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Title: The illustrated story of evolution
Author: Gauvin, Marshall J.
Language: English
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EVOLUTION ***
Transcriber’s Notes:
Underscores “_” before and after a word or phrase indicate _italics_
in the original text.
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[Illustration: CHARLES DARWIN]
The Illustrated Story of Evolution
BY
Marshall J. Gauvin
President of the American Secular Union; Author of
“Is There a Real God?”, “Is There a Life After Death?” etc.
[Illustration]
New York
Peter Eckler Publishing Company
1921
COPYRIGHT, 1921,
BY
THE PETER ECKLER PUBLISHING CO.
Printed in the U. S. A.
_TO MY WIFE_
_Whose fine literary taste
applauds the slightest beauty
of a phrase, and whose interest
in this book was helpful in
its preparation._
Introduction
The Greek philosophers from Thales to Aristotle, more than two thousand
years ago, entertained the notion that all things have been developed
from primitive beginnings. This view was shared in the fourth century
of the Christian era by St. Augustine, probably the greatest of the
church “Fathers.” Then came the Dark Age,—an intellectual night of a
thousand years—an era when reason and science were buried in the grave
of superstition,—and at its close, the Revival of Learning, the dawn of
the modern period.
In that golden Renaissance of rational thought and scientific
speculation, philosophical thinkers—Bruno, Campanella and
others—influenced by the theories of the Greeks and by the astronomical
discoveries of Kepler, Copernicus and Galileo, sought to explain the
universe as an unfoldment from a simple, early condition of matter.
But such speculation was denounced as dangerous, and Bruno died a
martyr in the flames. Still the idea that there has been an evolution
in nature persisted and grew, and the writings of Spinoza in Holland,
of Locke in England, of Kant in Germany, of Lamarck in France,—to
mention but a few philosophers—encouraged men to think that the secret
of existence lay in the fact of growth.
Then came the greatest of books on the development of living things.
In 1859, Darwin gave the world his “Origin of Species,” a work which
laid the foundation of the science of evolution. Earlier thinkers had
groped and guessed with little knowledge of Nature’s laws. But Darwin
had discovered the laws of organic life, and, with an amazing array of
evidential facts patiently observed and gathered in a score of years,
he was able to support his view that species have been evolved “by
means of natural selection” through “the preservation or favored races
in the struggle of life.”
In the interest of the six-days creation legend, a storm of theological
wrath assailed the great man’s head. Knowing that truth was on his
side, the saint of science paid no heed to slander and patiently
worked on. And in twenty-three years he wrought a greater, a more
farreaching revolution in the thoughts of intelligent mankind than
was ever accomplished by any other of the sons of men; and when he
died, England was glad to honor his dust with burial in her sacred
Westminster Abbey.
Evolution is as firmly established to-day as the fact of gravitation.
The intellect of the whole world acclaims it as the one and only
principle that explains the phenomena of existence. True it is, that
many naturalists disagree with Darwin with respect to some of the
details of the _process_ by which evolution has been brought about, but
these men are one and all thoroughgoing evolutionists. There is no man
of science living who believes in special creation. Every university
now teaches evolution.
Every science studies its facts to-day, in the light of growth and
change from simplicity to complexity. The astronomer traces the
course of evolution in the heavens; the geologist follows the path of
evolution in the crust of the earth; the biologist threads the process
of growth through succeeding forms of life; the psychologist considers
the gradual emergence of mind from the lowly animal to civilized man;
the sociologist elucidates the progressive development of society
from its rude barbaric dawn; the inquiries of the anthropologist
illuminate the evolution of religion, of government, of law. Every
phase of existence and life and thought opens its treasury of secrets
when touched by evolution’s master key. Where all the facts point
resistlessly to one conclusion, that conclusion must perforce be
accepted as true. The foundations of evolution are laid in all the
active phenomena of nature and the super-structure is being fashioned
by all the facts of growth and change.
The purpose of this little book is to set before the busy reader some
of the principal facts illustrating the evolution of the universe and
of living things.
MARSHALL J. GAUVIN
Pittsburgh, Pa., August 30, 1921.
List of Illustrations
Charles Darwin _Frontispiece_
Fig. 1.—The Great Nebula in Orion 15
Fig. 2.—The Great Spiral Nebula 17
Fig. 3.—An Elongated Irregular Nebula 19
Fig. 4.—Lunar Craters: Hyginus and Albategnius 21
Fig. 5.—The Cluster in Hercules 23
Fig. 6.—A Pillar of Stratified Rocks 25
Fig. 7.—Segmentation of the Fertilized Ovum and Gastrulation 27
Fig. 8.—Cambrian Fossils and Upper Silurian Fossils 29
Fig. 9.—The Amphioxus 31
Fig. 10.—The Earliest Known Form of Fish and
Three Other Early Forms of Fishes 33
Fig. 11.—Lampreys—The Mouth of a Lamprey 35
Fig. 12.—Lung Fishes 37
Fig. 13.—The Flying Fish 39
Fig. 14.—The Climbing Perch 41
Fig. 15.—The Evolution of the Frog 43
Fig. 16.—The Head of the Famous Archaegosaurus 45
Fig. 17.—The Ceratosaurus 47
Fig. 18.—The Archaeopteryx 49
Fig. 19.—The Duck-bill, known in Australia as the Platypus 51
Fig. 20.—A Kangaroo with her Young One in her Pouch 53
Fig. 21.—The Pariasaurus Baini 55
Fig. 22.—The Ring-tailed Lemur of Madagascar 57
Fig. 23.—The Slow Loris—another type of Lemur 59
Fig. 24.—The Baboon 61
Fig. 25.—The White-handed Gibbon 63
Fig. 26.—A Female Gorilla 65
Fig. 27.—Male Giant Gorilla 67
Fig. 28.—The Baldheaded Chimpanzee 69
Fig. 29.—The Skeleton of Man and of the Four Anthropoid Apes 71
Fig. 30.—Skull of the Fossil Ape-man of Java 73
Fig. 31.—A Restoration of the Neanderthal Man 75
Fig. 32.—Evolution of the Proboscidea 77
Fig. 33.—Eohippus, the “Dawn Horse,” from the Lower Eocene Rocks 79
Fig. 34.—Fossil Antlers 81
Fig. 35.—Antlers of One Deer at Different Stages of Their
Development 83
Fig. 36.—Embryos of Four Mammals 85
Fig. 37.—Tail of a Six-Months-old Boy 87
Fig. 38.—The Vermiform Appendix in the Orang,
in Man, and in the Human Foetus 89
Fig. 39.—The Rudimentary Muscles of the Ear 91
Fig. 40.—Hair Tracts on Arms of Man and Ape 93
Fig. 41.—The Head of Miss Julia Pastrana 95
Fig. 42.—The Brains of Anthropoid Apes and Men 99
Fig. 43.—Joe and Sallie at Home 103
Fig. 44.—The Genealogical Tree of Humanity 107
Fig. 45.—Two Pigs 111
Fig. 46.—Dogs 115
Fig. 47.—Pigeons 117
_The Illustrated Story of Evolution_
Our fathers, many ages ago, looked out upon the world with mingled
feelings of reverence and fear. They saw the sun that dazzled their
eyes with the brightness of his beams as he flamed his way across the
path of day; they saw the white light of the moon, hung like a spirit
lamp amid the clouds that sailed over the face of night; they saw
the stars, now spangling the darkness with the glory of their sheen,
now veiling their faces with the sable void; they saw the infinite
variety of plants, the animals of every size and form; they saw man
himself, the master of the earth; and they would know something of
the mighty scheme. They did not dream of natural law, but they were
curious. Destitute of science, they were full of wonder. What could be
the driving power back of what they saw? Existence was a challenge.
They must essay an explanation. Their minds refused to rest content in
ignorance. They must know how things came to be.
It was the age of gods. Gods were in the wind and rain, in the flood
and flame, in the roar of the thunder and the echo of the forest
gorge, in the harvest that sustained and the disease that destroyed—in
everything that helped or hurt the sons of men. Man could do things;
the gods could do things too. Man could build a home; the gods could
build a world. So reasoned our primitive fathers. Of this reasoning
were born the creation stories of the ancient religions; and these
stories, coming down to our day, have fixed the beliefs of countless
generations of men.
In one of these creation myths, regarded as of divine authority because
it is found in the Bible, we are naively told that the world with its
myriad forms of life and the star-studded universe beyond, were created
in six days; and as this childish story is inseparably interwoven with
popular religious notions, millions still regard it as sacredly true.
But this is an age of science, of a growing knowledge of reality.
During the last few generations, the facts of nature have been studied
as they never were studied before. As a result of this study, nature
has yielded to man’s inquiring mind a growing knowledge of her methods.
This knowledge is now accepted by the educated world as the science of
evolution.
[Illustration: FIG. 1.—THE GREAT NEBULA IN ORION.
This illustration and the four that follow are reprinted from Sir
Robert Stawell Ball’s “The Earth’s Beginning,” with acknowledgments to
Cassel & Co., London, and D. Appleton & Co., New York.]
We can imagine only two ways by which the world and its forms of life
came into existence. One is to suppose that all things were created
out of nothing, and made perfect at once, by a being of infinite power
and intelligence who never had beginning. That is the biblical, the
miraculous, the supernatural way. The other is to suppose that the raw
material always existed, and that all things have been developed from
primitive origins, the higher forms gradually emerging by evolution out
of the lower. That is the scientific, the natural way. The first view
is an assumption utterly devoid of support. The evidence proves that
nothing was made, that things have grown.
Not only do we know that a creating God is a mere guess; that he is
unthinkable in quantity or quality, that he bears no conceivable mark
of reality; not only do we know that the creation of a universe out
of nothing is wholly unintelligible; but the evidence of astronomy
points clearly to the conclusion that our planet has been evolved by
condensation from a nebula—from the raw material of which worlds are
made; the evidence of geology portrays the fact that the earth has
become what it is through a process of continuous change covering many
millions of years; and the evidence of botany and of biology, studied
in living forms and in fossil remains, proves conclusively that the
plants and animals of the world have acquired their present character
and mould as a result of infinite variations from and improvements upon
the first simple forms of life that arose in the primeval world.
[Illustration: FIG. 2.—THE GREAT SPIRAL NEBULA.]
Not creation, then, but evolution, is the secret of the world’s
infinite diversity of things. Nothing was made; everything has grown.
Perfection is not at the beginning, but at the end of nature’s
efforts. All things have been fashioned by a process of endless
transformation—blind, boundless, staggering, stumbling—at times falling
back, but on the whole moving forward, pressed by the relentless forces
inherent in substance and shaped in accordance with immutable law. Such
a process has covered the earth with its amazing display of vegetation,
and with its strange and wondrous population of things that swim and
creep and fly and run.
