The Act of Creation (63 page)
Read The Act of Creation Online
Authors: Arthur Koestler
These genetic potentials are the residues of the cell's erstwhile
totipotentiality before differentiation set in -- its original power
to create a whole new organism. Some of that power is reactivated when
the regeneration tissue -- the part designed to replace the lost organ
or limb -- is released from the controls which under normal conditions
keep it under restraint. For this partial or total secession of the part
from the whole, C. M. Child coined the useful concept of 'physiological
isolation'. [5]
Physiological isolation may be regarded as a drastic form of
disequilibrium between the part and the whole. Its consequences may be
beneficial or deleterious. Child distinguishes four causes for it. (a)
Growth of the whole beyond a critical limit may make it ungovernable so
that parts of it find themselves outside the range of central dominance
and control. This may lead in lower organisms to reproduction by fission
or budding: the isolated part is either shed (as, for instance, the
planarian's tail) to form a new organism, or it may de-differentiate
and reintegrate into a complete organism by budding. (b) Decline of the
organism's powers of control (through senescence, metabolic or hormonal
disorders) may, in combination with other causes, lead to a pathological
regression of cells and tissues with untramelled proliferation and
without reintegration, resulting in malignant growths. (c) Partial
obstruction or total blockage of (nervous and chemical) communications,
and (d) persistent local excitation beyond a critical limit, may release
the part from its normal controls and activate, for better or worse,
its latent potentialities.
We shall see that Child's 'isolation' concept has a wide range of
applicability. In all cases, isolation of the part from the whole leads
to de-differentiation or other forms of regression; in some cases this
is followed by re-differentiation and reintegration. Isolation leading to
regression of an irreversible kind plays a considerable part in pathology,
psycho-pathology, and social pathology.* On the other hand, regression
followed by a progressive rebound releases creative potentials which are
normally under restraint. Its magic can be observed on every level: from
asexual reproduction to the repair of structural damage and functional
disorder, and further up to psychotherapy, scientific discovery, and
artistic creation. In the chapter which follows I shall briefly discuss
the manifestations of 'super-flexibility -- of
reculer pour mieux
sauter
-- on these various levels.
NOTE
To
p. 453
. Thus, for instance, Smithers in
A
Clinical Prospect of the Cancer Problem
(1960) stresses the decisive
influence which Child's "Physiological Foundations of Behaviour" had on
the development of his ideas.
RECULER POUR MIEUX SAUTER
Structural Regenerations
In
primitive
organisms such as the flatworm, and in the early
embryonic stages of higher organisms, a physiologically isolated part
tends in general 'to lose its characteristics as a part and to become or
approach the condition of a new whole individual'. [1] Liberation of
the part's previously restrained genetic potential 'involves a change
in behaviour and structure from that of a part towards that of a whole
organism'. [2] Such organisms could be said to live not only in dynamic
equilibrium with their environment, but in a kind of 'regenerative
equilibrium' which enables them to rise to virtually any challenge by
means of these secondary adaptations.
Some
higher animals
are still capable of regenerating lost
organs or limbs. Let us have a closer look how it is done. When a
salamander's leg has been amputated, the tissues near the wound surface
de-differentiate and the cells acquire an embryonic appearance. This
is the regressive or 'catabolic' phase. Around the fourth day begins
the formation of the blastema -- the regeneration bud; and from here
on throughout the 'anabolic' or synthetic phase the process follows
closely the formation of limbs in normal embryonic development.* The
blastema elongates into a cone and develops axially, the toes at its
tip appearing first, and the rest of the limb gradually taking shape
as it grows in length. When the organ is completed, central control is
taken over by the nervous system, just as in the case of the embryo. The
nervous system, however, also plays an indispensable part in initiating
the first, catabolic phase. If no peripheral nerves are present in the
amputation stump, regeneration does not occur.**
The 'isolated part' in this case is the amputation stump. The blastema
has in the beginning the multi-potential characteristics of the organ
primordia, and its re-differentiation again proceeds stepwise: if the
field is split in half, each half gives rise to a whole organ; if one half
is removed, the remaining half will still develop into a complete limb.
