SCIENTIFIC JUSTIFICATION OF THE THEORY OF DESCENT.
HISTORY OF CREATION ACCORDING TO LINNÆUS.
The Theory of Descent, or Doctrine of Filiation, as the
Monistic Explanation of Organic Natural Phenomena.—Its
Comparison with Newton’s Theory of Gravitation.—Limits
of Scientific Explanation and of Human Knowledge in
general.—All Knowledge founded originally on Sensuous
Experience, _a posteriori_.—Transition of _a posteriori_
knowledge, by Inheritance, into _a priori_
knowledge.—Contrast between the Supernatural Hypotheses
of the Creation according to Linnæus, Cuvier, Agassiz,
and the Natural Theories of Development according to
Lamarck, Goethe, and Darwin.—Connection of the former
with the Monistic (mechanical), of the latter with the
Dualistic Conception of the Universe.—Monism and
Materialism.—Scientific and Moral Materialism.—The
History of Creation according to Moses.—Linnæus as the
Founder of the Systematic Description of Nature and
Distinction of Species.—Linnæus’ Classification and
Binary Nomenclature.—Meaning of Linnæus’ Idea of
Species.—His History of Creation.—Linnæus’ view of the
Origin of Species.
The value which every scientific theory possesses is measured by the
number and importance of the objects which can be explained by it, as
well as by the simplicity and universality of the causes which are
employed in it as grounds of explanation. On the one hand, the greater
the number and the more important the meaning of the phenomena explained
by the theory, and the simpler, on the other hand, and the more general
the causes which the theory assigns as explanations, the greater is its
scientific value, the more safely we are guided by it, and the more
strongly are we bound to adopt it.
Let us call to mind, for example, that theory which has ranked up to the
present time as the greatest achievement of the human mind—the Theory
of Gravitation, which Newton, two hundred years ago, established in his
Mathematical Principles of Natural Philosophy. Here we find that the
object to be explained is as large as one can well imagine. He undertook
to reduce the phenomena of the motion of the planets, and the structure
of the universe, to mathematical laws. As the most simple cause of these
intricate phenomena of motion, Newton established the law of weight or
attraction, the same law which is the cause of the fall of bodies, of
adhesion, cohesion, and many other phenomena.
If we apply the same standard of valuation to Darwin’s theory, we must
arrive at the conclusion that this theory, also, is one of the greatest
achievements of the human mind, and that it may be placed quite on a
level with Newton’s Theory of Gravitation. Perhaps this opinion will
seem a little exaggerated, or at any rate very bold, but I hope in the
course of this treatise to convince the reader that this estimate is not
too high. In the preceding chapter, some of the most important and most
general phenomena in organic nature, which have been explained by
Darwin’s theory, have been named. Among them are the variations in form
which accompany the individual development of organisms, most varied and
complicated phenomena, which until now presented the greatest
difficulties in the way of mechanical explanation, that is, in the
tracing of them to active causes. We have mentioned the _rudimentary
organs_, those exceedingly remarkable structures in animals and plants
which have no object and refute every teleological explanation seeking
for the final purpose of the organism. A great number of other phenomena
might have been mentioned, which are no less important, and are
explained in the simplest manner by Darwin’s reformed Theory of Descent.
For the present I will only mention the phenomena presented to us by the
_geographical distribution of animals and plants_ on the surface of our
planet, as well as the _geological distribution of the extinct and
petrified organisms_ in the different strata of the earth’s crust. These
important palæontological and geographical phenomena, which were
formerly only known to us as _facts_, are now traced to their active
_causes_ by the Theory of Descent.