In sketching the story of evolution, as that story is revealed to us by
science, let us begin with the evolution of the starry heavens, that we
may learn how the world was born.
As the giant telescope sweeps the abysmal depths of space over a
distance of at least 4,000 billion miles, it reveals here and there
among the hundred million stars, vast patches of cloud-like material.
This material is called nebula, and it is the original substance of
which all suns and planets are made. One hundred and twenty thousand of
these nebulæ come within the range of the great Crossley Reflector at
the Lick Observatory. The telescope photographs the nebula—celestial
photography is one of the most interesting and instructive branches of
modern astronomy—and when you look at a picture of a nebula, you see
an actual photograph of an object that marks the beginning of Nature’s
work.
[Illustration: FIG. 3.—AN ELONGATED IRREGULAR NEBULA.]
According to Sir Robert Stawell Ball, the nebula in Orion (Fig. 1), one
of the most beautiful objects revealed by the telescope, covers an area
more than a million times larger than that occupied by our entire solar
system. Many of the nebulæ are of the spiral form, which shows their
whirling motion. To the astronomer, the Great Spiral Nebula (Fig. 2)
represents a mighty sun and system of planets in process of formation.
Fig. 3 shows an elongated, irregular nebula, from the Constellation
Cygnus. This sketchy streak of nebulous material, although it is still
many millions of miles wide, is but the remaining thread of a once
mighty nebula that has condensed and is still condensing into the
surrounding stars.
The nebulæ represent various stages of evolution into suns and worlds.
Some resemble great clouds of rarified matter; some are distinctly
spiral in form; some show advanced condensation into stars with
attendant planetary systems. The stars, too, exhibit various degrees of
progress from their birth in the nebula. Some are white, which shows
that they are young; some are yellow, which indicates that they have
reached middle age; some are red, which is the mark of their declining
years.
[Illustration: FIG. 4.—LUNAR CRATERS: HYGINUS AND ALBATEGNIUS.]
So the stars, the glowing suns, grow old and die, and, lifeless, wheel
in space, like mighty cinders cold and dark, reflecting, like the moon,
the light that shines on them from brilliant orbs.
The moon (Fig. 4) is a dead star. Its light and heat are gone. It
wheels in space, an extinct cinder, and by the borrowed light which
enables us to see the craters on its surface, it prophesies for us the
fate that one day will overtake the earth. But that will be millions of
years from now; so we need not worry!
But how is the nebula formed? The cluster in the constellation Hercules
(Fig. 5), if it is not in fact a colossal nebula, shows that some of
the stars are very close together. Now, these immense objects, that in
blind fury dash through space, may come into collision with one another
and explode into a nebulous cloud; or they may plough through dense
swarms of meteorites, with a resultant explosion on a smaller scale;
or, torn by internal convulsions, they may burst into fragments and
scatter their dead dust over the abyss of space. In one or all of these
ways the nebula is born, to begin again the recurring cycle of Nature’s
life.
[Illustration: FIG. 5.—THE CLUSTER IN HERCULES.]
Is there further evidence of this? There is. On the night of February
21, in the year 1901, a luminous object appeared in the constellation
Perseus. From a region where all was darkness the night before, a
new and wondrous body now blazed forth its treasures of light. To
the astronomers, who with lively curiosity watched the new birth for
months, it meant that a tremendous conflagration had taken place in the
heavens. A new nebula had been given to the universe, not, however, on
the night when its light was first seen, but when Napoleon was dazzling
the world with his victories; for the glowing mass was 500 billion
miles away, and its messenger light, flying across space with the awful
velocity of 186,000 miles a second, had been hurrying ninety-nine years
to bring the news to our world!
Science now warrants a further step—one which reveals the origin and
nature of matter—the ultimate source of the nebula itself.
Ether fills all space. It penetrates even the most solid substances.
The universe of matter swims in an ocean of ether. Only by the presence
of ether is the force of gravitation made possible—it must have ether
upon which to act. The wings of ether alone transmit to us the light of
the sun and stars. Now science is telling us that this indispensable
ether, this infinitely attenuated and invisible substance, is the
birthplace of matter—that atoms of matter are composed of minute
centres of energy, or electrons, in ether. The atom is built of
thousands of electrons whirling with inconceivable velocity in the
space of their tiny, invisible universe; just as the visible universe
is composed of myriads of suns and planets rushing forward through the
boundless etherial ocean. Matter, then, whether nebulous or solid, was
evolved out of the ether.
[Illustration: GENERAL TABLE OF THE STRATIFIED SYSTEM AND FORMATIONS,
ETC.
FIG. 6.—A PILLAR OF STRATIFIED ROCKS.
This illustration and others in this book are reproduced from Dennis
Hird’s excellent work, “A Picture Book of Evolution,” with the kind
permission of the publishers, Watts & Co., London.]
Millions of ages ago, a collision or an explosion produced a nebula
in the region now occupied by our solar system. That nebula spread
out over thousands of millions of miles of space. Here and there, in
its mighty body, a more solid nucleus drew to itself volumes of the
surrounding substance. In this manner the planets arose, leaving the
sun, with his giant mass, in the center of the field. As the nebula
revolved in one direction, mathematical necessity imparted to all
the forming bodies a whirling motion around the central sphere. The
smaller bodies cooled rapidly, so to speak, and crusted over; but the
sun, owing to his immense bulk, has continued to glow through all
these countless ages, and still sends forth enough light and heat to
illuminate and warm many billions of worlds like ours. How long a time
has elapsed since the earth began to condense from the nebula, the
human mind cannot conceive; but Sir G. H. Darwin, the son of Charles
Darwin, declares it is not unreasonable to suppose that from five
hundred to a thousand million years have passed away since the moon was
detached from the earth.
[Illustration]
[Illustration]
[Illustration: FIG. 7.—SEGMENTATION OF THE FERTILIZED OVUM AND
GASTRULATION.
4, morula; 5, section through blastula showing hollow sphere; 6,
gastrula showing outer layer of cells (epiblast) and inner layer
(hypoblast); the 6 is at the mouth of the cavity (enteron) of the
gastrula. From Dr. D. Kerfoot Shute’s “A First Book in Organic
Evolution.” Courtesy of The Open Court Publishing Co.]
When the moon was born, the earth was in a plastic state, and many
millions of years had yet to elapse before anything like a solid
surface could begin to appear upon it. When, at length, the cooling
globe did begin to form a crust, that crust was from time to time
shattered to fragments by violent eruptions from within. Later, the
immense quantities of hydrogen and oxygen that were in the atmosphere
combined into molecules of water, and torrents of rain settled upon the
hot surface of the earth. Owing to the large admixture of carbonic acid
gas which it contained, the atmosphere was then fifty times heavier
than it is to-day; but notwithstanding this great pressure upon it,
the water that settled on the hot crust of the earth could not remain,
and was sent, hissing, into the air in clouds of steam. The time came,
however, when the cooling surface of the planet no longer offered such
vigorous resistance to the water that fell upon it, and gradually
as the rain fell, the earth became almost entirely covered with a
boiling ocean. But the hot earth, even under the enormous weight of its
ocean and its dense air, was restless, and as time passed away, great
stretches of land emerged. Upon this new land, the rain now poured down
in floods. This caused a great washing of debris into the surrounding
sea. There the debris settled, and beneath the tremendous pressure of
the ocean, it became solidified into the oldest stratified rocks.
[Illustration]
[Illustration: FIG. 8.—CAMBRIAN FOSSILS (above); UPPER SILURIAN FOSSILS
(below).]
The rock pillar (Fig. 6) represents the rock formation of the crust
of the earth. It gives us an idea of what a cross-section of the
earth’s crust would look like, if all the rock deposits could be found
superimposed one above the other in any one place. These rocks, built
up layer upon layer, by sedimentary deposits in the ocean, are believed
by geologists to reach a depth of more than forty miles; and it is held
that it must have required at least a hundred million years—perhaps a
thousand million years—to lay down all the strata, all the series of
layers of rock, that form the crust of the globe.
That these immense depths of rock have been formed by a slow process
of growth, of gradual up-building, is certain. The world was not made
in a day. It has grown through innumerable ages. It is still growing.
At the present time, the rivers of England are carrying away thousands
of tons of land every year and depositing it on the floor of the sea.
Every year the Mississippi river carries four hundred million tons of
solid material into the Gulf of Mexico. This one stream alone displaces
more than a million tons of solid matter every day. Similar things
are occurring, in greater or less degree, in every part of the world.
Everywhere rivers are widening and deepening their channels, cutting
their way into mountains, depositing sediment for rock formations, or
overflowing and fertilizing soil; everywhere mountains and hills are
being worn down by the action of the elements; continents are crumbling
into the ocean; island surfaces are rising above or falling beneath the
waves. Nature is ever flowing. Throughout her infinite domain there is
everlasting movement. Her trademark is eternal change. Nowhere is she
at rest. Her labors never cease. To-day, as in the past, she builds and
destroys. In her endless process of evolution, every day is a day of
creation.
[Illustration: FIG. 9.—THE AMPHIOXUS.
This illustration and several others used in this book are reprinted
from J. A. S. Watson’s “Evolution.” Courtesy of The Frederick A. Stokes
Co.]
These rocks contain fossils, the skeletons of creatures that lived
during the periods when the rocks were being formed. This fact is one
of the keys to the temple of evolution; for when we know the kind of
fossils the different rocks contain, as we rise from the lower to the
higher, we know the kind of creatures that lived in the various periods
when those rocks were formed. Let myth-makers say what they will,
Nature does not lie.
As the crust of the earth cooled, the enveloping ocean gradually lost
its high temperature, and having fallen far below the boiling point,
continued to be warm for ages. In that warm primeval ocean, where the
various elements entered into all sorts of combinations, the necessary
elements combined in the proper proportions, and, as a result of that
happy combination, life was born into the world. Just as the requisite
proportions of charcoal, sulphur and saltpeter unite in making
gunpowder—a high explosive, vastly different from its constituent
elements—so, simple elements, uniting in due proportions, produced the
phenomenon of living matter.
[Illustration: FIG. 10.—THE EARLIEST KNOWN FORM OF FISH (upper); THREE
OTHER EARLY FORMS OF FISHES (lower).]
Whether life is still being evolved from non-living matter, or whether
its origin was confined to a peculiar set of favorable conditions—very
high temperature, and unusual chemical and electrical conditions—in
the early world, remains as yet unknown. On this question, the most
distinguished biologists entertain diverse opinions. Among those who
hold that the evolution of life is still one of the ordinary processes
of Nature’s day’s work may be mentioned Professor Benjamin Moore,
F.R.S., whose views are set forth in his excellent little work, “The
Origin and Nature of Life.”
All living things, from the blade of grass to the giant oak, from the
worm to the philosopher, are composed of cells, and all cells are
composed of protoplasm. Protoplasm is, therefore, the physical basis
of life. This wonderful substance is a compound of carbon, hydrogen,
nitrogen and oxygen, and the story of the evolution of living things
spells the limitless transformations of which this vital substance is
capable.
