In developing his conception of organic evolution Charles Darwin was
of necessity brought into contact with some of the problems of mental
evolution. In "The Origin of Species" he devoted a chapter to "the
diversities of instinct and of the other mental faculties in animals of
the same class." ("Origin of Species" (6th edition), page 205.) When
he passed to the detailed consideration of "The Descent of Man", it
was part of his object to show "that there is no fundamental difference
between man and the higher mammals in their mental faculties." ("Descent
of Man" (2nd edition 1888), Vol. I. page 99; Popular edition page 99.)
"If no organic being excepting man," he said, "had possessed any mental
power, or if his powers had been of a wholly different nature from those
of the lower animals, then we should never have been able to convince
ourselves that our high faculties had been gradually developed." (Ibid.
page 99.) In his discussion of "The Expression of the Emotions" it
was important for his purpose "fully to recognise that actions readily
become associated with other actions and with various states of the
mind." ("The Expression of the Emotions" (2nd edition), page 32.) His
hypothesis of sexual selection is largely dependent upon the exercise
of choice on the part of the female and her preference for "not only the
more attractive but at the same time the more vigorous and victorious
males." ("Descent of Man", Vol. II. page 435.) Mental processes and
physiological processes were for Darwin closely correlated; and he
accepted the conclusion "that the nervous system not only regulates most
of the existing functions of the body, but has indirectly influenced
the progressive development of various bodily structures and of certain
mental qualities." (Ibid. pages 437, 438.)
Throughout his treatment, mental evolution was for Darwin incidental
to and contributory to organic evolution. For specialised research
in comparative and genetic psychology, as an independent field of
investigation, he had neither the time nor the requisite training.
None the less his writings and the spirit of his work have exercised a
profound influence on this department of evolutionary thought. And, for
those who follow Darwin's lead, mental evolution is still in a
measure subservient to organic evolution. Mental processes are the
accompaniments or concomitants of the functional activity of specially
differentiated parts of the organism. They are in some way dependent on
physiological and physical conditions. But though they are not physical
in their nature, and though it is difficult or impossible to conceive
that they are physical in their origin, they are, for Darwin and his
followers, factors in the evolutionary process in its physical or
organic aspect. By the physiologist within his special and well-defined
universe of discourse they may be properly regarded as epiphenomena; but
by the naturalist in his more catholic survey of nature they cannot
be so regarded, and were not so regarded by Darwin. Intelligence has
contributed to evolution of which it is in a sense a product.
The facts of observation or of inference which Darwin accepted are
these: Conscious experience accompanies some of the modes of animal
behaviour; it is concomitant with certain physiological processes; these
processes are the outcome of development in the individual and
evolution in the race; the accompanying mental processes undergo a like
development. Into the subtle philosophical questions which arise out
of the naive acceptance of such a creed it was not Darwin's province
to enter; "I have nothing to do," he said ("Origin of Species" (6th
edition), page 205.), "with the origin of the mental powers, any more
than I have with that of life itself." He dealt with the natural history
of organisms, including not only their structure but their modes of
behaviour; with the natural history of the states of consciousness which
accompany some of their actions; and with the relation of behaviour
to experience. We will endeavour to follow Darwin in his modesty and
candour in making no pretence to give ultimate explanations. But we must
note one of the implications of this self-denying ordinance of science.
Development and evolution imply continuity. For Darwin and his followers
the continuity is organic through physical heredity. Apart from
speculative hypothesis, legitimate enough in its proper place but here
out of court, we know nothing of continuity of mental evolution as such:
consciousness appears afresh in each succeeding generation. Hence it is
that for those who follow Darwin's lead, mental evolution is and must
ever be, within his universe of discourse, subservient to organic
evolution. Only in so far as conscious experience, or its neural
correlate, effects some changes in organic structure can it influence
the course of heredity; and conversely only in so far as changes in
organic structure are transmitted through heredity, is mental evolution
rendered possible. Such is the logical outcome of Darwin's teaching.
Those who abide by the cardinal results of this teaching are bound to
regard all behaviour as the expression of the functional activities
of the living tissues of the organism, and all conscious experience
as correlated with such activities. For the purposes of scientific
treatment, mental processes are one mode of expression of the same
changes of which the physiological processes accompanying behaviour
are another mode of expression. This is simply accepted as a fact
which others may seek to explain. The behaviour itself is the adaptive
application of the energies of the organism; it is called forth by some
form of presentation or stimulation brought to bear on the organism by
the environment. This presentation is always an individual or personal
matter. But in order that the organism may be fitted to respond to the
presentation of the environment it must have undergone in some way
a suitable preparation. According to the theory of evolution this
preparation is primarily racial and is transmitted through heredity.
Darwin's main thesis was that the method of preparation is predominantly
by natural selection. Subordinate to racial preparation, and always
dependent thereon, is individual or personal preparation through
some kind of acquisition; of which the guidance of behaviour through
individually won experience is a typical example. We here introduce
the mental factor because the facts seem to justify the inference. Thus
there are some modes of behaviour which are wholly and solely dependent
upon inherited racial preparation; there are other modes of behaviour
which are also dependent, in part at least, on individual preparation.
In the former case the behaviour is adaptive on the first occurrence
of the appropriate presentation; in the latter case accommodation to
circumstances is only reached after a greater or less amount of acquired
organic modification of structure, often accompanied (as we assume) in
the higher animals by acquired experience. Logically and biologically
the two classes of behaviour are clearly distinguishable: but the
analysis of complex cases of behaviour where the two factors cooperate,
is difficult and requires careful and critical study of life-history.