The same statement applies further to all the general laws of
_Comparative Anatomy_, especially to the great law of _division of
labour_ or _separation_ (polymorphism, or differentiation), a law which
determines the form or structure of human society, as well as the
organization of individual animals and plants. It is this law which
necessitates an ever _increasing variety_, as well as a _progressive
development_ of organic forms. This law of the division of labour has,
up to the present time, been only recognized as a fact, and it, like the
law of progressive development, or the law of progress which we perceive
active everywhere in the history of nations (as also in that of animals
and plants), is explained by Darwin’s Doctrine of Descent. Then, if we
turn our attention to the great whole of organic nature, if we compare
all the individual groups of phenomena of this immense domain of life,
it cannot fail to appear, in the light of the Doctrine of Descent, no
longer as the ingeniously designed work of a Creator building up
according to a definite purpose, but as the necessary consequence of
active causes, which are inherent in the chemical combination of matter
itself, and in its physical properties.
In fact, we can most positively assert, and I shall justify this
assertion in the course of these pages, that by the Doctrine of
Filiation, or Descent, we are enabled for the first time to reduce all
organic phenomena to a single law, and to discover a single active cause
for the infinitely intricate mechanism of the whole of this rich world
of phenomena. In this respect, Darwin’s theory stands quite on a level
with Newton’s Theory of Gravitation; indeed, it even rises higher than
Newton’s theory!
The grounds of explanation are equally simple in the two theories. In
explaining this most intricate world of phenomena, Darwin does not make
use of new or hitherto unknown properties of matter, nor does he, as one
might suppose, make use of discoveries of new combinations of matter or
of new forces of organization; but it is simply by extremely ingenious
combination, by the synthetic comprehension, and by the thoughtful
comparison of a number of well-known facts, that Darwin has solved the
“holy mystery” of the living world of forms. The consideration of the
interchanging relations which exist between two general properties of
organisms, viz., _Inheritance and Adaptation_, is what has here been of
the first importance. Merely by considering the relations between these
two vital actions or physiological functions of organisms, also further
by considering the reciprocal interaction which all animals and plants,
living in one and the same place, necessarily exert on one
another—solely by the correct estimate of these simple facts, and by
skilfully combining them, Darwin has succeeded in finding the true
active causes (causæ efficientes) of the immensely intricate world of
forms in organic nature.
In any case we are in duty bound to accept this theory till a better one
be found, which will undertake to explain the same amount of facts in an
equally simple manner. Until now we have been in utter want of such a
theory. The fundamental idea that all different animal and vegetable
forms must be descended from a few or even from one single, most simple
primary form, was indeed not new. This idea was long since distinctly
formulated—first by the great Lamarck, at the beginning of our century.
But Lamarck in reality only expressed the hypothesis of the Doctrine of
Filiation, without establishing it by an explanation of the active
causes. And it is just the demonstration of these causes which marks the
extraordinary progress which Darwin’s theory has made beyond that of
Lamarck. In the physiological properties of Inheritance and Adaptation
of organic matter, Darwin discovered the true cause of the genealogical
relationship of organisms. It was not possible for the genius of Lamarck
in his day to command that colossal material of biological facts which
has been collected by the patient zoological and botanical
investigations of the last fifty years, and which has been used by
Darwin as an overpowering apparatus of evidence.
Darwin’s theory is therefore not what his opponents frequently represent
it as being—an unwarranted hypothesis taken up at random. It is not for
zoologists or botanists to accept or reject this as an explanatory
theory, as they please; they are rather compelled and obliged to accept
it, according to the general principle observed in all natural sciences,
that we must accept and retain for the explanation of phenomena any
theory which, though it has only a feeble basis, is compatible with the
actual facts—until it is replaced by a better one. If we do not adopt
it, we renounce a scientific explanation of phenomena, and this is, in
fact, the position which many biologists still maintain. They look upon
the whole domain of animate nature as a perfect mystery, and upon the
origin of animals and plants, the phenomena of their development and
affinities, as quite inexplicable and miraculous; in fact, they will not
allow that there _can_ be a true understanding of them.
