In these four senses the word evolution is used with some degree of
accuracy. But in the current literature of the day the word has many
other meanings, some of them very far from any just basis. Some things
which evolution is not we may here notice briefly.
Evolution is not a theory that "man is a developed monkey." The question
of the immediate origin of man is not the central or overshadowing
question of evolution. This question offers no special difficulties in
theory, although the materials for exact knowledge are in many
directions incomplete. Homologies more perfect than those connecting man
with the great group of monkeys could not exist. These imply the
blood-relationship of the human race with the great host of apes and
monkeys. As to this there can be no shadow of a doubt. And as similar
homologies connect man with all members of the group of mammals, similar
blood-relationship must exist. And homologies, less close but equally
unmistakable, connect all backboned animals one with another; and the
lowest backboned types are closely joined to worm-like forms not usually
classed as vertebrates.
It is perfectly true that, with the higher or anthropoid apes, the
relations with man are extremely intimate. But man is not simply "a
developed ape." Apes and men have diverged from the same primitive
stock, apelike, manlike, but not exactly the one or the other. No apes
or monkeys now extant could apparently have been ancestors of primitive
man. None can ever "develop" into man. As man changes and diverges, race
from race, so do they. The influence of effort, the influence of
surroundings, the influence of the sifting process of natural selection,
acts upon them as it acts upon man.
The process of evolution is not progress, but better adaptation to
conditions of life. As man becomes fitted for social and civic life, so
does the ape become fitted for life in the tree-tops. The movement of
monkeys is towards "simianity," not humanity. The movement of cat-life
is towards felinity, that of the dog-races towards caninity. Each step
in evolution upward or downward, whatever it may be, carries each
species or type farther from the primitive stock. These steps are never
retraced. For an ape to become a man he must go back to the simple
characters of the simple common type from which both have sprung. These
characters are shown in the ape-baby and in the human embryo in its
corresponding stages. For ancestral traits lost in the adult are
preserved in the young. This comes through the operation of the great
force of race-memory, we call heredity.
Evidence of biology points to the descent of all mammals, of all
vertebrates, of all animals, of all organic beings, from a common stock.
Of all the races of animals, the anthropoid apes are nearest man. Their
divergence from the same stock must be comparatively recent. Man is the
nomadic, the apes the arboreal, branch of the same great family.
Evolution does not teach that all or any living forms are tending
towards humanity. It does not teach, as in Bishop Wilberforce's
burlesque, "that every favorable variety of the turnip is tending to
become man." It is not true that evolutionists expect to find, as Dr.
Seelye has affirmed, "the growth of the highest alga into a zooephyte, a
phenomenon for which sharp eyes have sought, and which is not only
natural but inevitable on the Darwinian hypothesis, and whose discovery
would make the fame of any observer."
It is no wonder that a clear thinker should have rejected "the Darwinian
hypothesis," when stated in such terms as this. The line of junction in
evolution is always at the bottom. It is the lowest mammals which
approach the lowest reptiles. It is the lower types of plants which
approach the lower types of animals. It would be the lowest alga, to use
Dr. Seelye's illustration, which would be transmutable into the lowest
zooephyte. It is the unspecialized, undifferentiated type from which
branches diverge in different ways. Humanity is not the "goal of
evolution," not even that of human evolution. There will be no second
"creation of man," except from man's own loins. There will not be a
second Anglo-Saxon race, unless it has the old Anglo-Saxon blood in its
veins.
Adaptation by divergence--for the most part by slow stages--is the
movement of evolution. While occasional leaps or sudden changes occur in
the process, they are by no means the rule. In most cases of "saltatory
evolution," the suddenness is in appearance only. It comes from our
inability to trace the intermediate stages. When an epoch-making
character is acquired, as the wings of a bird or the brain of man, the
process of readjustment of other characters goes on with greatly
increased rapidity. But this rapidity of evolution is along the same
lines as the slower processes. Radical changes from generation to
generation never occur. We do not expect to find birds arising from a
"flying-fish in the air, whose scales are disporting into feathers." A
flying-fish is no more of the nature of a bird than any other fish is. A
cow will never give birth to a horse, nor a horse to a cow. The slow
operation of existing causes is the central fact of organic evolution,
as it is of the evolution of mountains and valleys. Seasons change as
the relations which produce them change. But midsummer never gives way
to midwinter in an instant. Nor does the child in an instant become a
man, though in some periods of growth epoch-marking causes may make
development more rapid. Life is conservative. The law of heredity is the
expression of its conservatism. It changes slowly, but it must
constantly change, and all change is by necessity divergence.
There is in nature no single "law of progress," nor is progress in any
group a necessity regardless of conditions. That which we call progress
rests simply on the survival of the better adapted, their survival being
accompanied by their reproduction. Those that live repeat themselves.
The "innate tendency towards progression" of the early evolutionists is
a philosophic myth. Progress and degeneration are alike the resultants
of the various forces at work from generation to generation on and
within a race or species. The same forces which bring progress to a
group under one set of conditions will bring degradation under another.
In their essence the factors of evolution are no more laws of progress
than the attraction of gravitation is. Cosmic order comes from
gravitation. Organic order comes from the factors of evolution.
Evolution is simply orderly change.
