THE MULTIPLICATION OF EFFECTS.
§ 116. To the cause of increasing complexity set forth in the last
chapter, we have in this chapter to add another. Though secondary in
order of time, it is scarcely secondary in order of importance. Even in
the absence of the cause already assigned, it would necessitate a change
from the homogeneous to the heterogeneous; and joined with it, it makes
this change both more rapid and more involved. To come in sight of it,
we have but to pursue a step further, that conflict between force and
matter already delineated. Let us do this.
When a uniform aggregate is subject to a uniform force, we have seen
that its constituents, being differently conditioned, are differently
modified. But while we have contemplated the various parts of the
aggregate as thus undergoing unlike changes, we have not yet
contemplated the unlike changes simultaneously produced on the various
parts of the incident force. These must be as numerous and important as
the others. Action and re-action being equal and opposite, it follows
that in differentiating the parts on which it falls in unlike ways, the
incident force must itself be correspondingly differentiated. Instead of
being as before, a uniform force, it must thereafter be a multiform
force—a group of dissimilar forces. A few illustrations will make this
truth manifest.
A single force is divided by conflict with matter into forces that
widely diverge. In the case lately cited, of a body shattered by violent
collision, besides the change of the homogeneous mass into a
heterogeneous group of scattered fragments, there is a change of the
homogeneous momentum into a group of momenta, heterogeneous in both
amounts and directions. Similarly with the forces we know as light and
heat. After the dispersion of these by a radiating body towards all
points, they are re-dispersed towards all points by the bodies on which
they fall. Of the Sun’s rays, issuing from him on every side, some few
strike the Moon. These being reflected at all angles from the Moon’s
surface, some few of them strike the Earth. By a like process the few
which reach the Earth are again diffused through surrounding space. And
on each occasion, such portions of the rays as are absorbed instead of
reflected, undergo refractions that equally destroy their parallelism.
More than this is true. By conflict with matter, a uniform force
is in part changed into forces differing in their directions; and in
part it is changed into forces differing in their kinds. When one body
is struck against another, that which we usually regard as the effect,
is a change of position or motion in one or both bodies. But a moment’s
thought shows that this is a very incomplete view of the matter. Besides
the visible mechanical result, sound is produced; or, to speak
accurately, a vibration in one or both bodies, and in the surrounding
air: and under some circumstances we call this the effect. Moreover, the
air has not simply been made to vibrate, but has had currents raised in
it by the transit of the bodies. Further, if there is not that great
structural change which we call fracture, there is a disarrangement of
the particles of the two bodies around their point of collision;
amounting in some cases to a visible condensation. Yet more, this
condensation is accompanied by disengagement of heat. In some cases a
spark—that is, light—results, from the incandescence of a portion struck
off; and occasionally this incandescence is associated with chemical
combination. Thus, by the original mechanical force expended in the
collision, at least five, and often more, different kinds of forces have
been produced. Take, again, the lighting of a candle. Primarily, this is
a chemical change consequent on a rise of temperature. The process of
combination having once been set going by extraneous heat, there is a
continued formation of carbonic acid, water, &c.—in itself a result more
complex than the extraneous heat that first caused it. But along with
this process of combination there is a production of heat; there is a
production of light; there is an ascending column of hot gases
generated; there are currents established in the surrounding air. Nor
does the decomposition of one force into many forces end here. Each of
the several changes worked becomes the parent of further changes. The
carbonic acid formed, will by and by combine with some base; or under
the influence of sunshine give up its carbon to the leaf of a plant. The
water will modify the hygrometric state of the air around; or, if the
current of hot gases containing it come against a cold body, will be
condensed: altering the temperature, and perhaps the chemical state, of
the surface it covers. The heat given out melts the subjacent tallow,
and expands whatever it warms. The light, falling on various substances,
calls forth from them reactions by which it is modified; and so divers
colours are produced. Similarly even with these secondary actions, which
may be traced out into ever-multiplying ramifications, until they become
too minute to be appreciated. Universally, then, the effect is
more complex than the cause. Whether the aggregate on which it falls be
homogeneous or otherwise, an incident force is transformed by the
conflict into a number of forces that differ in their amounts, or
directions, or kinds; or in all these respects. And of this group of
variously-modified forces, each ultimately undergoes a like
transformation.
Let us now mark how the process of evolution is furthered by this
multiplication of effects. An incident force decomposed by the reactions
of a body into a group of unlike forces—a uniform force thus reduced to
a multiform force—becomes the cause of a secondary increase of
multiformity in the body which decomposes it. In the last chapter we saw
that the several parts of an aggregate are differently modified by any
incident force. It has just been shown that by the reactions of the
differently modified parts, the incident force itself must be divided
into differently modified parts. Here it remains to point out that each
differentiated division of the aggregate, thus becomes a centre from
which a differentiated division of the original force is again diffused.
And since unlike forces must produce unlike results, each of these
differentiated forces must produce, throughout the aggregate, a further
series of differentiations. This secondary cause of the change
from homogeneity to heterogeneity, obviously becomes more potent in
proportion as the heterogeneity increases. When the parts into which any
evolving whole has segregated itself, have diverged widely in nature,
they will necessarily react very diversely on any incident force—they
will divide an incident force into so many strongly contrasted groups of
forces. And each of them becoming the centre of a quite distinct set of
influences, must add to the number of distinct secondary changes wrought
throughout the aggregate. Yet another corollary must be added. The
number of unlike parts of which an aggregate consists, as well as the
degree of their unlikeness, is an important factor in the process. Every
additional specialized division is an additional centre of specialized
forces. If a uniform whole, in being itself made multiform by an
incident force, makes the incident force multiform; if a whole
consisting of two unlike sections, divides an incident force into two
unlike groups of multiform forces; it is clear that each new unlike
section must be a further source of complication among the forces at
work throughout the mass—a further source of heterogeneity. The
multiplication of effects must proceed in geometrical progression. Each
stage of evolution must initiate a higher stage.