In the world of to-day, we see the finished forms that have been beaten
out, as it were, upon the anvil of the evolutionary process; and if
we would appreciate the progressive march that life has made, from
the simple forms of early days to the highly developed and complex
creatures of to-day, we must trace the story of evolution through the
numberless ages of the past.
[Illustration: FIG. 11.—LAMPREYS (left). THE MOUTH OF A LAMPREY
(right).]
The first living things consisted of a single cell—the Protozoa. As
this cell grew, it divided into two; the two, having grown somewhat,
divided into four; the four into eight; the eight into sixteen, and so
on. In this way, the growing cells increased their numbers by division,
and what was at first a single cell became an organized group of cells.
Fig. 7 illustrates the process of division and growth from the single
cell—the fertilized ovum—to the gastrula. This division is the law of
life. Every living creature begins its existence in this way.
Gradually, some cells specialized in the performance of the simplest
animal functions, like the catching of food and digestion; and in the
course of time, such simple forms of life as sponges and marine worms
appeared. From flat worms, life advanced to the annelid or ringed
worms—little creatures with a food canal and a body cavity filled with
blood. In the worm begins the first development of the brain. A few
sensitive cells in the fore end of the body, that beginning of mental
life, is a far-flung prophecy of the genius that will one day thrill
the world. Primitive depressions, lined with pigment cells, in the
worm-like head, represent Nature’s first reaching for eyes; two other
sensitive nerve pits are the beginning of the nose; yet a further pair
of susceptible concave surfaces are destined to develop into the ears
of land animals. Creatures with these primitive structures still exist
among Nature’s lowly forms.
[Illustration: FIG. 12.—LUNG FISHES.
Australian Lung Fish, Ceratodus (top); South African Lung Fish,
Protopterus (middle); South American Lung Fish, Lepidosiren (bottom).]
From worms and worm-like creatures, were developed snails and a great
variety of small animals, covered with shells. The Cambrian Rocks, the
earliest rocks that have preserved fossils, have yielded the remains
of some of these shell creatures (Fig. 8, upper). The Upper Silurian
Rocks, belonging to a period much later than the Cambrian, have
entombed the fossils of the molluscs shown in Fig. 8 (lower).
We must understand that by this time living things had been evolving
for millions of years, yet these shelled animals were the highest
forms that had so far appeared. We must understand, too, that only the
skeletons of creatures possessing a bony frame could be preserved as
fossils. The fleshy part of the body, Nature destroyed. Moreover, it
must be realized that of the countless billions of creatures that have
lived, the rocks have preserved the fossil remains of only a few. We
must not expect too much from Nature’s mutilated record. It is enough
to know that the specimens that have been preserved prove the gradual
unfoldment of life, and enable us to interpret the wonderful story of
evolution.
[Illustration: FIG. 13.—THE FLYING FISH.]
There is a small animal known as the Amphioxus (Fig. 9). Standing
midway between the worm and the fish, its distinguishing peculiarity
lies in the fact that it has a rod of cartilage—the notochord—extending
along its back, over which runs a line of nerve cells. This creature,
the child of the worm and the parent of the fish, is of singular
importance, since it foretells the coming of the vertebrates—the
creatures with a backbone. In due time the fishes were evolved from
the Amphioxus. The first fish appeared in the Devonian period, that is
to say, when about one-third of the whole geological series of rocks
had been formed. Fig. 10 (upper) represents a fossil of the earliest
known fish. The skeleton shows a primitive form. The lower specimens
represent other early fishes. Observe the curious worm-like resemblance
of the middle one. There are still fishes of very unfinished form.
Lampreys (Fig. 11) show, as it were, fishes in the making. They have
strangely undeveloped heads, no jaws, and only a crude sucker-like
cavity for a mouth.
The early fishes had no bones in their bodies. Their skeletons were
composed of cartilage. Primitive fishes of to-day—sharks, rays, and
others—have no bones. These fishes continue lines of descent from
ancestors that appeared before the bony frame had been evolved.
Life was born in the sea; it moved from the sea to the land; and when
this advance was made, it was the fishes that led the way. Some fishes
developed lungs and began, tentatively at first, to live on the shore
or in marshes. Life was moving towards the amphibians, and the evidence
of its advance in this direction has been preserved. As the Amphioxus
is the link between the worm and the fish, so lung fishes are links
between the true fishes and the amphibians. Fig. 12 (at the top) shows
the Burnett salmon, of Queensland—a fish with one lung; below are two
mud-fishes of Africa and Brazil—fishes with two lungs. These lung
fishes, or double-breathers, have the characteristics both of the fish
and the frog. To scales and gills and fins and other features of the
fish, they add lungs, nostrils, the beginning of a three-chambered
heart, and other features of the frog. Living in regions from which the
water periodically disappears, these creatures build around themselves
in the dry season a shell of mud and leaves, and there, while awaiting
the return of the water, they breathe air, and live on the fat stored
up in their tails.
[Illustration: FIG. 14.—THE CLIMBING PERCH.]
These lung fishes can walk on their fins; in fact, the fins of some of
them are formed more like legs than fins.
The Flying Fish (Fig. 13) is another variation. This fish can sustain
itself in the air for a hundred yards or more. Yet another curious fish
that will not stay in the water is the Climbing Perch (Fig. 14). This
fish may be seen crossing fields in India, and with the use of its fins
it even climbs trees. These strange fishes are surely links to higher
forms of life.
That the amphibian has been evolved from the fish may be seen in the
evolution of the frog (Fig. 15). Number 1 shows the newly-hatched
tadpoles; 2 and 2a show the branching, external gills; 3 to 8
illustrate further steps in the evolutionary process. The fish-like
tail, so prominent in the early stages, is finally absorbed and we have
the finished frog.
In the evolution of the frog we have a most suggestive illustration of
the transformation of a creature during a single lifetime. The fish
becomes an amphibian; the gilled, water-breathing creature becomes a
lunged, air-breather; a water animal leaves its habitat for a home on
land; a vegetable diet is abandoned for one of flesh. Truly a striking
summary instance of the power of evolution!
[Illustration: FIG. 15.—THE EVOLUTION OF THE FROG.]
All that man has become, all the wealth and worth of the civilization
he has achieved, has been due to the fact that he has possessed a hand
which could obey the command of his brain. Without a hand, without
fingers, man would still be a wild beast of the forest. It was in the
amphibian that Nature first produced the five divisions of the foot,
which, inherited by the reptiles and then by the mammals, in the end
became specialized into the human hand. The beginning of the hand is
seen in the foot of the frog.
In the Carboniferous period, when the coal measures were laid down,
appeared the wedge-headed amphibian, shown in Fig. 16 (above) and
later, in the Permian period, the roof-headed amphibian (Fig. 16,
below) was born into the world. This roof-headed amphibian is all
the more interesting, for from some of these creatures were born the
reptiles, from which, in turn, arose the mammals.
From the amphibians were developed the true reptiles, and these
branched out into many forms. Some lived in the water, some roamed
on the land, some flew in the air. In a warm climate, and where food
abounded, some of these creatures, like the Ceratosaurus (Fig. 17), the
Atlantosaurus and the Diplodocus, grew to a prodigious size. Some were
fifty, some a hundred, some a hundred and fifty feet long; some had
a hundred teeth, and eyes fifteen inches across; some weighed ninety
tons, and made footprints a yard square. It was in the Mesozoic times,
millions of ages ago, when these ungainly monsters were the monarchs of
the earth. Happily, they have long since been extinct, and to-day their
colossal, though harmless, skeletons may be studied in the museums of
the world.
[Illustration: FIG. 16.—THE HEAD OF THE FAMOUS ARCHAEGOSAURUS.
The wedge-headed Amphibian (above); the Branchiosaurus—the roof-headed
Amphibian (below).]
From the reptiles came the birds. The first birds had teeth, claws
on their wings, and bony tails of many joints (Fig. 18). The fossil
remains of two of these reptile-birds—the earliest birds known—were
found, some years ago, in the Jurassic limestone strata of Bavaria.
These creatures had thirty-two teeth, three clawed fingers on each
wing, and a lizard-like tail of twenty joints, with two long feathers
growing out of each vertebra. Occupying the ground midway between the
reptile and the bird, having the characteristics of both—the link
between the four-legged animal and the feathered songster of the
air—the Archaeopteryx, as this ancient bird is called, was about the
size of a crow.
Another line of development led from the reptiles to the mammals—the
hair-clothed creatures that suckle their young. This was the most
promising line of Nature’s advance, for at the end of this line, man
was destined to appear.
[Illustration: FIG. 17.—THE CERATOSAURUS.
A giant reptile of the Jurassic Period.]
An amazingly curious link, which connects the reptile with the bird on
the one hand and with the mammal on the other, is the Duck-bill (Fig.
19). This creature, whose home is in Australia, is covered with dense
fur and suckles its young, like a mammal; but, on the other hand, it
lays eggs like the reptile and the bird. The eggs have large yolks,
like those of birds; are hatched by the warmth of the mother’s body;
and when the young is born, it lives on milk drawn from its mother’s
breast. Observe, too, that the mother Duck-bill has no nipples, but
mere depressions in the breast, from which the milk oozes out among the
fur, to be sucked up by the young. Think of a fur-covered, five-toed,
web-footed, duck-billed, flesh-eating, swimming animal, housing itself
in a burrow in the bank of a stream, being born from an egg, like a
bird; formed in part like a reptile, and deriving its early sustenance
by sucking the milk-ooze from its mother’s teatless breast! This link
between reptile, bird and mammal, this crude combination of three forms
of life, shows finished forms in the making. It is the living proof
of the manner in which Nature has accomplished her work—of the steps
by which evolution has advanced. It is what Darwin called “a living
fossil.”
After the Duck-bills came the marsupial mammals—mammals whose young,
born not yet fully developed, are carried for a time in a pouch
attached to the body of the mother. The kangaroo (Fig. 20) belongs to
this class. Here the advance is from an egg-laying mammal to one whose
young is partly formed in the body of the mother. I say partly formed,
for, although the kangaroo is as large as a man, its young, when born,
though it is no larger than the little finger, is still a fœtus, so
imperfectly formed that it must be carried for months in the mother’s
pouch, so that it may complete its development as a babe. Meanwhile,
being unable to feed itself, the mother, by an exercise of her muscles,
forces milk down its throat. Once more Nature, in her forward march,
is blazing a new trail. Life, by employing crude makeshifts and
adaptations, is fashioning for itself a higher mould.
[Illustration: FIG. 18.—THE ARCHAEOPTERYX.
The lower picture shows the joints of the tail with the tail feathers.]
