INHERITED MEMORY.
Many of our observations seemed to suggest a quasi-intelligent action on
the part of the beings under examination; and we were led, early in the
course of our studies, to adopt provisionally the hypothesis that memory
was inherited--that the whole was consequently wiser than its parts, the
species wiser than the individual, the genus wiser than the species.
One illustration will suffice to show the possibility of memory being
inherited. Chickens, as a rule, are hatched with a full knowledge of how
to pick up a living, only a few stupid ones having to be taught by the
mother the process of pecking. When eggs are hatched artificially,
ignorant as well as learned chicks are produced, and the less
intelligent, having no hen instructor, would infallibly die in the midst
of plenty. But if a tapping noise, like pecking, be made near them, they
hesitate awhile, and then take to their food with avidity. Here the
tapping noise seems certainly to have awakened the ancestral memory
which lay dormant.
It may be said all this is habit. But what is habit? Is it any
explanation to say a creature performs a given action by habit? or is it
not rather playing with a word which expresses a phenomenon without
explaining it? Directly we bring memory into the field we get a real
explanation. A habit is acquired by repetition, and could not arise if
the preceding experience were forgotten. Life is largely made up of
repetition, which involves the formation of habits; and, indeed,
everyone's experience (habit again) shows that life only runs smoothly
when certain necessary habits have been acquired so perfectly as to be
performed without effort. A being at maturity is a great storehouse of
acquired habits; and of these many are so perfectly acquired, _i.e._,
have been performed so frequently, that the possessor is quite
unconscious of possessing them.
Habit tends to become automatic; indeed, a habit can hardly be said to
be formed until it is automatic. But habits are the result of experience
and repetition, that is, have arisen in the first instance by some
reasoning process; and reasoning implies consciousness. Nevertheless,
the action once thought out, or reasoned upon, requires less conscious
effort on a second occasion, and still less on a third, and so on, until
the mere occurrence of given conditions is sufficient to ensure
immediate response without conscious effort, and the action is performed
mechanically or automatically: it is now a true habit. Habit, then,
commences in consciousness and ends in unconsciousness. To say,
therefore, when we see an action performed without conscious thought,
that consciousness has never had part in its production, is as illogical
as to say that because we read automatically we can never have learned
to read.
The thorough appreciation of this principle is absolutely essential to
the argument of this work; for to inherited memory we attribute not only
the formation of habits and instincts, but also the modification of
organs, which leads to the formation of new species. In a word, it is to
memory we attribute the possibility of evolution, and by it the struggle
for existence is enabled to re-act upon the forms of life, and produce
the harmony we see in the organic world.
Our own investigations had led us very far in this direction; but we
failed to grasp the entire truth until Mr. S. Butler's remarkable work,
"Life and Habit," came to our notice. This valuable contribution to
evolution smoothed away the whole of the difficulties we had
experienced, and enabled us to propound the views here set forth with
greater clearness than had been anticipated.
The great difficulty in Mr. Darwin's works is the fact that he starts
with variations ready made, without trying, as a rule, to account for
them, and then shows that if these varieties are beneficial the
possessor has a better chance in the great struggle for existence, and
the accumulation of such variations will give rise to new species. This
is what he means by the title of his work, "The Origin of Species by
means of Natural Selection or the Preservation of Favoured Races in the
Struggle for Life." But this tells us nothing whatever about the origin
of species. As Butler puts it, "Suppose that it is an advantage to a
horse to have an especially broad and hard hoof: then a horse born with
such a hoof will, indeed, probably survive in the struggle for
existence; but he was not born with the larger and harder hoof _because
of his subsequently surviving_. He survived because he was born fit--not
he was born fit because he survived. The variation must arise first and
be preserved afterwards."[3]
Mr. Butler works out with admirable force the arguments, first, that
habitual action begets unconsciousness; second, that there is a unity of
personality between parent and offspring; third, that there is a memory
of the oft-repeated acts of past existences, and, lastly, that there is
a latency of that memory until it is re-kindled by the presence of
associated ideas.
As to the first point, we need say no more, for daily experience
confirms it; but the other points must be dealt with more fully.
Mr. Butler argues for the absolute identity of the parent and offspring;
and, indeed, this is a necessity. Personal identity is a phrase, very
convenient, it is true, but still only a provisional mode of naming
something we cannot define. In our own bodies we say that our identity
remains the same from birth to death, though we know that our bodily
particles are ever changing, that our habits, thoughts, aspirations,
even our features, change--that we are no more really the same person
than the ripple over a pebble in a brook is the same from moment to
moment, though its form remains. If our personal identity thus elude our
search in active life, it certainly becomes no more tangible if we trace
existence back into pre-natal states. We _are_, in one sense, the same
individual; but, what is equally important, we _were_ part of our
mother, as absolutely as her limbs are part of her. There is no break of
continuity between offspring and parent--the river of life is a
continuous stream. We judge of our own identity by the continuity which
we see and appreciate; but that greater continuity reaching backwards
beyond the womb to the origin of life itself is no less a fact which
should be constantly kept in view. The individual, in reality, never
dies; for the lamp of life never goes out.
