CHAPTER VII

_THE EVOLUTION OF ANIMAL BEHAVIOUR_

I.--THE PHYSIOLOGICAL ASPECT

At the outset of our inquiry, we used the word “behaviour” in a wide

and comprehensive sense. Thus broadly used, I said, the term in all

cases indicates and draws attention to the reaction of that which

we speak of as behaving in response to certain surrounding forces

or circumstances which evoke the behaviour. The behaviour of living

cells is dependent on changes in their environment; that of deciduous

trees, as they put forth their leaves in the spring or shed them in

the autumn, is related to the change of the season; instinctive,

intelligent, and emotional behaviour are called forth in response

to those circumstances which exercise a constraining influence at

the moment of action. Used in this comprehensive sense, the term

“behaviour” neither implies nor excludes the presence of consciousness.

We know from our own experience, however, that consciousness does in

some cases accompany behaviour, and we infer that in many other cases

it may be present. But we need a criterion of its presence to guide

our inferences, and this criterion we found in the ability of living

beings to profit by experience. In Dr. Stout’s phraseology, if a thing

seems to acquire meaning for such a being, and the behaviour is guided

in accordance with such acquired meaning, we infer the presence of

consciousness as supplying conditions effective in determining its

course. Still this does not exclude, nay, rather it presupposes the

presence of sentience at a lower stage of evolution, a sentience which

is as yet ineffective since the process of conscious coalescence has

not begun, or has not been carried far enough.

In foregoing chapters we have constantly held the problems of evolution

in view, and in special sections directed attention to them. But the

subject is so central to modern thought and discussion, that some

further consideration of certain aspects of the evolutionary process

and products will fitly serve to bring our inquiry to a conclusion.

We must accept, as a datum from the physiological point of view, the

fact that protoplasm does respond to stimuli,--that it possesses the

fundamental property of irritability. It is a substance that is in a

state of unstable equilibrium. Its tendency to pass to a condition of

more stable equilibrium is that in and through which organic behaviour

in its very simplest expression is possible. And this, with progressive

complication, runs through the whole gamut of animal behaviour, and

eventually passes over into the sphere of consciousness. “The tendency

to equilibrium,” writes Dr. Stout,[187] “is the physiological correlate

of what on the psychical side we call conation,--the striving aspect of

consciousness.” But, protoplasm at the outset--or as near the outset

as we can get--is, in technical phrase, differentially responsive. The

nature of the stimulus and the nature of the conditions decide what

the nature of the response shall be. And even in that jelly-like speck

of living matter, the _Amœba_, the responses conspire to a biological

end. If they did not so conspire, we should not have the phenomena of

life. The mere act of living, building up from food-stuff and oxygen an

unstable substance which “explodes” and contracts under stimulation,

implies that the processes which thus conspire are related in such

a manner as to fulfil and secure their end. In higher unicellular

animals, such as the _Paramecium_, the relations are less simple; but

in them the continuance of that sum of organic behaviour which we

call life, is secured only on the condition that these less simple

relations are duly preserved, and that the vital processes conspire

with sufficient unity of biological purpose. And when we pass to the

higher creatures in which many cells unite to form one animal, the very

word “unite” indicates that the vital processes of all must conspire

with sufficient _unity_ of biological purpose to insure the continued

life of the whole.

Now, in all the higher and more active animals a nervous system is

developed, which has for its purpose and end the preservation and

furtherance of unity amid circumstances of progressively increasing

diversity. And in the course of its evolution an added means of

preserving and furthering the essential unity is provided in

consciousness, which, through the coalescence of scattered units of

sentience, leads behaviour to acquire a new and higher unanimity of

purpose. Thus a mental evolution is engrafted on the organic evolution

which precedes it. But every step in this mental evolution presupposes

a step in organic evolution. And such is the complexity of structure

and process in all the higher animals that much of the business of

behaviour is relegated to quasi-independent nervous centres, which

perform this business automatically, and will continue to perform it,

with much subsidiary unity of end, when they are left to themselves and

all connection with the supremely unifying sensorium has been severed.

Before proceeding to give some examples of this fact, and to indicate

its bearing on our interpretation of behaviour, it may be well to

state distinctly that no attempt is or will be here made to trace in

detail the course of the evolution of animal behaviour through the

ascending grades of life, nor, indeed, to prove that there has been any

such evolution. Evolution by natural genesis is here assumed as the

only hypothesis with which science has any concern. If it be false,

then have the labours of workers and thinkers, since Darwin and Mr.

Herbert Spencer worked and thought, been vain. Special creation is

not a scientific hypothesis, but a reference of biological and mental

phenomena to an ultimate cause, which lies beyond and altogether apart

from the scope of scientific inquiry. The fundamental assumption of

the man of science is, that any natural event he may select for

detailed study has natural conditions and antecedents. And it is only

in such detailed study--taking this or that particular occurrence and

endeavouring to ascertain what were its related antecedents--that

advance in the evolutionary interpretation of nature can be secured.

Such advance has been secured by the labours of those physiologists

who have established by careful experiment the quasi-independent

action of subsidiary nerve-centres as constituents of the nervous

system as a whole. In such animals as the crayfish and the lobster

the central nervous system consists of a chain of “ganglia,” or

nerve-knots, which are connected together by nerve-strands. If these

strands be cut between the thorax, which carries the walking limbs,

and the abdomen or hinder portion of the body, the nerve-connection

between these parts is severed. If the forepart be irritated through

its sense-organs, the limbs of that part will respond; but, whereas

an unmutilated crayfish, subjected to such irritation, would give a

vigorous flap of the tail, this does not take place in the crippled

animal.[188] Still, if the abdomen be irritated, it will respond by a

strong and swift contraction. The two portions of the body are each

capable of acting independently with well co-ordinated movements, but

no longer of working together with unity of purpose. In the hinder

portion the abdominal limbs, or swimmerets, all swing backwards and

forwards simultaneously with rhythmic strokes; they act in concert.

Sever now the connections between their ganglia, and each pair of

limbs will continue to swing rhythmically but not with concerted

rhythm. We have isolated a number of quasi-independent centres, and

rendered them really independent. Each is concerned with its own

proper co-ordination, but can no longer combine with others in a

wider co-ordination. Mr. Hyde[189] has shown that in the king-crab,

_Limulus_, when the nerve-chain is severed just in front of the

abdominal region, the rhythmic respiratory movements of the abdominal

segments still proceed regularly and co-ordinately. Even when only

a fraction of the nerve-cord, separated by severances in front and

behind, is left, corresponding with a single abdominal segment,

the rhythmic action of that segment continues; but it is no longer

synchronous with that of adjacent segments similarly isolated.

It will probably not be contended that the co-ordinated rhythm of

the isolated segment in crayfish or king-crab is anything but a bit

of organic and physiological behaviour. Whether it be accompanied by

consciousness--a bit of consciousness isolated from other bits--we

do not know; but we have no grounds for supposing that the rhythmic

behaviour is guided by consciousness. And when, as Dr. Carpenter

pointed out half a century ago, a water-beetle, from which the “brain”

has been removed, swims forwards if placed in water, we must surely

regard the co-ordinated progression as organic behaviour, whatever view

we may hold with regard to a consciousness which in such a case is in

a very literal sense a divided consciousness.

In these invertebrates the central nervous system is obviously

segmented--one can distinguish the ganglia and their connecting

nerve-strands. In the vertebrate the brain and spinal cord form a

continuous mass of nerve-tissue without obvious segmentation. But the

pairs of spinal nerves, each nerve with its afferent and efferent

“root,” indicate a really segmented condition, though in the cord

itself the segments so run together and overlap that they cease to be

externally obvious. And there is a certain, though limited, amount of

overlap in the distribution of these segmental nerves. Still, well

co-ordinated responses occur when comparatively short portions of the

spinal cord are isolated by severance from the rest. In the male frog,

especially during the breeding season, a clasping reflex is produced by

stimulating the dark swollen pads on the inner side of the hand, and

this, as Goltz has shown, is exhibited when all the central nervous

system has been destroyed save the segments to which the nerves for

the arms proceed. “Similarly,” writes Dr. Sherrington,[190] “in the

cat and monkey, the reflex wagging of the tail persists when behind

the spinal transection only the sacral region of the cord is left

intact.” When the spinal cord of the dog is severed, so as to isolate

that portion which is concerned with movements of the hinder part of

the body, pressure on the pad of one hind-foot usually produces, not

only a lifting of that leg, but also an extension of its fellow--that

is to say, a co-ordinated response of the two limbs. But in the case

of the vertebrates, more than in that of the invertebrates, the

co-ordinated response of an isolated part of the central nervous system

seems to lack the furtherance of its action, which normally comes

from the higher centres from which it has been severed. “The spinal

reflexes significant of progression seem,” says Dr. Sherrington,[191]

“to contribute chiefly towards preparatory posture in readiness for

the onset of action executed by the musculature under the driving of

higher centres. Thus the well-known reflex spinal posture of the frog

is flexion of the hind limbs, the extensors of the joints being taut

and ready for the jump. The spinal reflexes, which in their results

approximate most closely to the normal reactions of the unmutilated

individual, are those connected with the pelvic and abdominal

viscera,” many of which “are executed as spinal reflexes in a manner

presenting little or no physiological defect from the normal. And if

the bulb”--the continuation of the spinal cord within the skull to form

the basal portion of the brain--“be included with the spinal cord, and

these together, including their nerves, be isolated from the rest of

the nervous system, the animal as regards its visceral life, including

that of the heart and lungs, is practically intact.”