The marsupial mammals were followed by the placental mammals, animals
whose young are nourished before birth by a disc-like organ, called the
placenta—the after-birth.
The Pariasaurus Baini (Fig. 21) shows Nature, the apprentice, trying to
make a quadruped. I say trying, for see what a crude, raw specimen this
monster was. The best thing that can be said of this fellow is that he
had his day of fighting for a place in the sun and was then supplanted
by higher creatures.
Many ages of progress, during which life assumed a rich variety of
forms, including the early stages of most of the hoofed animals,
brought the process of evolution to the lemurs, the monkey-like
creatures that make their home in trees (Fig. 22). The lemurs differ
from monkeys in that the milk glands of the female are on the abdomen
instead of the breast, while the index finger of each hand, and the
second toe of each foot, are furnished with claws, all the other
fingers and toes having flat nails. Here again is a link between the
lower and the higher life. Nature is stumbling and bungling, but
getting there.
[Illustration: FIG. 19.—THE DUCK-BILL, KNOWN IN AUSTRALIA AS THE
PLATYPUS.]
After the lemurs came the Slow Loris (Fig. 23). This species of the
Loris has no tail, and its front foot bears a strong resemblance
to the human hand. From these creatures, or possibly from similar
creatures, were evolved the true apes (Fig. 24), and from these came
the anthropoid or man-like apes.
There are still in existence four genera, or kinds, of these anthropoid
apes—the gibbon, the gorilla, the orang, and the chimpanzee. The gibbon
(Fig. 25) shows an alert, human-like expression, which is fully borne
out in his pose. The picture of a female gorilla (Fig. 26) suggests
with even greater force that we have here a human being in the making.
Yet this creature, be it understood, may be separated from the lowest
living human being by millions of years of development. The giant
gorilla (Fig. 27), shot by Paschen, in the Cameroons, differed from
the ordinary gorilla in the development of the skull and in size.
He was six feet, eight inches tall from the crown of his head to
his middle toe; the span of his arms was six feet, nine inches; his
chest measurement was twice as great as that of a strong man. Yes, a
dangerous gentleman to meet!
[Illustration: FIG. 20.—A KANGAROO WITH HER YOUNG ONE IN HER POUCH.
The illustration to the right shows a young Kangaroo shortly after
birth. That the creature is a quite unfinished fœtus is obvious.]
The approach to the human look on the face of the bald-headed
chimpanzee (Fig. 28) is nothing less than remarkable. The form of the
skull shows a decided advance towards the human. The countenance is, of
course, a little open, but—well, the whole head so strongly resembles
the human that he might almost be mistaken for one who believes the
story of Jonah and the whale!
That man is related to the anthropoid apes becomes evident when his
anatomical structure is compared with theirs (Fig. 29). While these
creatures differ from one another as do the different races of men, as,
for example, in the color of the skin, in the size and shape of the
skull, and in the length of the arms and legs, they are all essentially
man-like. And while all these creatures are like human beings in the
formation of their skeletons, in their anatomical structure, and in
their physiological functioning, each of them approaches more closely
to man than any of the others in the development of some part of its
body. Thus, “the orang approaches closest to man in the formation of
the brain, the chimpanzee in the shape of the spine and in certain
characteristics of the skull, the gorilla in the development of the
feet and in size, and the gibbon in the formation of the throat and
teeth.” Prof. Ernst Haeckel, in the “Riddle of the Universe,” sums up
man’s relation to the anthropoids as follows:
[Illustration: FIG. 21.—THE PARIASAURUS BAINI.
This skeleton was found in the Permian Strata of South Africa.]
“Thus comparative anatomy proves to the satisfaction of every
unprejudiced and critical student the significant fact that the body of
man and that of the anthropoid ape are not only peculiarly similar, but
they are practically one and the same in every important respect. The
same two hundred bones, in the same order and structure, make up our
inner skeleton; the same three hundred muscles effect our movements;
the same hair clothes our skin; the same groups of ganglionic cells
build up the marvellous structure of our brain; the same four-chambered
heart is the central pulsometer in our circulation; the same thirty-two
teeth are set in the same order in our jaws; the same salivary,
hepatic, and gastric glands compass our digestive process; the same
reproductive organs insure the maintenance of our race.”
Like human beings, these apes stand from three to six feet tall; like
human beings, they weigh from one hundred to three hundred pounds;
like human beings, they have only a rudimentary tail of from three to
five joints imbedded at the extremity of the spine; like human beings,
they stand on their hind legs and grasp things with their hands; like
human beings, they live in families; like human beings, they are brave,
quarrelsome, impulsive, emotional, and capable of a limited exercise of
reason.
In their native forests, apes laugh, sing, dance, and converse with one
another. Their language is a series of sounds with definite meanings.
[Illustration: FIG. 22.—THE RING-TAILED LEMUR OF MADAGASCAR.]
Yet it is not held that man has descended from any of these existing
anthropoid apes. What is held is that these creatures and human beings
represent two different lines of development from the same ancestors.
But what of the “missing link” between the early ape-like creatures
and primitive man? In 1891, Dr. Eugene Dubois, a Dutch military
physician, found near Trinil, in Java, some interesting bones and some
teeth. The International Zoological Congress, held at Leyden in 1894,
voted that these bones had belonged to a form intermediary between
ape-like creatures and men. The creature was named the Pithecanthropus
Erectus—the erect ape-man.
Fig. 30 (upper) shows a restoration of the skull of this ape-like
human being, placed, to facilitate comparison, above the skull of a
modern man. The formation of the skull of this creature represents a
decided advance over any existing anthropoid ape; but the prominent
supra-orbital ridges, the low, retreating forehead, and the massive,
prognathous jaws, which gave a brutish angle to the face, are
distinctly ape-like characteristics.
[Illustration: FIG. 23.—THE SLOW LORIS—ANOTHER TYPE OF LEMUR.
There are fifty known species of the lemur, of which thirty-six belong
to Madagascar. The others are found in Africa and South-Eastern Asia.
They were formerly much more widely distributed, and many fossil lemurs
have been found in North America.]
The most interesting feature of this primitive creature’s approach
to man was the volume of his brain. The quantity of the brain of
the highest ape measures about 600 cubic centimetre units. In some
Australian “black fellows” the brain capacity runs as low as 900 units,
while in others it reaches 1500. The brains of civilized men vary in
bulk from 1000 to 2000 units, which gives 1500 cubic centimetres as the
brain capacity of the average man. Now the skull of the Pithecanthropus
Erectus shows that his brain measured nearly a 1000 cubic centimetres.
In other words, the brain capacity of this primitive ape-man was about
equal to that of some of the exceptionally low existing savages, and
somewhat less than midway between that of the highest anthropoid ape
and the average civilized man. This man lived some 500,000 years ago.
Men of science believe that the first human beings arose in Southern
Asia, if not, indeed, in a region still more southerly than the present
Asiatic boundary—in Lemuria, the former land extension now submerged
beneath the Indian Ocean. The evidence of fossils supports this view.
And it is significant that the bones of the ape-man of Java were found
on the very edge of the Indian Ocean.
From Asia, the rude forefathers of our race migrated over the earth.
Asia was then united to Africa, and joined hands with Europe at the
Dardanelles and Sicily, and with North America at Behring Strait.
Other land connections joined Africa to Europe at Gibraltar and flung
a broad thoroughfare from the Dark Continent to Australia. Over these
land routes and others some of our naked ancestors in humanity’s early
dawn wandered from the cradle of the race in Asia and took up their
habitations in the different continents and in the islands of the seas.
[Illustration: FIG. 24.—THE BABOON.
There are numerous species of the Baboon as of the other “true apes”—a
name applied to them as animals that run on all fours. The Baboons
are now confined to Africa and Arabia, though they formerly inhabited
India. They have short tails, short, strong limbs, hands and feet
remarkably like human hands and feet, and well-developed brains.
They go in troops, following the lead of a patriarch and guarded by
a sentinel. They attack other animals and make raids on property.
“They are sometimes caught by being intoxicated with liquor purposely
exposed near their haunts, fondness for stimulants being one of their
often observed vices.”—“Chamber’s Encyclopaedia.” “The Anubis Baboons,
as shown by the frescoes, were tamed by the ancient Egyptians and
trained to pluck sycamore figs from the trees.”—“The Encyclopaedia
Britannica.”]
Since 1848, numerous fossil remains of man have been found, first,
at Gibraltar, and later in Germany, Belgium, France, England, the
Caucasus, Africa, and North and South America. These bones, which range
from fragments of skulls, jaws and teeth to entire skeletons, represent
various stages of human development from ape-like creatures to modern
man. The possessors of some of these bones were “missing links” in our
ancestry.
In 1911, a remarkable skull, which is believed to be approximately
400,000 years old, was found at Piltdown, in Sussex, England. This
skull is essentially human in its smooth forehead, the absence of
bulging ridges over the eyes, and in the development of the bones of
the brain case. The brain it held was about equal in size to that of
the savages of Australia. Yet it is remarkably flat and very thick,
like that of an anthropoid ape. The teeth are longer than in modern man
and bulging, and the prominent canines are distinctly ape-like, while
the chin retreats in heavy jaws. Uniting as he did such decidedly human
and ape-like characters, the owner of this skull, the Piltdown man, has
been described as “man in the making” and called the “dawn man.”
[Illustration: FIG. 25.—THE WHITE-HANDED GIBBON
The Gibbon, of which there are many species, is found in Assam, the
Malay Peninsula, Java, Sumatra and Borneo. The animal is remarkable
for its agility and for the weird cries with which it makes the
woods resound at night. The above illustration and the following
illustrations of anthropoid apes are reproduced from Professor Ernst
Haeckel’s great work “The Evolution of Man,” with the permission of the
publishers, Watts & Co., London.]
In the Maure sands, near Heidelberg, in 1907, there was found, in a
perfect state of preservation, a complete jaw with the teeth. The
relic belonged to a member of the Heidelberg race—a very low type of
human being. Speaking of this discovery in his “Men of the Old Stone
Age,”; Professor Henry Fairfield Osborn, after describing it as “one
of the most important in the whole history of anthropology,” says it
is “unquestionably human from the nature of the teeth,” and adds that
it “ranks not far from the point of separation between man and the
anthropoid apes.” Professor Osborn estimates the age of this human
relic at about 250,000 years.
The Heidelberg race was followed by the Neanderthal race, which
entered Europe probably from Africa. All the physical features of
Neanderthal man (Fig 31), unite in constituting him a “distinct species
of man.” Though he bore in his body the obvious marks of his simian
origin—heavy, overhanging eyebrows, a markedly retreating forehead,
large jaws and a diminutive chin—he nevertheless possessed a signal
advantage over every earlier race of creatures. He had a large head,
and in the cavern of his skull he carried the largest and best brain
that had so far appeared in Europe. In stature, the Neanderthal man was
short, broad shouldered, stocky; his arms and legs were muscular and
powerful and his hands large.
