Janus (33 page)

 

The problem which remains is in fact not 'how have vertebrates been
formed by sea-squirts?', but how have vertebrates eliminated
the [adult] sea -- squirt stage from their life history? It is
wholly reasonable to consider that this has been accomplished by
paedomorphis. [17]
* A term proposed by Julian Huxley (1952), p. 532.

 

Sir Gavin de Beer compared the process to the re-winding of a biological
clock when evolution is in danger of running down and coming to a standstill:
'A race may become rejuvenated by pushing the adult stage of its individuals
off from the end of their ontogenies, and such a race may then radiate out
in all directions.' [18]

 

 

The record from palaeontology and comparative anatomy does indeed
suggest that this retracing of steps to escape from the blind alleys
of over-specialization was repeated at each major evolutionary turning
point. I have mentioned the evolution of the vertebrates from the larval
stage of some primitive echinoderm. Hardy and Koltsov
^[19]
have given numerous other examples and Takhtajan
^[20]
has
shown that paedomorphosis is also a common occurrence in the evolution of
plant life. Insects have in all likelihood evolved from a millipede-like
ancestor -- not, however, from its adult form, whose structure is too
specialized, but from its larval form. The conquest of the dry land
was pioneered by amphibians whose ancestry can be traced back to some
primitive type of lung-breathing fish, whereas the later lines of highly
specialized gill-breathing fishes came to a dead end. The examples
could be multiplied; but the most striking case of paedomorphosis is
the evolution of our own species.

 

 

Since Bolk's pioneering work, published in 1926, it is now generally
accepted that the human adult resembles the embryo of an ape rather than
an adult ape.

 

In both simian embryo and human adult, the ratio of the weight of
the brain to total body weight is disproportionately high. In both,
the closing of the sutures between the bones of the skull is
retarded to permit the brain to expand. The back-to-front axis
though man's head -- i.e., the direction of his line of sight --
is at right angles to his spinal column: a condition which, in apes
and other mammals, is found only in the embryonic, not in the adult
stage. The same applies to the angle between backbone and uro-genital
canal -- which may account for the singularity of the human way of
copulating face to face. Other embryonic -- or, to use Bolk's term,
foetalized -- characteristics in adult man are: the absence
of brow-ridges; the scantiness and late appearance of body hair;
pallor of the skin; retarded growth of the teeth, and a number of
other features . . . [21]

 

The 'missing link' between ape and man will probably never be found --
because it was an embryo.

 

 

 

7

 

 

Paedomorphosis -- or juvenilization -- thus appears to play an important
part in the grand strategy of evolution. It involves a retreat from
specialized adult forms to earlier, less committed and more plastic stages
in the development of organisms -- followed by a sudden advance in a new
direction. It is as if the stream of life had momentarily reversed its
course, flowing uphill for a while towards its original source; then
opened up a new stream-bed -- leaving the koala bear stranded on his tree
like a discarded hypothesis. In other words, we are faced here with the
same pattern of
reculer pour mieux sauter
, 'step back to leap', which
we have encountered at the critical turning points in the evolution of
science and art. Biological evolution is to a large extent a history of
escapes from the blind alleys of over-specialization, the evolution of
ideas a series of escapes from the tyranny of mental habits and stagnant
routines. In biological evolution the escape is brought about by a retreat
from the adult to a juvenile stage as the starting-point for the new
line; in mental evolution by a temporary regression to more primitive
and uninhibited modes of ideation, followed by the creative forward
leap (the equivalent of a sudden burst of 'adaptive radiation'). Thus
these two types of progress -- the emergence of evolutionary novelties
and the creation of cultural novelties -- reflect the same undoing --
redoing pattern and appear as analogous processes on different levels.

 

 

Neither biological evolution nor cultural progress follows a
continuous curve. Neither of them is strictly cumulative in the sense
of continuing to build where the previous generation had left off. Both
progress in the zigzag fashion described in
Chapter
VIII
. The advance of science is continuous only during those periods
of consolidation and elaboration which follow a main breakthrough or
'paradigm-change'. Sooner or later, however, consolidation leads
to increasing rigidity, orthodoxy, and so into the blind alley
of over-specialization -- the equivalent of the Irish elk or the
koala bear. But the new theoretical structure which emerges from the
breakthrough is not just added to the old edifice; it branches out from
the point where the evolution of ideas has taken the wrong turn. The
great revolutions in the history of science have a decidedly paedomorphic
character. In the history of literature and art, the zigzag course is even
more in evidence: we have seen how the periods of cumulative progress
within a given 'school' or technique end inevitably in stagnation,
mannerism or decadence, until the crisis is resolved by a revolutionary
shift in sensibility, emphasis, style.

 

 

 

8

 

 

The analogy between biological and cultural evolution can be further
substantiated if we turn our attention to one of the fundamental
attributes of living organisms: their power of self-repair, and to the
dramatic manifestation of that power in the phenomena of regeneration
(which Needham called 'one of the more spectacular pieces of magic in
the repertoire of living organisms').* It is as fundamental to life
as the capacity for reproduction, and in some lower organisms which
multiply by fission or budding, regeneration and reproduction are often
indistinguishable. Thus if a flatworm is transversely cut into halves,
the head part will grow a new tail, and the tail-end will grow a new head;
even if cut into half a dozen slices, each will regenerate a complete
animal. Flatworms, hydra, sea-squirts and starfish, all of which can
regenerate a whole individual from a small fraction of the body, could
be called biological holograms.