Although the isolated part, transformed into a new organ primordium
(or its close equivalent), enjoys a high degree of independence and
controls the formation of the new limb, its ties with the higher levels
of the hierarchy are not completely severed. Its function in the whole
has changed; its normal controls (through the nervous system and local
chemical gradients) are out of action or even reversed; but the organism
as a whole nevertheless assists the regenerating part by certain emergency
measures -- a 'general alarm reaction' followed by a 'general adaptation
syndrome', each stage indicated by metabolic changes and by the appearance
of specific proteins and hormones in the circulatory system.
Thus the isolation of the part is only temporary and relative; and
when the process is completed, the regenerated limb assumes its normal
function in the whole. The entire regressire-progressive sequence is
the means by which the animal's 'regenerative equilibrium' enables it
to adjust to traumatic experiences from the environment.
Looked at from a different angle, one might say that the whole process is
designed to prevent or correct malformations, i.e. faulty integrations.
Without the initial nerve supply, the regressing amputation stump
would be resorbed, the scar tissue would close over it, and the animal
would achieve a modus vivendi as a cripple -- a faulty integration. On
the other hand, a frog which will not normally regenerate a lost limb
will do so if the nerve supply to the stump is artificially augmented,
providing the initial stimulus to start the process. Traumatic challenges
can only be met by the liberation of the organism's latent powers --
a temporary return to a more youthful or primitive condition.
Reversed Gradients
An important part in regeneration, as in morphogenesis, is played by
axial gradients
. The apical or 'head' end of the fertilized
egg, the growing embryo, or the regenerating limb, are exposed to the
highest degree of stimulation and show the highest rate of metabolism,
protein synthesis, and RNA activity. Thus the anterior end becomes the
dominant region, the 'head' in the literal and metaphorical sense, and
exercises a restraining influence on the genetic potentials along the
axial gradient -- so that activity is highest at the front and lowest
at the tail end (higher organisms have of course a complex pattern of
interacting gradients, some axial, some radial). But physical isolation by
blockage or hyper-excitation (Child's third and fourth cause) of parts in
previously subordinate positions can be shown to alter or
reverse
the gradient. In plants, where the dominant region is the growing tip
of the shoot, pruning makes previously subordinate parts burst into
activity. If in the marine polyp, tubularia, a piece of the stem is cut
out, the frontal end of the fragment will normally regenerate the hydrant
which is its 'head'; but if a ligature is applied to isolate the front end
of the fragment, the gradient is reversed and the tail end, now the region
of maximum excitation, becomes dominant and grows a head. Similarly, short
pieces of planaria sometimes regenerate one head at the front and another
at the tail end, if the metabolism of both cut surfaces is equally high.
The Dangers of Regression
Two more phenomena must be mentioned in this context: the first
illustrates the flexibility, the second the vulnerability of regenerative
processes.
If the crystalline lens of a salamander-eye is removed, part of the
iris de-differentiates, forms a vesicle, enters the cavity through the
pupil, re-differentiates, and forms a normal lens -- whereas in embryonic
development the lens is formed by the epidermis overlaying the eye-cup,
without participation of the iris. Thus the morphogenetic skill of making
a lens can make use of either of two different materials; the code is
again invariant, the strategy adaptable.*
On the other hand, the factors which, in a higher organism, determine
whether a given trauma will lead to regenerative or pathological changes
are of an extremely delicate nature. Thus Smithers [3] writes:
'outside the standardized range of normal experience of the species
during its developmental peak period. They do not differ from the normal
regulatory responses, however, in any fundamental particular. . . . Tissue
overgrowth as a response to a long-continued external irritant, is of the
same order as heat regulation, wound-healing or lactation. . . . Useless
or harmful regulating mechanisms and tissue responses to isolation,
injury, or stimulation are not fundamentally different in kind from those
favourable ones which have become incorporated into the inheritance of the
species because they promoted survival through the period of reproductive
activity. . . . The tissues most often called on for regeneration and
repair, or most liable to recurrent stimulation into specialized activity,
are those most prone to tumour formation.' [4]
'Routine Regenerations'
The last sentence that I have quoted leads into the borderland between
regenerative and 'normal' processes: namely routine replacements. They
range from the periodic moulting of feathers and shedding of the antlers,
to the replacement of the whole human epidermis about once a month
owing to wear and tear, and the replacement of red blood cells at the
rate of 3 x 10^11 per day; not to mention the metabolic turnover on the
molecular level which consumes about thirty per cent of our total protein
intake. This type of routine (or so-called 'physiological') regeneration
which goes on all the time is sometimes described as a constant 'renewal'
or 'rejuvenation' of the body. It is often impossible to make a clear
distinction between 'wear' and 'tear' -- for instance in minor abrasions
of the skin. The differential factor is obviously the degree of stress,
which, past a critical threshold, will bring general alarm reactions and
'adaptations of the second order' into play.