The foundations of the mental life are laid in the conscious experience
that accompanies those modes of behaviour, dependent entirely on racial
preparation, which may broadly be described as instinctive. In the
eighth chapter of "The Origin of Species" Darwin says ("Origin of
Species" (6th edition), page 205.), "I will not attempt any definition
of instinct... Every one understands what is meant, when it is said
that instinct impels the cuckoo to migrate and to lay her eggs in other
birds' nests. An action, which we ourselves require experience to enable
us to perform, when performed by an animal, more especially by a very
young one, without experience, and when performed by many individuals in
the same way, without their knowing for what purpose it is performed, is
usually said to be instinctive." And in the summary at the close of the
chapter he says ("Origin of Species" (6th edition), page 233.), "I have
endeavoured briefly to show that the mental qualities of our domestic
animals vary, and that the variations are inherited. Still more briefly
I have attempted to show that instincts vary slightly in a state of
nature. No one will dispute that instincts are of the highest importance
to each animal. Therefore there is no real difficulty, under changing
conditions of life, in natural selection accumulating to any extent
slight modifications of instinct which are in any way useful. In many
cases habit or use and disuse have probably come into play."
Into the details of Darwin's treatment there is neither space nor need
to enter. There are some ambiguous passages; but it may be said that for
him, as for his followers to-day, instinctive behaviour is wholly the
result of racial preparation transmitted through organic heredity. For
the performance of the instinctive act no individual preparation under
the guidance of personal experience is necessary. It is true that Darwin
quotes with approval Huber's saying that "a little dose of judgment
or reason often comes into play, even with animals low in the scale of
nature." (Ibid. page 205.) But we may fairly interpret his meaning to be
that in behaviour, which is commonly called instinctive, some element of
intelligent guidance is often combined. If this be conceded the strictly
instinctive performance (or part of the performance) is the outcome of
heredity and due to the direct transmission of parental or ancestral
aptitudes. Hence the instinctive response as such depends entirely on
how the nervous mechanism has been built up through heredity; while
intelligent behaviour, or the intelligent factor in behaviour, depends
also on how the nervous mechanism has been modified and moulded by use
during its development and concurrently with the growth of individual
experience in the customary situations of daily life. Of course it is
essential to the Darwinian thesis that what Sir E. Ray Lankester has
termed "educability," not less than instinct, is hereditary. But it is
also essential to the understanding of this thesis that the differentiae
of the hereditary factors should be clearly grasped.
For Darwin there were two modes of racial preparation, (1) natural
selection, and (2) the establishment of individually acquired habit. He
showed that instincts are subject to hereditary variation; he saw that
instincts are also subject to modification through acquisition in the
course of individual life. He believed that not only the variations but
also, to some extent, the modifications are inherited. He therefore held
that some instincts (the greater number) are due to natural selection
but that others (less numerous) are due, or partly due, to the
inheritance of acquired habits. The latter involve Lamarckian
inheritance, which of late years has been the centre of so much
controversy. It is noteworthy however that Darwin laid especial emphasis
on the fact that many of the most typical and also the most
complex instincts--those of neuter insects--do not admit of such an
interpretation. "I am surprised," he says ("Origin of Species"
(6th edition), page 233.), "that no one has hitherto advanced this
demonstrative case of neuter insects, against the well-known doctrine of
inherited habit, as advanced by Lamarck." None the less Darwin admitted
this doctrine as supplementary to that which was more distinctively his
own--for example in the case of the instincts of domesticated animals.
Still, even in such cases, "it may be doubted," he says (Ibid. pages
210, 211.), "whether any one would have thought of training a dog to
point, had not some one dog naturally shown a tendency in this line... so
that habit and some degree of selection have probably concurred in
civilising by inheritance our dogs." But in the interpretation of the
instincts of domesticated animals, a more recently suggested hypothesis,
that of organic selection (Independently suggested, on somewhat
different lines, by Profs. J. Mark Baldwin, Henry F. Osborn and the
writer.), may be helpful. According to this hypothesis any intelligent
modification of behaviour which is subject to selection is probably
coincident in direction with an inherited tendency to behave in this
fashion. Hence in such behaviour there are two factors: (1) an
incipient variation in the line of such behaviour, and (2) an acquired
modification by which the behaviour is carried further along the same
line. Under natural selection those organisms in which the two factors
cooperate are likely to survive. Under artificial selection they are
deliberately chosen out from among the rest.
Organic selection has been termed a compromise between the more strictly
Darwinian and the Lamarckian principles of interpretation. But it is not
in any sense a compromise. The principle of interpretation of that which
is instinctive and hereditary is wholly Darwinian. It is true that some
of the facts of observation relied upon by Lamarckians are introduced.
For Lamarckians however the modifications which are admittedly factors
in survival, are regarded as the parents of inherited variations; for
believers in organic selection they are only the foster parents or
nurses. It is because organic selection is the direct outcome of and a
natural extension of Darwin's cardinal thesis that some reference to it
here is justifiable. The matter may be put with the utmost brevity as
follows. (1) Variations (V) occur, some of which are in the direction
of increased adaptation (+), others in the direction of decreased
adaptation (-). (2) Acquired modifications (M) also occur. Some of these
are in the direction of increased accommodation to circumstances (+),
while others are in the direction of diminished accommodation (-). Four
major combinations are
(a) + V with + M,
(b) + V with - M,
(c) - V with + M,
(d) - V with - M.
Of these (d) must inevitably be eliminated while (a) are selected.
The predominant survival of (a) entails the survival of the adaptive
variations which are inherited. The contributory acquisitions (+M) are
not inherited; but they are none the less factors in determining the
survival of the coincident variations. It is surely abundantly clear
that this is Darwinism and has no tincture of Lamarck's essential
principle, the inheritance of acquired characters.
Whether Darwin himself would have accepted this interpretation of some
at least of the evidence put forward by Lamarckians is unfortunately
a matter of conjecture. The fact remains that in his interpretation
of instinct and in allied questions he accepted the inheritance of
individually acquired modifications of behaviour and structure.
Darwin was chiefly concerned with instinct from the biological rather
than from the psychological point of view. Indeed it must be confessed
that, from the latter standpoint, his conception of instinct as a
"mental faculty" which "impels" an animal to the performance of certain
actions, scarcely affords a satisfactory basis for genetic treatment. To
carry out the spirit of Darwin's teaching it is necessary to link more
closely biological and psychological evolution. The first step towards
this is to interpret the phenomena of instinctive behaviour in terms
of stimulation and response. It may be well to take a particular case.
