Francis J. (Francis Joseph) Hall.

Evolution and the fall online

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for instance, smooth seeds and wrinkled seeds. It
should be added that the separate pairs of differentiat-
ing characters or allelomorphs obey Mendel's law in
complete and mutual independence. This mutual
separation, along with the numerical law of their com-
binations in germ-cells, determines the results of cross-
breeding; and the practical application of Mendel's
discovery enables cross-breeders to select desirable
variations in such a manner as to produce varieties
which breed true and hold their own.^

The facts upon which Mendel's law is based consti-
tute an important part of the data by which Hugo de
Vries was led to maintain the evolutionary theory of
heterogenesis, commonly called the mutations theory.
This theory had been enunciated by several earher

* On Mendel's law, see R. H. Lock, op. cit., chh. vii, viii; Bateson,
Mendel's Prins. of Heredity (which gives translations of Mendel's
own papers); Baldwin's Die. of Philos., s. v. "Evolution (Mendel)."



70 THE EVOLUTIONARY THEORY

writers, but his elaborate experiments and careful
arguments have for the first time given it a recognized
place among scientific theories — one that threatens
to destroy the influence of neo-Darwinism. You will
remember that Darwin and the neo-Dar^vinians make
slight, fluctuating, and continuous variations the basis
of the process of natural selection, and maintain that
a new species is formed by means of such selection, and
by a gradual accentuation and accumulation of the
variations selected. The new theory excludes natural
selection from any part in species-forming. Accord-
ing to it a new species is produced by sudden and dis-
continuous variations. These variations may be slight
in degree when severally considered, but a sufficient
number of them coincide to produce immediately by
their cumulative effect an independent species, suffi-
ciently differentiated to escape the swamping effects
of inter-breeding, and capable of perpetuating itself.
Biologic isolation is complete, and the number of
members of the new species which are thus produced
is also sufficient for their self-propagation.

The new theory is thus directly opposed to Darwin-
ism in its explanation of the formation of new species.
But it leaves a place for natural selection in determin-
ing the general course of natural evolution. DeVries
says: *' Darwin discovered the great principle which
rules the evolution of organisms. It is the principle
of natural selection. It is the sifting out of all organ-
isms of minor worth through the struggle for life. It
is only a sieve, and not a force of nature, no direct



POST-DARWINIAN VIEWS 71

cause of improvement. ... It is only a sieve, which
decides which is to Hve, and what is to die. ... It is
the sieve that keeps evolution on the main line, kilHng
all or nearly all that try to go in other directions. By
this means natural selection is the one directing cause
of the broad hues of evolution." ^ In brief, the muta-
tions theory makes natural selection begin its work
with species already formed, and restricts its opera-
tion to an ehmination of unfit species and an exclusive
preservation of such as are fitted to survive.

The mutations theory is free from some of the most
troublesome difficulties attendant upon the view of
Darwin, that new species arise from natural selection
and an accumulation of continuous variations. More-
over, de Vries has been able to furnish direct evidence,
for he has observed actual instances of sudden origin
of new species by mutation of the discontinuous kind.
It has been objected that these instances, while they
estabHsh the fact that species do at times thus origi-
nate, are altogether too few to warrant such a general-
ization as is represented by the mutations theory. It
has been answered that, as the origin of new species
is not an every-day event, the instances observed must
necessarily be somewhat Hmited in number, and that
further observation will probably afford additional
evidence, now that investigators are looking in the
right direction. Furthermore, it is urged that, if the

1 Species and Varieties, Their Origin by Mutation (ed. by Mac-
Dougal, 1905), p. 6. On the mutations theory, see R. H. Lock, op.
cit., ch. v; V. L. Kellogg, op. cit., ch. xi. The facts upon which the
theory is chiefly based are given below, pp. 87-88.



72 THE EVOLUTIONARY THEORY

number of instances of mutation which have been
observed is small, no indisputable instances whatever
have been perceived of the origin of new species by
the selection of accumulating continuous variations.
The evidence by which Darwin's theory is thought to
be estabHshed is wholly indirect — being either con-
jectural or, at least, circumstantial. The battle has
not been entirely fought through, and it is too early
at present to come to final conclusions as to the out-
come. But the new theory has brought the difficulties
which attend neo-Darwinism into bold rehef, and we
are not Hkely to see any permanent return to pure
Darwinism.