For a full exposition of this problem, Mr. Butler's "Life and Habit"
must be consulted, where the reader will find it treated in a masterly
way.
This point was very early appreciated in our work; and in a
paper read before the Anthropological Institute[4] in the year 1879,
but not published, this continuity was insisted upon by means of
diagrams, both of animal and plant life, and its connection with heredity
was clearly shown, though its relation to memory was only dimly
seen. From this paper the following passage may be quoted: "If, as
I believe, the origin of form and decoration is due to a process similar
to the visualising of object-thoughts in the human mind, the power
of this visualising must commence with the life of the being. It
would seem that this power may be best understood by a correct
insight into biological development. It has always excited wonder
that a child, a separate individual, should inherit and reproduce the
characters of its parents, and, indeed, of its ancestors; and the
tendency of modern scientific writing is often to make this obscure
subject still darker. But if we remember that the great law of all
living matter is, that the child is _not_ a separate individual, but a
part of the living body of the parent, up to a certain date, when it
assumes a separate existence, then we can comprehend how living
beings inherit ancestral characters, for they are parts of one continuous
series in which not a single break has existed or can ever
take place. Just as the wave-form over a pebble in a stream
remains constant, though the particles of water which compose it
are ever changing, so the wave-form of life, which is heredity,
remains constant, though the bodies which exhibit it are continually
changing. The retrospection of heredity and memory, and the
prospection of thought, are well shown in Mrs. Meritt's beautiful
diagram."
This passage illustrates how parallel our thoughts were to Mr. Butler's,
whose work we did not then know. What we did not see at the time was,
that the power of thinking or memory might antedate birth. It is quite
impossible adequately to express our sense of admiration of Mr. Butler's
work.
Granting then the physical identity of offspring and parent, the
doctrine of heredity becomes plain. The child becomes like the parent,
because it is placed in almost identical circumstances to those of its
parent, and is indeed part of that parent. If memory be possessed by all
living matter, and this is what we now believe, we can clearly see how
heredity acts. The embryo develops into a man like its parent, because
human embryos have gone through this process many times--till they are
unconscious of the action, they know how to proceed so thoroughly.
Darwin, after deeply pondering over the phenomena of growth, repair of
waste and injury, heredity and kindred matters, advanced what he wisely
called a provisional hypothesis--pangenesis.
"I have been led," he remarks, "or, rather, forced, to form a view which
to a certain extent, connects these facts by a tangible method. Everyone
would wish to explain to himself even in an imperfect manner, how it is
possible for a character possessed by some remote ancestor suddenly to
reappear in the offspring; how the effects of increased or decreased use
of a limb can be transmitted to the child; how the male sexual element
can act, not solely on the ovules, but occasionally on the mother form;
how a hybrid can be produced by the union of the cellular tissue of two
plants independently of the organs of generation; how a limb can be
reproduced on the exact line of amputation, with neither too much nor
too little added; how the same organism may be produced by such widely
different processes as budding and true seminal generation; and, lastly,
how of two allied forms, one passes in the course of its development
through the most complex metamorphoses, and the other does not do so,
though when mature both are alike in every detail of structure. I am
aware that my view is merely a provisional hypothesis or speculation;
but until a better one be advanced, it will serve to bring together a
multitude of facts which are at present left disconnected by any
efficient cause."[5]
After showing in detail that the body is made up of an infinite number
of units, each of which is a centre of more or less independent action,
he proceeds as follows:--
"It is universally admitted that the cells or units of the body increase
by self-division or proliferation, retaining the same nature, and that
they ultimately become converted into the various tissues of the
substances of the body. But besides this means of increase I assume that
the units throw off minute granules, which are dispersed throughout the
whole system; that these, when supplied with proper nutriment, multiply
by self-division, and are ultimately developed into units like those
from which they were originally derived. These granules may be called
gemmules. They are collected from all parts of the system to constitute
the sexual elements, and their development in the next generations forms
a new being; but they are likewise capable of transmission in a dormant
state to future generations, and may then be developed. Their
development depends on their union with other partially developed or
nascent cells, which precede them in the regular course of growth....
Gemmules are supposed to be thrown off by every unit; not only during
the adult state, but during each stage of development of every organ;
but not necessarily during the continued existence of the same unit.