Swimming on the part of a duckling is, from the biological point
of view, a typical example of instinctive behaviour. Gently lower a
recently hatched bird into water: coordinated movements of the limbs
follow in rhythmical sequence. The behaviour is new to the individual
though it is no doubt closely related to that of walking, which is
no less instinctive. There is a group of stimuli afforded by the
"presentation" which results from partial immersion: upon this
there follows as a complex response an application of the functional
activities in swimming; the sequence of adaptive application on the
appropriate presentation is determined by racial preparation. We know,
it is true, but little of the physiological details of what takes place
in the central nervous system; but in broad outline the nature of the
organic mechanism and the manner of its functioning may at least
be provisionally conjectured in the present state of physiological
knowledge. Similarly in the case of the pecking of newly-hatched chicks;
there is a visual presentation, there is probably a cooperating group of
stimuli from the alimentary tract in need of food, there is an adaptive
application of the activities in a definite mode of behaviour. Like
data are afforded in a great number of cases of instinctive procedure,
sometimes occurring very early in life, not infrequently deferred until
the organism is more fully developed, but all of them dependent upon
racial preparation. No doubt there is some range of variation in the
behaviour, just such variation as the theory of natural selection
demands. But there can be no question that the higher animals inherit
a bodily organisation and a nervous system, the functional working of
which gives rise to those inherited modes of behaviour which are termed
instinctive.
It is to be noted that the term "instinctive" is here employed in the
adjectival form as a descriptive heading under which may be grouped many
and various modes of behaviour due to racial preparation. We speak
of these as inherited; but in strictness what is transmitted through
heredity is the complex of anatomical and physiological conditions under
which, in appropriate circumstances, the organism so behaves. So far the
term "instinctive" has a restricted biological connotation in terms
of behaviour. But the connecting link between biological evolution and
psychological evolution is to be sought,--as Darwin fully realised,--in
the phenomena of instinct, broadly considered. The term "instinctive"
has also a psychological connotation. What is that connotation?
Let us take the case of the swimming duckling or the pecking chick, and
fix our attention on the first instinctive performance. Grant that just
as there is, strictly speaking, no inherited behaviour, but only the
conditions which render such behaviour under appropriate circumstances
possible; so too there is no inherited experience, but only the
conditions which render such experience possible; then the cerebral
conditions in both cases are the same. The biological behaviour-complex,
including the total stimulation and the total response with the
intervening or resultant processes in the sensorium, is accompanied by
an experience-complex including the initial stimulation-consciousness
and resulting response-consciousness. In the experience-complex are
comprised data which in psychological analysis are grouped under the
headings of cognition, affective tone and conation. But the complex is
probably experienced as an unanalysed whole. If then we use the term
"instinctive" so as to comprise all congenital modes of behaviour which
contribute to experience, we are in a position to grasp the view that
the net result in consciousness constitutes what we may term the
primary tissue of experience. To the development of this experience each
instinctive act contributes. The nature and manner of organisation of
this primary tissue of experience are dependent on inherited biological
aptitudes; but they are from the outset onwards subject to secondary
development dependent on acquired aptitudes. Biological values are
supplemented by psychological values in terms of satisfaction or the
reverse.
In our study of instinct we have to select some particular phase of
animal behaviour and isolate it so far as is possible from the life of
which it is a part. But the animal is a going concern, restlessly active
in many ways. Many instinctive performances, as Darwin pointed out
("Origin of Species" (6th edition), page 206.), are serial in their
nature. But the whole of active life is a serial and coordinated
business. The particular instinctive performance is only an episode in
a life-history, and every mode of behaviour is more or less closely
correlated with other modes. This coordination of behaviour is
accompanied by a correlation of the modes of primary experience. We may
classify the instinctive modes of behaviour and their accompanying modes
of instinctive experience under as many heads as may be convenient
for our purposes of interpretation, and label them instincts of
self-preservation, of pugnacity, of acquisition, the reproductive
instincts, the parental instincts, and so forth. An instinct, in this
sense of the term (for example the parental instinct), may be described
as a specialised part of the primary tissue of experience differentiated
in relation to some definite biological end. Under such an instinct
will fall a large number of particular and often well-defined modes of
behaviour, each with its own peculiar mode of experience.
It is no doubt exceedingly difficult as a matter of observation and of
inference securely based thereon to distinguish what is primary from
what is in part due to secondary acquisition--a fact which Darwin fully
appreciated. Animals are educable in different degrees; but where they
are educable they begin to profit by experience from the first. Only,
therefore, on the occasion of the first instinctive act of a given type
can the experience gained be weighed as WHOLLY primary; all subsequent
performance is liable to be in some degree, sometimes more, sometimes
less, modified by the acquired disposition which the initial behaviour
engenders. But the early stages of acquisition are always along the
lines predetermined by instinctive differentiation. It is the task of
comparative psychology to distinguish the primary tissue of experience
from its secondary and acquired modifications. We cannot follow up the
matter in further detail. It must here suffice to suggest that this
conception of instinct as a primary form of experience lends itself
better to natural history treatment than Darwin's conception of an
impelling force, and that it is in line with the main trend of Darwin's
thought.
In a characteristic work,--characteristic in wealth of detail, in
closeness and fidelity of observation, in breadth of outlook, in candour
and modesty,--Darwin dealt with "The Expression of the Emotions in
Man and Animals". Sir Charles Bell in his "Anatomy of Expression" had
contended that many of man's facial muscles had been specially created
for the sole purpose of being instrumental in the expression of his
emotions. Darwin claimed that a natural explanation, consistent with the
doctrine of evolution, could in many cases be given and would in other
cases be afforded by an extension of the principles he advocated. "No
doubt," he said ("Expression of the Emotions", page 13. The passage is
here somewhat condensed.), "as long as man and all other animals are
viewed as independent creations, an effectual stop is put to our natural
desire to investigate as far as possible the causes of Expression.