Those opponents of Darwin who do not exactly wish to renounce a
scientific explanation are in the habit of saying, “Darwin’s theory of
the common origin of the different species is only _one_ hypothesis; we
oppose to it _another_, the hypothesis that the individual animal and
vegetable species have not developed one from another by descent, but
that they have come into existence independently of one another, by a
still undiscovered law of nature.” But as long as it is not shown how
this coming into existence is to be conceived of, and what that “law of
nature” is—as long as not even _probable_ grounds of explanation can be
brought forward to account for the independent coming into existence of
animal and vegetable species, so long this counter-hypothesis is in fact
no hypothesis, but an empty unmeaning phrase. Darwin’s theory ought,
moreover, not to be called an hypothesis. For a scientific hypothesis is
a supposition, postulating the existence of unknown properties or
motional phenomena of natural bodies, which properties have not as yet
been observed by the experience of the senses. But Darwin’s theory does
not assume such unknown conditions; it is based upon general properties
of organisms that have long been recognized, and—as has been
remarked—it is the exceedingly ingenious and comprehensive combination
of a number of phenomena which had hitherto stood isolated, which gives
the theory its extraordinarily great and intrinsic value. By it we are
for the first time in a position to demonstrate an active cause for all
the known morphological phenomena in the animal and vegetable kingdoms;
and, in fact, this cause is always one and the same, viz., the alternate
action of Adaptation and Inheritance, therefore a physiological, that
is, a physico-chemical or mechanical, relationship. For these reasons
the acceptance of the Doctrine of Filiation, as mechanically established
by Darwin, is a binding and unavoidable necessity for the whole domain
of zoology and botany.
As, therefore, in my opinion the immense importance of Darwin’s theory
lies in the fact that it has _mechanically explained those organic
phenomena of forms_ which had hitherto been unexplained, it is perhaps
necessary that I should here say a few words about the different ideas
connected with the word “explanation.” It is very frequently said, in
opposition to Darwin’s theory, that it does indeed explain those
phenomena by Inheritance and Adaptation, but that it does not at the
same time explain those properties of organic matter, and that therefore
we do not arrive at first causes. This objection is quite correct, but
it applies equally to _all_ explanations of phenomena. We _nowhere_
arrive at a knowledge of first causes. The origin of every simple salt
crystal, which we obtain by evaporating its mother liquor, is no less
mysterious to us, as far as concerns its first cause, and in itself no
less incomprehensible than the origin of every animal which is developed
out of a simple cell. In explaining the most simple physical or chemical
phenomena, as the falling of a stone, or the formation of a chemical
combination, we arrive, by discovering and establishing the active
causes—for example, the gravitation or the chemical affinity—at other
remoter phenomena, which in themselves are mysterious. This arises from
the limitation or relativity of our powers of understanding. We must not
forget that human knowledge is absolutely limited, and possesses only a
relative extension. It is, in its essence, limited by the very nature of
our senses and of our brains.
All knowledge springs from sensuous perceptions. In opposition to this
statement, the innate, _à priori_ knowledge of man may be brought up;
but we can see that the so-called _à priori_ knowledge can by Darwin’s
theory be proved to have been acquired _à posteriori_, being based on
experience as its first cause. Knowledge which is based originally upon
purely empirical observations, and which is therefore a purely sensuous
experience, but has then been transmitted from generation to generation
by inheritance, appears in later generations as if it were independent,
innate, and _à priori_. In our late animal ancestors, all our so-called
“_à priori_ knowledge” was originally acquired _à posteriori_, and only
gradually became _à priori_ by inheritance. It is based in the first
instance upon experiences, and by the laws of Inheritance and Adaptation
we can positively prove that knowledge _à priori_ and knowledge _à
posteriori_ cannot rightly be placed in opposition, as is usually done.
On the contrary, sensuous experience is the original source of _all_
knowledge. For this reason alone, all our knowledge is limited, and we
can never apprehend the _first causes_ of any phenomena. The force of
crystallization, the force of gravitation, and chemical affinity remain
in themselves just as incomprehensible as do Adaptation and Inheritance.