[Illustration: FIG. 26.—A FEMALE GORILLA.
The gorilla is the largest of the man-like apes. It is distinguished
from the other anthropoids by its small thumb, small ears, elongated
head, a deep groove alongside the nostrils and other features. The
gorilla is a black animal whose home is in West Equatorial Africa. The
outstanding great toe of the gorilla and the other anthropoid apes is
found, though in a less pronounced condition, among savage tribes of
Asia. See the photograph of “One of the ‘Monkey Men’” in an article on
the Malekula tribes in “Asia, The American Magazine On The Orient,” for
June, 1921. Of this savage, Mr. Martin Johnson, the Asiatic explorer,
says: “He could grasp a branch with his great flat feet as easily as I
could with my hands.”]
The Neanderthal people spread over Croatia, Austria, Hungary, Germany,
Switzerland, Belgium, France and England; and in the soil of all those
countries, buried now in some places to a depth of forty feet below the
actual surface, they left millions of imperishable memorials of their
handiwork—weapons and tools made from chipped flint and other kinds of
stone—sharp weapons for throwing and cutting, and tools for dressing
skins and shaving wood.
Contemporary with this early race in the wilds of Europe, were the
hippopotamus and rhinoceros, the cave bear and hyena, the woolly
mammoth, the giant deer, the bison, the sabre-toothed tiger and other
long since extinct creatures. These the Neanderthals hunted, eating
their flesh, splitting the larger bones for the marrow, opening the
skulls for the brains, making anvils of the large, flat bones, and in
the cold winters clothing themselves with the skins. This and more is
evidenced to-day by the numerous bones of these animals which are found
associated with the tools which Neanderthal man used at least 200,000
years ago.
Turning their attention to art, these people made drawings on bones and
stones of various animals and human beings. The human forms are always
represented in the nude, and it is noteworthy that they invariably show
signs of being covered with hair.
[Illustration: FIG. 27.—MALE GIANT GORILLA.
Killed by H. Paschen, at Yaunde, in the interior of the Cameroons, and
stuffed by Umlauff.]
The Neanderthal race had its day and disappeared from Europe. Perhaps
it was greatly reduced by the rigors of the fourth glacial period.
Perhaps its remaining numbers were decimated in wars with a superior
people; for that superior people was at hand.
Some 25,000 years ago, a new race—the Cro-Magnon people—invaded
Europe. These people were from Asia. They belonged to a stock totally
different from the Neanderthals from whom they wrested a continent.
Tall in physique, with high, straight foreheads, and large, well formed
brains, they were a hardy race of hunters and the most intelligent
and progressive race the world then knew. Their superior industry in
the working of flint everywhere superseded the Neanderthal. They had
imagination, ideals, and knew the customs of civilized life. They were
artists with a high sense of beauty and proportion. Their carvings on
bone implements, their sculptures, and the realistic paintings on the
walls of their caves represent an art whose delicate finish and superb
proportion remained unrivalled in its field until the reign of the
Greeks. They decorated their dead with strings of perforated shells,
and with them buried flint weapons and offerings of food. Writing of
these people with evident enthusiasm, Professor John M. Tyler, in “The
New Stone Age in Northern Europe,” observes: “The Cro-Magnon people
have excited the wonder and admiration of all anthropologists.”
[Illustration: FIG. 28.—THE BALDHEADED CHIMPANZEE.
The Chimpanzee is a native of West and Central Equatorial Africa.
“There are various races or varieties of Chimpanzee, and all of them
show a degree of black pigmentation. In one variety the skin becomes
totally black; in another, pigmentation of the face and of other
parts, is delayed until late in life; in others the face never becomes
absolutely black.”—“Man, a History of the Human Body,” by Dr. Arthur
Keith.]
In the Cro-Magnons evolution had at last produced a race of real
men—men with well moulded heads, with large, competent brains, with a
straight facial angle, with well formed jaws and teeth and chin, with
manly eyes looking out beneath an intellectual brow and lighting up a
face whose whole contour was rugged but thoroughly human.
Other races came upon the scene, and there was a mingling of races
and a clashing of cultures; but the Cro-Magnons, though they declined
in numbers, persisted, and became, as is believed, one of the lineal
ancestral races of modern man.
The geographical centre of the European distribution of the Cro-Magnon
people was at Dordogne, in southwestern France, and in the present
inhabitants of Dordogne, of Brittany, and of other districts in France
are found essentially the same skull formation, features and complexion
as were characteristic of this remarkable type of prehistoric man.
Of this unique racial continuity, Prof. Ripley, in his learned work
on “The Races of Europe,” says: “It is, perhaps, the most striking
instance known of a persistency of population unchanged through
thousands of years.”
[Illustration: FIG. 29.—THE SKELETON OF MAN AND OF THE FOUR ANTHROPOID
APES.
From Haeckel’s “Evolution of Man.” From left to right the order of the
skeletons is as follows: Gibbon, Orang, Chimpanzee, Gorilla, Man.]
The evolution of animal life was paralleled by the rise of an equal
diversity of forms in the vegetable world. From the Monera—organisms
so lowly that it cannot be determined whether they are plant or
animal—life diverged in opposite directions, producing, on the one
hand, the plant, on the other, the animal. Organisms that could feed
on inorganic matter assumed a stationary character and became the
ancestors of the plants. Creatures that required organic food developed
powers of locomotion to facilitate the search for sustenance, and of
these were born the varied forms of earth’s animal population. From
the first microscopic plants, vegetable life proceeded to seaweed,
to mosses, to ferns, to the pine and the yew, to the vines, the
fruit-bearing and flowering plants that crowd the forests and beautify
the gardens of the world.
The truth of this wonderful story of evolution, of the progressive
improvement of living forms with the advance of time, is proved by
several lines of evidence. One of these lines of evidence is found in
the fossil remains of the life of earlier times. Fossils are relics of
forms that lived in the long ago. Dying, they were buried in sediment
by the hand of time, and to-day they are found in rock formations,
where they have been preserved from the destructive power of the ages.
Now, if living things have developed in an increasing variety of
forms as time has gone on, and if the stratified rocks of the earth’s
crust, as they have grown from age to age, have kept a record of these
living things, these testimonies of the rocks must prove the gradual
unfoldment of the world’s life. Such precisely is the case. The earlier
rocks are poor in fossils, because in the earlier ages the world was
poor in life; but in the succeeding rocks, there is a larger deposit of
fossils; and the rocks of every progressively later age show an ever
increasing wealth of fossil remains.
[Illustration: FIG. 30.—SKULL OF THE FOSSIL APE-MAN OF JAVA.
(_Pithecanthropus Erectus._)
Restored by Dr. Eugene Dubois, and the skull of a modern European.]
The earlier rocks contain fossils of the lower forms of life, like
seaweed and simple creatures in shells; in succeeding rocks come the
fishes—the first living things with a backbone—primitive forms being
followed by more elaborate types; in later strata are found the fossil
remains of the amphibians; following these, in rocks higher up, are the
relics of the reptiles; then come the reptile-birds, and in still later
rocks appear the primitive mammals; onward and upward rises the spiral
of life, and in yet later rocks occur placental mammals—early horses,
marmosets and lemurs; higher still, the strata imprison fossil cats,
pigs, elephants, antelopes and apes; and over the fossil remains of all
other creatures, in the rock-crust of the earth, as is required by the
facts of biological unfoldment, lie the fossilized forms of man-like
apes and men. Thus geology confirms the conclusions of biology.
[Illustration: FIG. 31.—A RESTORATION OF THE NEANDERTHAL MAN.
This picture is a retouched photograph taken of a model made by
Guernsey Mitchell according to instructions of Prof. Henry A. Ward of
Chicago. Reprinted with the permission of The Open Court Publishing
Co.]
In Fig. 32 we have a series of fossil heads from different periods in
the ascending geological order, illustrating the gradual development
of the elephant’s tusks and trunk. See how the tusk, beginning as an
upper tooth in the Eocene period when the elephant was no larger than
a rabbit, gradually lengthens as the periods pass, until we get, after
millions of years, the great curved tusk of the elephant of to-day.
The growth of the trunk kept pace, of course, with the extension of
the tusks. On the left side may be seen the gradual and corresponding
modification of the elephant’s teeth.
The horse, the noblest of the quadrupeds, has been evolved from a
small five-toed animal. The Eohippus, the “dawn horse,” whose fossil
remains have been found in the lower Eocene rocks, was no bigger than
a small fox (Fig. 33). It had four toes and a splint on each front
foot, and three toes and two splints on each hind foot—which proves
that its ancestors had five toes on each foot. The “dawn horse” was a
browsing animal. Restorations of this little horse, and of the larger
three-toed horse that followed him, are now familiar figures in natural
history museums. Evolution, you see, is not a figment of somebody’s
imagination; it is, rather, the compelling, common sense interpretation
of the facts of nature.
[Illustration]
[Illustration]
[Illustration: FIG. 32.—EVOLUTION OF THE PROBOSCIDEA.
On the right, a series of skulls; on the left, last lower molar.
Reprinted with the permission of the author and publishers from
Prof. William B. Scott’s “A History of Land Mammals in the Western
Hemisphere.” The Macmillan Co., New York.]
All modern horned animals have been evolved from ancestors that were
without horns. The progenitors of the deer, the elk, the caribou,
the moose, before the Miocene period, were entirely destitute of
horns. Then the first horns appeared, each as a simple prong. As the
succeeding ages passed away, the horns gradually increased in size and
took on more prongs. The fossil antlers, found in the successive rock
formations from the Miocene period onward, show the gradual evolution
of the horns that adorn the heads of living animals (Fig. 34).
But this is only half the story. The history of an individual creature
is called ontogeny. The history of a race of creatures is called
phylogeny. Now, it is a biological law that ontogeny is always a
recapitulation of phylogeny; that is to say, that every creature in
the course of its development, especially before birth, passes through
the various stages permanently occupied by its ancestors. We see this
law beautifully illustrated in the growth of the antlers of one living
deer (Fig. 35). During the first year, or thereabout, the deer develops
one plain horn, and each year thereafter another prong is added, until
after a series of years, the antlers are full grown and full-pronged.
In other words, each and every deer, in the development of his horns,
repeats the long experience of his race in acquiring horns.
[Illustration: FIG. 33.—EOHIPPUS, THE “DAWN HORSE,” FROM THE LOWER
EOCENE ROCKS.
Restored from a skeleton in the American Museum of Natural History,
New York. Reprinted with the permission of the author and publishers
from Prof. William B. Scott’s “A History of Land Mammals in the Western
Hemisphere.” The Macmillan Co., New York.]
Now, this process of recapitulation applies to man as well as to all
other creatures. This brings us to another line of evidence which
proves the truth of evolution—embryology, or development before birth.