By this doctrine, anything and everything can be equally well
explained... With mankind, some expressions... can hardly be understood,
except on the belief that man once existed in a much lower and
animal-like condition. The community of certain expressions in distinct
though allied species... is rendered somewhat more intelligible, if we
believe in their descent from a common progenitor. He who admits on
general grounds that the structure and habits of all animals have been
gradually evolved, will look at the whole subject of Expression in a new
and interesting light."
Darwin relied on three principles of explanation. "The first of these
principles is, that movements which are serviceable in gratifying some
desire, or in relieving some sensation, if often repeated, become
so habitual that they are performed, whether or not of any service,
whenever the same desire or sensation is felt, even in a very weak
degree." (Ibid. page 368.) The modes of expression which fall under
this head have become instinctive through the hereditary transmission of
acquired habit. "As far as we can judge, only a few expressive movements
are learnt by each individual; that is, were consciously and voluntarily
performed during the early years of life for some definite object, or in
imitation of others, and then became habitual. The far greater number of
the movements of expression, and all the more important ones, are innate
or inherited; and such cannot be said to depend on the will of the
individual. Nevertheless, all those included under our first principle
were at first voluntarily performed for a definite object,--namely,
to escape some danger, to relieve some distress, or to gratify some
desire." (Ibid. pages 373, 374.)
"Our second principle is that of antithesis. The habit of voluntarily
performing opposite movements under opposite impulses has become firmly
established in us by the practice of our whole lives. Hence, if certain
actions have been regularly performed, in accordance with our first
principle, under a certain frame of mind, there will be a strong and
involuntary tendency to the performance of directly opposite actions,
whether or not these are of any use, under the excitement of an opposite
frame of mind." ("Expression of the Emotions", page 368.) This principle
of antithesis has not been widely accepted. Nor is Darwin's own position
easy to grasp.
"Our third principle," he says (Ibid. page 369.), "is the direct action
of the excited nervous system on the body, independently of the will,
and independently, in large part, of habit. Experience shows that
nerve-force is generated and set free whenever the cerebro-spinal system
is excited. The direction which this nerve-force follows is necessarily
determined by the lines of connection between the nerve-cells, with each
other and with various parts of the body."
Lack of space prevents our following up the details of Darwin's
treatment of expression. Whether we accept or do not accept his three
principles of explanation we must regard his work as a masterpiece of
descriptive analysis, packed full of observations possessing lasting
value. For a further development of the subject it is essential that
the instinctive factors in expression should be more fully distinguished
from those which are individually acquired--a difficult task--and that
the instinctive factors should be rediscussed in the light of modern
doctrines of heredity, with a view to determining whether Lamarckian
inheritance, on which Darwin so largely relied, is necessary for an
interpretation of the facts.
The whole subject as Darwin realised is very complex. Even the term
"expression" has a certain amount of ambiguity. When the emotion is in
full flood the animal fights, flees, or faints. Is this full-tide effect
to be regarded as expression; or are we to restrict the term to the
premonitory or residual effects--the bared canine when the fighting mood
is being roused, the ruffled fur when reminiscent representations of the
object inducing anger cross the mind? Broadly considered both should
be included. The activity of premonitory expression as a means of
communication was recognised by Darwin; he might, perhaps, have
emphasised it more strongly in dealing with the lower animals. Man so
largely relies on a special means of communication, that of language,
that he sometimes fails to realise that for animals with their keen
powers of perception, and dependent as they are on such means of
communication, the more strictly biological means of expression are full
of subtle suggestiveness. Many modes of expression, otherwise useless,
are signs of behaviour that may be anticipated,--signs which stimulate
the appropriate attitude of response. This would not, however, serve to
account for the utility of the organic accompaniments--heart-affection,
respiratory changes, vaso-motor effects and so forth, together
with heightened muscular tone,--on all of which Darwin lays stress
("Expression of the Emotions", pages 65 ff.) under his third principle.
The biological value of all this is, however, of great importance,
though Darwin was hardly in a position to take it fully into account.
Having regard to the instinctive and hereditary factors of emotional
expression we may ask whether Darwin's third principle does not alone
suffice as an explanation. Whether we admit or reject Lamarckian
inheritance it would appear that all hereditary expression must be due
to pre-established connections within the central nervous system and to
a transmitted provision for coordinated response under the appropriate
stimulation. If this be so, Darwin's first and second principles are
subordinate and ancillary to the third, an expression, so far as it is
instinctive or hereditary, being "the direct result of the constitution
of the nervous system."
Darwin accepted the emotions themselves as hereditary or acquired
states of mind and devoted his attention to their expression. But
these emotions themselves are genetic products and as such dependent
on organic conditions. It remained, therefore, for psychologists who
accepted evolution and sought to build on biological foundations to
trace the genesis of these modes of animal and human experience. The
subject has been independently developed by Professors Lange and James
(Cf. William James, "Principles of Psychology", Vol. II. Chap. XXV,
London, 1890.); and some modification of their view is regarded by many
evolutionists as affording the best explanation of the facts. We must
fix our attention on the lower emotions, such as anger or fear, and on
their first occurrence in the life of the individual organism. It is
a matter of observation that if a group of young birds which have been
hatched in an incubator are frightened by an appropriate presentation,
auditory or visual, they instinctively respond in special ways. If we
speak of this response as the expression, we find that there are many
factors. There are certain visible modes of behaviour, crouching at
once, scattering and then crouching, remaining motionless, the braced
muscles sustaining an attitude of arrest, and so forth. There are also
certain visceral or organic effects, such as affections of the heart and
respiration. These can be readily observed by taking the young bird in
the hand. Other effects cannot be readily observed; vaso-motor changes,
affections of the alimentary canal, the skin and so forth. Now the
essence of the James-Lange view, as applied to these congenital effects,
is that though we are justified in speaking of them as effects of the
stimulation, we are not justified, without further evidence, in speaking
of them as effects of the emotional state. May it not rather be that the
emotion as a primary mode of experience is the concomitant of the
net result of the organic situation--the initial presentation, the
instinctive mode of behaviour, the visceral disturbances? According to
this interpretation the primary tissue of experience of the emotional
order, felt as an unanalysed complex, is generated by the stimulation
of the sensorium by afferent or incoming physiological impulses from the
special senses, from the organs concerned in the responsive behaviour,
from the viscera and vaso-motor system.
