Vernon L. (Vernon Lyman) Kellogg.

Darwinism to-day; a discussion of present-day scientific criticism of the Darwinian selection theories, together with a brief account of the principal other proposed auxilary and alternative theories of species-forming online

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Online LibraryVernon L. (Vernon Lyman) KelloggDarwinism to-day; a discussion of present-day scientific criticism of the Darwinian selection theories, together with a brief account of the principal other proposed auxilary and alternative theories of species-forming → online text (page 8 of 38)
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confusion, instead of the species being, as we see them, well
defined ?"

Professor Morgan, in his "Evolution and Adaptation,"
discusses this objection in the following paragraphs (pp.
129-131) :

"The answer that Darwin gives [to his own just quoted
query] is, that by competition the new form will crowd out
its own less-improved parent form, and other less-favoured
forms. But is this a sufficient or satisfactory answer? If


we recall what Darwin has said on the advantage that
those forms will have in which a great number of new
variations appear to fit them to the great diversity of
natural conditions, and if we recall the gradations that exist
in external conditions, I think we shall find that Darwin's
reply fails to give a satisfactory answer to the question.

"It is well known, and Darwin himself has commented on
it, that the same species often remains constant under very
diverse external conditions, both inorganic and organic.
Hence I think the explanation fails, in so far as it is based
on the accumulation by selection of small individual varia-
tions that are supposed to give the individuals some slight
advantage under each set of external conditions. Darwin
admits that 'this difficulty for a long time quite confounded
me. But I think it can be in large part explained.' The
first explanation that is offered is that areas now continuous
may not have been so in the past. This may be true in
places, but the great continents have had continuous areas
for a long time, and Darwin frankly acknowledges that he
'will pass over this way of explaining the difficulty.' The
second attempt is based on the supposed narrowness of the
area, where two species, descended from a common parent,
overlap. In this region the change is often very abrupt,
and Darwin adds :

" 'To those who look at climate and the physical condi-
tions of life as the all-important elements of distribution,
these facts ought to cause surprise, as climate and height
or depth graduate away insensibly. But when we bear in
mind that almost every species, even in its metropolis, would
increase immensely in numbers, were it not for other com-
peting species ; that nearly all either prey on or serve as
prey for others ; in short, that each organic being is either
directly or indirectly related in the most important manner
to other organic beings, we see that the range of the in-
habitants of any country by no means exclusively depends


on insensibly changing physical conditions, but in a large
part on the presence of other species, on which it lives, or
by which it is destroyed, or with which it comes into com-
petition; and as these species are already defined objects,
not blending one into another by insensible gradations, the
range of any one species, depending as it does on the range
of others, will tend to be sharply defined.'

"Here we have a petitio principii. The sharp definition of
species, that we started out to account for, is explained by
the sharp definition of other species !

"A third part of the explanation is that, owing to the
relative fewness of individuals at the confines of the range
during the fluctuations of their enemies, or of their prey,
or in the nature of the seasons, they would be extremely
liable to utter extermination. If this were really the case,
then new species themselves which, on the theory, are at
first few in numbers ought to be exterminated. On the
whole, then, it does not appear that Darwin has been very
successful in his attempt to meet this objection to the

A rather surprising objection is that of Pfeffer," who

contends that selection cannot be the cause of the formation

of species, for if it were real, however feeble

Pfeffer's objeo- .

tion based on the J ts effects, it would transform species much
slowness of spe- more rapidly than they are transformed: and in

cies change. .

order to transform a species in a long time the
protection afforded by the selection of small additions or
modifications is so feeble as to be illusory. And adequate
protection under such a system of species transformation
is imperative. This is a curious argument, for it has always
been one of the claims of the mutationists that a "hurry-
up" theory is needed in order to satisfy the familiar objec-
tion that the physicists' estimate of the actual age of the
world is too low to admit of the production of the hosts of
kinds of animals and plants which we know to have existed


by the process of natural selection. But Pfeffer, who is
an ingenious debater, makes out a very plausible case for his