Seeing that Darwin’s theory explains from a single point of view the
totality of all those phenomena of which we have given a brief survey,
that it demonstrates one and the same quality of the organism as the
active cause in all cases, we must allow that it gives us for the
present _all_ that we can desire. Moreover, we have good reason to hope
that at some future time we shall learn to explain the first causes at
which Darwin has arrived, namely, the properties of Adaptation and
Inheritance; and that we shall succeed in discovering in the composition
of albuminous matter certain molecular relations as the remoter, simpler
causes of these phenomena. There is indeed no prospect of this in the
immediate future, and we content ourselves for the present with the
tracing back of organic phenomena to two mysterious properties, just as
in the case of Newton’s theory we are satisfied with tracing the
planetary motions to the force of gravitation, which itself is likewise
a mystery to us and not cognizable in itself.
Before commencing our principal task, which is the careful discussion of
the Doctrine of Descent, and the consequences that arise out of it, let
us take an historical retrospect of the most important and most widely
spread of those views, which before Darwin men had elaborated
concerning organic creation, and the coming into existence of the many
animal and vegetable species. In doing this I have no intention of
entertaining the reader with a statement of all the innumerable stories
about the creation which have been current among the different human
species, races, or tribes. However interesting and gratifying this task
would be, from an ethnographical point of view, as well as in a history
of civilization, it would lead us here much too far from our subject.
Besides, the great majority of all these legends about creation bear too
clearly the stamp of arbitrary fiction, and of a want of a close
observance of nature, to be of interest in a scientific treatment of the
history of creation. I shall therefore only select the Mosaic history
from among those that are not founded on scientific investigation, on
account of the unparalleled influence which it has gained in the western
civilized world; and then I shall immediately take up the scientific
hypothesis about creation, which originated with Linnæus as late as the
commencement of last century.
All the different conceptions which man has ever formed about the coming
into existence of the different animal and vegetable species may
conveniently be divided into two great contrasted groups—the natural
and supernatural histories of creation.
These two groups, on the whole, correspond with the two different
principal forms of the human notions of the universe which we have
already contrasted as the _monistic and the dualistic_ conception of
nature. In the usual dualistic or teleological (vital) conception of the
universe, organic nature is regarded as the purposely executed
production of a Creator working according to a definite plan. Its
adherents see in every individual species of animal and plant an
“embodied creative thought,” the material expression of a _definite
first cause_ (causa finalis) acting for a set purpose. They must
necessarily assume supernatural (not mechanical) processes for the
origin of organisms. With justice, we may therefore designate their
scheme of the world’s growth as the _Supernatural History of Creation_.
Among all such teleological histories of creation, that of Moses has
gained the greatest influence, since even so distinguished a naturalist
as Linnæus has claimed admittance for it in Natural Science. Cuvier’s
and Agassiz’s views of creation also belong to this group, as do in fact
those of the great majority of both scientific and unscientific men.
On the other hand, the theory of development carried out by Darwin,
which we shall have to treat of here as the _Non-miraculous_ or _Natural
History of Creation_, and which has already been put forward by Goethe
and Lamarck, must, if carried out logically, lead to the monistic or
mechanical (causal) conception of the universe. In opposition to the
dualistic or teleological conception of nature, our theory considers
organic, as well as inorganic, bodies to be the necessary products of
natural forces. It does not see in every individual species of animal
and plant the embodied thought of a personal Creator, but the expression
for the time being of a mechanical process of development of matter, the
expression of a necessarily active cause, that is, of a mechanical cause
(causa efficiens). Where teleological Dualism seeks the arbitrary
thoughts of a capricious Creator in the miracles of creation, causal
Monism finds in the process of development the necessary effects of
eternal immutable laws of nature.
The Monism here maintained by us is often considered identical with
Materialism. Now, as Darwinism, and in fact the whole theory of
development, has been designated as “_materialistic_,” I cannot avoid
here at once guarding myself against this ambiguous word, and against
the malice with which, in certain quarters, it is employed to stigmatize
our doctrine.