* * * * *
§ 117. The force of aggregation acting on irregular masses of rare
matter, diffused through a resisting medium, will not cause such masses
to move in straight lines to their common centre of gravity; but, as
before said, each will take a curvilinear path, directed to one or other
side of the centre of gravity. All of them being differently
conditioned, gravitation will impress on each a motion differing in
direction, in velocity, and in the degree of its curvature—uniform
aggregative force will be differentiated into multiform momenta. The
process thus commenced, must go on till it produces a single mass of
nebulous matter; and these independent curvilinear motions must result
in a movement of this mass round its axis: a simultaneous condensation
and rotation in which we see how two effects of the aggregative force,
at first but slightly divergent, become at last widely differentiated. A
gradual increase of oblateness in this revolving spheroid, must take
place through the joint action of these two forces, as the bulk
diminishes and the rotation grows more rapid; and this we may set down
as a third effect. The genesis of heat, which must accompany
augmentation of density, is a consequence of yet another order—a
consequence by no means simple; since the various parts of the mass,
being variously condensed, must be variously heated. Acting throughout a
gaseous spheroid, of which the parts are unlike in their temperatures,
the forces of aggregation and rotation must work a further series of
changes: they must set up circulating currents, both general and local.
At a later stage light as well as heat will be generated. Thus without
dwelling on the likelihood of chemical combinations and electric
disturbances, it is sufficiently manifest that, supposing matter to have
originally existed in a diffused state, the once uniform force which
caused its aggregation, must have become gradually divided into
different forces; and that each further stage of complication in the
resulting aggregate, must have initiated further subdivisions of this
force—a further multiplication of effects, increasing the previous
heterogeneity.
This section of the argument may however be adequately sustained,
without having recourse to any such hypothetical illustrations as the
foregoing. The astronomical attributes of the Earth, will even alone
suffice our purpose. Consider first the effects of its momentum round
its axis. There is the oblateness of its form; there is the alternation
of day and night; there are certain constant marine currents; and there
are certain constant aërial currents. Consider next the secondary series
of consequences due to the divergence of the Earth’s plane of rotation
from the plane of its orbit. The many differences of the seasons, both
simultaneous and successive, which pervade its surface, are thus caused.
External attraction acting on this rotating oblate spheroid with
inclined axis, produces the motion called nutation, and that slower and
larger one from which follows the precession of the equinoxes, with its
several sequences. And then by this same force are generated the tides,
aqueous and atmospheric.
Perhaps, however, the simplest way of showing the multiplication of
effects among phenomena of this order, will be to set down the
influences of any member of the Solar System on the rest. A planet
directly produces in neighbouring planets certain appreciable
perturbations, complicating those otherwise produced in them; and in the
remoter planets it directly produces certain less visible perturbations.
Here is a first series of effects. But each of the perturbed planets is
itself a source of perturbations—each directly affects all the others.
Hence, planet A having drawn planet B out of the position it would have
occupied in A’s absence, the perturbations which B causes are different
from what they would else have been; and similarly with C, D, E, &c.
Here then is a secondary series of effects: far more numerous though far
smaller in their amounts. As these indirect perturbations must to some
extent modify the movements of each planet, there results from them a
tertiary series; and so on continually. Thus the force exercised by any
planet works a different effect on each of the rest; this different
effect is from each as a centre partially broken up into minor different
effects on the rest; and so on in ever multiplying and diminishing waves
throughout the entire system.
* * * * *
§ 118. If the Earth was formed by the concentration of diffused matter,
it must at first have been incandescent; and whether the nebular
hypothesis be accepted or not, this original incandescence of the Earth
must now be regarded as inductively established—or, if not established,
at least rendered so probable that it is a generally admitted geological
doctrine. Several results of the gradual cooling of the Earth—as the
formation of a crust, the solidification of sublimed elements, the
precipitation of water, &c., have been already noticed—and I here again
refer to them merely to point out that they are simultaneous effects of
the one cause, diminishing heat. Let us now, however, observe the
multiplied changes afterwards arising from the continuance of this one
cause. The Earth, falling in temperature, must contract. Hence the
solid crust at any time existing, is presently too large for the
shrinking nucleus; and being unable to support itself, inevitably
follows the nucleus. But a spheroidal envelope cannot sink down into
contact with a smaller internal spheroid, without disruption: it will
run into wrinkles, as the rind of an apple does when the bulk of its
interior decreases from evaporation. As the cooling progresses and the
envelope thickens, the ridges consequent on these contractions must
become greater; rising ultimately into hills and mountains; and the
later systems of mountains thus produced must not only be higher, as we
find them to be, but they must be longer, as we also find them to be.