I have ignored other theories of species forming, of
which several have appeared during the past two or
three decades,^ because none of them have seemed to
gain the attention of scientists that has been paid
to Weismannism and the mutations theory. But I
ought not to omit mention of the fact that there is an
increasing reahzation among scientists of the part played
in evolution by what are called "unknown factors."
The problem as to the causes of variation, and as to
the laws which determine their direction and Hmits,
has become more and more pressing. The fact that
natural selection does not positively cause variation,
but merely eliminates unsuitable results thereof, is
now well established. IVIany scientists have escaped
the hampering influence of naturahsm, and perceive

1 A general account of them, with numerous references, is given
by V. L. Kellogg, op. cit., chh. viii-x.



POST-DARWINIAN VIEWS 73

that the unknown factors which cause and limit the
variations of organic Hfe transcend mechanical explana-
tion, and operate in a manner that suggests intelhgent
direction.^ Others reject such views as unscientific,^
by which they mean that teleology cannot be de-
scribed in mechanical terms. That is, they forget
the Hmitations of the mechanical method of interpre-
tation, and refuse to be influenced in their views by
evidence of the presence in nature of superphysical
causation. Such an attitude is not really scientific,
but is the result of mistaking a section of the model
of nature for the whole model, and of the one-sided
and defective philosophy called naturalism.

I believe that the scientific outlook is most encour-
aging to those who believe in the unity of all things, in
the reahty of the superphysical and supernatural, and
in the possibility of acquiring such knowledge of the
universe as will forever vindicate our assurance that a
beneficent divine ordering and purpose explains and
controls natural evolution.

I hope in these lectures to show also that neither the
evolutionary theory in general nor any explanation of
evolution that can rightly be called scientific mihtates
against the truth of genuinely catholic doctrine, — in
particular against the doctrine of man's primitive state
and fall. But before undertaking this task it is desir-
able to exhibit the evidence which has been advanced

1 For example, Nageli, Korschinsky, and R. Otto.

2 V. L. Kellogg rejects them, op. cit., p. 278, as do all believers in
naturalism.



74 THE EVOLUTIONARY THEORY

in support of the general theory of a natural evolu-
tion of species, and to consider whether, and how far,
that theory explains man's origin and distinctive
mental and moral characteristics. To do so will be
the aim of my next lecture.



LECTURE III

EVroENCES AND LIMITATIONS

The purpose of this lecture is to exhibit within brief
compass the evidences which are thought to support
the theory of a natural evolution of species, and to con-
sider whether, and to what extent, we can rightly regard
the human species as a product of such evolution. At
the outset permit me to remind you again of the dis-
tinction between the general theory that existing species
have somehow been naturally developed from earlier
and simpler ones and the various explanations of this
development which Darwin and others have advanced.
One may become con\dnced of the futihty of any one,
or of all, of these explanations, and yet regard the evi-
dence for natural evolution as conclusive. It is this
evidence for natural evolution that I now ask you to
consider.

In estimating the evidence of a scientific hypothesis
we ought not to expect mathematical demonstration.
From the nature of things no demonstrative e\ddence
can be had, and its absence will not deter an intelli-
gent thinker from accepting a scientific hypothesis which
appears to be the best available explanation of the
observed facts, and works well. He may indeed accept
it provisionally only, while waiting for the results of

75



76 EVIDENCES AND LIMITATIONS

wider investigation; but to accept the best available
working hypothesis because of its present working value
is a truly scientific procedure, and upon such acceptance
depends to a large degree the possibility of scientific
progress.^

The method by which a scientific hypothesis is arrived
at and established is inductive. That is, facts are in-
dustriously collected and co-ordinated in their apparent
relations, and speculative imagination is exercised to
devise a theory which will fit in with and, to some
extent at least, explain the facts that have been accu-
mulated. The process involves an element of con-
jecture and guesswork, followed, to borrow a figure
from the tailor's work, by trying the new garment on
to nature's model in order to discover how it fits. If
it fits well, it is accepted; if imperfectly, it is modi-
fied; if not at all, it is rejected and another theory is
devised. We must accept this method, and be con-
trolled in our views of nature by its results, or else aban-
don hope of acquiring a scientific knowledge of nature.