Reorganizations of Function
The transplanted salamander limb which functions normally in spite
of its randomized nervous connections can be regarded as an example
of both regeneration of structure and reorganization of function. The
pathways leading into the limb all seem to be equipotential in their
capacity as conductors of the excitation-clang. Without entering the old
controversy about equipotentiality versus localization of functions in
nervous tissues, it seems to be safe to say that in repetitive routines
and local reflexes, equipotentiality has 'frozen up' into fixed local
arrangements; whereas in case of injury to the pathways in question,
the equipotentiality (or rather, multi-potentiality) of alternative
'canal-systems' is revived, and they take over the function of the injured
system. To quote Lashley: 'The results indicate that when habitually
used motor organs are rendered non-functional by removal or paralysis,
there is an immediate, spontaneous use of other motor systems which had
not previously been associated with, or used in, the performance of the
activity.' [5] Nearly a century earlier Pflüger had shown that even
the spinal reflexes of a frog are capable of 'crisis adaptations'. If a
drop of acid is placed on the back of the left front limb of a decapitated
frog, it will attempt to wipe it away with the left hind limb; but if
prevented from doing so it will use the right hind limb -- which it
normally never does in the exercise of the wiping reflex.
Turning from the spinal level to the brain, Lashley's celebrated maze
experiments have shown what astonishing regenerative adaptations the
cerebral cortex is capable of. If a rat is trained to choose between
two doors the one where a brighter light is shown, this habit (or at
least part of it) must be localized in its optical cortex, for if this
is extirpated, the habit is lost. But a rat with its optical cortex cut
out can still be taught or re-taught the same skill. This means that some
other cortical area has taken over the learning function after extirpation
of the proper area -- just as in the morphogenetic field intact tissue
will deputize for lost tissue. Moreover, if a rat has learned to run
a certain maze, no matter what parts of its motor cortex are injured,
it will follow its path -- even if it has to roll the whole way with
paralysed legs; and if the injury makes it incapable of executing a right
turn, it will achieve its aim by a three-quarter turn to the left. The rat
may be blinded, deprived of its smell, partially paralysed in various ways
-- each of which would throw the chain-reflex automaton, which the rat was
supposed to be, completely out of gear. Yet: 'One drags himself through
[the maze] with his forepaws; another falls at every step but gets through
by a series of lunges; a third rolls over completely in making each turn,
yet avoids rolling into a cul-de-sac and makes an errorless run. The
behaviour presents exactly the same problem of direct adaptation of any
motor organs to the attainment of a given end which was outstanding in
my earlier observations on monkeys after destruction of the pre-central
gyri. If the customary sequence of movements employed in reaching the food
is rendered impossible, another set, not previously used in the habit,
and constituting an entirely different motor pattern, may be directly
and evidently substituted without any random activity.' [6]
In human beings, structural regeneration -- of skin, bone, muscle, and
peripheral nerves -- is confined to tissue-outgrowth: that is to say,
the new structures are derived from cells of their own kind, not from
de-differentiating tissues. But though we have lost the amphibian's
enviable powers of replacing a lost limb, we have gained a unique
super-flexibility of functions in our nervous system.