Thus, leaving out of view other modifying forces, we see what immense
heterogeneity of surface arises from the one cause, loss of heat—a
heterogeneity which the telescope shows us to be paralleled on the Moon,
where aqueous and atmospheric agencies have been absent. But we
have yet to notice another kind of heterogeneity of surface, similarly
and simultaneously caused. While the Earth’s crust was still thin, the
ridges produced by its contraction must not only have been small, but
the tracts between them must have rested with comparative smoothness on
the subjacent liquid spheroid; and the water in those arctic and
antarctic regions where it first condensed, must have been evenly
distributed. But as fast as the crust grew thicker and gained
corresponding strength, the lines of fracture from time to time caused
in it, necessarily occurred at greater distances apart; the intermediate
surfaces followed the contracting nucleus with less uniformity; and
there consequently resulted larger areas of land and water. If any one,
after wrapping an orange in wet tissue paper, and observing both how
small are the wrinkles and how evenly the intervening spaces lie on the
surface of the orange, will then wrap it in thick cartridge-paper, and
note both the greater height of the ridges and the larger spaces
throughout which the paper does not touch the orange, he will realize
the fact, that as the Earth’s solid envelope thickened, the areas of
elevation and depression became greater. In place of islands more or
less homogeneously scattered over an all-embracing sea, there must have
gradually arisen heterogeneous arrangements of continent and ocean, such
as we now know. This double change in the extent and in the
elevation of the lands, involved yet another species of
heterogeneity—that of coast-line. A tolerably even surface raised out of
the ocean will have a simple, regular sea-margin; but a surface varied
by table-lands and intersected by mountain-chains, will, when raised out
of the ocean, have an outline extremely irregular, alike in its leading
features and in its details. Thus endless is the accumulation of
geological and geographical results slowly brought about by this one
cause—the escape of the Earth’s primitive heat.
When we pass from the agency which geologists term igneous, to aqueous
and atmospheric agencies, we see a like ever-growing complication of
effects. The denuding actions of air and water have, from the beginning,
been modifying every exposed surface: everywhere working many different
changes. As already shown (§ 80) the original source of those gaseous
and fluid motions which effect denudation, is the solar heat. The
transformation of this into various modes of force, according to the
nature and condition of the matter on which it falls, is the first stage
of complication. The sun’s rays, striking at all angles a sphere, that
from moment to moment presents and withdraws different parts of its
surface, and each of them for a different time daily throughout the
year, would produce a considerable variety of changes even were the
sphere uniform. But falling as they do on a sphere surrounded by an
atmosphere in some parts of which wide areas of cloud are suspended, and
which here unveils vast tracts of sea, there of level land, there of
mountains, there of snow and ice, they initiate in its several parts
countless different movements. Currents of air of all sizes, directions,
velocities, and temperatures, are set up; as are also marine currents
similarly contrasted in their characters. In this region the surface is
giving off water in the state of vapour; in that, dew is being
precipitated; and in the other rain is descending—differences that arise
from the ever-changing ratio between the absorption and radiation of
heat in each place. At one hour, a rapid fall in temperature leads to
the formation of ice, with an accompanying expansion throughout the
moist bodies frozen; while at another, a thaw unlocks the dislocated
fragments of these bodies. And then, passing to a second stage of
complication, we see that the many kinds of motion directly or
indirectly caused by the sun’s rays, severally produce results that vary
with the conditions. Oxidation, drought, wind, frost, rain, glaciers,
rivers, waves, and other denuding agents effect disintegrations that are
determined in their amounts and qualities by local circumstances. Acting
upon a tract of granite, such agents here work scarcely an appreciable
effect; there cause exfoliations of the surface, and a resulting heap of
_débris_ and boulders; and elsewhere, after decomposing the feldspar
into a white clay, carry away this with the accompanying quartz and
mica, and deposit them in separate beds, fluviatile and marine. When the
exposed land consists of several unlike formations, sedimentary and
igneous, changes proportionably more heterogeneous are wrought. The
formations being disintegrable in different degrees, there follows an
increased irregularity of surface. The areas drained by different rivers
being differently constituted, these rivers carry down to the sea unlike
combinations of ingredients; and so sundry new strata of distinct
composition arise. And here indeed we may see very simply illustrated,
the truth, that the heterogeneity of the effects increases in a
geometrical progression, with the heterogeneity of the object acted
upon. A continent of complex structure, presenting many strata
irregularly distributed, raised to various levels, tilted up at all
angles, must, under the same denuding agencies, give origin to immensely
multiplied results: each district must be peculiarly modified; each
river must carry down a distinct kind of detritus; each deposit must be
differently distributed by the entangled currents, tidal and other,
which wash the contorted shores; and every additional complication of
surface must be the cause of more than one additional consequence. But
not to dwell on these, let us, for the fuller elucidation of this truth
in relation to the inorganic world, consider what would presently follow
from some extensive cosmical revolution—say the subsidence of Central
America. The immediate results of the disturbance would themselves be
sufficiently complex. Besides the numberless dislocations of strata, the
ejections of igneous matter, the propagation of earthquake vibrations
thousands of miles around, the loud explosions, and the escape of gases,
there would be the rush of the Atlantic and Pacific Oceans to supply the
vacant space, the subsequent recoil of enormous waves, which would
traverse both these oceans and produce myriads of changes along their
shores, the corresponding atmospheric waves complicated by the currents
surrounding each volcanic vent, and the electrical discharges with which
such disturbances are accompanied. But these temporary effects would be
insignificant compared with the permanent ones. The complex currents of
the Atlantic and Pacific would be altered in directions and amounts. The
distribution of heat achieved by these currents would be different from
what it is. The arrangement of the isothermal lines, not only on the
neighbouring continents, but even throughout Europe, would be changed.
The tides would flow differently from what they do now. There would be
more or less modification of the winds in their periods, strengths,
directions, qualities. Rain would fall scarcely anywhere at the same
times and in the same quantities as at present. In short, the
meteorological conditions thousands of miles off, on all sides, would be
more or less revolutionized. In these many changes, each of which
comprehends countless minor ones, the reader will see the immense
heterogeneity of the results wrought out by one force, when that force
expends itself on a previously complicated area; and he will readily
draw the corollary that from the beginning the complication has advanced
at an increasing rate.