Huxley graphically describes the actions of a frog from which the

cerebral hemispheres have been removed. “If that operation,” he

says,[192] “is performed quickly and skilfully, the frog may be kept

in a state of full bodily vigour for months, or it may be for years;

but it will sit unmoved. It sees nothing; it hears nothing. It will

starve sooner than feed itself, although food put into its mouth is

swallowed. On irritation, it jumps or walks; if thrown into water it

swims. If it be put on the hand it sits there, crouched, perfectly

quiet, and would sit there for ever. If the hand be inclined very

gently and slowly, so that the frog would naturally tend to slip off,

the creature’s fore paws are shifted on to the edge of the hand, until

he can just prevent himself from falling. If the turning of the hand

be slowly continued, he mounts up with great care and deliberation,

putting first one leg forward and then another, until he balances

himself with perfect precision on the edge; and if the turning of

the hand is continued, he goes through the needful set of muscular

operations, until he comes to be seated in security on the back of the

hand. The doing of all this requires a delicacy of co-ordination and a

precision of adjustment of the muscular apparatus of the body which are

only comparable to those of a rope-dancer.”

Now, why have we entered into these details? To reinforce, from a

somewhat different point of view, that which has again and again been

urged in the preceding sections of this inquiry, that much of animal

behaviour is an organic legacy. A going mechanism of great delicacy,

with ready-made co-ordinations, the products of biological evolution,

affords to consciousness a vast body of its primary data. As Dr.

Sherrington himself says,[193] “co-ordination is abundantly shown

to result from the independent power of the spinal arcs, altogether

apart from the influence of the great cranial sense-organs, and of

the cerebral arcs superposed upon them. These senses and the brain

find the elementary co-ordination of the skeletal musculature an

achievement already provided and to hand in the spinal cord. And no

doubt the product of the instrument is, with the instrument itself,

given over to their use in the reactions they elicit from the spinal

musculature.” We have seen how instinctive behaviour, in those animals

in which it is best studied, affords in hereditary biological outline,

a sketch which subsequent acquisition, under experience, serves only

to elaborate by the filling in of details and of the more delicate

shading in behaviour. But in the higher animals, in which a period of

youth is a time for the acquisition of experience--for experimentation

and practice,--it might seem that the inherited biological legacy was

of less importance. The “spinal animal,” as Dr. Sherrington calls

it,--that is, the animal in which the spinal centres are isolated

from the cerebral centres--goes far to disprove any such view. In

them the cerebral senses and the brain find elementary co-ordination

of the bodily movements an achievement already provided and to hand

in the spinal cord. But when different animals are compared--frog,

bird, rabbit, dog, and monkey--the permanent effects of severance of

brain connection, the effects which remain when the temporary period

of disturbing “shock” is over, are more marked in the higher than

the lower types. And concerning this, Dr. Sherrington says,[194]

“The deeper depression of reaction into which the higher animal, as

contrasted with the lower, sinks when made spinal, appears to me

significant of this, that in the higher types, more than in the lower,

the great cerebral senses actuate the motor organs, and impel the

motions of the individual.”

Whether in the animal in which all direct connection between the

anterior and posterior portions of the central nervous system has been

severed there is a double consciousness--a cerebral consciousness and a

spinal consciousness--we are not in a position accurately to determine.

If the generally accepted opinion, that the higher brain-centres

constitute the sensorium or seat of consciousness, be correct, we must

suppose that a maimed consciousness, with many avenues of experience

closed, is retained in the anterior moiety, while the posterior is

relegated to a condition of mere sentience at best. In any case all

relation between the two is prevented. The two--if two there be--are

rendered quite independent through severance of the cord in the region

of the neck. But there is a point of view indicated by Dr. Sherrington

which is full of suggestion and interest.

“It is significant in the evolution of animal form,” he says,[195]

“that the organ that exhibits most uninterrupted and harmonious

increase in development, as studied successively in passing from lowest

to highest, is the brain. And it is significant that in the nervous

system--segmental system as it is--the brain is developed, not in those

segments whose sense organs are ordinary cutaneous (tactual, etc.),

muscular and visceral, but in the segments connected with the visual,

olfactory, and auditory sense-organs; in other words, the brain is

developed in the head. The head is, so to say, the individual; it has

the mouth, it takes the food, including air and water, and it has the

main sense organs providing data for both space and time. To this the

body, an elongated motor organ with a share of the viscera and the

skin, is appended primarily as a machine for locomotion. This latter

must of necessity lie at the behest of the great sense organs of the

head.”

Now let us try and picture to ourselves a spinal animal, or one which

retains only the lowest portion of the brain, the part known as the

bulb or _medulla oblongata_; let us assume that it is conscious and

capable of acquiring experience through the association and coalescence

of the data afforded by the senses that remain to it; and let us try

to imagine the conscious situations which would arise, and their

value in the guidance of behaviour. The senses that remain are touch

and the temperature sense, the motor sense affording data from the

muscles, joints, and tendons, and those which supply certain visceral

sensations. There is not one of much, if any, guiding value left. There

is not one of what we may term anticipatory use. There is not one

which could serve to infuse anything like definite meaning into the

situation. For, after all, meaning is expectation. There is an element

of anticipation in all those senses which are of any real guiding value

in the conscious situation. Sight, hearing, and, especially for some

animals, smell,--these are the senses which forewarn of something

which may follow; of other sensations with which in the course of

experience they have coalesced. And they are all cut off from the

supposed spinal animal. A light touch might in some cases forewarn

of the shock or severe pressure, which would perhaps follow. But the

shocks would so often come suddenly that it is questionable whether the

warning would be of much avail. Still, touch is a warning and cognitive

sense, and through it the environment would acquire a limited amount of

meaning.

Now, the biological value of coalescent association lies in this

very element of warning. The anticipatory senses, sight, hearing,

smell, are in their several degrees the “projective” senses, the

senses which carry with them the quantity of “outness.” And their

“projective” character is the necessary psychological expression of

their distinctive biological end. They must be projective, must carry

with them “outness,” if they are to convey what we, following Dr.

Stout, have so often spoken of as meaning. But if the biological value

of coalescent association lies in the expectation it renders possible;

and if, in the spinal animal, there are no senses left save touch,

which could receive from the environment preparatory warning of what

is coming; it would seem exceedingly improbable that it should develop

quasi-independent conscious situations of its own. In the unmutilated

animal, at any rate, tactual experience would most probably coalesce

with that derived from the senses which more distinctively take the

lead in the acquisition of meaning. And we may therefore, on these

grounds, as well as on others, acquiesce in the current view that the

quasi-independent functioning of the spinal cord and its constituent

segments is, at best, lit up with those flashes of mere sentience of

which Sir Michael Foster speaks in the passage we quoted in an earlier

section.[196]

If from the consideration of the isolated spinal animal we turn for a

moment to that of the isolated cerebral animal, we find it in a very

different position. It is possessed of the warning senses--those which

from several points of view are the leading senses--but they are

leaders without a following; they have only a very limited company to

conduct into action. The company is there, on the further side of the

severance, but they have lost touch with it. They know not what it is

doing, and have therefore neither the data nor the executive power to

guide its manœuvres in the field of behaviour. They can form maimed

coalescent situations, but they are as impotent as a mere theorist

devoid of all power of practical application. We need not, however,

follow the theme further. We need only add that, could we isolate

tracts of nervous tissue in the lower brain-centres of such a cerebral

animal, we should find that subsidiary co-ordinations would belong, as

a physiological heritage, to these isolated fragments.

The conclusions we may draw, then, with regard to the evolution of

behaviour, as viewed in its physiological aspect, are that it is,

in its simplest expression and in its most complex, conditioned by

sufficient unity of purpose to meet the biological end of survival;

that the complex unity of purpose may be analyzed into a multiplicity

of subsidiary processes each with its subsidiary unity of purpose; and

that the psychological coalescence which gives unity to experience

under the guidance of the leading senses, is paralleled in a

physiological coalescence within the nexus of the nervous system.

II.--THE BIOLOGICAL ASPECT

The biological aspect of behaviour--its relation to biological

ends--has so often come under our consideration in the foregoing

chapters that little need be added in this section: and that little

may be most appropriately devoted, first to the question whether

consciousness does influence behaviour; and secondly, this being

accepted, to the importance of the _rôle_ that is played by the

development of conscious situations in securing, in the higher animals,

the biological end of racial preservation.