The evolutionary hypothesis has been arrived at by
induction. A very great mass of biological data has
been gradually accumulated by the labours of succes-
sive generations of scientific investigators; and the
thought that the origin of species can best be explained
in its physical aspects by the supposition that existing

^ Cf. pp. 33-34, above.



SUMMARY OF EVIDENCE 77

species of life have originated by natural evolution from
one or more primitive types has come to be accepted
by the scientific world as best agreeing with and ex-
plaining the known facts of biology and of related
spheres of investigation. The e^ddence by which the
evolutionary hypothesis is supported consists, there-
fore, of innumerable facts, which, when considered
together, suggest such a theory, and do not appear to
be susceptible of any other physical explanation that
is so satisfactory and so free from difficulties. These
facts are gathered from a wide variety of sources, but
especially from results of investigations in morphology,
embryology, the geological succession of organisms,
their geographical distribution, and the observed pro-
duction of new varieties and species by artificial selec-
tion and by natural mutation.^

I. The universal occurrence in the organic world
of variation, and of the perpetuation of its results by
inheritance, has led scientific observers to abandon
behef in the fixity of species, and to look for some other
explanation of their origin than the ancient behef in a
separate creation of each by divine fiat. Moreover, so
far as we can imagine, there are but two alternatives
to this view — their spontaneous but separate origin,
one by one, out of lifeless matter, and their natural
evolution by means of variation and inheritance. Of

1 The evidences of natural evolution are given in most all the
works mentioned on p. 37, note 2, above. But note especially A. R.
Wallace, Darwinism; Chas. Darwin, Origin of Species, ch. xv;
A. Weismann, Evolution Theory, Lees, ii, iii; Thos. Huxley, Darwin-
iana, pp. 205-225; M. M. Metcalf, Organic Evolution, pp. 87-163.



78 EVIDENCES AND LIMITATIONS

spontaneous generation there is no trace in nature;
and carefully conducted experiments have compelled
scientists to reject that theory, — commonly called abio-
genesis/ The theory of natural evolution is the only
remaining alternative that has thus far been discovered ;
and if it agrees with the facts, it ought to be accepted
until a better explanation is forthcoming. It should
be remembered that our acceptance of it neither mili-
tates against belief in creation by the will of God nor
commits us to a mechanical explanation of the origin
of Hfe, mind, and moral sense. The theory of evolu-
tion merely describes the physical history of organic
life, and in its scientific form does not profess to account
for what is superphysical.

2. From the facts of variation and heredity we turn
to the similarity of structure and organic functioning
which is found to characterize the species in each
general group of species in the organic world. These
groups are not numerous, and if there has been a natural
evolution of species this fact seems to indicate that
such evolution originated in a very few primitive types,
each corresponding to one of the larger groups of

1 See F. R. Tennant, in Expository Times, May, 1908, pp. 352-
355, for an account of attempts to prove abiogenesis. Also O. Lodge,
Life and Matter, esp. ch. x; the author's Being and Attributes of God,
pp. 267, 268, where other references are given. If abiogenesis were
proved, this would not disprove a divine creation of life, but would
show a different method of the creation than the existing state of
evidence establishes. A. Weismann, Evolution Theory, Lee. xxxvi,
urges that abiogenesis cannot be disproved because, if it does occur,
the minuteness of its results makes them lie beyond observation by
the most powerful microscope.