Some psychologists, however, contend that the emotional experience
is generated in the sensorium prior to, and not subsequent to, the
behaviour-response and the visceral disturbances. It is a direct and not
an indirect outcome of the presentation to the special senses. Be
this as it may, there is a growing tendency to bring into the closest
possible relation, or even to identify, instinct and emotion in their
primary genesis. The central core of all such interpretations is that
instinctive behaviour and experience, its emotional accompaniments, and
its expression, are but different aspects of the outcome of the
same organic occurrences. Such emotions are, therefore, only a
distinguishable aspect of the primary tissue of experience and exhibit
a like differentiation. Here again a biological foundation is laid for a
psychological doctrine of the mental development of the individual.
The intimate relation between emotion as a psychological mode of
experience and expression as a group of organic conditions has an
important bearing on biological interpretation. The emotion, as the
psychological accompaniment of orderly disturbances in the central
nervous system profoundly influences behaviour and often renders it more
vigorous and more effective. The utility of the emotions in the struggle
for existence can, therefore, scarcely be over-estimated. Just as
keenness of perception has survival-value; just as it is obviously
subject to variation; just as it must be enhanced under natural
selection, whether individually acquired increments are inherited
or not; and just as its value lies not only in this or that special
perceptive act but in its importance for life as a whole; so the
vigorous effectiveness of activity has survival-value; it is subject
to variation; it must be enhanced under natural selection; and its
importance lies not only in particular modes of behaviour but in its
value for life as a whole. If emotion and its expression as a congenital
endowment are but different aspects of the same biological occurrence;
and if this is a powerful supplement to vigour effectiveness and
persistency of behaviour, it must on Darwin's principles be subject to
natural selection.
If we include under the expression of the emotions not only the
premonitory symptoms of the initial phases of the organic and mental
state, not only the signs or conditions of half-tide emotion, but the
full-tide manifestation of an emotion which dominates the situation, we
are naturally led on to the consideration of many of the phenomena
which are discussed under the head of sexual selection. The subject
is difficult and complex, and it was treated by Darwin with all the
strength he could summon to the task. It can only be dealt with here
from a special point of view--that which may serve to illustrate the
influence of certain mental factors on the course of evolution. From
this point of view too much stress can scarcely be laid on the dominance
of emotion during the period of courtship and pairing in the more highly
organised animals. It is a period of maximum vigour, maximum activity,
and, correlated with special modes of behaviour and special organic and
visceral accompaniments, a period also of maximum emotional excitement.
The combats of males, their dances and aerial evolutions, their
elaborate behaviour and display, or the flood of song in birds, are
emotional expressions which are at any rate coincident in time with
sexual periodicity. From the combat of the males there follows on
Darwin's principles the elimination of those which are deficient in
bodily vigour, deficient in special structures, offensive or protective,
which contribute to success, deficient in the emotional supplement
of which persistent and whole-hearted fighting is the expression,
and deficient in alertness and skill which are the outcome of the
psychological development of the powers of perception. Few biologists
question that we have here a mode of selection of much importance,
though its influence on psychological evolution often fails to receive
its due emphasis. Mr Wallace ("Darwinism", pages 282, 283, London,
1889.) regards it as "a form of natural selection"; "to it," he says,
"we must impute the development of the exceptional strength, size, and
activity of the male, together with the possession of special offensive
and defensive weapons, and of all other characters which arise from
the development of these or are correlated with them." So far there is
little disagreement among the followers of Darwin--for Mr Wallace,
with fine magnanimity, has always preferred to be ranked as such,
notwithstanding his right, on which a smaller man would have constantly
insisted, to the claim of independent originator of the doctrine of
natural selection. So far with regard to sexual selection Darwin and Mr
Wallace are agreed; so far and no farther. For Darwin, says Mr Wallace
(Ibid. page 283.), "has extended the principle into a totally different
field of action, which has none of that character of constancy and of
inevitable result that attaches to natural selection, including male
rivalry; for by far the larger portion of the phenomena, which he
endeavours to explain by the direct action of sexual selection, can only
be so explained on the hypothesis that the immediate agency is female
choice or preference. It is to this that he imputes the origin of
all secondary sexual characters other than weapons of offence and
defence... In this extension of sexual selection to include the action of
female choice or preference, and in the attempt to give to that choice
such wide-reaching effects, I am unable to follow him more than a very
little way."
Into the details of Mr Wallace's criticisms it is impossible to enter
here. We cannot discuss either the mode of origin of the variations in
structure which have rendered secondary sexual characters possible
or the modes of selection other than sexual which have rendered them,
within narrow limits, specifically constant. Mendelism and mutation
theories may have something to say on the subject when these theories
have been more fully correlated with the basal principles of selection.
It is noteworthy that Mr Wallace says ("Darwinism", pages 283, 284.):
"Besides the acquisition of weapons by the male for the purpose of
fighting with other males, there are some other sexual characters which
may have been produced by natural selection. Such are the various sounds
and odours which are peculiar to the male, and which serve as a call to
the female or as an indication of his presence. These are evidently a
valuable addition to the means of recognition of the two sexes, and
are a further indication that the pairing season has arrived; and the
production, intensification, and differentiation of these sounds and
odours are clearly within the power of natural selection. The same
remark will apply to the peculiar calls of birds, and even to the
singing of the males." Why the same remark should not apply to their
colours and adornments is not obvious. What is obvious is that "means
of recognition" and "indication that the pairing season has arrived" are
dependent on the perceptive powers of the female who recognises and for
whom the indication has meaning. The hypothesis of female preference,
stripped of the aesthetic surplusage which is psychologically both
unnecessary and unproven, is really only different in degree from that
which Mr Wallace admits in principle when he says that it is probable
that the female is pleased or excited by the display.