* * * * *
§ 119. We have next to trace throughout organic evolution, this same
all-pervading principle. And here, where the transformation of the
homogeneous into the heterogeneous was first observed, the production of
many changes by one cause is least easy to demonstrate. The development
of a seed into a plant, or an ovum into an animal, is so gradual; while
the forces which determine it are so involved, and at the same time so
unobtrusive; that it is difficult to detect the multiplication of
effects which is elsewhere so obvious. Nevertheless, by indirect
evidence we may establish our proposition; spite of the lack of direct
evidence.
Observe, first, how numerous are the changes which any marked stimulus
works on an adult organism—a human being, for instance. An alarming
sound or sight, besides impressions on the organs of sense and the
nerves, may produce a start, a scream, a distortion of the face, a
trembling consequent on general muscular relaxation, a burst of
perspiration, an excited action of the heart, a rush of blood to the
brain, followed possibly by arrest of the heart’s action and by syncope;
and if the system be feeble, an illness with its long train of
complicated symptoms may set in. Similarly in cases of disease. A minute
portion of the small-pox virus introduced into the system, will, in a
severe case, cause, during the first stage, rigors, heat of skin,
accelerated pulse, furred tongue, loss of appetite, thirst, epigastric
uneasiness, vomiting, headache, pains in the back and limbs, muscular
weakness, convulsions, delirium, &c.; in the second stage, cutaneous
eruption, itching, tingling, sore throat, swelled fauces, salivation,
cough, hoarseness, dyspnœa, &c.; and in the third stage, œdematous
inflammations, pneumonia, pleurisy, diarrhœa, inflammation of the brain,
ophthalmia, erysipelas, &c.: each of which enumerated symptoms is itself
more or less complex. Medicines, special foods, better air, might in
like manner be instanced as producing multiplied results. Now it
needs only to consider that the many changes thus wrought by one force
on an adult organism, must be partially paralleled in an
embryo-organism, to understand how here also the production of many
effects by one cause is a source of increasing heterogeneity. The
external heat and other agencies which determine the first complications
of the germ, will, by acting on these, superinduce further
complications; on these still higher and more numerous ones; and so on
continually: each organ as it is developed, serving, by its actions and
reactions on the rest, to initiate new complexities. The first
pulsations of the fœtal heart must simultaneously aid the unfolding of
every part. The growth of each tissue, by taking from the blood special
proportions of elements, must modify the constitution of the blood; and
so must modify the nutrition of all the other tissues. The distributive
actions, implying as they do a certain waste, necessitate an addition to
the blood of effete matters, which must influence the rest of the
system, and perhaps, as some think, initiate the formation of excretory
organs. The nervous connections established among the viscera must
further multiply their mutual influences. And so with every modification
of structure—every additional part and every alteration in the ratios of
parts. Still stronger becomes the proof when we call to mind the
fact, that the same germ may be evolved into different forms according
to circumstances. Thus, during its earlier stages, every embryo is
sexless—becomes either male or female as the balance of forces acting on
it determines. Again, it is well-known that the larva of a working-bee
will develop into a queen-bee, if, before a certain period, its food be
changed to that on which the larvæ of queen-bees are fed. Even more
remarkable is the case of certain entozoa. The ovum of a tape-worm,
getting into the intestine of one animal, unfolds into the form of its
parent; but if carried into other parts of the system, or into the
intestine of some unlike animal, it becomes one of the sac-like
creatures, called by naturalists _Cysticerci_, or _Cœnuri_, or
_Echinococci_—creatures so extremely different from the tape-worm in
aspect and structure, that only after careful investigations have they
been proved to have the same origin. All which instances imply that each
advance in embryonic complication results from the action of incident
forces on the complication previously existing. Indeed, the now
accepted doctrine of epigenesis necessitates the conclusion that organic
evolution proceeds after this manner. For since it is proved that no
germ, animal or vegetal, contains the slightest rudiment, trace, or
indication of the future organism—since the microscope has shown us that
the first process set up in every fertilized germ is a process of
repeated spontaneous fissions, ending in the production of a mass of
cells, not one of which exhibits any special character; there seems no
alternative but to conclude that the partial organization at any moment
subsisting in a growing embryo, is transformed by the agencies acting on
it into the succeeding phase of organization, and this into the next,
until, through ever-increasing complexities, the ultimate form is
reached. Thus, though the subtlety of the forces and the slowness
of the metamorphosis, prevent us from _directly_ tracing the genesis of
many changes by one cause, throughout the successive stages which every
embryo passes through; yet, _indirectly_, we have strong evidence that
this is a source of increasing heterogeneity. We have marked how
multitudinous are the effects which a single agency may generate in an
adult organism; that a like multiplication of effects must happen in the
unfolding organism, we have inferred from sundry illustrative cases;
further, it has been pointed out that the ability which like germs have
to originate unlike forms, implies that the successive transformations
result from the new changes superinduced on previous changes; and we
have seen that structureless as every germ originally is, the
development of an organism out of it is otherwise incomprehensible.
Doubtless we are still in the dark respecting those mysterious
properties which make the germ, when subject to fit influences, undergo
the special changes beginning this series of transformations. All here
contended is, that given a germ possessing these mysterious properties,
the evolution of an organism from it depends, in part, on that
multiplication of effects which we have seen to be a cause of evolution
in general, so far as we have yet traced it.