_Evolution is not Spontaneous Generation._ There is no necessary
connection between the one theory and the other. Spontaneous generation,
or birth without parentage, on the part of small or useless creatures
was accepted in early times without question. As men began to observe
these animals more carefully, the fact of their spontaneous generation
was doubted. A great step was made when it was found that to screen meat
from flies would protect it from maggots. A greater step came in our own
time when it was proved that to screen infusions from air dust is to
protect them from putrefaction or fermentation. Fermentation is "life
without air." It is the decomposition of sugar by minute creatures who
disintegrate it in their life processes. Putrefaction and decay are also
the same in nature. There is literal truth in Carlyle's statement that
there is still force in a fallen leaf, "else how could it rot?" It is
the force of the minute organisms hidden in the leaf, and whose life is
the leaf's decay. The decay and death of men from contagious diseases is
known to be due to life processes of minute organisms, as is the
gangrene which follows unskilful surgery. The study of the "fauna and
flora" within living organisms has now become a science of itself,
demanding the greatest care in observation and the most complete of
appliances. "_Omne vivum ex vivo_," "all life from life," was an
aphorism of the naturalists of a century or two ago. It was to them a
new and broad generalization. It has not yet been set aside. The classic
experiments of Tyndall show that this law applies to all creatures we
have yet recognized or classified. As far as science can tell,
spontaneous generation is still a myth, having no basis in observation,
no warrant in experiment. It remains as a pure deduction from the
philosophical conception of Monism, incapable of proof, insusceptible of
refutation. The argument for it is chiefly this: Life exists on a globe
once lifeless. How did life begin? If not through spontaneous
generation, how did it come? Must it not have been by the operation of
those laws and forces which through all time change lifeless into living
matter? Very likely, but we do not know. We know nothing whatever of
such laws and forces, and we gain nothing by veiling our ignorance under
a philosophical necessity.
Moreover, if spontaneous generation occurs as a resultant of any
forces, like forces would produce it again. We have never known it to
occur. Should it occur the organisms thus produced would have no bonds
of blood-relationship with those already in existence. With these they
should show no homology, as they could have no inheritance in common.
But all known organisms have common homologies. The factors of organic
evolution are essentially the same for all. The unity of life amid all
its diversity seems to point to origin from a common stock. If not from
one stock, the lines of division between one and another are hidden from
us. The study of embryology breaks down the time-honored branch lines of
vertebrates, articulates, mollusks, and radiates. The groups of animals
are more numerous, more complex, and more intertangled than Cuvier and
Agassiz thought. The number of primary branches of animals or plants is
uncertain, their boundaries undefined.
If spontaneous generation exists, it is a factor in evolution. If it is
a factor, our explanation of the meaning and nature of homology must be
fundamentally changed. But it may be that it should be changed. We
cannot show that spontaneous generation does not exist. All we know is
that we have no means of recognizing it. If there is now spontaneous
generation of protoplasm, it cannot take the form of any creature we
know. An organism fresh from the mint of creation would be too small for
us to see with any microscope. It would be too simple for us to trace by
any instrumentality now in our possession. It could contain but a few
molecules, and a molecule in a drop of water is as small as an orange
beside the sun. Our race of creatures, spontaneously generated, without
concessions to environment, would grow hoary with the centuries before
it came to our notice. Its descendants would have belonged for ages to
the unnumbered hosts of microbes before we should be aware of its
creation.
Evolution is not a creed or a body of doctrine to be believed on
authority. There is no saving grace in being an evolutionist. There are
many who take this name and have no interest in finding out what it
means or in making any application of its principles to the affairs of
life. For one who cares not to master its ideas, there is no power in
the word. Evolution is not a panacea or a medicine to be applied to
social or personal ills. It is simply an expression of the teaching of
enlightened common sense as to the order of changes in life. If its
principles are mastered a knowledge of evolution is an aid in the
conduct of life, as knowledge of gravitation is essential in the
building of machinery.
There is nothing "occult" in the science of evolution. It is not the
product of philosophic meditation or of speculative philosophy. It is
based on hard facts, and with hard facts it must deal.
It seems to me that it is not true that "Evolution is a new religion,
the religion of the future." There are many definitions to religion, but
evolution does not fit any of them. It is no more a religion than
gravitation is. One may imagine that some enthusiastic follower of
Newton may, for the first time, have seen the majestic order of the
solar system, may have felt how futile was the old notion of guiding
angels, one for each planet to hold it up in space. He may have received
his first clear vision of the simple relations of the planets, each
forever falling toward the sun and toward each other, each one by the
same force forever preserved from collision. Such a man might have
exclaimed, "Great is gravitation; it is the new religion, the religion
of the future!" In such manner, men trained in dead traditions, once
brought to a clear insight of the noble simplicity and adequacy of the
theory of evolution, may have exclaimed, "Great is evolution; it is the
new religion, the religion of the future!"
But evolution is religion in the same sense that every truth of the
physical universe must be religion. That which is true is the truest
thing in the world, and the recognition of the infinite soundness at the
heart of the universe is an inseparable part of any worthy religion.
But, whether religion or not, the truths of evolution must be their own
witness. They can be neither strengthened nor controverted by any
authority which may speak in the name of philosophy or of theology or of
religion. "_Roma locuta est; causa finita est_" is not a dictum which
science can regard. Her causes are never finished. No power on earth can
give beforehand the answer to her questions. Her only court of appeal is
the experience of man.