By the word “_Materialism_,” two completely different things are very
frequently confounded and mixed up, which in reality have nothing
whatever to do with each other, namely, scientific and moral
materialism. Scientific materialism, which is identical with our Monism,
affirms in reality no more than that everything in the world goes on
naturally—that every effect has its cause, and every cause its effect.
It therefore assigns to causal law—that is, the law of a necessary
connection between cause and effect—its place over the entire series of
phenomena that can be known. At the same time, scientific materialism
positively rejects every belief in the miraculous, and every conception,
in whatever form it appears, of supernatural processes. Accordingly,
nowhere in the whole domain of human knowledge does it recognize real
metaphysics, but throughout only physics; through it the inseparable
connection between matter, form, and force becomes self evident. This
scientific materialism has long since been so universally acknowledged
in the wide domain of inorganic science, in Physics and Chemistry, in
Mineralogy and Geology, that no one now doubts its sole authority. But
in Biology, or Organic science, the case is very different; here its
value is still continually a matter of dispute in many quarters. There
is, however, nothing else which can be set up against it, excepting the
metaphysical spectre of a vital power, or empty theological dogma. If we
can prove that all nature, so far as it can be known, is only _one_,
that the same “great, eternal, iron laws” are active in the life of
animals and plants, as in the growth of crystals and in the force of
steam, we may with reason maintain the monistic or mechanical view of
things throughout the domain of Biology—in Zoology and Botany—whether
it be stigmatized as “materialism” or not. In such a sense all exact
science, and the law of cause and effect at its head, is purely
materialistic.
_Moral_, or _ethical Materialism_, is something quite distinct from
scientific materialism, and has nothing whatever in common with the
latter. This real materialism proposes no other aim to man in the course
of his life than the most refined possible gratification of his senses.
It is based on the delusion that purely material enjoyment can alone
give satisfaction to man; but as he can find that satisfaction in no one
form of sensuous pleasure, he dashes on weariedly from one to another.
The profound truth that the real value of life does not lie in material
enjoyment, but in moral action—that true happiness does not depend upon
external possessions, but only in a virtuous course of life—this is
unknown to ethical materialism. We therefore look in vain for such
materialism among naturalists and philosophers, whose highest happiness
is the intellectual enjoyment of Nature, and whose highest aim is the
knowledge of her laws. We find it in the palaces of ecclesiastical
princes, and in those hypocrites who, under the outward mask of a pious
worship of God, solely aim at hierarchical tyranny over, and material
spoliation of, their fellow-men. Blind to the infinite grandeur of the
so-called “raw material,” and the glorious world of phenomena arising
from it—insensible to the inexhaustible charms of Nature, and without a
knowledge of her laws—they stigmatize all natural science, and the
culture arising from it, as sinful “materialism,” while really it is
this which they themselves exhibit in a most shocking form. Satisfactory
proofs of this are furnished, not only by the whole history of the
Catholic Popes, with their long series of crimes, but also by the
history of the morals of orthodoxy in every form of religion.
In order, then, to avoid in future the usual confusion of this utterly
objectionable Moral Materialism with our Scientific Materialism, we
think it necessary to call the latter either _Monism_ or _Realism_. The
principle of this _Monism_ is the same as what Kant terms the
“principle of mechanism,” and of which he expressly asserts, that
_without it there can be no natural science at all_. This principle is
quite inseparable from our Non-miraculous History of Creation, and
characterizes it as opposed to the teleological belief in the miracles
of a Supernatural History of Creation.