Of the many special questions that hay,e been asked of the
selectionists two may be mentioned, simply as examples illus-
trative of a rather formidable category of objections most
of which are concerned with certain particular phases of
evolution or groups of evolution phenomena rather than
with the whole problem of species-forming. Many such
special objections or questions touching specific cases were
taken up and answered by Darwin in his "Origin of
Species." Morgan has recently ("Evolution and Adapta-
tion") gone over critically many of these special objections
and Darwin's answers to them, and pointed out clearly
that in numerous cases Darwin relied for his answers on
evolution factors which the neo-Darwinians have attempted
to read out of court. In many tight places Darwin availed
himself of the Lamarckian factor of the cumulation, through
inheritance, of the effects of use and disuse, or of other
functional stimuli originating either in internal or ex-
trinsic conditions. That is, Darwin, while constantly trying
to rely, and whenever possible relying on natural selection
as the species-forming and adaptation-explaining cause,
never hesitated, when it seemed necessary, to admit the
influence and effect of the inheritance of acquired characters
or the influence of other, to him, unknown factors. In
most cases of degeneration, for example, he adopted a
Lamarckian explanation.

The question of how sterility between species could have

arisen is a case in point. "That this property of species is

useful to them in the somewhat unusual sense

eipSn^inter- that li kee P s them from freel y mingling with
species sterility other species is true," says Morgan ; "but this

by selection.

would be a rather peculiar kind of adaptation.
If, however, it be claimed that this property is useful to


species, as Darwin himself claims, then, as he also points out,
it is a useful acquirement that cannot have arisen through
natural selection. It is not difficult to show why this must
be so. If two varieties were to some extent at the start
less fertile, inter se, than with their own kind, the only way
in which they could become more infertile through selection
would be by selecting those individuals in each generation
that' are still more infertile, but the forms of this sort would,
ex hypothese, become less numerous than the descendants
of each species itself, which would, therefore, supplant the
less fertile ones." Darwin admits that this situation cannot
apparently be explained by natural selection, and simply
says that to him it appears "that the sterility both of first
crosses and of hybrids is simply incidental or dependent on
unknown differences in their reproductive systems."

Wolff 9 has urged strongly the objection that natural selec-
tion does not explain the degeneration or atrophy of parts,
at ^ east not ^ ar e or near ty complete reduction.

OVection tha
selection cannot And Weismann and other selectionists long

l ago conceded that some sort of auxiliary prin-
generationof ciple was necessary to explain degeneration on
a Darwinian basis. This principle was supplied
by Weismann, under the name of panmixia, which is, simply,
that a constantly active selection is necessary not only for
the evolutionary development or specialisation of an organ
but as well for its retention in specialised condition. 19 '
So that an organ which is no longer used and is therefore
useless comes no longer under the supporting influence of
selection (on the basis of advantage) and must consequently
degenerate. But, as Wolff says, it seems obvious that such
an influence or effect of the cessation of selection or of
panmixia (so-called by Weismann because all variations
good and bad alike mix and compensate each other) can
at best lead to degeneration or atrophy only when the
negative or reducing variations are in the majority, for when


this is not the case the average of the survivors cannot
change. Weismann himself has in recent years recognised
the inadequacy of panmixia alone to explain degenerative
phenomena. He says : 12 . . . "In most retrogressive pro-
cesses active selection in Darwin's sense plays no part,
and advocates of the Lamarckian principle, as above re-
marked, have rightly denied that active selection, that is,
the selection of individuals possessing the useless organ in
its most reduced state, is sufficient to explain the process of
degeneration. I, for my part, have never assumed this,
and have on this very account enunciated the principle of
panmixia. Now, although this, as I have still no reason
for doubting, is a perfectly correct principle, which really
does have an essential and indispensable share in the process
of retrogression, still it is not alone sufficient for a full ex-
planation of the phenomena. My opponents, in advancing
this objection, were right, to the extent indicated, and as
I expressly acknowledge, although they were unable to
substitute anything positive in its stead or to render my
explanation complete. The very fact of the cessation of
control over the organ is sufficient to explain its degenera-
tion, that is, its deterioriation, the disharmony of its parts,
but not the fact which actually and always occurs where an
organ has become useless viz., its gradual and unceasing
diminution continuing for thousands and thousands of years
and culminating in its final and absolute effacement."