SUMMARY OF EVIDENCE 79

existing species. This similarity of structure appears
the more remarkable the more closely morphological
study of organisms is conducted. To use an obvious
illustration given by R. H. Lock, it is found that "in
the hand of a man, the paw of a dog, the wing of a bat,
and the paddle of a whale, almost identically the same
series of bones can be traced." The uses to which these
several members are put differ widely, but, as Lock
adds, "An obvious explanation is to be found in the
supposition that these parts have arisen by a divergent
modification of parts which were originally identical." ^
Throughout each group of species certain correspond-
ing organs have been discovered which appear to be
biiilt in accordance with one general plan. Nor is this
all. Amid much divergence of organic functioning the
general laws of assimilation of food, of propagation,
and even of disease, are essentially the same; as is
illustrated by the success with which experiments upon
lower animals are employed as the basis of medical and
surgical treatment of human disorders.

3. A third group of facts which suggests and con-
firms the evolutionary theory is found in the gradation of
organisms which appears within the several chief groups
of species. In each case a hierarchy of organic forms
appears, stretching all the way from seemingly undif-
ferentiated organisms up to the most highly organized
species. It is a reasonable inference from this that the
higher forms are most recent in origin, and have been
produced by a progressive differentiation of earher and

^ Recent Progress, p. 31.



8o EVIDENCES AND LIMITATIONS

simpler organisms. This supposition is confirmed by
the evidence bearing upon the comparative antiquity
of species which has been obtained by other Hnes of
investigation.

4. Another argument for the natural evolution of
species is derived from embryology, or the study of
immature and unborn offspring. A remarkable sim-
ilarity is found in their manner of development in
different species of the same general group. The
similarity is most complete in the earliest stages, so
complete indeed that, prior to a certain stage of devel-
opment, the embryos of the different species are indis-
tinguishable from each other. It is also noticed that
the higher organisms to an observable extent recapitu-
late in their embryonic growth the phases of develop-
ment of their several species which the evolutionary
theory hypothecates. These phenomena are most
readily interpreted and accounted for from the evolu-
tionary standpoint. The parallehsm between the
growth of individual organisms and the development
of species is not indeed complete, but this is easily
accounted for by the supposition that the variations
which result in the divergence of species may to some
extent modify the embryonic stage of growth. The
more or less defective but recognizable resume of earlier
natural history which is still discoverable seems to declare
an ancient pedigree, and a common ancestry for the
species which are thus shown to be mutually related.

5. Somewhat connected with this argument is the
inference made from the presence of rudimentary and



SUMMARY OF EVIDENCE 8i

useless organs in members of higher species. The
vermiform appendix of our own bodies affords a criti-
cal instance, one that obtrudes itself upon our attention
with painful insistence in the disease known as appen-
dicitis. This and other organs of the same apparently
useless nature bear the appearance of being survivals
of a previous stage of evolution, for they are found in
lower species and there discharge useful functions.
Mr. A. R. Wallace gives interesting examples.^ He
says, *'A11 the higher animals present rudiments of
organs which, though useless to them, are useful in
some allied group, and are beheved to have descended
from a common ancester in which they were useful." ^
Some of these rudiments appear only in exceptional
individuals. Thus certain persons carry a projecting
point on the outer fold of the ear, corresponding faintly
to the pointed ear of numerous species of lower ani-
mals — an earmark of ancestry.

6. We come next to the teaching of geology and
paleontology as to the comparative antiquity of species,
and as to the time-order of their origin. This teaching
is derived from the distribution of ancient fossils, found
in various strata of the earth's crust, the relative
antiquity of which has been estimated by the methods
of geological science. This testimony of the rocks is,
of course, far from complete. Many organisms are
too soft and jelly-like to be preserved in this manner,
unless petrified — a comparatively rare event. Then
in order that an organism should be preserved after

1 Darwinism, ch. xv. 2 Page 448.

7



82 EVIDENCES AND LIMITATIONS

its life is extinct, it should be buried in time and in a
manner to escape entire distintegration either by the
action of the atmosphere or by other destructive causes.
Only a small fraction of the organisms of by-gone ages
can have left their traces in the deposits that have since
accumulated. Finally, only a very limited portion of
the earth's crust has been sufficiently examined to lay
bare the secrets which it contains.^