Let us now first of all glance at the most important of all the
supernatural histories of creation, I mean that of Moses, as it has been
handed down to us in the Bible, the ancient document of the history and
laws of the Jewish people. The Mosaic history of creation, since in the
first chapter of Genesis it forms the introduction to the Old Testament,
has enjoyed, down to the present day, general recognition in the whole
Jewish and Christian world of civilization. Its extraordinary success is
explained not only by its close connection with Jewish and Christian
doctrines, but also by the simple and natural chain of ideas which runs
through it, and which contrasts favourably with the confused mythology
of creation current among most of the other ancient nations. First the
Lord God creates the earth as an inorganic body; then he separates light
from darkness, then water from the dry land. Now the earth has become
inhabitable for organisms, and plants are first created, animals
later—and among the latter the inhabitants of the water and the air
first, afterwards the inhabitants of the dry land. Finally God creates
man, the last of all organisms, in his own image, and as the ruler of
the earth.
Two great and fundamental ideas, common also to the non-miraculous
theory of development, meet us in this Mosaic hypothesis of creation,
with surprising clearness and simplicity—the idea of separation or
_differentiation_, and the idea of progressive development or
_perfecting_. Although Moses looks upon the results of the great laws of
organic development (which we shall later point out as the necessary
conclusions of the Doctrine of Descent) as the direct actions of a
constructing Creator, yet in his theory there lies hidden the ruling
idea of a progressive development and a differentiation of the
originally simple matter. We can therefore bestow our just and sincere
admiration on the Jewish lawgiver’s grand insight into nature, and his
simple and natural hypothesis of creation, without discovering in it a
so-called “divine revelation.” That it cannot be such is clear from the
fact that two great fundamental errors are asserted in it, namely,
first, the _geocentric_ error that the earth is the fixed central point
of the whole universe, round which the sun, moon, and stars move; and
secondly, the _anthropocentric_ error, that man is the premeditated aim
of the creation of the earth, for whose service alone all the rest of
nature is said to have been created. The former of these errors was
demolished by Copernicus’ System of the Universe in the beginning of the
16th century, the latter by Lamarck’s Doctrine of Descent in the
beginning of the 19th century.
Although the geocentric error of the Mosaic history was demonstrated by
Copernicus, and thereby its authority as an absolutely perfect divine
revelation was destroyed, yet it has maintained, down to the present
day, such influence, that it forms in many wide circles the principle
obstacle to the adoption of a natural theory of development. Even in our
century, many naturalists, especially geologists, have tried to bring
the Mosaic theory into harmony with the recent results of natural
science, and have, for example, interpreted Moses’ seven days of
creation as seven great geological periods. However, all these ingenious
attempts at interpretation have so utterly failed, that they require no
refutation here. The Bible is no scientific book, but consists of
records of the history, the laws, and the religion of the Jewish people,
the high merit of which, as a history of civilization, is not impaired
by the fact that in all scientific questions it has no commanding
importance, and is full of gross errors.
We may now make a great stride over more than three thousand years, from
Moses, who died about the year 1480 before Christ, to Linnæus, who was
born in the year 1707 after Christ. During this whole period no history
of creation was brought forward that gained any lasting importance, or
the closer examination of which would here be of any interest. Indeed,
during the last fifteen hundred years, since Christianity gained its
supremacy, the Mosaic history of creation, together with the dogmas
connected with it, has become so generally predominant, that the 19th
century is the first that has dared positively to rise against it. Even
the great Swedish naturalist, Linnæus, the founder of modern natural
history, linked his System of Nature most closely to the Mosaic history
of creation.
The extraordinary progress which Charles Linnæus made in the so-called
descriptive natural sciences, consists, as is well known, in his having
established a system of nomenclature of animals and plants, which he
carried out in a manner so perfectly logical and consistent, that down
to the present day it has remained in many respects the standard for all
succeeding naturalists engaged in the study of the forms of animals and
plants. Although Linnæus’ system was artificial, although in classifying
animal and vegetable species he only sought and employed single parts as
the foundation for his divisions, it has, nevertheless, gained the
greatest success; firstly, in consequence of its being carried out
consistently, and secondly, by its nomenclature of natural bodies, which
has become extremely important, and at which we must here briefly
glance.