When, leaving the development of single plants and animals, we pass to
that of the Earth’s flora and fauna, the course of the argument again
becomes clear and simple. Though, as before admitted, the fragmentary
facts Palæontology has accumulated, do not clearly warrant us in saying
that, in the lapse of geologic time, there have been evolved more
heterogeneous organisms, and more heterogeneous assemblages of
organisms; yet we shall now see that there _must_ ever have been a
tendency towards these results. We shall find that the production of
many effects by one cause, which, as already shown, has been all along
increasing the physical heterogeneity of the Earth, has further
necessitated an increasing heterogeneity in its flora and fauna,
individually and collectively. An illustration will make this clear.
Suppose that by a series of upheavals, occurring, as they are now
known to do, at long intervals, the East Indian Archipelago were to be
raised into a continent, and a chain of mountains formed along the axis
of elevation. By the first of these upheavals, the plants and animals
inhabiting Borneo, Sumatra, New Guinea, and the rest, would be subjected
to slightly-modified sets of conditions. The climate in general would be
altered in temperature, in humidity, and in its periodical variations;
while the local differences would be multiplied. These modifications
would affect, perhaps inappreciably, the entire flora and fauna of the
region. The change of level would produce additional modifications;
varying in different species, and also in different members of the same
species, according to their distance from the axis of elevation. Plants,
growing only on the sea-shore in special localities, might become
extinct. Others, living only in swamps of a certain humidity, would, if
they survived at all, probably undergo visible changes of appearance.
While more marked alterations would occur in some of the plants that
spread over the lands newly raised above the sea. The animals and
insects living on these modified plants, would themselves be in some
degree modified by change of food, as well as by change of climate; and
the modification would be more marked where, from the dwindling or
disappearance of one kind of plant, an allied kind was eaten. In the
lapse of the many generations arising before the next upheaval, the
sensible or insensible alterations thus produced in each species, would
become organized—in all the races that survived there would be a more or
less complete adaptation to the new conditions. The next upheaval would
superinduce further organic changes, implying wider divergences from the
primary forms; and so repeatedly. Now however let it be observed that
this revolution would not be a substitution of a thousand modified
species for the thousand original species; but in place of the thousand
original species there would arise several thousand species, or
varieties, or changed forms. Each species being distributed over an area
of some extent, and tending continually to colonize the new area
exposed, its different members would be subject to different sets of
changes. Plants and animals migrating towards the equator would not be
affected in the same way with others migrating from it. Those which
spread towards the new shores, would undergo changes unlike the changes
undergone by those which spread into the mountains. Thus, each original
race of organisms would become the root from which diverged several
races, differing more or less from it and from each other; and while
some of these might subsequently disappear, probably more than one would
survive in the next geologic period: the very dispersion itself
increasing the chances of survival. Not only would there be certain
modifications thus caused by changes of physical conditions and food;
but also in some cases other modifications caused by changes of habit.
The fauna of each island, peopling, step by step, the newly-raised
tracts, would eventually come in contact with the faunas of other
islands; and some members of these other faunas would be unlike any
creatures before seen. Herbivores meeting with new beasts of prey,
would, in some cases, be led into modes of defence or escape differing
from those previously used; and simultaneously the beasts of prey would
modify their modes of pursuit and attack. We know that when
circumstances demand it, such changes of habit _do_ take place in
animals; and we know that if the new habits become the dominant ones,
they must eventually in some degree alter the organization.
Observe now, however, a further consequence. There must arise not
simply a tendency towards the differentiation of each race of organisms
into several races; but also a tendency to the occasional production of
a somewhat higher organism. Taken in the mass, these divergent
varieties, which have been caused by fresh physical conditions and
habits of life, will exhibit alterations quite indefinite in kind and
degree; and alterations that do not necessarily constitute an advance.
Probably in most cases the modified type will be not appreciably more
heterogeneous than the original one. But it _must_ now and then occur,
that some division of a species, falling into circumstances which give
it rather more complex experiences, and demand actions somewhat more
involved, will have certain of its organs further differentiated in
proportionately small degrees—will become slightly more heterogeneous.
Hence, there will from time to time arise an increased heterogeneity
both of the Earth’s flora and fauna, and of individual races included in
them. Omitting detailed explanations, and allowing for the
qualifications which cannot here be specified, it is sufficiently clear
that geological mutations have all along tended to complicate the forms
of life, whether regarded separately or collectively. That
multiplication of effects which has been a part-cause of the
transformation of the Earth’s crust from the simple into the complex,
has simultaneously led to a parallel transformation of the Life upon its
surface.[17]
The deduction here drawn from the established truths of geology and the
general laws of life, gains immensely in weight on finding it to be in
harmony with an induction drawn from direct experience. Just that
divergence of many races from one race, which we inferred must have been
continually occurring during geologic time, we know to have occurred
during the pre-historic and historic periods, in man and domestic
animals. And just that multiplication of effects which we concluded must
have been instrumental to the first, we see has in a great measure
wrought the last. Single causes, as famine, pressure of population, war,
have periodically led to further dispersions of mankind and of dependent
creatures: each such dispersion initiating new modifications, new
varieties of type. Whether all the human races be or be not derived from
one stock, philology makes it clear that whole groups of races, now
easily distinguishable from each other, were originally one race—that
the diffusion of one race into different climates and conditions of
existence has produced many altered forms of it. Similarly with domestic
animals. Though in some cases (as that of dogs) community of origin will
perhaps be disputed, yet in other cases (as that of the sheep or the
cattle of our own country) it will not be questioned that local
differences of climate, food, and treatment, have transformed one
original breed into numerous breeds, now become so far distinct as to
produce unstable hybrids. Moreover, through the complication of effects
flowing from single causes, we here find, what we before inferred, not
only an increase of general heterogeneity, but also of special
heterogeneity. While of the divergent divisions and subdivisions of the
human race, many have undergone changes not constituting an advance;
others have become decidedly more heterogeneous. The civilized European
departs more widely from the vertebrate archetype than does the savage.