That this end is secured without the aid of consciousness in the

case of many organic species, in all those, for example, which we

classify as plants, must not be taken as presumptive evidence that in

other species, for instance in the multitudinous host of insects, the

development of conscious situations is of no biological value. The fact

that chlorophyll is not developed in any mammal does not show that the

possession of this substance is of no service to the higher plants.

It would not be worth while to give expression to this very obvious

truth, were it not that critics of natural selection persistently

argue that because one species gets on perfectly well without this

or that particular character it can have played no part in securing

the survival of another species. When I described, at a meeting of

naturalists, how well young chicks could swim, such a critic drew me

aside after the meeting, and expressed his surprise that this did

not convince me that the webbed foot of the duck could not logically

be attributed to natural selection. This is an extreme case, and one

obviously taken on peculiarly weak grounds. But even Huxley urged

that, because a frog, from which the cerebral hemispheres have been

removed, performs many co-ordinated actions without conscious guidance,

consciousness is, throughout nature, merely an accompaniment of certain

molecular changes in the brain. “Such a frog,” he says,[197] “walks,

hops, swims, and goes through his gymnastic performances quite as well

without consciousness, and consequently without volition, as with it;

and if a frog, in his natural state, possesses anything corresponding

with what we call volition, there is no reason to think that it is

anything but a concomitant of the molecular changes in the brain which

form part of the series involved in the production of motion.

“The consciousness of brutes,” he continues, “would appear to be

related to the mechanism of their body simply as a collateral product

of its working, and to be as completely without any power of modifying

that working as the steam-whistle which accompanies the work of

a locomotive engine is without influence on its machinery. Their

volition, if they have any, is an emotion indicative of physical

changes, not a cause of such changes. It does not enter into the chain

of causation of their actions at all.”

If the literal truth of this contention--the logical soundness of this

conclusion--be admitted, it seems absurd to speak of the biological

value of consciousness in behaviour or to discuss the importance of the

_rôle_ that is played by the development of conscious situations in

securing the biological end of racial preservation.

Now, consciousness is regarded by an influential school of thinkers as

a sort of _deus ex machina_, which, sitting enthroned, and crowned with

a capital letter as Will, directs, like a being from another sphere,

the doings of the body. It was against the doctrines of this school

that Huxley took up arms. They do not concern us here. The will, or

volition, as an underlying cause, stands outside the pale of scientific

inquiry. It belongs to the wide realm of metaphysics; its plea must be

heard in another court. In this part of his contention Huxley was, we

believe, unquestionably right from the scientific standpoint. Neither

will, nor impulse, nor instinct, nor consciousness itself, should be

introduced into any scientific description or explanation of phenomena

as a cause of their existence or being, for as such it does not enter

into the sequence of events; it is that which metaphysics claims as

their _raison d’être_--that which gives them being. Science in this

matter should be frankly agnostic--neither affirming nor denying

aught. This, of course, is not equivalent to saying that the agnostic

position is the true end of human reason. That would only be so on the

assumption that the problems of science are the only problems with

which that reason can deal. To exclude metaphysics from science is not

to exclude it from human thought. As a matter of fact such exclusion

is neither possible nor reasonable. But to clearly distinguish the

problems of science from those of metaphysics is absolutely necessary,

if we are to prevent hopeless confusion of issues.

In contending, however, against the introduction of metaphysical

doctrines into the region of scientific explanation, Huxley seems

to have been carried too far by the force of his own attack. So long

as he held to the position that every conscious state has, as its

concomitant, a molecular change in the brain, he had all the forces

of evolution on his side. But when he said that consciousness is

merely the steam-whistle of life’s locomotive, or merely answers to

the sound which the animal-bell gives out when it is struck, he takes

up another position of far less strategical strength. For whereas

the frog from which the physical centres of consciousness have been

removed sits crouched and motionless, and “will starve sooner than

feed itself, although food put into its mouth is swallowed;” the frog

in which conscious situations can take form in unmutilated cerebral

hemispheres behaves in a very different manner. It is nothing less

than pure assumption to say that the consciousness, which is admitted

to be present, has practically no effect whatever upon the behaviour.

And we must ask any evolutionist who accepts this conclusion, how he

accounts on evolutionary grounds for the existence of a useless adjunct

to neural processes.

“It is,” says Huxley,[198] “experimentally demonstrable--any one who

cares to run a pin into himself may perform a sufficient demonstration

of the fact--that a mode of motion of the nervous system is the

immediate antecedent of a state of consciousness. We have as much

reason for regarding the mode of motion as the cause of the state of

consciousness, as we have for regarding any event as the cause of

another. How the one phenomenon causes the other we know as much, or as

little, as in any other case of causation; but we have as much right

to believe that the sensation is an effect of the molecular change, as

we have to believe that motion is an effect of impact; and there is as

much propriety in saying that the brain evolves sensation, as there is

in saying that an iron rod, when hammered, evolves heat.” But if we

speak of the related antecedent as the cause, it is not obvious why we

should not describe the desire to demonstrate the supposed fact as the

cause of running in the pin. We seem to have just as much reason for

calling this antecedent state of consciousness the cause of certain

movements and behaviour, as of calling a mode of motion in the brain

the cause of a further state of consciousness. It is true that we

have not the least idea how the desire can cause the act; but Huxley

practically admits that we have no idea how molecular change can be the

cause of consciousness. In the one case we are no worse off than we

are in the other. Neither position is logically defensible; since each

assumes that physical events and states of consciousness can constitute

links in the same causal chain.

The philosophical hypothesis known as monism regards the molecular

change, not as the antecedent of a conscious state, but as its

concomitant. That which from a physical and physiological point of

view is a complex molecular disturbance is, at the same time, from a

psychological point of view, a state of consciousness. The two are

different aspects of one natural occurrence. Why such an occurrence

should have two so different aspects we have not the faintest idea; but

here we are not one whit worse off than we were before. The hypothesis

does, however, help us to get over our difficulty. An essential

feature of Huxley’s contention is that the physical and physiological

chain of causation is complete in itself, which may be granted; and

further, that if consciousness does arise it is merely an adjunct

without influence on the sequence of events--what is influential is

the molecular disturbance, not the consciousness which accompanies it.

But according to monism the state of consciousness actually is that

very same something which the physiologist calls, in the language of

physics, a molecular disturbance. And in saying that consciousness

influences behaviour one who accepts this hypothesis is merely avoiding

a cumbrous form of circumlocution. He puts it in this way instead

of saying that the nerve-changes in the cerebral hemispheres, or

elsewhere, which from a psychological point of view _are_ a conscious

situation, influence and determine the course of behaviour. But from

this point of view it is absurd to say that the consciousness is merely

an adjunct--absurd to say that were there no conscious situation the

neural situation would remain unchanged. They are the very same thing

from different points of view; and to say there is no influential

conscious situation is simply equivalent to saying that there is not

this determining neural situation.

However we explain the fact, there are few who hesitate to accept it

for the purposes of scientific explanation. The conscious situation,

having no doubt for the physiologist a neural aspect if he could only

get at it as a whole, does practically determine the behaviour of the

animal which has gained the requisite experience. If we accept the

fact, we may pass on to its importance in securing the biological end

of race preservation.

It is a commonplace of evolutionary doctrine that, other things being

equal, those races will survive, in the constituent members of which

intelligent behaviour enables them to deal most effectually with an

environment of increasing complexity. And it is a matter of familiar

observation that such behaviour is closely connected with delicacy

and refinement of development in those senses which take the lead in

cognitional process, and with rapidity and precision in the motor

co-ordination through which prompt and skilful advantage is taken of

the situation which has, through experience, acquired meaning.

But though the importance of intelligent adjustment to the

circumstances of life is widely admitted as a general principle, it

is perhaps through a study of animal behaviour that we are best able

to realize its full range and extent. Biologists are so largely, and

quite wisely, occupied in the study of morphological and physiological

problems, which admit of a treatment more exact than the most ardent

advocate of the investigation of behaviour, under natural or even

under experimental conditions, can claim; they devote, again quite

rightly, so large a share of attention to the variation and natural

selection of adaptive structure in its adult condition and embryonic

stages; the pendulum of opinion has, under the teaching of Professor

Weismann, swung so far in the direction of the non-acceptance of

the hereditary transmission of characters individually acquired

through intelligent adjustment or otherwise; that the part played by

consciousness in the evolution of the higher and more active animals is

apt to pass unnoticed or unrecorded. It is well, therefore, to put in

a reminder that a great number of animals would never reach the adult

state in which they pass into the hands of the comparative anatomist

save for the acquisition of experience, and the effective use of the

consciousness to which they are heirs; that their survival is due,

not only to their possession of certain structures and organs, but,

every whit as much, to the practical use to which these possessions

are put in the give and take of active life; and that many interesting

problems which are keenly discussed by evolutionists in the light of

natural selection presuppose conscious situations which are more or

less tacitly taken for granted.