Before Linnæus’ time, many vain attempts had been made to throw light
upon the endless chaos of different animal and vegetable forms (then
known) by adopting for them suitable names and groupings; but Linnæus,
by a happy hit, succeeded in accomplishing this important and difficult
task, when he established the so-called “_binary nomenclature_.” The
binary nomenclature, or the twofold designation, as Linnæus first
established it, is still universally applied by all zoologists and
botanists, and will, no doubt, maintain itself, for a long time to come,
with undiminished authority. It consists in this, that every species of
animal and plant is designated by two names, which stand to each other
in the same relation as do the christian and surnames of a man. The
special name which corresponds with the christian name, and expresses
the idea of “a species,” serves as the common designation of all
individual animals or plants, which are equal in all essential matters
of form, and are only distinguished by quite subordinate features. The
more general name, on the other hand, corresponding with the surname,
and which expresses the idea of a genus, serves for the common
designation of all the most nearly similar kinds or species.
According to Linnæus’ plan, the more general and comprehensive generic
name is written first; the special subordinate name of the species
follows it. Thus, for example, the common cat is called Felis domestica;
the wild cat, Felis catus; the panther, Felis pardus; the jaguar, Felis
onca; the tiger, Felis tigris; the lion, Felis leo. All these six kinds
of animals of prey are different species of one and the same
genus—Felis. Or, to add an example from the vegetable kingdom,
according to Linnæus’ designation the pine is Pinus abies; the fir,
Pinus picea; the larch, Pinus larix; the Italian pine, Pinus pinea; the
Siberian stone pine, Pinus cembra; the knee timber, Pinus mughus; the
common pine, Pinus silvestris. All these seven kinds of pines are
different species of one and the same genus—Pinus.
Perhaps this advance made by Linnæus may seem to some only of
subordinate importance in the practical distinction and designation of
the variously formed organisms. But in reality it was of the very
greatest importance, both from a practical and theoretical point of
view. For now, for the first time, it became possible to arrange the
immense mass of different organic forms according to their greater or
less degree of resemblance, and to obtain an easy survey of the general
outlines of such a “system.” Linnæus facilitated the tabulation and
survey of this “system” of plants and animals still more by placing
together the most nearly similar genera into so-called orders (ordines);
and by uniting the most nearly similar orders into still more
comprehensive main divisions or classes. Thus, according to Linnæus,
each of the two organic kingdoms were broken up into a number of
classes, the vegetable kingdom into twenty-four, and the animal kingdom
into six. Each class again contains several orders. Every single order
may contain a number of genera, and, again, every single genus several
species.
Valuable as was Linnæus’ binary nomenclature in a _practical_ way, in
bringing about a comprehensive systematic distinction, designation,
arrangement, and division of the organic world of forms, yet the
incalculable _theoretical_ influence which it gained forthwith in
relation to the history of creation was no less important. Even now all
the important fundamental questions as to the history of creation turn
finally upon the decision of the very remote and unimportant question,
_What really are kinds or species?_ Even now the _idea of organic
species_ may be termed the central point of the whole question of
creation, the disputed centre, about the different conceptions of which
Darwinists and Anti-Darwinists fight.
According to Darwin’s opinion, and that of his adherents, the different
species of one and the same genus of animals and plants are nothing else
than differently developed descendants of one and the same original
primary form. The different kinds of pine mentioned above would
accordingly have originated from a single primæval form of pine. In like
manner the origin of all the species of cat mentioned above would be
traced to a single common form of Felis, the ancestor of the whole
genus. But further, in accordance with the Doctrine of Descent, all the
different genera of one and the same order ought also to be descended
from one common primary ancestor, and so, in like manner, all orders of
a class from a single primary form.
On the other hand, according to the idea of Darwin’s opponents, all
species of animals and plants are quite independent of each other, and
only the individuals of each species have originated from a single
primary form. But if we ask them how they conceive these original
primary forms of each species to have come into existence, they answer
with a leap into the incomprehensible, “They were created.”