* * * * *
§ 120. A sensation does not expend itself in arousing some single state
of consciousness; but the state of consciousness aroused is made up of
various represented sensations connected by co-existence, or sequence
with the presented sensation. And that, in proportion as the grade of
intelligence is high, the number of ideas suggested is great, may be
readily inferred. Let us, however, look at the proof that here too, each
change is the parent of many changes; and that the multiplication
increases in proportion as the area affected is complex.
Were some hitherto unknown bird, driven say by stress of weather from
the remote north, to make its appearance on our shores, it would excite
no speculation in the sheep or cattle amid which it alighted: a
perception of it as a creature like those constantly flying about, would
be the sole interruption of that dull current of consciousness which
accompanies grazing and rumination. The cow-herd, by whom we may suppose
the exhausted bird to be presently caught, would probably gaze at it
with some slight curiosity, as being unlike any he had before seen—would
note its most conspicuous markings, and vaguely ponder on the questions,
where it came from, and how it came. The village bird-stuffer would have
suggested to him by the sight of it, sundry forms to which it bore a
little resemblance; would receive from it more numerous and more
specific impressions respecting structure and plumage; would be reminded
of various instances of birds brought by storms from foreign parts—would
tell who found them, who stuffed them, who bought them. Supposing the
unknown bird taken to a naturalist of the old school, interested only in
externals, (one of those described by the late Edward Forbes, as
examining animals as though they were merely skins filled with straw,)
it would excite in him a more involved series of mental changes: there
would be an elaborate examination of the feathers, a noting of all their
technical distinctions, with a reduction of these perceptions to certain
equivalent written symbols; reasons for referring the new form to a
particular family, order, and genus would be sought out and written
down; communications with the secretary of some society, or editor of
some journal, would follow; and probably there would be not a few
thoughts about the addition of the _ii_ to the describer’s name, to form
the name of the species. Lastly, in the mind of a comparative anatomist,
such a new species, should it happen to have any marked internal
peculiarity, might produce additional sets of changes—might very
possibly suggest modified views respecting the relationships of the
division to which it belonged; or, perhaps, alter his conceptions of the
homologies and developments of certain organs; and the conclusions drawn
might not improbably enter as elements into still wider inquiries
concerning the origin of organic forms.
From ideas let us turn to emotions. In a young child, a father’s anger
produces little else than vague fear—a disagreeable sense of impending
evil, taking various shapes of physical suffering or deprivation of
pleasures. In elder children, the same harsh words will arouse
additional feelings: sometimes a sense of shame, of penitence, or of
sorrow for having offended; at other times, a sense of injustice, and a
consequent anger. In the wife, yet a further range of feelings may come
into existence—perhaps wounded affection, perhaps self-pity for
ill-usage, perhaps contempt for groundless irritability, perhaps
sympathy for some suffering which the irritability indicates, perhaps
anxiety about an unknown misfortune which she thinks has produced it.
Nor are we without evidence that among adults, the like differences of
development are accompanied by like differences in the number of
emotions that are aroused, in combination or rapid succession—the lower
natures being characterized by that impulsiveness which results from the
uncontrolled action of a few feelings; and the higher natures being
characterized by the simultaneous action of many secondary feelings,
modifying those first awakened.
Possibly it will be objected that the illustrations here given, are
drawn from the functional changes of the nervous system, not from its
structural changes; and that what is proved among the first, does not
necessarily hold among the last. This must be admitted. Those, however,
who recognize the truth that the structural changes are the slowly
accumulated results of the functional changes, will readily draw the
corollary, that a part-cause of the evolution of the nervous system, as
of other evolution, is this multiplication of effects which becomes ever
greater as the development becomes higher.