Yet, in spite of these limitations, the science of
paleontology, which is concerned with the study of
fossil remains whether animal or vegetable, has thrown
much light upon the past history of organic life on this
planet. The time measures which here have to be
employed are purely geological, and cannot be trans-
lated accurately into such terms as years and centuries.
But the strata of the earth's crust have been distributed
with approximate accuracy into a series of successive
periods; and paleontologists by means of this distri-
bution have been enabled to ascertain the relative
antiquity of a large number of existing species as well
as of species now extinct, the fossil remains of which
have been discovered in various geological strata. The
results have been in accord with the requirements
of the evolutionary theory. The lower and simpler
species are most ancient, and in certain instances long
series of ancestral forms have been discovered which
seem to indicate the evolution of living species, through
many intervening stages, from remote and widely dif-
ferent forms of life.

» Darwin discusses this incompleteness in op. cit., ch. x.



SUMMARY OF EVIDENCE 83

7. The argument from the distribution of organisms
in time is corroborated by their distribution in space
— their geographical distribution. If the evolution-
ary theory is true, we may expect to find that closely
related species are frequently located near each other;
and that when they are widely separated — for example,
by seas or oceans — facts are available which point to
the possibility and even the likelihood of their early
migration from a common centre. We may also ex-
pect to find that when the fauna and flora of two terri-
tories have always been effectually isolated from each
other, whether by insurmountable mountain ranges or
by geologically permanent bodies of water, their species
differ widely. The facts agree with this expectation
to a marked degree. It is true that apparent excep-
tions exist. Closely allied species are found on oppo-
site sides of the globe; and the fauna and flora of
certain islands — for example, Madagascar and New
Zealand — differ widely from those of neighbouring
continents and islands. But these anomalies can
usually be accounted for by geological investigation.
North America and the continent of Europe were in
former ages connected by land. The comparative
similarity which has been discovered between the
species of Great Britain and Japan is accounted for
by the absence of any permanent barriers between
them, whether of climate or of geological nature. On
the other hand the depth of water which now separates
Madagascar and New Zealand from the nearest land
seems to prove that the present isolation of their fauna



84 EVroENCES AND LIMITATIONS

and flora has existed without break from the earliest
geological period. Some apparent anomalies remain
to be explained, but the facts in general of geographical
distribution point to a common origin of species of the
same order, and no other explanation appears to be
available.^

The evidence which I have thus far summarized is
circumstantial and indirect; although its quantity and
diversity is very great, and it is regarded by those who
are most competent to estimate its value as very con-
vincing. The question remains to be faced, is there
any direct evidence? Has anyone ever observed the
origin of species by means of variation and descent
from older species ? If so, have the instances observed
been of sufficient number and diversity to justify such
an extensive generalization as the evolutionary hypothe-
sis? That direct evidence ought to be demanded for
such an important theory as this, if the nature of the
facts and processes involved permits their discovery,
is not to be denied. But if, from the nature of things,
little or no direct evidence can be expected to be forth-
coming, whether favourable or unfavourable to the
doctrine of evolution, and if the available indirect evi-
dence seems to be abundant and convincing, we ought
to be determined in our views by such evidence. This
is especially the case when such an attitude of mind
is entirely consistent with loyalty to revealed truth and
to the fundamental principles of supernatural religion.

1 A. R. Wallace treats clearly and adequately of this subject, in
Darwinism, ch. xii. See also Darwin, op. cit., chh. xii, xiii.



SUMMARY OF EVIDENCE 85

Now the natural development of species is either a
long-drawn-out process or a comparatively rare event,
whatever may be the true description of the method of
evolution. If the Darwinian description is correct, the
development of one independent species from another
must consume a much longer period of time than has
elapsed since men have begun to investigate the process.
If, on the other hand, the mutations theory of de Vries
is to be accepted, the origin of a new species, sudden
though it be, must occur at rare intervals — too rare
for the observance of many instances within the brief
time that has gone by since men have taken intelligent
notice of biological phenomena. The conclusion to
which we are driven is that we ought not to expect to
obtain much or conclusive direct evidence of the natural


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Online LibraryFrancis J. (Francis Joseph) HallEvolution and the fall → online text (page 6 of 17)