Dogs, cattle, sheep, elephants, horses, apes, men and all other mammals
had the same origin. Therefore, the early stages in the evolutionary
process were the same for all these creatures. That is to say, the
course of life’s development, before diverging toward these respective
forms, followed for a time a general line of advance.
The truth of this is strikingly illustrated in Fig. 36. Here we have
the embryos of four mammals in different stages of development—the
dog, the bat, the rabbit and man. These embryos prove that all these
creatures have come through the same line of development; that they
all had the same remote ancestors. The distant ancestors of all
these creatures were fishes in the sea, and here, in the embryo of
the dog, the bat, the rabbit and man, we have, still persisting, the
gill-clefts of the fish (top row). These gill-slits, which all mammals,
before birth, still inherit from the fishes through which ascending
life passed in the morning of the world, occasionally persist in
man throughout the embryonic period and appear in the child’s neck
as fissures pointing towards the throat, through which milk, when
swallowed, passes to the outside of the neck. Only on the theory that
all mammalian life, including man, has evolved through the fish stage
does the persistence of these gill-clefts become intelligible.
[Illustration: FIG. 34.—FOSSIL ANTLERS.]
The embryonic development of man and the other mammals demonstrates
their remote relationship and their gradual evolution. The dog, the
sheep, the ox, the horse, the ape and man and every other mammal begins
life as a single cell. That cell grows and divides into two; the two
enlarge and divide into four; the four divide into eight. Dividing
in this way, the cells come to form a cluster resembling a mulberry.
This is the morula stage. The cells now form a hollow sphere, one
cell in thickness, and the sphere fills with fluid—the blastula. Now
the sphere, like a punctured India rubber ball, falls in upon itself,
assuming a cup shape with double walls. This is the gastrula stage,
when the embryo resembles a worm in the figure of a horseshoe. A third
layer of cells is now formed between the other two, and from these
three layers of cells are gradually unfolded all the complex parts of
the body. From the outer cells arise the skin, the hair, the lenses of
the eyes, the nervous system, the membranes of the mouth and nose, and
the enamel of the teeth; from the inner cells arise the lining of the
larynx, the trachea and the lungs, the intestines, the liver and the
thyroid glands; from the middle layer of cells are formed the skeleton,
the inner structure of the teeth, the muscles, the blood-vessels and
the blood itself, the membranes of the heart and lungs, the kidneys and
the reproductive organs.
[Illustration: FIG. 35.—ANTLERS OF ONE DEER AT DIFFERENT STAGES OF
THEIR DEVELOPMENT.]
For a time the human embryo is a simple trunk, without skull or spine,
without arms or legs, with only a pulsating tube for a heart. Then
the rod of the amphioxus appears running down the back; then the
growing embryo resembles a fish, with gill-slits in its neck and with
a two-chambered fish heart; then comes the reptile stage when the
babe has a three-chambered heart and other features of his reptilian
ancestors; then the heart becomes four-chambered and the babe, passing
through other transformations, reaches the finished human form.
In all these details of growth, the development of man is paralleled
by the development of every other mammal. And certainly only one
conclusion may be drawn from the fact that for a time in the embryonic
life of the rabbit, the sheep, the pig, the dog, the ape and man, these
creatures are formed and look so nearly alike that even the man of
science, unaware of their identity, cannot distinguish one from the
other.
The significant structural similarity of nearly all living creatures
points unmistakably to evolution. For example, the limbs of amphibians,
reptiles, birds and mammals consists of one long bone above, then two
shorter bones below, then two transverse rows of bones forming the
ankle, with the foot ending in five toes. In the foot of the crocodile,
in the flipper of the seal, in the paddle of the whale and in the foot
of the dog may be seen the general plan of the human hand. So the wing
of the bat or bird, the forelimb of the lizard or elephant and the
little shovel-like leg and foot of the mole present the same number of
bones in essentially the same structural arrangement as do the arm and
hand of man. It is the different uses to which these organs have been
put that have determined their various developments.
[Illustration]
[Illustration]
[Illustration: FIG. 36.—EMBRYOS OF FOUR MAMMALS.
Dog, Bat, Rabbit, Man—at Three Different Stages of Development.]
Comparative anatomy traces the arms and legs of man through various
land forms back to the limbs of fishes. And the human heart and lungs,
the liver, kidneys and stomach, the eyes and ears, the nose and mouth,
have been fashioned from the organs of primitive creatures through
successive modifications during countless ages. The larynx, which makes
possible the human voice, appears in diverse stages of development in
the Amphibia.
Man’s remote ape-like progenitors had tails, and for a time in its
embryonic development, the human babe has a tail longer than his legs
(Fig. 36, middle row). Moreover, in the annals of medical science,
there are records of many otherwise well-formed children born with
tails. Professor Haeckel, in his “Evolution of Man,” shows photographs
of a six-months-old tailed boy (Fig. 37). The presence of this tail is
another rare instance of the vaulting power of heredity—a case in which
Nature recalls a phase of her distant life.
[Illustration: FIG. 37.—TAIL OF A SIX-MONTHS-OLD BOY.
Removed by Operation by Dr. Granville Harrison, in 1901. “A great
number of such cases,” says Haeckel, “are given by Max Bartells in his
essay on ‘Tailed Men,’ 1884.”]
Every human being carries the rudiment of an ancestral tail, the
coccyx, at the base of his spine. In the human embryo, the very muscles
for wagging this tail are still found. In adult man, these muscles
are represented, as a rule, by bands of fibrous tissue. Occasionally,
however, the dissecting surgeon finds these muscles well developed
in the body of a man or woman. Science says that evolution alone can
explain this lingering relic of a tail, with its attendant muscles, in
the human body.
This brings us to another line of evidence, which proves the truth
of evolution—the presence of rudimentary organs. Fig. 38 shows the
vermiform appendix in the orang, in man, and in the babe before birth.
It is much larger in the ape than in man. Man has inherited it from his
ape-like ancestors, and while it serves no purpose in his body, its
infection is the source of the frequently fatal disease, appendicitis.
Then there are the rudimentary muscles of the ear (Fig. 39). In our
remote progenitors these muscles were developed, and with them they
could move their ears. Monkeys move their ears, though not with the
facility characteristic of horses and dogs. Occasionally a man is found
who can move his ears as we move the skin of the forehead. But in the
anthropoid apes and in most men these muscles are inoperative. Through
disuse they have become rudimentary. When the ancestors of these apes
and men began to assume the erect posture, they also began to turn
their heads, instead of their ears, in the direction of sound. As the
erect posture was improved, the turning head answered with increasing
loyalty the call of the sound waves, and after innumerable ages of
comparative rest and disuse, the ear muscles dwindled into their
present impotence. Here, again, evolution alone explains the facts.
[Illustration: FIG. 38.—THE VERMIFORM APPENDIX IN THE ORANG, IN MAN,
AND IN THE HUMAN FOETUS.]
Moreover, the whole external ear is a rudimentary organ—a structure
that has outlived its function. The male breasts point to a time when
the father as well as the mother suckled the young. In some men the
breasts are as well developed as in women and supplied with milk, and
in many known instances babes have been suckled at these male breasts.
Again, in some women and occasionally in men, two or more pairs of
breasts appear—a fact which plainly shows that man has descended
through humbler forms of life. Still another rudimentary organ is the
nictitating membrane—the little fleshy pad at the inner corner of the
eye—the relic of a third eyelid that our ancestors in the dim past
flashed across the eyeball as the turtle and the eagle do to-day.
Man has evolved from creatures that went on all fours and lived in
trees, and in consequence of his upright posture and changed habits
of life, some structures which are active in the apes are rudimentary
in the human body. A shoulder muscle that is a source of strength to
the apes in climbing, lingers in man as a mere fibrous remnant that
has dwindled through disuse. Another muscle which runs through the
wrist into the palm of the hand, another which extends from the calf
of the leg to the sole of the foot, another which passes from the
shoulder to the neck and was once used to lift the collar bone—these
muscles, which are well developed in the true apes, and less developed
in the anthropoids, are rudimentary in man. These rudimentary organs
and muscles are links in the chain of man’s descent and they point
unerringly to the source of his origin.
The long heel and the poorly developed calf of the anthropoid ape
remind us that he has but recently, so to speak, acquired the upright
posture. In the negroid races also the long heel and diminutive calf
are notable characteristics; while in the white and yellow races the
heel is short and the calf well formed and muscular. Once more, the
obvious conclusion is that the black man’s long heel and slender calf
represent a more primitive development; while the leg and heel of the
white man and the Mongolian show the work of evolution farther advanced.
[Illustration: FIG. 39.—THE RUDIMENTARY MUSCLES OF THE EAR.]
Three months before birth, the human babe is covered with a luxuriant
growth of soft, brown hair, called the “lanugo,” precisely the same
as the ape baby. And throughout life the body of every human being
is covered with a rudimentary growth of hair. But this it not all.
It is as suggestive as it is interesting that in man and in the
anthropoid apes the hair on the upper arm and the hair on the lower
arm always grows towards the elbow (Fig. 40)—a phenomenon which occurs
nowhere else in the animal world except in a few American monkeys.
In a primitive Australian race, the Ainos of Japan, and the pygmies
of the Upper Nile, the extreme hairiness of the body is a notable
characteristic. And the photograph of Julia Pastrana, a Siamese (Fig.
41), shows that this lady was not only bearded like a man, but that her
entire body was plentifully clothed with hair. Some chimpanzees, on the
other hand, are remarkably hairless. One variety is, in fact, almost
entirely bald.
If any organ in the human body could distinguish man as a creature
standing apart, and argue that he has not been evolved from ape-like
ancestors, that organ should be the brain. But the brain yields
surprising evidence of man’s kinship with these creatures. Fig. 42
is introduced to show the remarkable similarity in the brains of the
anthropoid apes and men. The lower four are the brains of apes; the
upper one to the right is the brain of a Bushman, and the one at the
upper left is the brain of an European. Mark that while the brains of
the apes differ from one another, there is also a striking difference
between the brain of the savage and that of the civilized man. Observe,
too, how wonderfully these ape brains resemble the human brains, not
alone in general form, but also in the number and depth of their
convolutions. In fact, the brains of man-like apes and men consist of
the same parts—the cerebrum, the cerebellum, the corpus callosum, and
the hippocampus minor—and in both anthropoid and man the cortex of the
brain is folded in essentially the same convolutions.
[Illustration: FIG. 40.—HAIR TRACTS ON ARMS OF MAN AND APE.]
If any thoughtful person is still unconvinced of man’s rise from
ape-like ancestors, let him compare his mental image of some human
beings he has seen with Fig. 43.