Let us for our present purpose leave on one side and regard as sub
judice the question whether the specific details of secondary sexual
characters are the outcome of female choice. For us the question is
whether certain psychological accompaniments of the pairing situation
have influenced the course of evolution and whether these psychological
accompaniments are themselves the outcome of evolution. As a matter of
observation, specially differentiated modes of behaviour, often very
elaborate, frequently requiring highly developed skill, and apparently
highly charged with emotional tone, are the precursors of pairing. They
are generally confined to the males, whose fierce combats during the
period of sexual activity are part of the emotional manifestation. It is
inconceivable that they have no biological meaning; and it is difficult
to conceive that they have any other biological end than to evoke in
the generally more passive female the pairing impulse. They are based
on instinctive foundations ingrained in the nervous constitution
through natural (or may we not say sexual?) selection in virtue of
their profound utility. They are called into play by a specialised
presentation such as the sight or the scent of the female at, or a
little in advance of, a critical period of the physiological rhythm.
There is no necessity that the male should have any knowledge of the
end to which his strenuous activity leads up. In presence of the female
there is an elaborate application of all the energies of behaviour,
just because ages of racial preparation have made him biologically and
emotionally what he is--a functionally sexual male that must dance or
sing or go through hereditary movements of display, when the appropriate
stimulation comes. Of course after the first successful courtship
his future behaviour will be in some degree modified by his previous
experience. No doubt during his first courtship he is gaining the
primary data of a peculiarly rich experience, instinctive and emotional.
But the biological foundations of the behaviour of courtship are laid
in the hereditary coordinations. It would seem that in some cases, not
indeed in all, but perhaps especially in those cases in which secondary
sexual behaviour is most highly evolved,--correlative with the ardour
of the male is a certain amount of reluctance in the female. The pairing
act on her part only takes place after prolonged stimulation, for
affording which the behaviour of male courtship is the requisite
presentation. The most vigorous, defiant and mettlesome male is
preferred just because he alone affords a contributory stimulation
adequate to evoke the pairing impulse with its attendant emotional tone.
It is true that this places female preference or choice on a much lower
psychological plane than Darwin in some passages seems to contemplate
where, for example, he says that the female appreciates the display of
the male and places to her credit a taste for the beautiful. But Darwin
himself distinctly states ("Descent of Man" (2nd edition), Vol. II.
pages 136, 137; (Popular edition), pages 642, 643.) that "it is not
probable that she consciously deliberates; but she is most excited or
attracted by the most beautiful, or melodious, or gallant males." The
view here put forward, which has been developed by Prof. Groos ("The
Play of Animals", page 244, London, 1898.), therefore seems to have
Darwin's own sanction. The phenomena are not only biological; there are
psychological elements as well. One can hardly suppose that the female
is unconscious of the male's presence; the final yielding must surely be
accompanied by heightened emotional tone. Whether we call it choice or
not is merely a matter of definition of terms. The behaviour is in part
determined by supplementary psychological values. Prof. Groos regards
the coyness of females as "a most efficient means of preventing the
too early and too frequent yielding to the sexual impulse." (Ibid. page
283.) Be that as it may, it is, in any case, if we grant the facts, a
means through which male sexual behaviour with all its biological and
psychological implications, is raised to a level otherwise perhaps
unattainable by natural means, while in the female it affords
opportunities for the development in the individual and evolution in the
race of what we may follow Darwin in calling appreciation, if we empty
this word of the aesthetic implications which have gathered round it in
the mental life of man.
Regarded from this standpoint sexual selection, broadly considered, has
probably been of great importance. The psychological accompaniments
of the pairing situation have profoundly influenced the course of
biological evolution and are themselves the outcome of that evolution.
Darwin makes only passing reference to those modes of behaviour in
animals which go by the name of play. "Nothing," he says ("Descent of
Man", Vol. II. page 60; (Popular edition), page 566.), "is more common
than for animals to take pleasure in practising whatever instinct they
follow at other times for some real good." This is one of the very
numerous cases in which a hint of the master has served to stimulate
research in his disciples. It was left to Prof. Groos to develop this
subject on evolutionary lines and to elaborate in a masterly manner
Darwin's suggestion. "The utility of play," he says ("The Play of
Animals", page 76.), "is incalculable. This utility consists in the
practice and exercise it affords for some of the more important duties
of life,"--that is to say, for the performance of activities which will
in adult life be essential to survival. He urges (Ibid. page 75.) that
"the play of young animals has its origin in the fact that certain very
important instincts appear at a time when the animal does not seriously
need them." It is, however, questionable whether any instincts appear
at a time when they are not needed. And it is questionable whether
the instinctive and emotional attitude of the play-fight, to take
one example, can be identified with those which accompany fighting in
earnest, though no doubt they are closely related and have some common
factors. It is probable that play, as preparatory behaviour, differs in
biological detail (as it almost certainly does in emotional attributes)
from the earnest of after-life and that it has been evolved through
differentiation and integration of the primary tissue of experience,
as a preparation through which certain essential modes of skill may be
acquired--those animals in which the preparatory play-propensity was
not inherited in due force and requisite amount being subsequently
eliminated in the struggle for existence. In any case there is little
question that Prof. Groos is right in basing the play-propensity on
instinctive foundations. ("The Play of Animals" page 24.) None the less,
as he contends, the essential biological value of play is that it is a
means of training the educable nerve-tissue, of developing that part of
the brain which is modified by experience and which thus acquires new
characters, of elaborating the secondary tissue of experience on the
predetermined lines of instinctive differentiation and thus furthering
the psychological activities which are included under the comprehensive
term "intelligent."
In "The Descent of Man" Darwin dealt at some length with intelligence
and the higher mental faculties. ("Descent of Man" (1st edition),
Chapters II, III, V; (2nd edition), Chapters III, IV, V.) His object, he
says, is to show that there is no fundamental difference between man and
the higher mammals in their mental faculties; that these faculties are
variable and the variations tend to be inherited; and that under natural
selection beneficial variations of all kinds will have been preserved
and injurious ones eliminated.
