EVOLUTION AND THE GREAT NATURALISTS.
One of the outstanding figures of zoology, and for that matter, of
all natural science is Carl von Linne, more commonly known as Carolus
Linnaeus[8]. For many years naturalists had been struggling to
establish a satisfactory system of naming and arranging the various
forms of animals, plants and fossils, but without very definite
or satisfactory results. Linnaeus devised a very simple method of
naming organisms--one that is followed almost without modification
even today. He chose Latin and ancient Greek as the languages in
which the names should be cast, primarily because both of them were
more or less familiar to all students of his day, and neither was an
important language of modern times. The name itself was in two parts,
one denoting the particular species, the other the group to which
that species belonged. Thus the common chipping sparrow is _Spizella
socialis_, just as a man is William Jones, or James Thompson. The
only difference is that in Linnaeus’ system of naming, the family
name comes first; if the same plan were used in human names William
Jones would become Jones William. This may sound awkward, but as a
matter of fact it is extremely convenient, just as in a directory or
telephone book it is convenient to have the family name given first.
In the early editions of Linnaeus’ great work, the “Systema Naturae”
(System of Nature), published from 1735 to 1751, the great naturalist
stated specifically that he believed in the absolute fixity of
species from the time of their creation, according to the literal
interpretation of Genesis. But Linnaeus was too close a student
to hold this idea for long, and in his edition of 1762 we find
him expressing the opinion that many new species arose from the
interbreeding of those originally created. However, he maintained
that only species originated in this manner, and attributed the more
general resemblances of animals and plants to similarities of form
implanted by the Creator. Plainly, therefore, Linnaeus was at heart
a believer in special creation in a very slightly restricted sense,
and was by no means as progressive in this respect as the old Greek
philosopher Aristotle.
Foremost among the contemporaries of Linnaeus was George Buffon,
(1707-1788), the Frenchman whom Osborn has called the “naturalist
founder of the modern applied form of the evolutionary theory.”
During his early work Buffon held essentially the same views as his
contemporary, Linnaeus, stating that the species of animals were
separated by a gap which could not be bridged, and that everywhere
were evidences of “the Creator, dictating his simple but beautiful
laws and impressing upon each species its immutable characters.”
As early as 1755, however, Buffon found that his studies in
comparative anatomy placed many difficulties in the way of these
“simple but beautiful laws” and “immutable characters.” He calls
attention to the fact that the pig is plainly the “compound of
other animals,” possessing many parts for which it has no use, and
concludes that “Nature is far from subjecting herself to final causes
in the formation of her creatures,” and that by continually searching
for such causes men “deprive philosophy of its true character, and
misrepresent its object, which consists in the knowledge of the
‘how’ of things.” In 1761 he acknowledged a belief in the frequent
modification of species, but believed that some animals were much
more subject to variation than others. He understood the struggle
for existence, with its consequent elimination of the species least
capable of living under unfavorable circumstances, and stated it very
clearly.
One of the most interesting portions of Buffon’s evolutionary
philosophy was his belief that external conditions could directly
modify the structure of animals and plants, and that these
modifications were hereditary. This was, in essence, the theory of
transmission of acquired characters--a theory which was to be greatly
elaborated by one of Buffon’s successors, and which was to cause
trouble among evolutionists for many decades. Buffon applied it
particularly to the animals of the western hemisphere, showing how
they were changed by climate, food, etc., so that eventually animals
coming from the eastern hemisphere to the western[9] would become
new species. In this connection he emphasizes the fact, also pointed
out by Kant, that man must study the changes taking place in his own
period in order to understand those which have been accomplished in
the past, and might be accomplished in the future.
Even at the time when he believed most thoroughly in evolution and
variation, Buffon was troubled by the Bible account of creation,
and wavered between the two. Some time after 1766 he abandoned his
advanced stand on evolution, and concluded that species were neither
static nor changeable, but instead that “specific types could assume
a great variety of forms[10],” and that no definite assertions might
be made regarding the origin of any particular animal or plant.
One cannot but wonder what was the cause for Buffon’s confusion
and changes of attitude. From special creationist to radical
evolutionist, and then to conservative occupying a position halfway
between was a remarkable mental evolution to be covered in the space
of less than sixty years. What was the cause of it?