To supply the lack in the present neo-Darwinian explana-
tion of retrogression Weismann calls on his new theory of
germinal selection, the "rehabilitator of the natural selec-
tion theory" (for an account of this theory see chapter viii).
But Wolff and Morgan and others have shown how unsatis-
factory and inadequate this third attempt at an explanation
is, even if we grant the actuality of germinal selection, a
hypothesis which has by no means met with any general
acceptance by biologists.


In all our discussion of the effectiveness of the natural
selection theory one feature of it has so far not been ques-
tioned. And that is the actual selecting power when the
variations or differences among individuals are large enough
to be conceivably of real advantage or disadvantage to the
respective organisms. That is to say, we have not brought
into question the alleged rigour of the struggle for existence
upoi> which rigour depends, of course, the selection and the
survival of the fittest. The very phrases "struggle for ex-
istence" and "survival of the fittest" presuppose and assume
a rigour of competition and a life-and-death-determining
value of the variations or differences that are fundamental
features of the natural selection theory. Let us, however,
not hesitate to scrutinise these basic assumptions of the

What of the actual rigour of the struggle that must be
presupposed in order to give small variations a life-and-
death-determining worth ? Does it exist ? Has
claimed extreme it been observed? Is the actual (admitted)
Sgglf and the production of thousands or millions of eggs

consequent per- or embryos in localities capable of supporting
sonal selection. , , ,, ..,..,, /-/-

but tens or hundreds of individuals, sufficient
reason for deducing an endless, searching, utterly rigorous
competition sufficient to give the slightest variations
a weight in the balances determining death , or life ?
In the first place, this tremendous competition must be
largely over, if it exists, before the individuals come to
maturity. Especially is this absolutely true of all species
that live for a long time in immature stages and a very short
time in the adult stage, as the Mayflies 1S with only a night-
long adult life. Many insects of complete metamorphosis
(/. e., those whose adult stage, assumed during a quiescent
encased pupal stage, is very different from their larval
stage) which have very elaborate structural specialisations in
the adult stage have had their fate as offspring-producing;


agents decided for them in immature, /. e., egg, larval, or
pupal, life, and this immature life is in most cases by far
the larger part of the insect's duration of existence.

Henslow 14 sowed together the same quantity of two
kinds of wheat in a square yard of ground. The young
wheat plants that came up were many times as many as the
soil could support ; the passive struggle for life was intense.
In the end twenty heads ripened and these were all of one
of the two kinds sown. The experiment was repeated in
the following year with the same result. In the struggle
one kind of wheat had a distinct advantage over the other.
But this selection depended wholly on special characters or
strength of the young stages. None of the adult characters
cut any figure in this selection, which was decided before
ever the plants came to maturity. And this is true, it seems
to me, of most of struggle and selection.

It is not in the adult state that the oppressive abundance
exists : in the forest to-day are about as many crows as last
year ; in the meadows as many yellow butterflies as in sum-
mers by. The eggs and the young are the stages which
figure in mortality tables. They need the variations and
adaptations ; the pressure is largely gone before maturity is
reached. However, the adaptations of the fully-developed
body, in structure and function, certainly do not fall behind
those of the embryonic and immature stages. Indeed they
obviously are more complex and perfected.