Linnæus himself defined the idea of species in this manner by saying,
“There are as many different species as there were different forms
created in the beginning by the infinite Being.” (“Species tot sunt
diversæ, quot diversas formas ab initio creavit infinitum ens.”) In this
respect, therefore, he follows most closely the Mosaic history of
creation, which in the same way maintains that animals and plants were
created “each one after its kind.” Linnæus, accepting this, held that
originally of each species of animals and plants either a single
individual or a pair had been created; in fact a pair, or, as Moses
says, “a male and a female” of those species which have separate sexes,
but of those species in which each individual combines both sexual
organs (hermaphrodites), as for instance the earthworm, the garden and
vineyard snails, as well as the great majority of plants, a single
individual.
Linnæus further follows the Mosaic legend in regard to the flood, by
supposing that the great general flood destroyed all existing organisms,
except those few individuals of each species (seven pairs of the birds
and of clean animals, one pair of unclean animals) which Noah saved in
the ark, and which were placed again on land, on Mount Ararat, after the
flood had subsided. He tried to explain the geographical difficulty of
the living together of the most different animals and plants, as
follows: Mount Ararat, in Armenia, being situated in a warm climate, and
rising over 16,000 feet in height, combines in itself the conditions for
a temporary common abode of such animals as live in different zones.
Accordingly, animals accustomed to the polar regions could climb up the
cold mountain ridges, those accustomed to a warm climate could go down
to the foot of the mountain, and the inhabitants of a temperate zone
could remain midway up the mountain. From this point it was possible for
them to spread north and south over the earth.
It is scarcely necessary to remark that this Linnæan hypothesis of
creation, which evidently was intended to harmonize most closely with
the prevailing belief in the Bible, requires no serious refutation. When
we consider Linnæus’ clearness and sagacity in other matters, we may
doubt whether he believed it himself. As to the simultaneous origin of
all individuals of each species from one pair of ancestors respectively
(or in the case of the hermaphrodite species, from one original
hermaphrodite), it is clearly quite untenable; for, apart from other
reasons, in the first days after the creation, the few animals of prey
would have sufficed to have utterly demolished all the herbivorous
animals, as the herbivorous animals must have destroyed the few
individuals of the different species of plants. The existence of such an
equilibrium in the economy of nature as obtains at present cannot
possibly be conceived, if only one individual of each species, or only
one pair, had originally and simultaneously been created.
Moreover, how little importance Linnæus himself attached to this
untenable hypothesis of creation is clear, among other things, from the
fact that he recognized _Hybridism_ (crossing) as a source of the
production of new species. He assumed that a great number of independent
new species had originated by the interbreeding of two different
species. Indeed, such hybrids are not at all rare in nature, and it is
now proved that a great number of species, for example, of the genus
Rubus (bramble), mullen (Verbascum), willow (Salix), thistle (Cirsium),
are hybrids of different species of these genera. We also know of
hybrids between hares and rabbits (two species of the genus Lepus),
further of hybrids between different species of dog (genus Canis), etc.,
which can be propagated as independent species.
It is certainly very remarkable that Linnæus asserted the physiological
(therefore mechanical) origin of new species in this process of
hybridism. It clearly stands in direct opposition to the supernatural
origin of the other species by creation, which he accepted as put
forward in the Mosaic account. The one set of species would therefore
have originated by dualistic (teleological) creation, the other by
monistic (mechanical) development.
The great and well merited authority which Linnæus gained by his
systematic classification and by his other services to Biology, was
clearly the reason why his views of creation also remained, throughout
the whole of the last century, undisputed and generally recognized. If
throughout systematic Zoology and Botany the distinctions,
classification, and designations of species, introduced by Linnæus, and
the dogmatic ideas connected therewith had not been maintained—more or
less unaltered—we should be at a loss to understand how his idea of an
independent creation of single species could have stood, by itself down
to the present day. It is only owing to his great authority, and through
his attaching himself to the prevailing Biblical belief, that his
hypothesis of creation has retained its position so long.