Lastly, I assume that the gemmules in their dormant state have a mutual
affinity for each other, leading to their aggregation into buds, or into
the sexual elements. Hence, it is not the reproductive organs or buds
which generate new organisms, but the units of which each individual is
composed."[6]
Now, suppose that instead of these hypothetic gemmules we endow the
units with memory in ever so slight a degree, how simple the explanation
of all these facts becomes! What an unit has learned to do under given
conditions it can do again under like circumstances. Memory _does_ pass
from one unit to another, or we could not remember anything as men that
happened in childhood, for we are not physically composed of the same
materials. It is not at all necessary that an unit should remember it
remembers any more than we in reading are conscious of the efforts we
underwent in learning our letters. Few of us can remember learning to
walk, and none of us recollect learning to talk. Yet surely the fact
that we do read, and walk, and talk, proves that we have not forgotten
how.
Bearing in mind, then, the fundamental laws that the offspring is one in
continuity with its parents, and that memory arises chiefly from
repetition in a definite order (for we cannot readily reverse the
process--we cannot sing the National Anthem backwards), it is easy to
see how the oft-performed actions of an individual become its
unconscious habits, and these by inheritance become the instincts and
unconscious actions of the species. Experience and memory are thus the
key-note to the origin of species.
Granting that all living matter possesses memory, we must admit that all
actions are at first conscious in a certain degree, and in the "sense of
need" we have the great stimulation to action.
In Natural Selection, as expounded by Mr. Darwin, there is no principle
by which small variations can be accumulated. Take any form, and let it
vary in all directions. We may represent the original form by a spot,
and the variations by a ring of dots. Each one of these dots may vary in
all directions, and so other rings of dots must be made, and so on, the
result not being development along a certain line, but an infinity of
interlacing curves. The tree of life is not like this. It branches ever
outwards and onwards. The eyes of the Argus pheasant and peacock have
been formed by the accumulation, through long generations, of more and
more perfect forms; the mechanism of the eye and hand has arisen by the
gradual accumulation of more and more perfect forms, and these processes
have been continued along definite lines.
If we grant memory we eliminate this hap-hazard natural selection. We
see how a being that has once begun to perform a certain action will
soon perform it automatically, and when its habits are confirmed its
descendants will more readily work in this direction than any other, and
so specialisation may arise.
To take the cases of protective resemblance and mimicry. Darwin and
Wallace have to start with a form something like the body mimicked,
without giving any idea as to how that resemblance could arise. But with
this key of memory we can open nature's treasure house much more fully.
Look, for instance, at nocturnal insects; and one need not go further
than the beetles (_Blatta_) in the kitchen, to see that they have a
sense of need, and use it. Suddenly turn up the gas, and see the hurried
scamper of the alarmed crowd. They are perfectly aware that danger is at
hand. Equally well do they feel that safety lies in concealment; and
while all the foraging party on the white floor are scuttling away into
dark corners, the fortunate dweller on the hearth stands motionless
beneath the shadow of the fire-irons; a picture of keen, intense
excitement, with antennæ quivering with alertness. On the clean floor a
careless girl has dropped a piece of flat coal, and on it beetles stand
rigidly. They are as conscious as we are that the shadow, and the colour
of the coal afford concealment, and we cannot doubt that they have
become black from their sense of the protection they thus enjoy. They do
not say, as Tom, the Water Baby, says, "I must be clean," but they know
they must be black, and black they are.
There is, then, clearly an effort to assimilate in hue to their
surroundings, and the whole question is comparatively clear.
Mr. Wallace, in commenting upon the butterfly (_Papilio nireus_)--which,
at the Cape, in its chrysalis state, copies the bright hues of the
vegetation upon which it passes its dormant phase--says that this is a
kind of natural colour photography; thus reducing the action to a mere
physical one. We might as well say the dun coat of the sportsman among
the brown heather was acquired mechanically. Moreover, Wallace
distinctly shows that when the larvæ are made to pupate on unnatural
colours, like sky-blue or vermilion, the pupæ do not mimic the colour.
There is no reason why "natural photography" should not copy this as
well as the greens, and browns, and yellows. But how easy the
explanation becomes when memory, the sense of need, and Butler's little
"dose of reason," are admitted! For ages the butterfly has been
acquainted with greens, and browns, and yellows, they are every day
experiences; but it has no acquaintance with aniline dyes, and therefore
cannot copy them.
The moral of all this is that things become easy by repetition; that
without experience nothing can be done well, and that the course of
development is always in one direction, because the memory of the road
traversed is not forgotten.
[Illustration]
[3] Evolution, Old and New, p. 346.
[4] On a New Method of Expressing the Law of Specific Change. By A.
Tylor.
[5] Animals and Plants under Domestication, vol. ii., p. 350.
[6] Animals and Plants under Domestication, vol. ii., p. 370.