoric men, little need be said. We
cannot know whether the races now living in the regions where these
remains are found are really the descendants of the older types, and so a
direct comparison cannot be made. It is true that the brain capacities of
the man of Spy, of the Neanderthal, and of the English caverns are lower
than those of modern civilized races, but the differences are not so
striking and not so clearly indicative of the apelike ancestor of man as
in the case of the previous comparison of _Pithecanthropus_ with apes and
men.

* * * * *

The foregoing facts illustrate the conclusive evidence brought forward by
science that human evolution in physical respects is true. Even if we
wished to do so, we cannot do away with the facts of structure and
development and fossil history, nor is there any other explanation more
reasonable than evolution for these facts. If now we should inquire into
the causes of this process, we would find again that the present study of
man and men reveals their subjection to the laws of nature which
accomplish evolution elsewhere in the organic world.

The fact of human variation requires no elucidation; it is as real for men
as for insects and trees. Indeed, some of the most significant facts of
variation have been first made out in the case of the human species. The
struggle for existence can be seen in everyday life. We cannot doubt its
reality when scores perish annually because of their failure to withstand
the extreme degrees of temperature during midwinter and midsummer; when
starvation causes so many deaths, and when the incessant combat with
bacterial enemies alone brings the list of casualties on the human side in
our own country to more than two hundred and fifty thousand a year. As in
nature at large, the more unfit are eliminated as a result of this
struggle, while the more adapted succeed. In the long run, that particular
applicant for a clerkship or any other work who may be the more fitted is
the one who gets it. While the severity of competition may be somewhat
mitigated as the result of social organization, and while our altruistic
charitable institutions enable many to prolong a more or less efficient
existence, the struggle for existence cannot be entirely done away with.
Heredity also is a real human process, and it follows the same course as
in animals at large; as in the case of variation, some of the fundamental
laws of its operation have been first worked out in the case of human
phenomena, and have been found subsequently to be of general application.

Reverting to the specific question as to the earliest divergence of man
from the apes, we can readily see how the superior development of the
ape-man's brain gave him a great advantage over his nearest competitors,
and how truly human ingenuity enabled the earliest men to employ weapons
and crude instruments instead of brute force. Thus the gap between men and
apes widened more and more, as reasoning power increased through
successive generations. This is another aspect of the statement that the
supreme position of man has been gained, not by superior organization in
physical respects outside of the nervous system, but by the superior
control of human organization by the higher organs of this system.

The unity of nature and of its processes is established more and more
surely as the naturalist classifies the facts of structure, development,
fossil history, and evolutionary method. Our own species is not unique; it
takes its high place among other organic forms whose lives are controlled
in every way by the uniform consistent laws of the world.

* * * * *

The physical evolution of human races is the next major division of the
large subject before us. Heretofore the obvious differences displayed by
various races have been disregarded and the species has been treated as a
unit, in order that its evolution from pre-human ancestors might be made
clear. Knowing now how the facts of structure show that the supreme
position of our kind has been attained mainly as the result of the
progressive elaboration of the higher portions of the brain, and not
because new and unique structures have been developed, we are prepared to
turn our attention to the diverse characteristics of human races; and
during this inquiry anatomical matters will still be the only ones to be
reviewed. The intellectual and social characters of numerous races belong
to the category of physiological or functional phenomena, which are to
receive due consideration at a later time. It is the meaning of the facts
of racial diversity for which we are now to look.

For many reasons this subject is more difficult to describe in a concise
outline than those taken up before. It is true that every one is familiar
with different types of human beings, such as the Negro and Japanese and
Chinese, while furthermore the obvious differences between such races as
the Norwegian and Italian are sufficiently marked to strike the attention
of any one who looks about at his fellow-passengers in a crowded street
car. But few indeed have a comprehensive knowledge of the wider range of
racial variation in which these familiar examples find their place.
Anthropology, or the science of mankind, is a large and well-organized
department of knowledge, dealing with the entire array of structural and
physiological characters of all men. One of its subdivisions,
anthropometry, is almost an independent discipline with methods of its
own; it describes the characteristics of human races as these are
determined by statistical methods of a somewhat technical nature. There is
still another science, ethnology, which deals more particularly with
institutions, customs, beliefs, and languages rather than with physical
matters, although it is clear that ethnology and anthropology cannot be
sharply separated, and that each must employ the results of the other for
its own particular purposes.

Because men have always been interested in the study of themselves, the
subject of racial evolution is literally enormous, and the attempt to give
anything like a complete description of what is known would obviously be
futile. But it is possible to obtain a clear conception of certain of the
fundamental principles that fall into line with the other parts of the
doctrine of organic evolution with which we have now become acquainted.
The main questions, therefore, may be stated in simple terms. The first
deals with the evidences as to the reality of evolution during the
historical and prehistoric development of the various types of man from
earlier common ancestors; the second asks whether the lines of racial
evolution are further continuations of the line leading from ape-like
ancestors to the human species as a type. In order to give the proper
perspective, it will be well to state at the present juncture, first, that
the various kinds of men do not vary from each other in a chance manner so
as to show all possible types and varieties, but that they fall into
natural groups or families distinguished by certain common
characteristics, just as do all other kinds of species of animals; in the
second place, it appears that some of the differences between the races
denoted higher on structural accounts and the lowest forms of man are of
the same nature as those observed in the review of the various species of
primates from the lemurs to man.