Let us cast a rapid glance over some of these topics of biological

discussion. The fascinating subject of mimicry, involving as it

necessarily does the discussion of the value of warning colours and

behaviour, a subject opening up an extensive group of problems so

brilliantly studied by Professor Poulton, is meaningless save in so

far as there is implied a conscious reaction to colour and form on the

part of animals which can learn from experience. The warning colours

reinstate a conscious situation, so that, misled by appearances, a bird

mistakes the mimicking insect for its nauseous “model.”

The whole range of behaviour, included under play, experimentation, and

practice, on the importance of which, following the lead so ably given

by Professor Groos, we have insisted, is equally meaningless, save as a

means to the acquisition of serviceable experience for use in the more

serious business of after-life; and experience is the establishment,

through association and coalescence, of conscious situations which

possess guiding value. And if, as we shall hereafter see, they may

also be regarded as a means of securing pleasure, as a psychological

end of behaviour, it is not less obvious that it is only through the

development of consciousness that such a psychological end can have any

existence.

It matters not if the particular form assumed by play and

experimentation be largely dependent on instinctive tendencies. For

all the phenomena of instinct, profoundly organic as are the modes of

behaviour comprised under this head, definite as are the inherited

co-ordinations in the most typical examples of its occurrence, have

also, except in some doubtful cases, a conscious aspect. At any rate

this is the case in so far as instinctive response forms the hereditary

basis on which is reared a more nicely adjusted intelligent edifice,

in so far as instinctive procedure is subsequently modified and guided

by acquired experience, in so far as there creeps in that “little dose

of judgment” which Huber found in bees, Lord Avebury attributes to

ants, Dr. Peckham sees in spiders and solitary wasps, and all observers

find in birds and mammals. For if in these cases instinctive behaviour

were unconscious, it would, as such, remain outside experience; and if

outside experience, there could be no data on which consciousness could

base any modification of inherited behaviour, no opportunity of taking

up the ready-formed responses into the mental synthesis and utilizing

them for the wider ends of intelligent purpose.

In social behaviour there is a reciprocity of suggestion between the

members of the community. And such suggestion is operative through an

appeal to consciousness. However instinctive the forms of procedure

may be in social insects, there remains much beyond which is hard to

explain on the hypothesis that there is, in them, nothing analogous to

a conscious situation; while in such vertebrates as birds and mammals

we cannot but believe that consciousness is the main determinant of

much behaviour which seems to imply the germs, or more than the germs,

of sympathy. The little monkey I saw in Hamburg cuddling up caressingly

to a wounded companion, must surely have experienced a conscious

situation analogous to that which prompts a child to nestle alongside

her companion in distress. And he who has seen no signs of sympathy in

dogs, has either watched their behaviour in vain, or is himself lacking

in sympathy.

In sexual selection by preferential mating, even if we follow Professor

Groos in believing that it is a special mode of natural selection,

the conscious situation is essential. If we accept the theory in any

form, we must regard the adornments, antics, and display of the male

as an appeal in some way to the consciousness of the female, whatever

particular form the effects in that consciousness may take, whether the

appeal evoke a sense of beauty, or simply be a means of exciting to the

consummation of the natural end of courtship. Even if we follow Mr.

Wallace in regarding plume and song as “recognition marks,” it is only

by their appeal to consciousness in this way, if in no other, that they

are of any biological value. And this, of course, applies equally to

the whole range of his theory of recognition marks--their sole utility

lies in their being a stimulus to consciousness through which the end

of recognition is secured. So, too, not only the specialized behaviour

which we dignify by the name of “courtship,” but every case in which

mate is drawn to mate through sight, smell, hearing--any of the leading

senses--testifies to the importance of consciousness in furthering an

end of supreme biological importance.

And if, as Darwin urged, the “law of battle” among the males

co-operates with preferential mating, as we can hardly deny, in

securing strong, vigorous, and healthy fathers of the generation they

beget, here, too, consciousness is an important factor. Can we conceive

a “law of battle” among unconscious beings? If success in the combat

were a mere matter of brute strength, it would imply some consciousness

in its dull exercise. But it is more. It is also a trial of skill.

Were it not so our forefathers would not have spent hours in watching

a cock-fight, or laid heavy odds on their particular “fancy.”

We need not labour the theme. In the search for food or a nesting

site, in the capture of prey and escape from enemies, in all that

demands attention, and in all that necessitates practice, in what

M. Houssay calls “the industries of animals,” and in that which Mr.

Hudson calls “tradition,” consciousness has a part to play. Even

plants unconsciously appeal to the consciousness of insects, birds,

and mammals. Their bright, scented, nectar-bearing flowers, and their

sweet, coloured fruits are means of effecting the biological ends of

fertilization and the dissemination of seeds, but only on condition

that their colours stimulate the sense of sight, and their scent and

sweetness the senses of smell and taste. It is, perhaps, going too far

to claim that, wherever sense-organs exist they imply at least some

dim and rudimentary form of conscious situation of guiding value so

far as it goes; for it is possible that in some cases the coalescence

of elementary items of sentience has not been carried far enough to

justify us in speaking of experience by which the animal can profit.

But it is surely not going too far to claim that, wherever two or three

such sense-organs are gathered together in any living being, there is

consciousness in the midst of them, beginning to exercise that guidance

which serves so markedly to differentiate the typical animal from the

typical plant.

But throughout the animal kingdom, until we reach its highest

development in man, the guidance of consciousness, important as it

is, seems to be almost wholly subservient to a biological end, that

of the preservation of the race, and for the race of the individual.

Practical utility is the touchstone of animal intelligence, and of the

whole range of feeling and emotion in beings still under examination in

the stern school of natural selection. By this we mean that practical

utility has determined what degree and complexity of intelligence,

feeling, and emotion shall be attained. If the requisite level be not

attained--elimination. Higher levels no doubt bring advantage--so long

as they are practically useful. But in the school of natural selection

useless accomplishments are not much taught. Although its examinations

are in a sense competitive, all are allowed to pass who qualify for

survival. But the competitors become more numerous and the standard

for a pass rises. As the school increases in size higher classes with

harder problems to solve are established. Progress is an incident of

the constant survival of the fittest when there are variations in

fitness.

III.--THE PSYCHOLOGICAL ASPECT

On the hypothesis of monism, the nature of which, so far as it bears

on our inquiry, was briefly indicated in the foregoing section, the

conscious situation is the psychical or mental expression of that

which for the physiologist is what we may term a neural situation. As

such it does not enter into the chain of physical causation; nor do

physical events as such--that is to say, save as experienced--enter

into the chain of mental causation. For mental development they have

no independent existence, and are negligible except in so far as they

enter as items of experience into the conscious situation.

But altogether apart from the way or ways in which we may attempt to

explain the fact, most of us believe, with unquestioning confidence,

that the growth of practical experience, somehow associated with

nervous changes in the brain or sensorium, is of real value in the

guidance of behaviour in such manner as to secure biological ends.

Conscious experience must therefore, in the animal world, serve its

biological purpose, or it will be of no avail. If there be not a

pre-established harmony, there must be an evolved harmony; and how such

a harmony could be evolved if consciousness be not by some means in

vital touch with behaviour, influenced by and in turn influencing it,

we cannot conceive. The steam-whistle theory of consciousness leaves

the matter, for the evolutionist, in this inconceivable position.

We need not, however, flog a dead horse. We need not ask how, on the

steam-whistle theory, those states of feeling which we broadly classify

as pleasurable could become associated with behaviour conducing to

welfare, and those which we group as hurtful with behaviour which

is biologically harmful. It is more important, again, to notice

that, associated and consonant with the biological end, there

arises a psychological end of behaviour--what we may term, with the

qualifications before considered,[199] the getting of pleasure and the

avoidance of pain. This is the purpose of behaviour as viewed from the

psychological aspect. The biological end of animal conation is racial

survival; its psychological end is individual satisfaction. And the two

ends are, in the main and broadly speaking, consonant--a result which

would unquestionably be secured by natural selection, but is on any

other naturalistic hypothesis difficult of explanation.

But the two ends are not only consonant; they are supplementary one

to the other. During much of the life of the higher animals there is

no need, immediately present and pressing, for the output of action

to meet biological ends. There are periods of life and intervals of

time when the sharp incidence of the struggle for existence does not

call for the serious business of behaviour. But at these periods and

in these intervals the animal is not inactive; indeed, it is restless

in its activity. Unless it be weary with unwonted exertion, or basking

in the psychical sunshine of content, due to the unsought advent of

pleasant stimulation or the after-effects of previous behaviour (for

example, when hunger has been relieved), the healthy animal must be up

and doing. This familiar fact no doubt affords the basis in observation

of the surplus-energy theory of play. But is it necessarily surplus

energy? Is it not rather normal energy which expends itself in this way

when there is no immediate and serious biological business on hand?