* * * * *
§ 121. If the advance of Man towards greater heterogeneity in both body
and mind, is in part traceable to the production of many effects by one
cause, still more clearly may the advance of Society towards greater
heterogeneity be so explained. Consider the growth of an industrial
organization. When, as must occasionally happen, some individual of a
tribe displays unusual aptitude for making an article of general use (a
weapon, for instance) which was before made by each man for himself,
there arises a tendency towards the differentiation of that individual
into a maker of weapons. His companions (warriors and hunters all of
them) severally wish to have the best weapons that can be made; and are
therefore certain to offer strong inducements to this skilled individual
to make weapons for them. He, on the other hand, having both an unusual
faculty, and an unusual liking, for making weapons (the capacity and the
desire for any occupation being commonly associated), is predisposed to
fulfil these commissions on the offer of adequate rewards: especially as
his love of distinction is also gratified. This first specialization of
function, once commenced, tends ever to become more decided. On the side
of the weapon-maker, continued practice gives increased skill—increased
superiority to his products. On the side of his clients, cessation of
practice entails decreased skill. Thus the influences that determine
this division of labour grow stronger in both ways: this social movement
tends ever to become more decided in the direction in which it was first
set up; and the incipient heterogeneity is, on the average of cases,
likely to become permanent for that generation, if no longer. Such
a process, besides differentiating the social mass into two parts, the
one monopolizing, or almost monopolizing, the performance of a certain
function, and the other having lost the habit, and in some measure the
power, of performing that function, has a tendency to initiate other
differentiations. The advance described implies the introduction of
barter: the maker of weapons has, on each occasion, to be paid in such
other articles as he agrees to take in exchange. Now he will not
habitually take in exchange one kind of article, but many kinds. He does
not want mats only, or skins, or fishing-gear; but he wants all these;
and on each occasion will bargain for the particular things he most
needs. What follows? If among the members of the tribe there exist any
slight differences of skill in the manufacture of these various things,
as there are almost sure to do, the weapon-maker will take from each one
the thing which that one excels in making: he will exchange for mats
with him whose mats are superior, and will bargain for the fishing-gear
of whoever has the best. But he who has bartered away his mats or his
fishing-gear, must make other mats or fishing-gear for himself; and in
so doing must, in some degree, further develop his aptitude. Thus it
results that the small specialities of faculty possessed by various
members of the tribe will tend to grow more decided. If such
transactions are from time to time repeated, these specializations may
become appreciable. And whether or not there ensue distinct
differentiations of other individuals into makers of particular
articles, it is clear that incipient differentiations take place
throughout the tribe: the one original cause produces not only the first
dual effect, but a number of secondary dual effects, like in kind but
minor in degree. This process, of which traces may be seen among
groups of school-boys, cannot well produce a lasting distribution of
functions in an unsettled tribe; but where there grows up a fixed and
multiplying community, such differentiations become permanent, and
increase with each generation. An addition to the number of citizens,
involving a greater demand for every commodity, intensifies the
functional activity of each specialized person or class; and this
renders the specialization more definite where it already exists, and
establishes it where it is but nascent. By increasing the pressure on
the means of subsistence, a larger population again augments these
results; since every individual is forced more and more to confine
himself to that which he can do best, and by which he can gain most. And
this industrial progress, by aiding future production, opens the way for
further growth of population, which reacts as before. Presently,
under the same stimuli, new occupations arise. Competing workers,
severally aiming to produce improved articles, occasionally discover
better processes or better materials. In weapons and cutting-tools, the
substitution of bronze for stone entails on him who first makes it, a
great increase of demand—so great an increase that he presently finds
all his time occupied in making the bronze for the articles he sells,
and is obliged to depute the fashioning of these articles to others; and
eventually the making of bronze, thus gradually differentiated from a
pre-existing occupation, becomes an occupation by itself. But now mark
the ramified changes which follow this change. Bronze soon replaces
stone, not only in the articles it was first used for, but in many
others; and so affects the manufacture of them. Further, it affects the
processes which such improved utensils subserve, and the resulting
products—modifies buildings, carvings, dress, personal decorations. Yet
again, it sets going sundry manufactures which were before impossible,
from lack of a material fit for the requisite tools. And all these
changes react on the people—increase their manipulative skill, their
intelligence, their comfort—refine their habits and tastes.
It is out of the question here to follow through its successive
complications, this increasing social heterogeneity that results from
the production of many effects by one cause. But leaving the
intermediate phases of social development, let us take an illustration
from its passing phase. To trace the effects of steam-power, in its
manifold applications to mining, navigation, and manufactures, would
carry us into unmanageable detail. Let us confine ourselves to the
latest embodiment of steam-power—the locomotive engine. This, as the
proximate cause of our railway-system, has changed the face of the
country, the course of trade, and the habits of the people. Consider,
first, the complicated sets of changes that precede the making of every
railway—the provisional arrangements, the meetings, the registration,
the trial-section, the parliamentary survey, the lithographed plans, the
books of reference, the local deposits and notices, the application to
Parliament, the passing Standing-Orders Committee, the first, second,
and third readings: each of which brief heads indicates a multiplicity
of transactions, and the further development of sundry occupations, (as
those of engineers, surveyors, lithographers, parliamentary agents,
share-brokers,) and the creation of sundry others (as those of
traffic-takers, reference-takers). Consider, next, the yet more marked
changes implied in railway construction—the cuttings, em-bankings,
tunnellings, diversions of roads; the building of bridges and stations;
the laying down of ballast, sleepers, and rails; the making of engines,
tenders, carriages, and wagons: which processes, acting upon numerous
trades, increase the importation of timber, the quarrying of stone, the
manufacture of iron, the mining of coal, the burning of bricks;
institute a variety of special manufactures weekly advertised in the
_Railway Times_; and call into being some new classes of
workers—drivers, stokers, cleaners, plate-layers, &c. &c. Then come the
changes, more numerous and involved still, which railways in action
produce on the community at large. The organization of every business is
more or less modified: ease of communication makes it better to do
directly what was before done by proxy; agencies are established where
previously they would not have paid; goods are obtained from remote
wholesale houses instead of near retail ones; and commodities are used
which distance once rendered inaccessible. The rapidity and small cost
of carriage, tend to specialize more than ever the industries of
different districts—to confine each manufacture to the parts in which,
from local advantages, it can be best carried on. Economical
distribution equalizes prices, and also, on the average, lowers prices:
thus bringing divers articles within the means of those before unable to
buy them, and so increasing their comforts and improving their habits.
At the same time the practice of travelling is immensely extended.
Classes who before could not afford it, take annual trips to the sea;
visit their distant relations; make tours; and so we are benefited in
body, feelings, and intellect. The more prompt transmission of letters
and of news produces further changes—makes the pulse of the nation
faster. Yet more, there arises a wide dissemination of cheap literature
through railway book-stalls, and of advertisements in railway carriages:
both of them aiding ulterior progress. And the innumerable changes here
briefly indicated are consequent on the invention of the locomotive
engine. The social organism has been rendered more heterogeneous, in
virtue of the many new occupations introduced, and the many old ones
further specialized; prices in all places have been altered; each trader
has, more or less, modified his way of doing business; and every person
has been affected in his actions, thoughts, emotions.