Darwin was too good an observer and too honest a man to minimise
the "enormous difference" between the level of mental attainment of
civilised man and that reached by any animal. His contention was that
the difference, great as it is, is one of degree and not of kind. He
realised that, in the development of the mental faculties of man,
new factors in evolution have supervened--factors which play but
a subordinate and subsidiary part in animal intelligence.
Intercommunication by means of language, approbation and blame, and
all that arises out of reflective thought, are but foreshadowed in the
mental life of animals. Still he contends that these may be explained
on the doctrine of evolution. He urges (Ibid. Vol. I. pages 70, 71;
(Popular edition), pages 70, 71.)" that man is variable in body
and mind; and that the variations are induced, either directly or
indirectly, by the same general causes, and obey the same general laws,
as with the lower animals." He correlates mental development with
the evolution of the brain. (Ibid. page 81.) "As the various mental
faculties gradually developed themselves, the brain would almost
certainly become larger. No one, I presume, doubts that the large
proportion which the size of man's brain bears to his body, compared to
the same proportion in the gorilla or orang, is closely connected with
his higher mental powers." "With respect to the lower animals," he says
("Descent of Man" (Popular edition), page 82.), "M.E. Lartet ("Comptes
Rendus des Sciences", June 1, 1868.), by comparing the crania of
tertiary and recent mammals belonging to the same groups, has come to
the remarkable conclusion that the brain is generally larger and the
convolutions are more complex in the more recent form."
Sir E. Ray Lankester has sought to express in the simplest terms the
implications of the increase in size of the cerebrum. "In what," he
asks, "does the advantage of a larger cerebral mass consist?" "Man,"
he replies "is born with fewer ready-made tricks of the
nerve-centres--these performances of an inherited nervous mechanism so
often called by the ill-defined term 'instincts'--than are the monkeys
or any other animal. Correlated with the absence of inherited ready-made
mechanism, man has a greater capacity of developing in the course of
his individual growth similar nervous mechanisms (similar to but not
identical with those of 'instinct') than any other animal... The power of
being educated--'educability' as we may term it--is what man possesses
in excess as compared with the apes. I think we are justified in forming
the hypothesis that it is this 'educability' which is the correlative of
the increased size of the cerebrum." There has been natural selection
of the more educable animals, for "the character which we describe as
'educability' can be transmitted, it is a congenital character. But the
RESULTS of education can NOT be transmitted. In each generation they
have to be acquired afresh, and with increased 'educability' they are
more readily acquired and a larger variety of them... The fact is
that there is no community between the mechanisms of instinct and the
mechanisms of intelligence, and that the latter are later in the history
of the evolution of the brain than the former and can only develop in
proportion as the former become feeble and defective." ("Nature", Vol.
LXI. pages 624, 625 (1900).)
In this statement we have a good example of the further development
of views which Darwin foreshadowed but did not thoroughly work out. It
states the biological case clearly and tersely. Plasticity of behaviour
in special accommodation to special circumstances is of survival value;
it depends upon acquired characters; it is correlated with increase in
size and complexity of the cerebrum; under natural selection therefore
the larger and more complex cerebrum as the organ of plastic behaviour
has been the outcome of natural selection. We have thus the biological
foundations for a further development of genetic psychology.
There are diversities of opinion, as Darwin showed, with regard to the
range of instinct in man and the higher animals as contrasted with lower
types. Darwin himself said ("Descent of Man", Vol. I. page 100.) that
"Man, perhaps, has somewhat fewer instincts than those possessed by the
animals which come next to him in the series." On the other hand, Prof.
Wm. James says ("Principles of Psychology," Vol. II. page 289.) that man
is probably the animal with most instincts. The true position is that
man and the higher animals have fewer complete and self-sufficing
instincts than those which stand lower in the scale of mental
evolution, but that they have an equally large or perhaps larger mass of
instinctive raw material which may furnish the stuff to be elaborated
by intelligent processes. There is, perhaps, a greater abundance of
the primary tissue of experience to be refashioned and integrated by
secondary modification; there is probably the same differentiation in
relation to the determining biological ends, but there is at the outset
less differentiation of the particular and specific modes of behaviour.
The specialised instinctive performances and their concomitant
experience-complexes are at the outset more indefinite. Only through
acquired connections, correlated with experience, do they become
definitely organised.
The full working-out of the delicate and subtle relationship of instinct
and educability--that is, of the hereditary and the acquired factors in
the mental life--is the task which lies before genetic and comparative
psychology. They interact throughout the whole of life, and their
interactions are very complex. No one can read the chapters of "The
Descent of Man" which Darwin devotes to a consideration of the mental
characters of man and animals without noticing, on the one hand, how
sedulous he is in his search for hereditary foundations, and, on the
other hand, how fully he realises the importance of acquired habits of
mind. The fact that educability itself has innate tendencies--is in fact
a partially differentiated educability--renders the unravelling of the
factors of mental progress all the more difficult.
In his comparison of the mental powers of men and animals it was
essential that Darwin should lay stress on points of similarity rather
than on points of difference. Seeking to establish a doctrine of
evolution, with its basal concept of continuity of process and community
of character, he was bound to render clear and to emphasise the
contention that the difference in mind between man and the higher
animals, great as it is, is one of degree and not of kind. To this end
Darwin not only recorded a large number of valuable observations of
his own, and collected a considerable body of information from reliable
sources, he presented the whole subject in a new light and showed that
a natural history of mind might be written and that this method of study
offered a wide and rich field for investigation. Of course those who
regarded the study of mind only as a branch of metaphysics smiled at
the philosophical ineptitude of the mere man of science. But the
investigation, on natural history lines, has been prosecuted with a
large measure of success. Much indeed still remains to be done; for
special training is required, and the workers are still few. Promise
for the future is however afforded by the fact that investigation is
prosecuted on experimental lines and that something like organised
methods of research are taking form. There is now but little reliance
on casual observations recorded by those who have not undergone the
necessary discipline in these methods. There is also some change of
emphasis in formulating conclusions. Now that the general evolutionary
thesis is fully and freely accepted by those who carry on such
researches, more stress is laid on the differentiation of the stages of
evolutionary advance than on the fact of their underlying community of
nature. The conceptual intelligence which is especially characteristic
of the higher mental procedure of man is more firmly distinguished
from the perceptual intelligence which he shares with the lower
animals--distinguished now as a higher product of evolution, no longer
as differing in origin or different in kind. Some progress has been
made, on the one hand in rendering an account of intelligent profiting
by experience under the guidance of pleasure and pain in the perceptual
field, on lines predetermined by instinctive differentiation for
biological ends, and on the other hand in elucidating the method of
conceptual thought employed, for example, by the investigator himself in
interpreting the perceptual experience of the lower animals.