And, as Professor Groos has pointed out, play is seen when we have

every reason to suppose there is no surplus energy, nay, even when the

normal energy is at a low ebb. There is no more pathetic sight than a

sick kitten, with energy obviously much below par, utilizing its little

remaining strength in feeble attempts to play.

It is unnecessary to do more than remind the reader of the theory

elaborated with so much skill and care by Professor Groos, that the

forms assumed by play--in which, it will be remembered, he includes a

very wide range of behaviour--have a very important indirect biological

end in practice and experimentation. Our present point is, that its

direct psychological end is the satisfaction it affords. Without

this the individual would not be impelled to the continuance of

performances which occupy a wide space in the field of animal behaviour

in which the biological end has reference, not to present requirements,

but to future needs.

No one has given better expression to the sway of this psychological

end than Mr. W. H. Hudson. “We see,” he says,[200] “that the inferior

animals, when the conditions of life are favourable, are subject to

periodical fits of gladness, affecting them powerfully and standing

out in vivid contrast to their ordinary temper. And we know what

this feeling is--this periodic intense elation which even civilized

man occasionally experiences when in perfect health, more especially

when young. There are moments when he is mad with joy, when he cannot

keep still, when his impulse is to sing and shout aloud and laugh at

nothing, to run and leap and exert himself in some extravagant way.

Among the heavier mammalians the feeling is manifested in loud noises,

bellowings, and screamings, and in lumbering, uncouth motions--throwing

up the heels, pretended panics, and ponderous mock battles.

“In smaller and livelier animals, with greater celerity and certitude

in their motions, the feeling shows itself in more regular and often in

more complex ways. Thus Felidæ, when young, and in very agile sprightly

species, like the puma, throughout life, simulate all the actions of

an animal hunting its prey--sudden, intense excitement of discovery,

concealment, gradual advance, masked by intervening objects, with

intervals of watching, when they crouch motionless, the eyes flashing

and tail waved from side to side; finally, the rush and spring, when

the playfellow is captured, rolled over on his back, and worried to

imaginary death. Other species of the most diverse kinds, in which

voice is greatly developed, join in noisy concerts and choruses; many

of the cats may be mentioned, also dogs and foxes, capybaras and other

loquacious rodents; and in the howling monkeys this kind of performance

rises to the sublime uproar of the tropical forest at eventide.

“Birds are more subject to this universal joyous instinct than mammals,

and there are times when some species are constantly overflowing with

it; and as they are so much freer than mammals, more buoyant and

graceful in action, more loquacious, and have voices so much finer,

their gladness shows itself in a greater variety of ways, with more

regular and beautiful motions, and with melody. But every species or

group of species has its own inherited form or style of performance;

and however rude and irregular this may be, as in the case of the

pretended stampedes and fights of wild cattle, that is the form in

which the feeling will always be expressed.”

That all this, which Mr. Hudson so graphically describes, belongs to

the psychological aspect of animal behaviour and is directly prompted

by conative tendencies whose immediate end is conscious satisfaction,

the mere joy of unrestrained and healthy activity, may be freely

admitted, without denying that all this exuberant psychical life

owes its evolution to the fact that it is in consonance with and

supplemental to biological ends which secure survival. It is with

animals as it is with man; play is the preparation for earnest. As I

have elsewhere said,[201] what our national games have done for the

English race it is difficult to overestimate. They train us to use our

bodies and expend our energies to the best advantage. An old soldier,

watching a football match, said, “That’s the training for our future

soldiers and sailors.” The playing fields are the finest school of

organized co-operation in the world. But, apart from compulsion, a

boy will not enter into the game with that zest through which alone

it acquires real value for training, unless there be an immediate

psychological end in the satisfaction he derives. And with animals

practice and preparation for the business of life could not occur if

the ultimate biological purpose of it all were not supplemented by the

enjoyment it brings for its own sake.

But in animal play, as indeed in that of human youth, we are perhaps

a little apt, in laying stress on the bodily skill and readiness

of response to which it so effectually ministers, to forget that it

is also a psychological training. In technical phraseology, we are

disposed to fix our attention on the acquired co-ordination of act

and movement rather than on the correlation of conscious data, which

renders possible the skilful performance. And yet, rightly considered,

the behaviour itself is simply the outcome of a conscious situation,

duly elaborated, and knit together through the association and

coalescence of its constituent data. It is a means to the unification

of consciousness by bringing into relation scattered and, at first,

quasi-independent sensory and emotional elements. Success is only

attained through the concentration of attention and effort on that

which is the centre of interest and also the focus of endeavour. And

this close attention and well-directed effort, which are trained in

the playful output of energy, are just the mental qualities which

will stand the animal in good stead when the real incidence of life’s

struggle comes upon it, when the reward of success is survival and

the penalty of failure elimination. For they are not merely physical

qualities, though their effects are bodily movements of attack and

defence, of active escape, or merely “lying low.” They are essential

psychological features of a unified and well-directed conative process.

In the fairly abundant play-time of animal life, this unification and

direction of conative process can take form under conditions wherein

the preliminary failures which accompany all forms of learning do

not entail the severe penalty of elimination. If we may so put it,

and so apply a deeply instructive parable, Natural Selection says

to her more favoured children, in which conscious situations can be

developed, “Here are the talents with which I have endowed you; make

use of them till I come, as come I shall in due time.” This animal

puts them out to usury in play; that animal keeps them laid up in the

napkin of inactivity. Then Natural Selection, the austere one, comes;

gives the commendation of survival to the animal that had learnt to

put its talents to use in the period of preparation, and condemns to

elimination that which had not traded with his talents at the bank of

play. In animal life, on the perceptual plane, we have the same need

for training in little things and seemingly unimportant matters in

preparation for the stress and storm which may, nay must, come upon

them, that we find in men and women on the higher ethical plane. To

those who think that the play of animals is too trifling a thing to

affect the question of survival, we would suggest the application, with

a necessary difference, of the thought which Miss Edith Simcox puts

into the following words: “Does it,” she says, “seem a trifling thing

to say that in the hours of passionate trial and temptation a man can

have no better help than his own past? Every generous feeling that has

not been crushed, every wholesome impulse that has been followed, every

just perception, every habit of unselfish action, will be present in

the background to guide or to sustain. It is too late, when the storm

has burst, to provide our craft with rigging fit to weather it; but we

may find a purpose for the years that oppress us by their dull calm, if

we elect to spend them in laying up stores of strength and wisdom and

emotional prejudices of a goodly human kind, whereby, if need arises,

we may be able to resist hereafter the gusts of passion that might else

bear us out of the straightforward course.” To apply the thought, the

trifles of play supply the psychological rigging which alone can save

the animal craft in the coming storm of the struggle for existence. And

the point on which we have to lay special stress in this section is,

that it is psychological rigging--or, if this seems to lay too much

emphasis on the genesis of conscious situations, we may at least urge

that the psychological ropes are of co-ordinate importance with the

biological spars.

So far, then, we reach the following conclusion: that if we classify

the behaviour of the higher and more intelligent animals under two

heads, the one comprising all those acts which are of direct biological

value in enabling the animal to escape elimination under the immediate

stress of the struggle for existence, and the other including all those

acts which are of indirect preparatory or educative value, the latter,

which are under their biological aspect not less important than the

former, are under their psychological aspect of perhaps even greater

importance. For the conditions of actual struggle are not those under

which mental development could most easily be furthered, though they

are those in which it is most effectually tested. Hence, the more

intelligent animals pass through a period during which they are more

or less shielded from the incidence of natural selection by their

parents, and this is the period of play and of psychological education.

And the tendency to play is so far organic, in that it is dependent on

inherited instinctive propensities, and so far psychological in that

it is accompanied by a felt want, which constitutes a conative impulse

finding its appropriate end in the consciousness of satisfaction. But

play--if we accept the term as the group-name for all these modes

of behaviour which fall under our second class, those of indirect

biological value--does not cease with the period of youth; it occupies

all the intervals in the more serious business of animal life. And no

discussion of animal behaviour can be adequate which does not assign

to this class its due place, alike in biological and in psychological

evolution.

The whole value of experience lies in the linkage and coalescence

of the data afforded to consciousness. It is true that an inherited

nervous system supplies the organic conditions of that physiological

linkage and functional coalescence of which experience is the

psychological expression. It is true that this physical integration

secures a ready-made grouping of the conscious data which are the

concomitants of orderly molecular changes in the brain or analogous

sensorium. Still, it also remains true that the value of experience

lies in the further linkage and coalescence that is acquired by the

individual in the course of what we may fitly call its education. Every

step in this education gets its psychological sanction through the

satisfaction it affords in consciousness; and the time of acquisition

is not during the stress of examination in the actual struggle for

existence, but rather in the youthful period and in the subsequent

intervals of preparation and practice during the play-time of animal

life.