The answer to this question is not a difficult one. Buffon was a
pioneer, and not an overly courageous one. He was staggered by the
immensity of the problem which he was trying to solve, and at the
same time, fettered by the orthodox ideas of his day. And back of
those ideas, as Buffon well knew, there was power--power of the
church, of society, and of the scientific world. And neither the
church, society, nor science was ready to accept the doctrine of
descent, of organic evolution. Linnaeus, as we have seen, was easily
the greatest and most influential zoologist of his day, and was at
the same time a strong anti-evolutionist. His influence was so great
that Buffon could hardly have escaped it, and this probably added to
the difficulties of the vacillating evolutionist.
And so, when we considered the difficulties under which Buffon
worked, we are not surprised that he found it hard to discover what
his ideas on evolution should finally be. He was evidently no hero,
willing to become a martyr for science, nor yet a dogmatist, willing
to lay his own ideas down as law. Instead of ridiculing him for
his indecision, therefore, we should sympathize with him because
of his difficulties. Probably few of us would say or write very
revolutionary things if we were loaded down with half-shed orthodoxy,
and threatened by social and scientific ostracism in case we made a
departure from the well beaten path.
The next important figure in evolution is Erasmus Darwin, grandfather
of the great Charles Darwin. He was a country physician, a poet, and
a very accurate naturalist, but unfortunately buried his ideas in
volumes of verse and of combined medicine and philosophy. He believed
in the spontaneous origin of the lower animals, but maintained that
all of the higher forms were products of natural reproduction. The
transition from water-to-land-dwelling animals he illustrated, not by
fanciful creations, but by the classic example of the development of
the frog, which begins life as a legless tadpole, and ends it as an
animal incapable of breathing under water.
To man Dr. Darwin gave much attention, devoting a whole canto to
the human hand--“The hand, first gift of Heaven!”--and outlining
the development of man’s various faculties. Farther on he describes
the struggle for existence in lines which remind one of Tennyson’s
description of nature, except that they lack Tennyson’s inevitable
syrupiness. Evidently, however, Darwin fails to connect this struggle
with its obvious result, the survival of the fittest.
Dr. Darwin’s theory of evolution differed from that of Buffon
in at least one important respect. Nowhere does he stress the
direct influence of environment in the production of variations;
on the contrary, he maintained that modifications spring from the
reactions of the organism. In this he clearly stated the theory
which is generally known as Lamarck’s version of the theory of the
transmission of acquired characters. In fact, he carried his ideas
much farther than did Lamarck, attributing to plants the attribute
of sendibility, and supposed their evolution to be due to their own
efforts toward the development of certain characters. Adaptations,
which Aristotle had believed to be caused by a definite plan, Dr.
Darwin interpreted in a purely naturalistic manner. The Creator
had, at the beginning, endowed organisms with the power to change
and develop, and that power was handed down from one generation
to another until it was possessed by every animal and plant. This
power was the cause of all variation, adaptation, and evolution, and
there was no further divine interference. Dr. Darwin did not see any
great, all-encompassing plan of improvement, such as is postulated
by the teleologists of today; to him everything was the logical and
necessary outcome of the original powers of living things. In this,
as we shall see, he believed essentially as do modern evolutionists
who do not see in the laws of the universe any necessity for
abandoning religion, but who at the same time do not believe in a
highly personal god who, as one theologian expressed it recently,
“works out His divine will through the processes of evolution.”
Dr. Darwin was author of two other distinctly modern ideas, among the
most important of his entire work. The first of these is that all
living things are descended from a single original living mass, or
“filament”--that every living thing on the earth is related to every
other living thing. The second is that the process of evolution is
almost inconceivably slow, and that millions upon millions of years
have been necessary for it. The first idea, while quite conceivably
true, can never be proved definitely, but the second has been
demonstrated over and over again. Just how many millions we shall
allow is, of course, undetermined; some authorities demand sixty;
others say that eight hundred is a figure none too large. In this
series of books the larger figure is adopted, not because we are
certain that it is right, but because it seems to fit more closely
with the facts of evolution than do the smaller ones. How fully Dr.