Thus there is a growing tendency to realise more fully that there
are two orders of educability--first an educability of the perceptual
intelligence based on the biological foundation of instinct, and
secondly an educability of the conceptual intelligence which
refashions and rearranges the data afforded by previous inheritance
and acquisition. It is in relation to this second and higher order of
educability that the cerebrum of man shows so large an increase of
mass and a yet larger increase of effective surface through its rich
convolutions. It is through educability of this order that the human
child is brought intellectually and affectively into touch with the
ideal constructions by means of which man has endeavoured, with more
or less success, to reach an interpretation of nature, and to guide the
course of the further evolution of his race--ideal constructions which
form part of man's environment.
It formed no part of Darwin's purpose to consider, save in broad
outline, the methods, or to discuss in any fulness of detail the results
of the process by which a differentiation of the mental faculties of
man from those of the lower animals has been brought about--a
differentiation the existence of which he again and again
acknowledges. His purpose was rather to show that, notwithstanding
this differentiation, there is basal community in kind. This must be
remembered in considering his treatment of the biological foundations
on which man's systems of ethics are built. He definitely stated that he
approached the subject "exclusively from the side of natural history."
("Descent of Man", Vol. I. page 149.) His general conclusion is that the
moral sense is fundamentally identical with the social instincts, which
have been developed for the good of the community; and he suggests
that the concept which thus enables us to interpret the biological
ground-plan of morals also enables us to frame a rational ideal of the
moral end. "As the social instincts," he says (Ibid. page 185.), "both
of man and the lower animals have no doubt been developed by nearly the
same steps, it would be advisable, if found practicable, to use the same
definition in both cases, and to take as the standard of morality,
the general good or welfare of the community, rather than the general
happiness." But the kind of community for the good of which the social
instincts of animals and primitive men were biologically developed may
be different from that which is the product of civilisation, as Darwin
no doubt realised. Darwin's contention was that conscience is a social
instinct and has been evolved because it is useful to the tribe in the
struggle for existence against other tribes. On the other hand, J.S.
Mill urged that the moral feelings are not innate but acquired, and Bain
held the same view, believing that the moral sense is acquired by each
individual during his life-time. Darwin, who notes (Ibid. page 150
(footnote).) their opinion with his usual candour, adds that "on the
general theory of evolution this is at least extremely improbable. It
is impossible to enter into the question here: much turns on the exact
connotation of the terms "conscience" and "moral sense," and on the
meaning we attach to the statement that the moral sense is fundamentally
identical with the social instincts."
Presumably the majority of those who approach the subjects discussed in
the third, fourth and fifth chapters of "The Descent of Man" in the full
conviction that mental phenomena, not less than organic phenomena,
have a natural genesis, would, without hesitation, admit that the
intellectual and moral systems of civilised man are ideal constructions,
the products of conceptual thought, and that as such they are, in
their developed form, acquired. The moral sentiments are the emotional
analogues of highly developed concepts. This does not however imply that
they are outside the range of natural history treatment. Even though
it may be desirable to differentiate the moral conduct of men from the
social behaviour of animals (to which some such term as "pre-moral" or
"quasi-moral" may be applied), still the fact remains that, as Darwin
showed, there is abundant evidence of the occurrence of such social
behaviour--social behaviour which, even granted that it is in large part
intelligently acquired, and is itself so far a product of educability,
is of survival value. It makes for that integration without which no
social group could hold together and escape elimination. Furthermore,
even if we grant that such behaviour is intelligently acquired, that
is to say arises through the modification of hereditary instincts and
emotions, the fact remains that only through these instinctive and
emotional data is afforded the primary tissue of the experience which is
susceptible of such modification.
Darwin sought to show, and succeeded in showing, that for the
intellectual and moral life there are instinctive foundations which a
biological treatment alone can disclose. It is true that he did not
in all cases analytically distinguish the foundations from the
superstructure. Even to-day we are scarcely in a position to do so
adequately. But his treatment was of great value in giving an impetus to
further research. This value indeed can scarcely be overestimated.
And when the natural history of the mental operations shall have been
written, the cardinal fact will stand forth, that the instinctive and
emotional foundations are the outcome of biological evolution and have
been ingrained in the race through natural selection. We shall more
clearly realise that educability itself is a product of natural
selection, though the specific results acquired through cerebral
modifications are not transmitted through heredity. It will, perhaps,
also be realised that the instinctive foundations of social behaviour
are, for us, somewhat out of date and have undergone but little change
throughout the progress of civilisation, because natural selection
has long since ceased to be the dominant factor in human progress. The
history of human progress has been mainly the history of man's
higher educability, the products of which he has projected on to his
environment. This educability remains on the average what it was a dozen
generations ago; but the thought-woven tapestry of his surroundings is
refashioned and improved by each succeeding generation. Few men have in
greater measure enriched the thought-environment with which it is the
aim of education to bring educable human beings into vital contact, than
has Charles Darwin. His special field of work was the wide province of
biology; but he did much to help us realise that mental factors have
contributed to organic evolution and that in man, the highest product of
Evolution, they have reached a position of unquestioned supremacy.
XXII. THE INFLUENCE OF THE CONCEPTION OF EVOLUTION ON MODERN PHILOSOPHY.
By H. Hoffding.
Professor of Philosophy in the University of Copenhagen.