Vanished at last are the old theories of gradual changes in species
perpetuated and accumulated by natural selection until at last wholly
new forms have in this way been produced. True variations are now seen
to be confined within well-marked and rather narrow limits, within which
ordinary variations may occur, perhaps induced by environment. These
fluctuating variations grade off into one another on all sides, and
their differences _can_ be plotted on a frequency curve; but the very
important thing for us to remember is that these fluctuating variations
_cannot be transmitted._ Beyond these fluctuating variations come the
unit characters or factors, which are distinct from each other, or
"discontinuous," to use the technical term, and which therefore _cannot
be plotted on a frequency curve_. These factors are not modified in the
least by the environment, and their peculiarities are faithfully
transmitted in heredity with all the precision of chemical law. But even
these factors are all within the bounds of the species. There is not a
shred of scientific evidence that either natural or artificial devices
have originated a single genetic factor that was not all the time
potentially latent in the ancestry, capable of being produced at will by
the proper combination.
It is a universal law of living things that all forms left to themselves
tend to degenerate. The necessity for continuous artificial selection in
the sugar beet, in Sea Island cotton, in corn, in Jersey and Holstein
cattle, in trotting horses, proves this universal tendency to
degenerate.[30] Natural selection in a somewhat similar way tends to
postpone this degeneracy by killing off the "unfit," but selection
either artificial or natural cannot originate anything new, and its
results are here displayed merely among the small fluctuating variations
mentioned above. Even among the real genetic factors it may show itself
by allowing some to survive alone; but as no combination of diverse
factors can originate anything really new, its field for operation among
these factors is extremely limited. Among species also it is operative,
killing off some and allowing others to survive. But neither among
fluctuations, among factors, nor yet among species can selection
originate anything new.
[Footnote 30: The following represents the consensus of scientific
opinion regarding the lessons to be drawn from the phenomena of our
improved races of domesticated plants and animals:
"One need not be a pessimist to assert the actual evidence thus far
obtained indicates that the supposed progress made in the improvement of
domesticated animals and plants is nothing more than the sorting out of
pure lines, and thus represents no advancement."--Prof. L.B. Walton,
_Science_, April 3, 1914.]
Nor is there any other method known to modern science by means of which
new factors can be originated which were not potentially latent in the
ancestry. The much heralded new "species" of de Vries and others are now
known to be merely new factors cropping out;[31] for though they remain
constant and breed true, they obey Mendel's Law when crossed with their
parental forms, and hence are merely the result of some new combination
of factors which can be reproduced at will by using the same method of
combination and segregation. The real scientific test for any form
supposed to be a new "species" would be twofold: (1) to show that some
new character had been added which no ancestor ever possessed; and (2)
to show that this new character will breed true under all circumstances
of hybridization and not merely segregate as a unit character or mere
analytic variety after hybridization. It is almost superfluous to say
that no "new species" originating in modern times has ever justified
itself under these tests.
[Footnote 31: Some of our leading biologists are now disposed to grow
somewhat humorous when speaking of this mutation theory of de Vries, as
may be illustrated by the following:
"The mutation theory of de Vries appears accordingly to lag useless on
the biological stage, and may apparently be now relegated to the limbo
of discarded hypotheses.... The present refutation has been undertaken
in the interest of biological progress in this country. It is now high
time, so far as the so-called mutation hypothesis, based on the conduct
of the evening primrose in cultures, is concerned, that the younger
generation of biologists should take heed lest the primrose path of
dalliance lead them imperceptibly into the primrose path to the
everlasting bonfire."--Prof. Edw. C. Jeffrey (Harvard), in _Science_,
April 3, 1914.]
In conclusion it may be remarked that biologists do not claim to have
solved all the problems connected with heredity and variation. But the
general results taught us by Mendelism are now established beyond
controversy. Led by the German biologists, the leading scientists of the
world had already acknowledged that "pure" Darwinism or natural
selection cannot explain the origin of new organs or new forms. And now
Mendelism destroys the other supposed foundation for biological
evolution, by showing that small variations cannot be accumulated into
large differences equal in value to a unit character or a new species.
Thus the whole foundation of biological evolution has been completely
undermined by these new discoveries; and were it not for the wide-spread
credence the evolutionary theory has already received, and the
intellectual momentum it has acquired tending to carry it on by its
inertia into the future, it could be only a very short time now before
the elaborate treatises attempting to orientate with it all the facts of
religion and history would have to be consigned to the shelves labeled,
"Of Historic Interest." For as Bateson remarked in his recent address as
President before the British Association at Melbourne, Australia, the
new knowledge of heredity shows that whatever evolution there is occurs
by loss of factors and not by gain, and that in this way the progress of
science is "destroying much that till lately passed for gospel."[32]
[Footnote 32: In commenting on these views of Bateson, Prof. S.C. Holmes,
of the University of California, well speaks of them as "an illustration
of _the bankruptcy of present evolutionary theory."--Science_, September
3, 1915.]
V
Let us sum up the situation. We began this chapter with the question,
Have new kinds of plants and animals originated in modern times
comparable in all essential respects with the idea of true species?
The answer of modern science is reluctantly obtained, but it is a
negative. De Vries and others have indeed originated new kinds that were
loudly hailed as new species, and are doubtless as deserving of specific
rank as many already listed for years in the treatises of specialists.
Indeed there is every reason to believe that almost countless numbers of
our taxonomic species have originated from common ancestral originals.
But as these so-called species are now known to be freely or moderately
cross fertile with other related species, their hybrids following the
ordinary laws of Mendelian inheritance, we see that they are not true
species but mere analytic varieties.
In short, we now know that our taxonomic classifications have been
marked off on altogether too narrow lines. This has tended greatly to
confuse the question at issue. But from our enlarged views of the laws
and nature of heredity and variation, as well as from the original
intent of the term _species_ as defined by the great scientist who
originated it, the verdict of an impartial investigator must be that we
have never seen a new species originate by any natural or artificial
method since the dawn of scientific observation.
Here again we find the record of Creation confirmed; for the failure of
the thousands of modern investigators to originate genuine new species
proves that in this respect also Creation is not now going on. And all
the analogies from the origin of matter, of energy, of life, and from
the laws of the reproduction of cells, indicate that we have at last
found rock bottom truth regarding the vexed question of the origin of
species. So far as science can observe and record, each living thing on
earth, in air, in water, reproduces "after its kind."