The only further fact demanding notice, is, that we here see more
clearly than ever, that in proportion as the area over which any
influence extends, becomes heterogeneous, the results are in a yet
higher degree multiplied in number and kind. While among the primitive
tribes to whom it was first known, caoutchouc caused but few changes,
among ourselves the changes have been so many and varied that the
history of them occupies a volume. Upon the small, homogeneous community
inhabiting one of the Hebrides, the electric telegraph would produce,
were it used, scarcely any results; but in England the results it
produces are multitudinous.
Space permitting, the synthesis might here be pursued in relation to all
the subtler products of social life. It might be shown how, in Science,
an advance of one division presently advances other divisions—how
Astronomy has been immensely forwarded by discoveries in Optics, while
other optical discoveries have initiated Microscopic Anatomy, and
greatly aided the growth of Physiology—how Chemistry has indirectly
increased our knowledge of Electricity, Magnetism, Biology, Geology—how
Electricity has reacted on Chemistry and Magnetism, developed our views
of Light and Heat, and disclosed sundry laws of nervous action. In
Literature the same truth might be exhibited in the still-multiplying
forms of periodical publications that have descended from the first
newspaper, and which have severally acted and reacted on other forms of
literature and on each other; or in the bias given by each book of power
to various subsequent books. The influence which a new school of
Painting (as that of the pre-Raphaelites) exercises on other schools;
the hints which all kinds of pictorial art are deriving from
Photography; the complex results of new critical doctrines; might
severally be dwelt on as displaying the like multiplication of effects.
But it would needlessly tax the reader’s patience to detail, in their
many ramifications, these various changes: here become so involved and
subtle as to be followed with some difficulty.
* * * * *
§ 122. After the argument which closed the last chapter, a parallel one
seems here scarcely required. For symmetry’s sake, however, it will be
proper briefly to point out how the multiplication of effects, like the
instability of the homogeneous, is a corollary from the persistence of
force.
Things which we call different are things which react in different ways;
and we can know them as different only by the differences in their
reactions. When we distinguish bodies as hard and soft, rough and
smooth, we simply mean that certain like muscular forces expended on
them are followed by unlike sets of sensations—unlike re-active forces.
Objects that are classed as red, blue, yellow, &c., are objects that
decompose light in strongly-contrasted ways; that is, we know contrasts
of colour as contrasts in the changes produced in a uniform incident
force. Manifestly, any two things which do not work unequal effects on
consciousness, either by unequally opposing our own energies, or by
impressing our senses with unequally modified forms of certain external
energies, cannot be distinguished by us. Hence the proposition that the
different parts of any whole must react differently on a uniform
incident force, and must so reduce it to a group of multiform forces, is
in essence a truism. A further step will reduce this truism to its
lowest terms.
When, from unlikeness between the effects they produce on consciousness,
we predicate unlikeness between two objects, what is our warrant? and
what do we mean by the unlikeness, objectively considered? Our warrant
is the persistence of force. Some kind or amount of change has been
wrought in us by the one, which has not been wrought by the other. This
change we ascribe to some force exercised by the one which the other has
not exercised. And we have no alternative but to do this, or to assert
that the change had no antecedent; which is to deny the persistence of
force. Whence it is further manifest that what we regard as the
objective unlikeness is the presence in the one of some force, or set of
forces, not present in the other—something in the kinds or amounts or
directions of the constituent forces of the one, which those of the
other do not parallel. But now if things or parts of things which we
call different, are those of which the constituent forces differ in one
or more respects; what must happen to any like forces, or any uniform
force, falling on them? Such like forces, or parts of a uniform force,
must be differently modified. The force which is present in the one and
not in the other, must be an element in the conflict—must produce its
equivalent reaction; and must so affect the total reaction. To say
otherwise is to say that this differential force will produce no effect;
which is to say that force is not persistent.
I need not develop this corollary further. It manifestly follows that a
uniform force, falling on a uniform aggregate, must undergo dispersion;
that falling on an aggregate made up of unlike parts, it must undergo
dispersion from each part, as well as qualitative differentiations; that
in proportion as the parts are unlike, these qualitative
differentiations must be marked; that in proportion to the number of the
parts, they must be numerous; that the secondary forces so produced,
must undergo further transformations while working equivalent
transformations in the parts that change them; and similarly with the
forces they generate. Thus the conclusions that a part-cause of
Evolution is the multiplication of effects; and that this increases in
geometrical progression as the heterogeneity becomes greater; are not
only to be established inductively, but are deducible from the deepest
of all truths.
-----
Footnote 17:
Had this paragraph, first published in the _Westminster Review_ in
1857, been written after the appearance of Mr. Darwin’s work on _The
Origin of Species_, it would doubtless have been otherwise expressed.
Reference would have been made to the process of “natural selection,”
as greatly facilitating the differentiations described. As it is,
however, I prefer to let the passage stand in its original shape:
partly because it seems to me that these successive changes of
conditions would produce divergent varieties or species, apart from
the influence of “natural selection” (though in less numerous ways as
well as less rapidly); and partly because I conceive that in the
absence of these successive changes of conditions, “natural selection”
would effect comparatively little. Let me add that though these
positions are not enunciated in _The Origin of Species_, yet a mutual
friend gives me reason to think that Mr. Darwin would coincide in
them; if he did not indeed consider them as tacitly implied in his
work.