The examination analogy--if, indeed, it may not be rightly regarded

as something more than an analogy--may be pressed a little further

as a means of fixing our attention on two points which are worthy

of consideration. The first is that, in the preparation for the

examination, specific practice as much of it is, cramming is not

the system exemplified by the higher animals. A good all-round

education in the acquisition of conscious situations more or less

coalescent into a unified system of experience, and in their effective

utilization without unnecessary delay and bungling along more or

less converging lines of practical behaviour; this is what secures a

“pass” in survival, especially where the circumstances of life have

reached a considerable degree of complexity. The instinctive act,

with its relatively definite response to a question which is almost

certain to be set to every candidate for survival, is that, which is

the analogue in behaviour to the result of a system of cram. Organic

nature does employ this system in the lower classes of her school;

definite responses are ground into merely instinctive types generation

after generation, and the right answers are given, automatically and

unintelligently, whenever the oft-recurrent questions are set. But this

will not do when the questions require the exercise of intelligence,

when they are of the nature of problems, with just those delicate but

not unimportant shades of difference which baffle the candidate who

has been drilled in a merely mechanical fashion. Hence the cramming

of instinct does not suffice for animals whose environment presents

problems of greater variety and greater complexity. Intelligence

is required to meet the particular combinations as they arise. The

greyhound, which is loosed on a hare, has never seen that hare run in

exactly that way over that special tract of country. But he has been

trained in such situations, and is thus prepared to meet the special

problem in its details as they present themselves in the light of the

experience he has gained of other like problems. And his skill in

pursuit has not only been gained through education in coursing. In a

thousand ways, as puppy and dog, he has learnt how to use well those

sinewy limbs. The training of his whole life is brought to bear on the

question immediately before him.

The general bearing of these facts is obvious. Play, as a means of

animal education, is varied, and has for its end all-round training

of the animal mind in its sphere of operation. Although there are

some specific propensities, certain observable trends of behaviour,

as in hunting-play, courtship-play, and the like, we must not expect,

nor do we find, anything like stereotyped definiteness of conative

activity. We find that freedom and elasticity in animal education which

is, perhaps, more often advocated than carried into practice in human

education.

The second point arising out of the examination analogy is, that its

range determines the level of preparation therefor. It is, for animals,

a practical examination, not a theoretical. Not a single question is

set demanding an explanation. The problems are such as can be solved by

intelligence, not such as require the exercise of reason, as we have

used the term in foregoing pages. These higher problems are only set

when the sixth form is reached, and there is no conclusive evidence

that any animals get into the sixth. This, however, is entirely a

question of evidence, and many of us will be glad to welcome them

there, if proved ability to deal reflectively with ideational questions

justifies their promotion.

If any of them do belong to this form, they have probably got there

through play. For in the stress of the actual examination there is not

much time for reflection. Or perhaps we may rather say that, not in

actual struggle, and not in active preparation for it in play-time,

but in intervals of leisure between both, when the animal lies quietly

turning over in his mind we know not what, will experience be reviewed,

and generalizations drawn as to the why of events in this strange

world. Probably the animal accepts things as they are, and does not

trouble about their explanation. But it may not be so. At any rate,

if animals lack the means of descriptive inter-communication, and

have no words as concrete pegs on which to hang abstract ideas, their

explanations cannot be carried far. Theories without the power of

disputation would be a poor solace in leisure moments.

One more point may be noticed with regard to the psychological aspect

of the evolution of behaviour--the reciprocal action of intelligence.

It is the intelligence of others that introduces so much variety and

complexity into the environment. Hunters and hunted, combatants,

rivals, mate and mate, enemies or companions in their varied aspects,

introduce through their intelligence complications which only

intelligence can meet. And, as intelligence begets intelligence, so do

emotional attitudes beget answering emotional states. Psychological

evolution translated into practical behaviour gives rise to situations

of reciprocal complexity. This point of view is, however, so familiar,

that nothing need be said in its further elucidation. The behaviour

of any given animal does not stand alone, but is closely related with

the behaviour of others. Among social animals the relationships are

peculiarly close, and it is among them that the psychological aspect of

behaviour reaches its highest expression.

IV.--CONTINUITY IN EVOLUTION

Under the head of organic behaviour, in the widest acceptation of

the term, fall the whole of physiology, the whole of embryological

development, nay, more, the whole of organic evolution; while mental

evolution, in all its stages, may be regarded as the psychological

aspect of that which, from the physiological aspect, is the evolution

of nervous systems. Life itself is the behaviour of a particular kind

of substance which is found more or less abundantly under natural

conditions. No other known substance behaves in this way, and so

ignorant are we as to the conditions of its natural origin, that it is

useless to guess at a scientific explanation. And even if we knew all

the antecedents and conditions of its origin we should be no nearer a

comprehension of why protoplasm has the peculiar properties which we

find it to possess. That is a question to which science can give no

answer. Who knows why a certain compound of oxygen and hydrogen in

certain proportions has the properties of that which we call water?

Let us note the distinction between saying, as we said above, that life

is the behaviour of protoplasm, and asserting that life is the cause

of this behaviour. The one is a scientific statement of observed fact,

the other an explanation of the fact in metaphysical terms, a reference

of the fact to its underlying cause. So long as we quite clearly

understand that we are talking the language of metaphysics, we may

speak of life as a cause of organic behaviour; but let us be careful

to remember that the statement has no more value for science than the

assertion that aqueosity is the cause of the behaviour of water.

Leaving on one side, then, the natural origin of protoplasm, the

conditions of which are unknown, we find that, as a matter of

observation, every bit of living substance, the history of which has

been traced, is a fragment detached from some other bit which behaved

in the same way. This is the basal fact of the continuity of organic

evolution. But such a detached fragment has the property of increasing

by taking up from the environment more of those elementary materials

from which it is itself compounded in subtle synthesis. Nay, further,

every fragment of which we know the history is found to increase in

such a way as to reach, in form, structure, and idiosyncracies of

behaviour, the likeness of the organism--plant or animal--from which it

was derived. In the higher plants and animals the separated fragments

or cells are the ova and sperms, or their equivalents, which unite,

with fusion or coalescence of their nuclear matter, and thus give rise

to a new individual in the course of embryological development.

Now, as we have already seen, much modern biological discussion centres

round the question whether the detached reproductive fragment, ovum or

sperm as the case may be, is derived from the whole body of the parent,

by what Darwin termed pangenesis or in some other way, or only from

germinal substance set apart in development for this end. And we have

provisionally accepted the hypothesis that it is the direct descendant

of other reproductive cells; and that, throughout a long ancestry,

stretching back into the far past, there never occurs in the direct

line of genealogical sequence, any highly differentiated cell, such as

a gland-cell, muscle-cell, nerve-cell; never, with certain reservations

into which we need not enter, is found the representative of any

tissue save that to which the reproductive function is restricted. In

technical phraseology, the continuity of organic evolution is due to

the continuity of the germinal substance.

During embryological development the fertilized ovum--consisting

of two fused fragments of this germinal substance--gives rise to a

host of ordered and marshalled cells, which are divisible into two

groups: the one forms the body with its muscles, bones, glands,

digestive system, skin, sense-organs, nerve-centres, and so forth;

the other forms a reserve store of germinal substance, from which

are derived the ova and sperms. The former take no direct share in

reproduction; they are off the line of continuous descent; they die

without issue. But they protect and minister to the reproductive

function of the second group--the potential ancestors of the races to

follow. But all instinctive and intelligent behaviour is the outcome

of the orderly working of the nervous system, is initiated through

sensory stimulation, and is executed by the motor organs; and all the

structural parts, through which such behaviour is possible, belong

to the body--that which dies without issue. How, then, can instinct

and intelligence be inherited? In a sense they are not inherited. The

nervous system which is their organic basis begets no heirs. But it is

begotten of germinal substance, which not only produced the body of

which the nervous system is a part, but also handed on, with that body,

samples of the same germinal substance capable of reproducing a similar

body and a like nervous system. Herein lies the basis of heredity.

The stress of the struggle for existence falls upon the body; and

instinctive or intelligent behaviour is a means to its preservation

in the struggle for existence. According as it survives or not, will

the samples of germinal substance it contains fulfil their biological

end or perish with it. Natural selection secures the survival of those

animals which bear the seed from which their like will be developed.

On this view all variation arises within the germinal substance, but it

is manifested in the body which is its product. How variations arise we

do not know with any exactness of detail. That the germinal substance

is influenced in its nutrition and in other ways by the surrounding

tissues is highly probable; and this influence may lead to changes

which are the source of variations; but it is very doubtful whether

such influence can be what we before termed “homœopathic.”[202] It is

improbable that the formation of the nerve-connections involved in

intelligent behaviour which has grown habitual through repetition,

can so influence the germinal cells as to give rise to variations of

like nature. In other words, acquired habit is probably not a direct

determinant of an inherited variation of like nature in instinctive

behaviour. Apart from such influence the only source of variations

which can be assigned is either the differential division of nuclei

in preparation for the process of fertilization,[203] or the process

of fertilization itself. The union of perhaps differentiated germinal

substance from two distinct parents affords the opportunities for the

admixture and compounding of hereditary qualities in the two samples,

from which variations favourable or the reverse may arise.