Consul II, a chimpanzee from Borneo, now in England, sits at the table,
tucks his napkin under his chin, uses a knife and fork, drinks his tea
from a cup, and has excellent table manners. After dinner, he sits
back, lights his pipe, and enjoys a smoke. He washes himself with soap
and water, dresses himself, shines shoes carefully, and, like a hotel
waiter, expects a tip for his service. Another, and far more remarkable
anthropoid, is Snooky, the educated chimpanzee who frequently appears
in the “movies” in the Chester Comedies. Dressed like a man, this ape
smokes a cigar, pretends to read a paper, poses as a chauffeur, rides a
tricycle, takes care of children, performs capers with boys, and takes
various parts with men and women. So intelligent and humorous is the
acting of this chimpanzee, so clever and human-like are its numerous
performances, that it is justly advertised as the “humanzee.”
[Illustration: FIG. 41.—THE HEAD OF MISS JULIA PASTRANA.
(From a photograph by Hintze).]
In considering the relation between the anthropoid apes and men, we
must not suppose that apes or ape-like creatures underwent a sudden
transformation into human beings. The highest existing apes represent
a development that preceded the appearance of man, some authorities
think, by some two or three million years. The difference between these
creatures and man is therefore the measure of life’s upward rise by
slow steps during that inconceivable time.
Man is related to the apes not alone in the structure of his body and
brain, but also in the blood stream that courses through his veins.
This has been conclusively proved by the remarkable series of blood
tests conducted by Professor G. H. F. Nuttall at Cambridge University.
By these tests, it was shown that man and the chimpanzee are blood
relations; that the gorilla is a more distant relative, and the orang
a relative more distant still. Below the anthropoids, the blood
relationship is represented with diminishing force in the baboons and
monkeys. These blood tests confirm the conclusions of zoology and prove
the truth of evolution.
Fig. 44 is a picture of Haeckel’s genealogical tree of humanity.
It enables us to visualize in its main outline the history of the
evolution of life. At the bottom of the tree are the monera and the
amœbæ—tiny creatures consisting of a single cell. As growing life
assumes diverse forms, the foremost creatures are represented by higher
and higher positions on the trunk of the tree, or by diverging branches
in the ascending order. Life is seen to progress from the simple to the
complex, past the sponges, the molluscs and the fishes, through the
amphibians, the reptiles, the marsupials, rising higher and higher in
the scale of being, through lemurs, apes and anthropoids, until, at the
topmost summit of the tree appears man.
And what has been the secret, the driving force back of this process
of evolution? To understand the causes of evolution, it is necessary
to understand the four fundamental laws of life. First, that while
creatures resemble their parents through heredity, they nevertheless
differ more or less from their parents—this is the law of variation.
Secondly, that more creatures are born than can survive—this is the law
of surplus population. Thirdly, that among living creatures, and owing
largely to over-population, there is continually going on a struggle
for existence—this is the law of struggle. And fourthly, that out of
this struggle there results the survival of the fittest. Variation,
surplus population, struggle, spell the survival of the fittest. In the
struggle for existence, those creatures possessing the best bodies and
the keenest minds, those that could best protect themselves from their
enemies and obtain their food—in a word, those that were best adapted
to their environment—survived, while the others perished. Those whose
variations were unfavorable, the weak, the inferior, died. But those
whose variations were an advantage, the strong, the superior, survived.
In consequence of the survival of the fittest, Nature, throughout the
unfolding ages, kept breeding from the best. And this practice could
have but one result—the gradual improvement of every race of creatures.
It will be well to elucidate somewhat the principles thus summarily
stated. First, then, as to variation. The offspring is never exactly
like its parents, and no two creatures are ever quite alike. The stems,
the leaves, the blossoms of the plants of any species, the size and
contour of their fruits, vary greatly. No two blades of grass, or ears
of corn, or grains of wheat are alike. Every tree has an individuality
of form. The young of dogs, cattle, horses, sheep, of fowls and birds,
invariably differ from their parents in size and form, in coloring and
character.
[Illustration: FIG. 42.—THE BRAINS OF ANTHROPOID APES AND MEN.
G-Gibbon. H-Chimpanzee. I-Orang. K-Gorilla. L-Bushman. M-Teuton. From
Haeckel’s “Evolution of Man.”]
So, too, in a large assemblage of people, you will see noses and ears
of numerous shapes and sizes, eyes displaying a variety of coloration
and expressiveness; you will observe that some foreheads are low
and others high, some heads flat and others pointed, some round and
others square; some men have long arms and legs, some the reverse;
some have long bodies and short limbs, some the opposite; some have
one ear, or shoulder, or hip, higher than the other, or are otherwise
disproportioned. Moreover, great differences may be observed in the
features of almost any family. The black haired mother has red haired
daughters; the father’s features are bequeathed to his sons except,
perhaps, for the eyes of one or the nose of another. Variation is a
basic law of life.
Secondly, as to the multiplication of creatures beyond the power of
Nature to sustain them. Darwin, in the “Origin of Species” says:
“There is no exception to the rule that every organic being naturally
increases at so high a rate, that, if not destroyed, the earth would
soon be covered by the progeny of a single pair. Even slow-breeding
man has doubled in twenty-five years, and at this rate, in less than
a thousand years, there would literally not be standing-room for his
progeny.”
On the fertility of the elephant, Darwin remarks: “The elephant is
reckoned the slowest breeder of all known animals, and I have taken
some pains to estimate its probable minimum rate of natural increase;
it will be safest to assume that it begins breeding when thirty years
old, and goes on breeding till ninety years old, bringing forth six
young in the interval, and surviving till one hundred years old; if
this be true, after a period of from 740 to 750 years there would be
nearly nineteen million elephants alive descended from the first pair.”
An illustration from the opposite extreme of the animal world will
show that the breeding propensities of the largest existing animal are
rivalled by those of the smallest. “The aphis or plant louse,” says Dr.
D. Kerfoot Shute in “A First Book in Organic Evolution,” “is so very
prolific that it has been estimated that the tenth brood of one female
alone would contain more ponderable matter than all the population of
China,—estimating this population at five hundred millions.”
The rabbits introduced into Australia, where they found conditions
ideally favorable to their increase, have multiplied so exceedingly
that they have become a veritable pest. In a brief period, the progeny
of a few rabbits has multiplied into millions, and these creatures
have become so destructive of agriculture that rabbit-killing parties
are organized from time to time and tens of thousands of the animals
are killed with sticks and stones, in open places, the object being to
exterminate as many rabbits as possible in the interest of the farmers’
crops.
In 1850, some enterprising citizens of Brooklyn imported a hundred
English sparrows and gave them to the free city air. A little later,
New York City imported two hundred and twenty of the noisy birds and
liberated them in the parks of the metropolis. Rochester imported one
hundred of the birds, and Philadelphia, with generous public spirit,
opened the bosom of brotherly love to one thousand of the little
strangers whose perpetual chatter formed a striking contrast to the
worshipful quiet dear to the heart of the Quaker City. In the parks,
among the trees, and in the streets of these cities, the sparrows—at
home everywhere—twittered and quarreled in their friendly way, and
multiplied. In twenty-five years the children of these birds had spread
over five hundred square miles. Ten years later they had flung their
domain over fifteen thousand square miles, and men were beginning to
doubt the wisdom of those who had invited them to our shores. Since
then the ubiquitous sparrow has about completed the conquest of the
continent. Darting like an arrow amongst horses’ feet, or dodging
hurrying automobiles, his legions are familiar sights among the traffic
of busy streets. He builds his rude nest under the eaves of houses,
and in the architectural pockets around the roofs of public buildings,
and thrives and multiplies through his wary association with man. The
phenomenal increase in the number of sparrows in North America during a
period of seventy years has been due to the gregarious habit of these
birds and to the favorable character of the environment.
[Illustration: FIG. 43.—JOE AND SALLIE AT HOME.
A Chimpanzee couple of Edward’s Zoological Exhibition. From Dr. Paul
Carus’s “The Rise of Man.” Courtesy of The Open Court Publishing Co.]
Some animals tend to multiply ten fold in a generation; some would
multiply to a hundred fold, and others to ten thousand fold. Not only
could the progeny of any land animal, if given the right of way, soon
crowd the earth, but the fishes, under favorable conditions, would, in
a short time, literally fill the sea. A million eggs are spawned by the
cod-fish in order that two cod-fish may reach maturity. The eel also
spawns millions of ova that a few eels may reach the spawning age. It
is clear, therefore, that if all these eggs produced fishes, and if
these reached maturity and in their turn multiplied with such lavish
prodigality, a few generations would suffice to transform the ocean
into a solid mass.
The same phenomenon obtains in the plant world. Every plant gives its
seeds to the soil as Autumn’s spendthrift hand gives its withered
leaves to the wind, but of the millions of seeds thus scattered,
comparatively few take root and mature and reproduce their kind.
Notwithstanding Nature’s tremendous efforts to overwhelm the earth
with the creatures of every species, the checks upon over-population
are so numerous and so effective that, speaking generally, the number
of animals and plants in any given area where the conditions are
unchanging remains fairly constant. This relatively rigid limitation of
the number of creatures that shall survive in any environment is due to
the operation of Nature’s efficient machinery whose grim function is
the destruction of life.
Millions of creatures live only by devouring other creatures.
The carnivorous animals eat the flesh and drink the blood of the
herbivorous. The larger carnivores feed upon the smaller. That the
badger may make a meal, a whole nest of bees must be destroyed. The
ant-eater swallows a tongue load of ants at a single gulp. The eagle
and the hawk dine on doves and other birds. To the appetite of smaller
birds are sacrificed worms, insects and larvae. Big fishes eat the
little ones; bigger fishes eat the eaters and in turn are eaten. On
land, in the air, and in the sea the incalculable sacrifice of life
proceeds without cessation. Pursuit and flight, capture and death—a
tragedy on which the curtain never falls!
This is the struggle for existence. In this struggle which, in a sense,
is a constant test of skill, the most highly qualified creatures
are the ones best adapted to catch their prey or to escape their
enemies. Differing from their parents and from one another in numerous
variations, some animals excel others in important respects—in having
stronger legs with which to run, better eyes with which to see, a
keener sense of smell, hearing more acute, and teeth and claws better
fitted to hold and rend their prey. To the animal that would obtain
food or avoid being eaten, some or all of these characters are prime
essentials. In the struggle for existence the animals possessing these
attributes in superior form will survive while those in which they are
less developed must perish.
Harmless creatures, no less than harmful, survive through favorable
characters—some by the wit with which they elude the pursuer, some by
flight, some by protective coloration; like the hare whose summer coat
resembles the ground and whose winter garment rivals the whiteness of
the snow, and the gorgeous butterfly, whose folded wings are a perfect
simulation of the form and color of a dead leaf.