totipotentiality before differentiation set in -- its original power
to create a whole new organism. Some of that power is reactivated when
the regeneration tissue -- the part designed to replace the lost organ
or limb -- is released from the controls which under normal conditions
keep it under restraint. For this partial or total secession of the part
from the whole, C. M. Child coined the useful concept of 'physiological
isolation'. [5]
Physiological isolation may be regarded as a drastic form of
disequilibrium between the part and the whole. Its consequences may be
beneficial or deleterious. Child distinguishes four causes for it. (a)
Growth of the whole beyond a critical limit may make it ungovernable so
that parts of it find themselves outside the range of central dominance
and control. This may lead in lower organisms to reproduction by fission
or budding: the isolated part is either shed (as, for instance, the
planarian's tail) to form a new organism, or it may de-differentiate
and reintegrate into a complete organism by budding. (b) Decline of the
organism's powers of control (through senescence, metabolic or hormonal
disorders) may, in combination with other causes, lead to a pathological
regression of cells and tissues with untramelled proliferation and
without reintegration, resulting in malignant growths. (c) Partial
obstruction or total blockage of (nervous and chemical) communications,
and (d) persistent local excitation beyond a critical limit, may release
the part from its normal controls and activate, for better or worse,
its latent potentialities.
We shall see that Child's 'isolation' concept has a wide range of
applicability. In all cases, isolation of the part from the whole leads
to de-differentiation or other forms of regression; in some cases this
is followed by re-differentiation and reintegration. Isolation leading to
regression of an irreversible kind plays a considerable part in pathology,
psycho-pathology, and social pathology.* On the other hand, regression
followed by a progressive rebound releases creative potentials which are
normally under restraint. Its magic can be observed on every level: from
asexual reproduction to the repair of structural damage and functional
disorder, and further up to psychotherapy, scientific discovery, and
artistic creation. In the chapter which follows I shall briefly discuss
the manifestations of 'super-flexibility -- of
reculer pour mieux
sauter
-- on these various levels.
NOTE
To
p. 453
. Thus, for instance, Smithers in
A
Clinical Prospect of the Cancer Problem
(1960) stresses the decisive
influence which Child's "Physiological Foundations of Behaviour" had on
the development of his ideas.
RECULER POUR MIEUX SAUTER
Structural Regenerations
In
primitive
organisms such as the flatworm, and in the early
embryonic stages of higher organisms, a physiologically isolated part
tends in general 'to lose its characteristics as a part and to become or
approach the condition of a new whole individual'. [1] Liberation of
the part's previously restrained genetic potential 'involves a change
in behaviour and structure from that of a part towards that of a whole
organism'. [2] Such organisms could be said to live not only in dynamic
equilibrium with their environment, but in a kind of 'regenerative
equilibrium' which enables them to rise to virtually any challenge by
means of these secondary adaptations.
Some
higher animals
are still capable of regenerating lost
organs or limbs. Let us have a closer look how it is done. When a
salamander's leg has been amputated, the tissues near the wound surface
de-differentiate and the cells acquire an embryonic appearance. This
is the regressive or 'catabolic' phase. Around the fourth day begins
the formation of the blastema -- the regeneration bud; and from here
on throughout the 'anabolic' or synthetic phase the process follows
closely the formation of limbs in normal embryonic development.* The
blastema elongates into a cone and develops axially, the toes at its
tip appearing first, and the rest of the limb gradually taking shape
as it grows in length. When the organ is completed, central control is
taken over by the nervous system, just as in the case of the embryo. The
nervous system, however, also plays an indispensable part in initiating
the first, catabolic phase. If no peripheral nerves are present in the
amputation stump, regeneration does not occur.**
The 'isolated part' in this case is the amputation stump. The blastema
has in the beginning the multi-potential characteristics of the organ
primordia, and its re-differentiation again proceeds stepwise: if the
field is split in half, each half gives rise to a whole organ; if one half
is removed, the remaining half will still develop into a complete limb.
Although the isolated part, transformed into a new organ primordium
(or its close equivalent), enjoys a high degree of independence and
controls the formation of the new limb, its ties with the higher levels
of the hierarchy are not completely severed. Its function in the whole
has changed; its normal controls (through the nervous system and local
chemical gradients) are out of action or even reversed; but the organism
as a whole nevertheless assists the regenerating part by certain emergency
measures -- a 'general alarm reaction' followed by a 'general adaptation
syndrome', each stage indicated by metabolic changes and by the appearance
of specific proteins and hormones in the circulatory system.