It is now generally recognized, however, that the origin of variations

is a problem quite distinct from that of the survival of those whose

direction is favourable to that end. The theory of natural selection,

as such, does not pretend to offer any explanation of the manner in

which variations arise; though of course a complete theory of organic

evolution must assign the antecedents and conditions of organic

progress in all its varied phases. We know that variations do occur;

we know, too, that more individuals are born than survive to procreate

their kind; and, on the theory of natural selection, we draw from these

data the conclusion that, on the average, the animals that escape

elimination are those in which the variations are of such a nature as

to conduce to this end.

It will be seen that, on the hypothesis of organic heredity, thus

briefly sketched, continuity can, in strictness and, as we may phrase

it, in its first intent, only be predicated of the germinal substance;

but that this substance gives rise to products--active vigorous animals

behaving in certain ways, each after his kind--which hold similar

germinal substance in trust for future use. Natural selection deals

with the trustees; and if they succumb, that which they hold in trust

is lost. To put the matter in another way: Nature says to the germinal

substance, “By your products you must be judged in accordance with the

criterion of utility and efficiency.” Practical use in the give and

take of active life is the touchstone of all behaviour which makes for

survival. This being secured, there may be a balance of behaviour for

other purposes. But in animals the balance is not of large amount, and

other purposes have not taken form and direction. It should be clearly

noticed that, on the hypothesis we are considering, use is the test

of survival, and though it is not the direct cause of variations, it

affords their sanction in survival. That animal escapes elimination

whose behaviour is of practical use; and it holds in trust for the

future a store of germinal substance from which is produced a successor

capable of behaving in like manner.

The whole drama of organic evolution may be regarded as the realization

in a succession of individuals of the evolving potentiality of

continuous lines of germinal substance. The successive individuals

die--but the germinal substance lives on in their heirs, if they have

any. In virtue of what intimate and hidden structure or disposition of

parts the germ possesses this potentiality we do not know. The ovum

of a dog is a microscopic speck less than one-hundredth of an inch in

diameter; the sperm is far more minute. They unite, and their nuclei

coalesce. The cellular product divides and subdivides. The cell colony

absorbs nutriment from the maternal tissues. Division proceeds apace,

and the cells are marshalled and ordered in embryological development;

definite tissues are formed; the stages of their genesis can be

predicted with accuracy; and in due time a puppy is born which shall

grow to the likeness of its parents and behave as they behaved. We can

trace the succession of events; we see that they form a related series;

we have good reason for believing that the state of matters at any

one moment is the antecedent condition of the state of matters at the

succeeding moment. More than this science cannot say. The underlying

cause is, for science, hidden in the mists of the unknown. Even for

metaphysics it is but part of the force that beats through the universe

and makes it not a chaos but a cosmos--a force known to us only in its

effects.

It will thus be seen that the conception of continuity in organic

evolution has, broadly considered, a threefold aspect. First,

there is the continuity of the germinal substance through whose

reproductive behaviour under the appropriate conditions embryological

development occurs; secondly, there is continuity in this embryological

development, stage by stage, from the fertilized ovum to the adult

which is its final product and expression; thirdly, there is continuity

in these final products, in the animals whose organic, instinctive,

and intelligent behaviour lie open to our study and investigation. The

first is germinal, the second developmental, the third evolutional

continuity.

Before attempting to summarize some of the contributions afforded by

our inquiry towards the doctrine of continuity in the last of these

three aspects, we must pause for a moment to consider how far and in

what sense continuity can be predicated of mental development.

We have regarded the conscious situation as the psychical aspect of a

nerve-situation in the sensorium; and the nervous system, capable of

behaving in this way, is in developmental continuity with the germinal

substance of the fertilized ovum. But what shall we say with regard to

the psychical aspect? Two hypotheses seem open to us, each of which

presents difficulties, but of different kinds. The first is, that when

the organic development of the nervous system reaches a certain level

and order of complexity consciousness emerges, how and whence we know

not. The second is, that consciousness is developed from sentience,

which is the concomitant of all organic behaviour; which accompanies

life wherever it occurs and therefore shares the continuity of the

germinal substance.

The difficulty inseparable from the first hypothesis, is that it

is contrary to the analogy of all that we know or infer elsewhere

throughout the realm of nature. Huxley[204] likened its emergence to

the production of heat when an iron bar is struck by repeated blows

of the hammer. But this analogy will not hold; for heat is a mode

of energy, and only emerges through the transformation of other and

pre-existing modes of energy. A certain amount of the energy of motion

in the massive hammer-head is transferred to the iron rod, and assumes

the form of that molecular vibration which we call heat. And by what

amount the one is the gainer, by that amount is the other the loser.

But we have no reason to suppose that the like takes place in the

origin of the mental concomitants of neural changes. No portion of the

brain’s store of physical energy is drained off to form the rivulet

of consciousness. Now, whenever we speak of a product elsewhere in

nature, we mean a specialized bit of something pre-existent. Water is

the product of pre-existing oxygen and hydrogen. Heat is the product

of other forms of energy. But this is not so on the first hypothesis,

according to which consciousness emerges when the functional activity

of the nervous system reaches a certain level and order of complexity.

The mental concomitants are not “products,” in the recognized sense

of the term. Furthermore, although on this hypothesis we may still

speak of what was termed above evolutional continuity in the mental

concomitants, there is nothing analogous to either developmental or

germinal continuity.

On the second hypothesis, according to which sentience is the

concomitant of all organic behaviour, such developmental and germinal

continuity, or their analogues in the psychical order of being, are

rendered conceivable. Consciousness is regarded as a developed form

of sentience. But the sentience is wholly hypothetical. It is at best

a “may be,” and its existence is incapable of proof. And science is

rightly impatient of hypotheses the validity of which cannot in any way

be verified. Our safest course, therefore, is to accept that which is

common to both hypotheses, evolutional continuity, and for the rest to

be content with a confession of ignorance.

We have already drawn attention to the fact that mere sentience,

if it exists, has no power of guidance over organic behaviour; but

consciousness, when it emerges, is a concomitant of nervous processes

which determine the nature and direction of such nerve-changes as are

the antecedents of intelligent behaviour. The steps by which this

control is established are unknown. It is, indeed, probable that

conscious guidance arises as an accompaniment of the differentiation

of controlling centres from the automatic centres of the nervous

system; but of how this takes place we are as ignorant as we are of

many other differentiations in the course of embryological development

and evolutional progress. Of those nervous arrangements within the

brain which are the physiological concomitants of the far later mental

processes of reflection, abstraction, generalization, and the formation

of ideals, we are, if it be possible, even yet more profoundly

ignorant. Nor would it serve any good purpose to indulge in speculation

where there are not even the data to enable us so much as to hazard

a probable guess. The utmost we are justified in attempting is to

show how organic behaviour leads up to and affords the requisite data

for the exercise of intelligence, and how both supply the necessary

preliminary stages in the development and evolution of what, following

Dr. Stout, we have termed ideational process. This we have endeavoured

to do in preceding pages; and all that is now required is to conclude

our inquiry with a brief summary by which the results, as affording

some basis for evolutional continuity, may be focussed.

We regard reflex action and instinctive behaviour, broadly considered,

as genetically prior to that which is intelligent. Their development

in the individual and their evolution in the race are reached by the

differentiation and integration of nerve-centres. In the abdominal

region of the crayfish, for example, special centres are differentiated

for the behaviour of each pair of swimmerets; but these are so

integrated that the whole series of like abdominal appendages swing

rhythmically with co-ordinated movements. Now, when a sensorium is

developed, it does not have to group by an act of conscious selection

and deliberate arrangement the multiplicity of scattered sensory

data which it receives; it does not have to organize from diverse

and hitherto unrelated elements some sort of system in experience:

it receives them as a physiological heritage already grouped, and to

some extent organized. Stimulus and response are organically linked;

and within the response inherited co-ordinations, often exceedingly

complex, afford a correlated group of sensory data. Just in so far

as organic heredity has provided a working system of bodily parts,

does consciousness receive systematic information of their orderly

working. No doubt it is true that the development and evolution of the

sensorium proceeds _pari passu_ with the development and evolution of

reflex actions compounded and co-ordinated to give rise to instinctive

behaviour. No doubt the progress of the one is in close touch and

relation with the progress of the other; for such relation receives

the emphatic sanction of utility. Still it is none the less true that

in individual development, as in racial evolution, the organic takes

the lead. What is intelligently acquired is something added to that

which has been engrained, through natural selection or otherwise,

as a potentiality of the germinal substance. What we have first to

note, then, is that organic evolution provides ready-grouped data to

consciousness.