But after all what determines just what millions of trout's
Indiscriminate e gg s shall be destroyed and what thousands
deathi shall hatch small fry ? Many a sharp-eyed trout

fisherman, many a keen-witted nature observer, many a
trained biologist will answer : Chiefly chance, the luck of
position, the good fortune of not being devoured by the
roaming things that paddle or crawl in the upper reaches of
trout streams. What shall decide when the big whale opens
his mouth in the midst of a shoal of myriads of tiny


Copepods floating in the pelagic waters of the Aleutian seas,
what Copepods shall disappear forever? Mainly, we may
say, the chance of position. A bit more or less of size, or
strength, or redness, or yellowness, or irritability or what
not of form and function is going to avail little when the
water rushes into the yawning throat. Now this chance
and this luck are the luck and chance of the law of prob-
abilities; that is, luck and chance capable of being mathe-
matically determined. Given so much ocean, with so many
whales swimming about in such and such curves at such and
such rates and opening and closing their mouths inter-
mittently at such and such intervals, and just so many
shoals of so many million Copepods, these shoals at such and
such distances apart, and any mathematical friend will
reckon for you the chances any one Copepod individual has
at any given moment of being swallowed. But Darwinian
variations in the Copepod body will be represented by no
function in the mathematician's formula. When the scores
of little streams dry in California every summer, what deter-
mines whether millions of Californian water-insects of
scores of kinds shall die in July or not? Mainly life or
death is determined for them by their good or ill luck in
being in one of the few streams that do not dry up, or in
one of the many that do dry. Kelsey Creek runs into
Clear Lake, in northern California ; it is usually ever-living,
but some summers it suddenly dries up. Fish play back and
forth between this stream and the lake ; at the time of the
sudden drying a few hundreds of thousands out of many
hundreds of thousands that habitually live in the stream and
adjacent lake waters find themselves one awful day gasping
painfully for water to wet their drying gills. They gasp a
short while and then die. Did they all have the same num-
ber of scales, the same shape and size of body, the same
tinges of fleeting colour ? No, they represented most of the
possible gamut of Darwinian variation for their particular


species. But they were dead all together, by the ill-chance
of position. In Lagunita, a small artificial lake on the
campus of Stanford University, water pours in from two or
three rivulets during the rainy season so as to fill it and
make it an abiding place for many aquatic organisms that
swim in or are washed in through the dikes. And thou-
sands of little fishes and water beetles and dragon-fly
nymphs and the like live contentedly there for seven or eight
months. But with the rainless summer months come swift
evaporation and steady leakage, and by September all the
thousands of little fishes and insects lie dying there together
in the last few puddles. It is the hard luck of a fatal chance
against which all the variations in colour, in size, in scales,
in spines, and what not are as one as far as helping or sav-
ing any of the gasping possessors is concerned.

One might go on tiresomely but one does not need to point
the moral of these tales. Wolff 1S has clearly fancied how
the fate of millions of tapeworms may hang on the recep-
tion in the German Reichstag of a clever speech for or
against meat laws. To go so far isn't necessary : the very
life-history of the tapeworm and of hundreds of similarly-
lived vermian parasites shows to what nearly absolute de-
gree chance rules their fate, and how utterly insignificant
a part in it miscellaneous individual variation can possibly

But aside from the part that what we may call fortune 1<r
of position plays in determining life or death among indi-
viduals, what of the actual rigour of the strug-
sonai^el*ction? r ~ ^ e * n those cases where death does not come
to thousands at a moment; in the whale's
mouth, by catastrophe of flood or drouth, or by the elephant's
tread on the ant-hill? To this question of the rigour of
intra-specific struggle I have given some personal attention
in insect life, and while to detail observations here would
be impossible, I may say baldly that no such rigour of in-


dividual selection based on variation 1T in colour, in pattern,
in venation and other wing characters, in hairs and in
numerous other structural characters, as demanded by the
needs of the selection theory, is to be detected. I find
just as much variation represented in series of mature
individuals collected miscellaneously after having lived for
more or less time a. free life exposed to all the dangers of
this life, exposed, that is, to the rigour of the individual
struggle for existence, as among series of similar extent of
individuals of the same species collected just at the time of
reaching maturity but before enjoying any opportunity to
be weeded out (on a basis of disadvantageous variation)
by the rigour of the life-struggle. Just as many varying
individuals, with variations of just as much extent and va-
riety, were found in series exposed to the struggle, in which
these variations are presumably capable of saving or losing
life, as among series not yet exposed; in other words, just
as much variation exists after enduring the selective rigour
of the struggle as existed on the day when the insects are
first exposed to it.