Thus the isolation of the part is only temporary and relative; and
when the process is completed, the regenerated limb assumes its normal
function in the whole. The entire regressire-progressive sequence is
the means by which the animal's 'regenerative equilibrium' enables it
to adjust to traumatic experiences from the environment.
Looked at from a different angle, one might say that the whole process is
designed to prevent or correct malformations, i.e. faulty integrations.
Without the initial nerve supply, the regressing amputation stump
would be resorbed, the scar tissue would close over it, and the animal
would achieve a modus vivendi as a cripple -- a faulty integration. On
the other hand, a frog which will not normally regenerate a lost limb
will do so if the nerve supply to the stump is artificially augmented,
providing the initial stimulus to start the process. Traumatic challenges
can only be met by the liberation of the organism's latent powers --
a temporary return to a more youthful or primitive condition.
Reversed Gradients
An important part in regeneration, as in morphogenesis, is played by
axial gradients
. The apical or 'head' end of the fertilized
egg, the growing embryo, or the regenerating limb, are exposed to the
highest degree of stimulation and show the highest rate of metabolism,
protein synthesis, and RNA activity. Thus the anterior end becomes the
dominant region, the 'head' in the literal and metaphorical sense, and
exercises a restraining influence on the genetic potentials along the
axial gradient -- so that activity is highest at the front and lowest
at the tail end (higher organisms have of course a complex pattern of
interacting gradients, some axial, some radial). But physical isolation by
blockage or hyper-excitation (Child's third and fourth cause) of parts in
previously subordinate positions can be shown to alter or
reverse
the gradient. In plants, where the dominant region is the growing tip
of the shoot, pruning makes previously subordinate parts burst into
activity. If in the marine polyp, tubularia, a piece of the stem is cut
out, the frontal end of the fragment will normally regenerate the hydrant
which is its 'head'; but if a ligature is applied to isolate the front end
of the fragment, the gradient is reversed and the tail end, now the region
of maximum excitation, becomes dominant and grows a head. Similarly, short
pieces of planaria sometimes regenerate one head at the front and another
at the tail end, if the metabolism of both cut surfaces is equally high.
The Dangers of Regression
Two more phenomena must be mentioned in this context: the first
illustrates the flexibility, the second the vulnerability of regenerative
processes.
If the crystalline lens of a salamander-eye is removed, part of the
iris de-differentiates, forms a vesicle, enters the cavity through the
pupil, re-differentiates, and forms a normal lens -- whereas in embryonic
development the lens is formed by the epidermis overlaying the eye-cup,
without participation of the iris. Thus the morphogenetic skill of making
a lens can make use of either of two different materials; the code is
again invariant, the strategy adaptable.*
On the other hand, the factors which, in a higher organism, determine
whether a given trauma will lead to regenerative or pathological changes
are of an extremely delicate nature. Thus Smithers [3] writes:
The type of structure regenerated, or the kind of neoplasm formed,Pathogenic regulatory responses are reactions to stimulations which are
will depend on the level of the controlling field-gradient against
which it is exerting itself, and the steepness of the gradient it
can itself establish and promote as shown by its tendency towards
undifferentiated cell-reproduction. The part which is physiologically
isolated then produces an imperfect portion of a new whole, giving rise
to whatever tissues it is capable of forming under the circumstances
pertaining. This may result in malformations of all degrees, from
simple overgrowth of adult tissues, through irregular mixtures of
recognizable, well-differentiated cells, to the most rapidly growing,
undifferentiated tumors.