Where the herbivorous food was insufficient for the mouths that would
feed upon it, and where animals devoured one another, it was inevitable
that the weak, the stupid, the ill-favored, the incompetent, should
fail in the struggle for existence, and that the strong, the cunning,
the efficient should survive and hand their superior qualities to their
offspring. And this survival of the fittest by right of might that has
been the supreme law of the animal world since life appeared upon this
globe, was bound to result in the accumulation of favorable variations,
in the consequent production of an ever increasing wealth of species,
and in the development of ever higher forms of life.
[Illustration: FIG. 44.—THE GENEALOGICAL TREE OF HUMANITY.]
The fitness of the present forms has been moulded by the death dealing
teeth of the past.
Though not by this means alone. Another potent factor that has wrought
tremendously for evolution has been the changing environment. We may
briefly consider the character of its work. For millions of years
before the close of the Carboniferous period, some ten million years
ago, the whole earth enjoyed a perpetual summer. During the last
million years or more of that vast era, while the dense Carboniferous
forests, overwhelmed again and again by the growing soil, were forming
the coal deposits of the earth, many kinds of amphibians and low
reptiles wandered over the marshes and among the trees.
Then in the succeeding period—the Permian—the climate began to be
colder. For a hundred thousand years or thereby the cold increased. At
last the summit of an ice age was reached, and some four million square
miles of the earth’s surface lay beneath a thick mantle of ice and
snow. That ice sheet covered a continent that then extended from India
to Australia, on the one hand, and to Africa on the other. The ice age,
which was due, probably, to the gradual elevation of the land, wrought
fearful havoc among the land animals, and with a ruthless hand pushed
evolution forward. It compelled animals—and plants also—to change or
die.
In the warm climate that preceded the ice age, all animals were
cold-blooded,—warm blood was not needed—and amphibians and reptiles
left their eggs on the earth to be incubated by the genial air. But in
the awful cold that followed warm blood was required, and, as the cold
destroyed their eggs, it was necessary for animals to develop means of
wooing their young to life within their bodies. Another required change
was that the cold reptile covering be abandoned for a warm coat of hair.
Only a few animals could make these adjustments. Accordingly, as
calculations based upon the fossils prevalent before and after the ice
age have shown, “thirty-nine out of every forty of all the species
of animals and plants on the earth during the coal forest age were
destroyed.” Of the animals that survived, some were saved by migrating
to favorable regions, and some by adapting themselves to the rigors of
the environment. These developed four-chambered hearts to keep their
blood warm; they developed coats of hair or fur to retain the heat
of their bodies; they made such changes in their internal economy as
enabled the young to develop in the body of the mother.
To produce these changes, Nature preserved the favorable variations
that appeared in different animals. From age to age these variations
along advantageous lines were accumulated, and so, in time, the new
creatures were evolved. The result was obtained through natural
selection of the fittest. In this manner arose the mammals, and,
through a variant line of development, the birds; for birds, like
mammals, have four-chambered hearts, and feathers, like hair, are but a
modification of primitive scales; while the bird hatches her eggs with
the warmth of her body. So we may thank that early ice age for the gift
of all mammalian and bird life. The originals of those animals whose
development culminated in man, and of our feathered friends of the air,
were fashioned by that incomparable sculptor—environment.
With the gradual passing of the Permian ice age, through the lowering
of the land, the long backward spring slowly merged into another
universal summer that continued for several million years. In this
mild period, when Europe was, for the most part, a group of scattered
islands, when a continent extended from America to Scotland, a new
garment of multiformed vegetation appeared upon the low-lying earth;
huge sharks and reptiles dominated the sea; while on the land, weird
and prodigious monsters basked in the brilliant sun. It was the age
when the giant reptiles,—some with sail-like wings, and all with
frightful teeth—and ponderous vegetarians held the earth their own and
led in the struggle for existence.
[Illustration: FIG. 45.—TWO PIGS.]
Then came another cold period, less drastic than the former, but severe
enough to give a signal forward urge to the work of evolution. The
great reptiles disappeared forever. And now the primitive birds and
mammals whose evolution had been retarded by their numerous enemies and
by the climate in the warm reptilian age, entered upon a period of more
rapid development. The bracing cold that required movement served as a
stimulant to accelerate their evolution into various forms.
Since that remote time there have been several glacial periods—periods
when great ice caps covered vast areas of the earth—periods whose
tremendous cold was followed by ages when the climate was temperate
and benign. These major changes in the environment, and the numberless
other changes of less striking character, have been among the leading
factors in the work of evolution.
Among the lesser, though important, environmental changes, may
be mentioned the gradual submergence of land beneath the water,
occasioning animal migrations which resulted in the mixing of stocks;
the drying up of swampy regions bringing new plant life; changes in the
food supply transforming animals into vegetarians or carnivores, or
otherwise modifying their habits, and in consequence, their structure.
In these changes that have succeeded one another in the lapse of the
innumerable ages, countless species of animals and plants have been
exterminated altogether; of others, only a few hardy or otherwise
adapted specimens have survived; from these have been bred the animals
and plants of the succeeding ages, which, in turn, have had to adapt
themselves to their environment or disappear; and everywhere the
struggle, whether with the environment or with other living things, has
resulted in the survival of the fittest and the slow improvement of the
fauna and the flora of the world.
The process of selecting the fittest to breed from, as it is carried on
by Nature in her blind way, is called natural selection; and when men,
in breeding stock, select the specimens possessing the most desirable
variations to breed from, the process is named artificial selection.
The great variety of our domestic animals and plants we owe to
artificial selection. Note, for example, the two pigs shown in Fig. 45.
The grizzly one, the wild boar, is the remote ancestor of the other,
the modern, favorite domestic porker. By breeding for many generations
from pigs possessing the most desirable details of form, the legs and
snout of the animal have been shortened, his body has been made more
shapely and greatly enlarged, and his commercial value enormously
increased.
Fig. 46 partially illustrates the diversity of dogs. The dog is a
civilized wolf. And the pugs and poodles, the spaniels and setters,
the hairless dogs and hounds, the terriers and mastiffs, the faithful
collies, the noble St. Bernards, and all the other dogs of every size
and form, have been developed by selecting parents with approved
variations and breeding for desirable results along chosen lines.
In like manner, the barnyard fowls have been developed by selective
breeding. The Leghorns and Minorcas, with their beautiful combs and
wattles, the Golden Spangled and the Silver Spangled Crested Hamburgs,
with their crowning hoods, the noble Plymouth Rocks, with their barred
bodies, the magnificent Light Brahmas and Buff Cochins, arrayed with
wing-like feathery growths to their very toes, the game fowls of the
various varieties—those sleek, trim birds that would rather fight than
eat—and the little Bantams of every sort, proud and beautiful in their
bearing—all these are the children of the rude jungle fowls whose male
birds still shriek a welcome to the morning sun from the wilds of India
and the Malay Islands.
Likewise, the hundred and fifty varieties of our pigeons—the graceful
Modena, the large Runt, the tall Carrier, the Trumpeter with his
strange coo, his hooded head, his winged legs, the Frill-back with his
feathers curling towards his head, the Pouter, with his tall, slender
body, and throat inflated as though a feathered football were pinched
between his beak and breast, the compact Fantail, leaning back with
pride in his beautiful tail that rises above his head like a screen,
the Tumbler, that from a lofty height tumbles with utter abandon
through the air—all these pigeons, whatever their size, their form,
their markings, their habits, have been developed during the last few
centuries from the modest blue rock pigeons of the European coast (Fig.
47).
[Illustration: FIG. 46.—DOGS.
Reading from the top downwards: St. Bernard, Bloodhound, Greyhound,
English Setter, Irish Spaniel, Dalmatian, Pug, Skye Terrier.]
Such is the story that rounds the vast circumference of life. All life
is one, and by the same means its varied ends have been attained. By
breeding from those creatures whose qualifications enabled them to
survive in their environment, Nature, without knowing why, selected the
fittest to become the parents of the creatures that were to follow.
Thus, of necessity, the life of the world, ever branching into an
increasing diversity of species, gradually improved in form, function
and intelligence. And with millions of ages in which to try every
experiment, to test every detail, to destroy her failures and seek
success along other lines, Nature was bound to reach our day with an
array of living creatures of finer development than those that perished
in the struggles of the vanished years.
The laws in accordance with which the humbler creatures have been
developed from still lower forms have presided over the evolution of
man from the beast; and, never pausing in their action, these forces
have slowly fashioned the glories of civilization from the dark crudity
of savage thought. The story of man but continues in another form the
story of life before man appeared.
[Illustration: FIG. 47.—PIGEONS.
Modena 10, Runt 19, Carrier 1, Trumpeter 4, Frill-back 37, Pouter 2,
Fantail 6, Tumbler 15. Rock Doves in Centre.]
The plant creations of Luther Burbank are renowned throughout the
world. The Burbank potato, the Burbank rose, the new walnut trees, the
varieties of plums and prunes, the pineapple quince, the spineless
cactus, the everlasting flower, the beautiful lilies—the many new
species of vegetables, plants, fruits and flowers which Burbank
has created by crossing inferior forms and breeding from the best
resulting specimens—these experimental triumphs in the plant world are
indubitable proofs of the truth of evolution. Mr. Burbank has shown
that plant life is not fixed in form, but plastic and ever-changing,
and that by breeding and selecting in accordance with Nature’s laws,
man can cover the earth with new vegetables, fruits and flowers and
vines and trees and grasses, more luxuriant and more wonderful than any
found in an uncultivated condition.
Life, like clay, is malleable. Slowly, under the urge of Nature,
rapidly in the hands of man, it shapes itself into new moulds. A
problem in mathematics is known to be solved when it can be proved.
In like manner, evolution is known to be certainly true, since, by
following its laws, man now brings into the world new species of
animals and plants that did not exist before.
A wonderful panorama is the story of evolution. From nebula to crusted
earth, to life’s first spark in the primal sea, to the myriad forms
that fought with teeth and claws in forest wilds, to the fierce-browed
creature that earth first knew as human, to the warmth of love and the
glow of thought in the heart and brain of finished man, the forces of
Nature have shaped existence and crowned it with the power of the human
brain. Man the builder, so long the victim of ignorance and fear, may
now shape his destinies in a world fashioned to his choice. The desert
has been made to blossom like the rose; cities of solid masonry have
arisen from the noisome swamp; industries supplying a thousand human
wants now occupy the sites where wild beasts once filled the jungle
with their savage roars; the ocean, earth and air have yielded to the
conquering power of thought; invention, art, discovery, have tapped
exhaustless stores of wealth and culture; literature, the press,
schools, disseminate intelligence; and, rising above earth, man now
solves the secrets of the stars and calculates with precision their
changing movements. Man, Nature’s gifted son, is Nature’s conqueror!
Let him then learn the means by which to further improve his life. Let
him equip his mind with truth. Let him solve his problems in the light
of knowledge and enjoy a rational existence in a well ordered world.
*** End of this LibraryBlog Digital Book "The illustrated story of evolution" ***
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