Darwin was a prophet of modern scientific chronology we are just
beginning to recognize.
The leadership in evolution, which for a time had gone to England,
was soon given back to France. The new champion of the theory
was Jean Baptiste Lamarck (1744-1829), one of the most pathetic
figures in the entire history of zoology. He was a brilliant man,
and a skilled zoologist, but because he was courageous, blind,
and desperately poor, he suffered little less than martyrdom
throughout much of his life, and was given but scant attention by his
contemporaries. Baron Cuvier, rich, talented, and a member of the
elite of the nation, dominated French zoology. He was a desperate
reactionary, holding out for a literal acceptance of the Bible
account of special creation, and ridiculed not only the theories of
Lamarck, but the whole conception of evolution. For years he blocked
the progress along all lines but his own restricted field of anatomy,
and waged bitter warfare on anyone who dared to oppose him. And so
the blind Lamarck lived in poverty and obscurity, neglected by both
scientists and those who knew nothing of zoology. And through this he
stood faithfully by the ideas which he believed but was too poor and
unknown to defend.
Lamarck first held to the old teaching that species were fixed, and
could neither change nor be changed. But as he learned more his views
changed, and in 1809 he published a book stating his interpretation
of evolution. One of his principal ideas was that the effects of the
use or disuse of any part of the body may be passed on from parent
to children until they finally become parts of the animal’s make-up.
It is well known that an arm that is never used becomes weak; that a
muscle which is constantly at work becomes strong and large. Lamarck
supposed that this increase or decrease in size could be inherited,
and thus races with short, thin arms, or heavy powerful muscles
could be developed. This is the “theory of inheritance of acquired
characteristics” again, first formulated by Erasmus Darwin. Just
how much there is to this theory no one has been able to say; some
believe it to be worthless while others, particularly those who study
fossil animals, think that it possesses a certain amount of truth.
Lamarck was, as we have said, a conscientious scientist, and made use
of his own accurate observations insofar as this was possible. But
when he became blind, dictating his books to his daughter in order
to get them written, observation was clearly out of the question. In
its stead the great naturalist was forced to rely upon the reports
of other observers, and those reports were none too reliable. The
obvious weakness of some of his second-hand facts reacted very
unfavorably upon the whole work of Lamarck, and gave his opponents
abundant weapons for their attacks upon his opinions.
But in spite of these handicaps, Lamarck did a very important work.
He not only stated his own position very clearly, marshalling such
facts as were at his disposal to its support; he devised a branching
system of animal descent which approximated the modern “evolutionary
tree” and represented far more truly than did the Aristotelian chain
the true state of things. He argued strongly and clearly against
the fallacious doctrine of special creations and numerous geologic
catastrophes which, supposedly, annihilated all of the life on earth
at the particular times of their occurrence and made a long series of
new creations necessary.
Perhaps the greatest of all Lamarck’s achievements was his clear
statements of the problems of evolution. As one writer has said,
he asked every one of the big, important questions which later
evolutionists have had to answer, and by the clear phrasing of his
questions, made the answers thereto the more easy.
* * * * *
In all France there was only one man who was willing to champion
this blind naturalist in his stand for evolution. Geoffrey
St.-Hilaire was at first a follower of Buffon, but he later became
convinced of the value of Lamarck’s work, and even went so far in
his belief as to champion Lamarck in a public debate with the great
Cuvier. Despite the fact that the debate brought a certain fame to
St.-Hilaire, he was judged the loser, and the affair was hailed as
a great and conclusive victory for those who upheld the theory of
special creation.
Although St.-Hilaire believed in the truth of organic evolution, he
did not wholly agree with Lamarck. He supposed that environment--that
is, surrounding conditions--determined the changes that took place
in animals, and preceded some of the most modern of evolutionists by
teaching that one species might arise suddenly from an earlier one,
without any intermediate forms. As a result of these sudden changes,
it was, said St.-Hilaire, often unnecessary to produce the “missing
links” over which adverse critics made such a to-do. It was also
unnecessary to show why variations would not be wiped out before they
were firmly established. According to his hypothesis, each new form
was complete, and no amount of normal interbreeding with other forms
would produce fertile hybrids between the two.