'outside the standardized range of normal experience of the species
during its developmental peak period. They do not differ from the normal
regulatory responses, however, in any fundamental particular. . . . Tissue
overgrowth as a response to a long-continued external irritant, is of the
same order as heat regulation, wound-healing or lactation. . . . Useless
or harmful regulating mechanisms and tissue responses to isolation,
injury, or stimulation are not fundamentally different in kind from those
favourable ones which have become incorporated into the inheritance of the
species because they promoted survival through the period of reproductive
activity. . . . The tissues most often called on for regeneration and
repair, or most liable to recurrent stimulation into specialized activity,
are those most prone to tumour formation.' [4]
'Routine Regenerations'
The last sentence that I have quoted leads into the borderland between
regenerative and 'normal' processes: namely routine replacements. They
range from the periodic moulting of feathers and shedding of the antlers,
to the replacement of the whole human epidermis about once a month
owing to wear and tear, and the replacement of red blood cells at the
rate of 3 x 10^11 per day; not to mention the metabolic turnover on the
molecular level which consumes about thirty per cent of our total protein
intake. This type of routine (or so-called 'physiological') regeneration
which goes on all the time is sometimes described as a constant 'renewal'
or 'rejuvenation' of the body. It is often impossible to make a clear
distinction between 'wear' and 'tear' -- for instance in minor abrasions
of the skin. The differential factor is obviously the degree of stress,
which, past a critical threshold, will bring general alarm reactions and
'adaptations of the second order' into play.
Reorganizations of Function
The transplanted salamander limb which functions normally in spite
of its randomized nervous connections can be regarded as an example
of both regeneration of structure and reorganization of function. The
pathways leading into the limb all seem to be equipotential in their
capacity as conductors of the excitation-clang. Without entering the old
controversy about equipotentiality versus localization of functions in
nervous tissues, it seems to be safe to say that in repetitive routines
and local reflexes, equipotentiality has 'frozen up' into fixed local
arrangements; whereas in case of injury to the pathways in question,
the equipotentiality (or rather, multi-potentiality) of alternative
'canal-systems' is revived, and they take over the function of the injured
system. To quote Lashley: 'The results indicate that when habitually
used motor organs are rendered non-functional by removal or paralysis,
there is an immediate, spontaneous use of other motor systems which had
not previously been associated with, or used in, the performance of the
activity.' [5] Nearly a century earlier Pflüger had shown that even
the spinal reflexes of a frog are capable of 'crisis adaptations'. If a
drop of acid is placed on the back of the left front limb of a decapitated
frog, it will attempt to wipe it away with the left hind limb; but if
prevented from doing so it will use the right hind limb -- which it
normally never does in the exercise of the wiping reflex.
Turning from the spinal level to the brain, Lashley's celebrated maze
experiments have shown what astonishing regenerative adaptations the
cerebral cortex is capable of. If a rat is trained to choose between
two doors the one where a brighter light is shown, this habit (or at
least part of it) must be localized in its optical cortex, for if this
is extirpated, the habit is lost. But a rat with its optical cortex cut
out can still be taught or re-taught the same skill. This means that some
other cortical area has taken over the learning function after extirpation
of the proper area -- just as in the morphogenetic field intact tissue
will deputize for lost tissue. Moreover, if a rat has learned to run
a certain maze, no matter what parts of its motor cortex are injured,
it will follow its path -- even if it has to roll the whole way with
paralysed legs; and if the injury makes it incapable of executing a right
turn, it will achieve its aim by a three-quarter turn to the left. The rat
may be blinded, deprived of its smell, partially paralysed in various ways
-- each of which would throw the chain-reflex automaton, which the rat was
supposed to be, completely out of gear. Yet: 'One drags himself through
[the maze] with his forepaws; another falls at every step but gets through
by a series of lunges; a third rolls over completely in making each turn,
yet avoids rolling into a cul-de-sac and makes an errorless run. The
behaviour presents exactly the same problem of direct adaptation of any
motor organs to the attainment of a given end which was outstanding in
my earlier observations on monkeys after destruction of the pre-central
gyri. If the customary sequence of movements employed in reaching the food
is rendered impossible, another set, not previously used in the habit,
and constituting an entirely different motor pattern, may be directly
and evidently substituted without any random activity.' [6]
In human beings, structural regeneration -- of skin, bone, muscle, and
peripheral nerves -- is confined to tissue-outgrowth: that is to say,
the new structures are derived from cells of their own kind, not from
de-differentiating tissues. But though we have lost the amphibian's
enviable powers of replacing a lost limb, we have gained a unique
super-flexibility of functions in our nervous system.
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