* * * * *

It is best to look at the whole question in a very simple and common-sense
way before undertaking an extended examination of the details of human
diversity. The most casual survey of the peoples that we know best because
of our own individual nearness to them enables us to realize that the
races now upon the earth have not existed forever and ever, or even for
the age of 6000 years as contended by Archbishop Ussher. They have all
come into existence as such, and they differ from their known antecedents;
so that at the very outset common-sense leads us to accept evolution as
true, if we admit that human races have changed during the course of
recent centuries. We know, for example, that the so-called Mexicans of
to-day are a people produced by a fusion of Spanish conquerors and Indian
aborigines the Mexican is neither Spaniard nor Indian, though he may
resemble both in certain respects; he is a product of natural evolution,
accomplished in this case by an amalgamation of two contrasted types. When
we speak of the American people, we must realize that it too has come into
existence as such, and even, indeed, that it is in the actual process of
evolution at the present time. The various foreign elements that have been
added during the last few decades by the hundreds of thousands are
becoming merged with the people who preceded them, just as the Dutch and
the French and the English coalesced during the days of early settlement
to form the young American nation. Perhaps most of us call ourselves
Anglo-Saxon, but we are in reality somewhat different even in physical
respects from the Englishmen of Queen Elizabeth's time, who alone deserved
the name Anglo-Saxon. This very term indicates an evolution of a type that
differs from both the Angles and the early Saxons of King Alfred's age.
These are simple examples which illustrate many features of the universal
history of human races wherever they are to be found. Even in the
comparatively peaceful times of our modern era the history of any race is
a veritable turmoil of constant changes; conquerors impress their
characters upon the vanquished, while the victors often adopt some of the
features of the conquered. Colonies split off from the mother nation to
follow out their destinies under other conditions. Nowhere does the
naturalist find evidence of long-established permanence, or an unentwined
course of an uninterrupted and unmodified line of racial descent.

It is the task of the student of human evolution to unravel the tangled
threads of human histories. The task is relatively simple when it is
concerned with recent times where the aid of written history may be
summoned but when the events of remote and prehistoric ages are to be
placed in order, the difficulties seem well-nigh insuperable. All is not
known, nor can it ever be known; but wherever facts can be established,
science can deal with them. By a study of the present races of mankind,
much of their earlier history can be worked out, for their genetic
relations may be determined by employing the principle that likeness means
consanguinity. Let us suppose an alien visitor to reach our planet from
somewhere else; if he were endowed with only ordinary human common-sense,
he would very soon ascertain the common origin of the English-speaking
people in Canada, the United States, Australia and New Zealand, South
Africa, and many other places. Even if he could not understand a word of
the English language, he would be justified in regarding them all as the
descendants of common ancestors because they agree in so many physical
qualities. The anthropologist works according to the same common-sense
principle, obtaining results that find no explanation other than evolution
when the varying characters that are used to determine social relationship
are properly classified and related. It is to these characters that we
must now give some attention.

* * * * *

The average stature of adults varies in different races from four feet one
inch in certain blacks to nearly six feet and seven inches, as among the
Patagonians. These are the extreme values for normal averages, although
dwarfs only fifteen inches high have been known, while "giants" sometimes
occur with a height of nine feet and five inches. Such individuals are of
course rare and abnormal, and are not to be taken into account in
establishing the average stature of a race for use in comparison with that
of another group.

The color of the skin is another criterion of racial relationship, though
it is more variable in races of common descent than we are wont to assume.
We are familiar with the fair and florid skin of the northern European,
the fair and pale skin in middle and southern Europe, the coppery red of
the American Indian, the brown of the Malay, of the Polynesian and of the
Moor, the yellowish cast of the Chinese and Japanese, and the deeper
velvety black of the Zulu; but it has been found that many of the close
relatives of the black are lighter in skin color than some of our
Caucasian relatives, so that this character cannot be taken by itself as a
single criterion of racial affinity.

Perhaps the most conservative and most reliable character that serves for
the broad classification of the human races is the shape of the individual
hairs of the head. We are familiar with the straight lank hair of the
Mongolian peoples and of the various tribes of American Indians, in whom
the hair possesses these peculiarities because each element grows as a
nearly perfect cylinder from the cells of the skin at the bottom of a tiny
pit or hair-follicle. The familiar wavy hair of white men owes its
character to the fact that the individual elements are formed by the skin,
not as pencil-like rods, but as flattened cylinders. They are oval or
elliptical in cross-section, and when they emerge from the skin they grow
into a long spiral. If, now, the hair is formed as a very much flattened
rod about one-half as wide in one diameter as in the other, it curls into
a very tight close spiral and gives the frizzly or woolly head-covering of
the Papuan and of the Negro.

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