We now come to one of the most interesting, and most remarkable of
evolutionists. Johann Wolfgang Goethe (1749-1832) was an anatomist,
a philosopher, and a great poet, and thus brought to the problem of
organic evolution a breadth of vision equalled by but few of the
workers who preceded him. As Osborn states:
“The brilliant early achievements of Goethe in science afford another
illustration of the union of imagination and powers of observation
as the essential characteristics of the naturalist. When he took his
journey into Italy, and the poetic instinct began to predominate over
the scientific, science lost a disciple who would have ranked among
the very highest, if not the highest. Of this time Goethe says: ‘I
have abandoned my master Loder for my friend Schiller, and Linnaeus
for Shakespeare.’ Yet Goethe, in the midst of poetry, never lost his
passion for scientific studies. He seems to have felt instinctively
that what contemporary science needed was not only observation, but
generalization.”[11]
Goethe derived much of his inspiration from Buffon and the German
natural philosophers. Unfortunately he never discovered the works of
Lamarck, although he anticipated that scientist in some of his work
with plants. There can be little doubt that, had Goethe discovered
the “Philosophie Zoologique,” he would have accepted its principal
doctrine, and would have proclaimed them with a vigor that would
have overcome even the antagonism of Cuvier. As it was, he confined
his theory to the idea of the “unity of type,” making it the chief
basis for his conception of evolution. In his own words, this theory
enabled him to “assert, without hesitation, that all the more perfect
organic natures, such as fishes, amphibious animals, birds, mammals,
and man at the head of the list, were all formed upon one original
type, which varies only more or less in parts which are none the less
permanent, and which still daily changes and modifies its form by
propagation.”
Akin to Goethe, in some respects, was Gottfried Treviranus
(1776-1837), a German naturalist who was a contemporary of
St.-Hilaire, Goethe, and Lamarck. Like the German natural
philosophers, he considered life as the result of chemical and
mechanical processes, and protested whole-heartedly against purely
speculative work, calling it “dreams and visions.” At the same time,
he complained that most of botany and zoology was made up of dry
registers of names and that the work of many naturalists consisted
of the “spirit killing ... reading and writing of compilations.”
Treviranus believed that it was quite within the abilities of man
to discover the basic philosophy of nature, largely by the use of
working hypotheses as a means of aiding the investigator in attaining
the actual facts.
In view of Treviranus’ modern stand on the study of animal life,
and the interpretation of ascertained facts, we might well expect
him to show an equal modernity in his conception of evolution. But
in this we are to be disappointed. As soon as he departed from his
principles of biology, and attempted to apply those principles to
the development of animal life, Treviranus became victim to those
same “dreams and visions” against which he protested so strongly.
He depended very largely upon the work of Buffon, and believed that
modification of form was due entirely to environment. He revived
the ancient doctrine of spontaneous generation of living things, or
abiogenesis, stating his belief very clearly.
All of this shows that Treviranus, although an ardent believer
in evolution, added very little to the idea. In his ideas of the
factors of evolution he did not advance beyond Buffon; in his ideas
of descent he was less clear and accurate than his contemporary,
Lamarck. But in his more general work, particularly in defining
and organizing the science of biology, he rendered great service
to future zoologists and evolutionists. And such service, slight
though it was, was of value. During the early part of the nineteenth
century the doctrine of evolution needed all the support that could
be given it, and even a mistaken scientist was a valuable defender of
a struggling cause.
Thus for more than two thousand years the theory of organic evolution
had been growing. Philosophers, country doctors, poets, and
naturalists had contributed their share to its volume, its character,
and its support. But as yet it was little more than an idea in the
rough, waiting for some one to refine it, to put it into clear and
unmistakable language, and to back it up by evidence secured directly
from studies made on living animals and plants. It might have been
compared to a piece of ---- waiting for someone to forge it into a
key--a key that would open the doors of conventional thought and
old-fashioned restriction, and thereby give an insight into life and
life’s history that would revolutionize human thought, and help in a
better understanding between man and man, and man and beast.