The second point is, that the germs of abstraction and generalization,

or rather processes which are the precursors of abstraction and

generalization, arise, and cannot fail to arise, in the genesis of

experience from the performance of inherited responses, and from

the coalescence of their results into a conscious situation. To a

quite young chick I gave pieces of yellow orange peel, which were

found to be distasteful and rejected. In Dr. Stout’s phraseology,

they acquired meaning in experience. Can one doubt that the colour

and taste were thus rendered predominant, and that the shape, size,

and other qualities of the bits of orange peel remained practically

unnoticed? Shortly afterwards the chick was given chopped and

crumbled egg; the fragments of “white” were eaten, but the bits of

hard-boiled yolk were untouched. They possessed a sufficient general

resemblance to the orange peel to carry the same meaning. In many

ways particular qualities of objects are emphasized in so far as

they incite to behaviour; they form centres of biological interest,

just as the abstract quality of ideational thought is the centre of

rational interest on a higher plane of mental development. And in

many ways objects presenting certain salient features in common,

amid differences which remain unnoticed, are unconsciously grouped

as the starting-points of similar perceptual situations, just as

in the generalization of ideational thought similar relationships

are deliberately grouped as the starting-points of like conceptual

situations. Both are purposive and have an end, which we as

investigators are able to assign; but only for reflection and

conceptual thought are they also purposeful--the end being foreseen and

realized, not only by the investigators, but by the agent concerned.

And the purpose or end itself is in the two cases different. In the one

case it is the biological end of practical behaviour; in the other case

it is the rational end of explanation--abstraction and generalization

being deliberately used as a means to this latter end. The question

has again and again been asked: Do animals reason? And different

answers are given by those who are substantially in agreement as to

the facts and their interpretation, but are not in agreement as to

their use of the word “reason.” Perhaps, if the question assume the

form--Are animals capable of explaining their own acts and the causes

of phenomena?--the position of those who find the evidence of their

doing so insufficient may be placed in a clearer light. This is what

is generally meant by the statement that animals have probably not

reached the level of rational beings.

But even if they have not reached this level, their perceptual

processes supply the antecedent conditions which are necessary if this

level is to be attained in the course of further evolution. We have

seen that, even in relatively simple cases, where conscious situations

mark only the beginnings of intelligence, there is a biological

emphasis of some, rather than others, among what we call the qualities

of objects, and there is a grouping, on biological grounds, of certain

things which have some quality in common--such, for example, as being

fit for food. Here we have at the outset of perceptual development the

germs of processes which are the precursors of the abstraction and

generalization of ideational thought. And in the more complex conscious

situations of the higher animals these processes attain to such degree

of development as is necessary to secure more difficult and more remote

biological ends, until all that is necessary, for their rational use,

is the quickening touch of a new purpose, that of explanation.

We have seen that, through what Dr. Stout terms “manipulation,” and

Professor Groos “experimentation”--names applied to a type of behaviour

widely exemplified among the higher animals,--things, as the nuclei of

conscious situations, become differentiated from the environment. One

can hardly question that a fly to the trout, a ball to the kitten, a

bone to the puppy are things distinguished from their surroundings, and

that they become marked off as special centres of interest. Here on the

perceptual plane is a process which is the antecedent of the conception

of quasi-independent objects on the ideational plane. For rational

thought the thing, as object, is not only the centre of a practical

situation leading to behaviour of direct or indirect biological value,

but is the nucleus around which we build all the qualities which

are ascertained by more elaborate manipulation and experimentation

carried out deliberately and of set purpose for rational ends. It

becomes capable of definition with the aim of explaining what are its

characteristics as an object.

There can be little doubt that the higher animals become intimately and

practically acquainted with their environment. The dog who accompanies

his master in many a ramble, the horse who carries him again and again

over all the surrounding country, has a good perceptual knowledge of

a somewhat extended environment. And this, again, is the precursor

of the far more extended conceptual knowledge which leads up at last

to a rational conception of the universe of objects in their varied

relationships. But only through the concentration of thought rendered

possible by much true abstraction and generalization,--only through

disentangling the relationships and regrouping them for the purpose of

framing an ideal scheme,--only, in short, by explanation and for the

sake of explanation is this difficult process brought to a more or less

successful issue.

Again, there can be little doubt that the higher animals, in the course

of experience begotten of behaviour, reach a perceptual sensing of

the bodily self, through experience derived from the non-projecting

senses, in pain and sickness, and often, we may hope, in the sense of

well-being, and the joy of existence. They do not probably set this

self in antithesis to the not-self. That comes with reflection, and is

the result of ideal construction based on the analysis of experience,

with a view to reaching some explanation of the genesis of experience.

But in their perceptual awareness of the embodied self, they have

that kind of consciousness which affords the necessary data, for

the later conception of the self--when experience is polarized into

its subjective and objective aspects and thus is explained, so far

as science can explain it; suggesting, indeed, long ere science has

attained this end, metaphysical explanations by reference to underlying

causes--too often accepted as an easy substitute for the difficult

tracing out of the antecedent conditions which science endeavours

painfully and by slow steps to formulate.

It is unnecessary to do more than remind the reader that we have found

that such processes as attention and imitation pass through instinctive

and intelligent stages which are the precursors of the ideational

stage, where they reach a higher expression as deliberately conscious

acts. In the young bird that instinctively pecks at some small, perhaps

moving, thing, which forms the starting point of a piece of responsive

behaviour, we have attention in the germ. When experience has caused

the thing to acquire meaning, attention passes into a succeeding

intelligent phase; but only when we desire to explain this meaning,

and attention thus has a deliberate purpose, do we find it entering

upon its higher ideational career. So, too, as we have seen, imitation

is at first a specialized form of instinctive behaviour, where the

response is seen to resemble that which stimulates it. Later it becomes

intelligent when the repetition of the imitative behaviour is due to

the satisfaction it introduces into the conscious situation. Then, at

last, it reaches the ideational stage, where reflection gives rise to

an ideal, which is to be realized in conduct. The imitation by the

child of its older companions is at first probably intelligent; but

when the child begins to consider why it imitates these and not those

among its companions, he is passing to the ideal stage, and imitation

becomes the sincerest form of hero-worship. The boy who merely imitates

his elder brothers playing at soldiers because he gets satisfaction

from so doing, becomes the subaltern who has his ideal soldier, and

will face death firmly rather than fall below his conception of how

such a soldier should behave.

We need not again attempt to indicate how among animals we have the

perceptual precursors of the æsthetic and ethical concepts. But we may

remind the reader that we endeavoured to show that intercommunication

had its foundation in instinctive sounds; and that it passed into the

intelligent stage in the perceptual life, when these sounds acquired

meaning, and hence became guides to behaviour. This is especially

instructive from our present standpoint, since it is probable that the

passage of communication from the indicating to the descriptive stage

afforded the conditions under which rational thought was evolved.

For such thought it is essential that attention should be focussed on

the relationships of things. And no description is possible without

making distinctly present to consciousness these relationships,

in time and space, the data for which are abundantly present in

the perceptual life, though lurking in the background, and needing

something to fix them and to aid consciousness in distinguishing them

clearly. In descriptive communication parts of speech, or their initial

equivalents, afford fixation points for these relationships, and serve

to render them distinct. If the reader will try to describe even the

simplest occurrence without introducing the symbols for the relations

which the events bear to each other, his failure will serve to bring

home how essential a feature this is. In social communication, then,

we probably have the key to the passage from perceptual to ideational

process; and in this passage description is the antecedent of, and

affords the conditions to, explanation. Words, moreover, as we have

already said, form the pegs upon which we can hang up, for ready

reference, the products of abstraction and generalization, or, to

modify the analogy, they form the bodies of which these products are

the rational soul.

If we are ever to trace the passage from the instinctive through

the indicating stage of communication, and so onwards through the

beginnings of description to its higher levels, and thus to the use of

language as a medium of explanation, it must be through child-study.

In every normal human child the passage does actually take place,

though, no doubt, in a condensed and abbreviated form as an epitomized

recapitulation in individual development, of the steps of evolutional

progress. Thus we may obtain a key to the solution of one of the most

difficult problems in evolution by continuous process--that of the

transition from animal behaviour to human conduct.

INDEX

A

Abstract and general ideas, 57

Abstraction, 166;

germs of, 332 ff.

Acceleration, 250

Accommodation defined, 36

Acquired characters, inheritance of, 35, 110

Acquired instincts (Wundt), 66, 106

Acquisition defined, 36;

ultimately dependent on natural selection, 289

Adaptation defined, 37

ADDISON on instinct, 63

Æsthetics, animal, 270

Afferent and efferent impulses, 32, 101

Aid, mutual, among animals, 227

_Ammophila_ mode of stinging prey, 75;

of carrying prey, 76;

deposition of egg, 77;

intelligent behaviour of, 127

_Amœba_, 296

Antlers of deer, 15