Conn 18 expresses his belief concerning destruction by
chance and the rigour of the struggle as follows :

Conn's discus- "Indiscriminate destruction occurs con-
sion of the chances stantly, and certainly influences the problem of
survival. Of the hundreds of individuals that
are produced where few can live, many are destroyed in-
discriminately, independent of the principle of survival of
the fittest, and of these that are thus killed doubtless some
are superior to those that survive. This principle of indis-
criminate elimination does not in the slightest deny the
force of the principle of survival of the fittest, but only indi-
cates that its action is not absolutely rigid. The fittest do
not always survive, for many of them are destroyed.

"On the other hand the least fit do not always perish.
Whether an individual shall live or die in the struggle is


largely a matter of accident. Many a well-equipped indi-
vidual will die, while many another, even though handi-
capped by decidedly unfavourable characters, will continue
to live and produce offspring because of some specially
favourable conditions. Nothing could seem to be more
decidedly disadvantageous than a broken leg, and, if the
principle of elimination of the unfit were rigid, broken-legged
individuals should be speedily destroyed. But it is quite
common to find animals with broken legs or arms which
yet succeed in living perfectly well. They have repaired
their broken members by processes of bone growth, and have
been able to carry on their part in the struggle for life and
survive competition. I have found a frog with the whole
of both feet bitten off, and yet with the wounds healed, the
animal living without feet, and hence hardly able to swim,
but side by side in competition with other well-developed
animals. I have found a clam that in its young condition
had received a severe rent in one gill, through which, by
some twist the body had been thrust, giving rise to the
extraordinary condition of three gills on one side of the
body and one on the other, a truly monstrous abnormity.
But this clam had lived to maturity and produced eggs in
quantities equal to any other clam.

"Now such instances simply show the complexity of the
conditions which determine survival. They indicate that
these animals were favoured in some respects sufficiently to
counteract the disadvantage of their mutilations. But the
fact that so many instances are found does show that single
characters do not always determine survival or elimination.
The question whether an individual survive is dependent
upon many factors, of which utility of various organs may
be one and accident another. What would seem more sure
from a logical standpoint, than that, in the intense struggle
for life due to numerous individuals seeking for food, a
frog who was unable to swim because of the loss of his


feet would be sure to be a loser? Even if the inflammation
caused by the wound did not destroy him, it would seem
impossible for the animal to obtain his share of food. Of
course, a footless race would be eliminated in a compara-
tively short time, but the survival of so many mutilated
individuals shows that selection is not so rigid as to eliminate
all unfit individuals, -even though their disadvantage be very

"If a very disadvantageous character may thus fail to pro-
duce destruction it must be still more true that a favour-
able character, occurring in a single individual, has really
little chance for survival. The individual possessing it will
have to compete with accident, with indiscriminate slaughter,
and with other conditions which we have just seen may be
sufficient to preserve even a broken-legged individual.
Nothing can seem more evident than that the web of the
foot and the muscles of the legs are of use in swimming,
and have therefore been developed by the preserving influ-
ence of natural selection. If anything is of selective value,
these characters certainly are. But when we find that a
frog with 'no feet can survive the struggle for existence, it
is evidently difficult to believe that single variations, either of
use or disadvantage, will have any special likelihood of sur-
viving at the expense of other members of the race, so as
eventually to replace all others. But only thus can they
be 'seized upon by natural selection and preserved.' "

There are two important objections to the natural selec-
tion theory based on the relations of this theory with the
two other selection theories, namely sexual
tion needs the selection and artificial selection. Wolff 1 ' has

Online LibraryVernon L. (Vernon Lyman) KelloggDarwinism to-day; a discussion of present-day scientific criticism of the Darwinian selection theories, together with a brief account of the principal other proposed auxilary and alternative theories of species-forming → online text (page 8 of 38)