 

* See Insight and Outlook, Ch. X.;
The Ghost in the Machine, Ch. XIII.

 

Higher up on the evolutionary ladder, amphibians are capable of regenerating
a lost limb or organ; and once more the magic is performed according to
the undoing-redoing formula; the tissue-cells near the amputation stump
de-differentiate and regress to a quasi-embryonic state, then
re-differentiate and re-specialize to form the regenerated structure.*

 

* A classic case of such 'metaplasia' is the regeneration of the
crystalline lens of the salamander eye: 'If the lens is carefully
removed with fine instruments, it is replaced by a new lens that
originates at the upper margin of the iris; the latter is the
pigmented part of the eye, enclosing the pupil. The first change,
following lens extirpation, is the disappearance of the pigment
in the upper iris; that is, a process of de-differentiation. Next,
the two tissue layers that comprise the iris separate and expand at
the rim where they are continuous, and form a small vesicle. This
vesicle grows downward to assume the normal position of a lens;
eventually it becomes detached from the iris and differentiates
into a typical lens.' [22]

 

Now the replacement of a lost limb or eye-lens is a phenomenon of a different
order from ordinary wound-healing. The
regenerative potential
of a species
provides it with an added safety device in the service of survival --
a method of self-repair which relies on the genetic plasticity of uncommitted
embryonic cells. But it signifies more than a mere safety device, for we
have just seen that the major evolutionary novelties were brought about
by a similar retreat from adult to embryonic levels. Indeed, the major
steps on the line of ascent which led up to our species could be described
as a series of operations of
phylogenetic self-repair
: of escapes from
blind alleys by the undoing and remoulding of maladapted structures.

 

 

As we continue our ascent toward the higher animals, from reptile
to mammal, the power of regenerating bodily structures decreases,
and is replaced by the increasing power of the brain and nervous
system to reorganize the organism's pattern of behaviour. In the
first half of this century, K. S. Lashley, in a series of classical
experiments, demolished the notion of the nervous system as a rigid
reflex-automaton. He demonstrated that brain tissues which in the rat
normally serve a specialized function can, in certain circumstances,
take over the function of other, injured brain tissues. For example, he
taught his rats certain visual discrimination skills; when he removed
their optical cortex, the skills were gone, as one would expect; but
contrary to what one would expect, the mutilated rats were able to
learn the task again. Some other brain area, not normally specializing
in visual learning, must have taken over this function, deputizing for
the lost area. Similar feats of what one might call meta-adaptations
have been reported in insects, birds, chimpanzees, and so on.*

 

* See The Act of Creation, Book II, Ch. III.

 

Lastly, in our own species, the ability to regenerate bodily structures is
reduced to a minimum, but compensated by man's unique power to re-mould
his patterns of thought and behaviour -- to meet critical challenges by
creative responses. And thus we have come full circle through biological
evolution back to the various manifestations of human creativity, based on
the undoing-redoing pattern, which runs as a leitmotif from paedomorphosis
to the revolutionary turning points in science and art; to the mental
regeneration at which the regressive techniques in psychotherapy
are aimed; and finally to the archetypes of death-and-resurrection,
withdrawal-and-return which recur in all mythologies.

 

 

 

9

 

 

One of the basic doctrines of the nineteenth-century mechanistic world-view
was Clausius' famous 'Second Law of Thermodynamics'. It asserted that
the universe was running down towards its final dissolution because its
energy is being steadily, inexorably dissipated into the random motion
of molecules, until it ends up as a single, amorphous bubble of gas
with a uniform temperature just above absolute zero: cosmos dissolving
into chaos.

 

 

Only fairly recently did science begin to recover from the hypnotic effect
of this gloomy vision, by realizing that the Second Law applies only in the
special case of so-called 'closed systems' (such as a gas enclosed
in a perfectly insulated container), whereas all living organisms are
'open systems' which maintain their complex structure and function by
continuously drawing materials and energy from their environment. Instead
of 'running down' like a mechanical clockwork that dissipates its
energy through friction, a living organism is constantly building 'up'
more complex substances from the substances it feeds on, more complex
forms of energy from the energies it absorbs, and more complex patterns
of information -- perceptions, knowledge, stored memories -- from the
input of its sensory receptors.

 

 

But although the facts were there for everyone to see, orthodox evolutionists
were reluctant to accept their theoretical implications. The idea that living
organisms, in contrast to machines, were primarily active, and not merely
reactive; that instead of passively adapting to their environment they
were, to quote Judson Herrick, 'creating in the sense that new patterns
of structure and behaviour are constantly fabricated' -- such ideas were
profoundly distasteful to Darwinians, behaviourists and reductionists in
general.
^[23]
That the venerated Second Law, which had been so useful
in physics, did not apply to living matter, and was in a sense
reversed
in living matter, was indeed hard to accept by an orthodoxy still convinced
that all phenomena of life could ultimately be reduced to the laws
of physics.

 

 

It was in fact a physicist, not a biologist, the Nobel laureate Erwin
Schrödinger, who put an end to the tyranny of the Second Law with
his celebrated dictum: 'What an organism feeds on is negative entropy.'
^[24]
Now
entropy
is the term for degraded energy
which has been dissipated by friction and other wasteful processes, and
cannot be retrieved; in other words, it is a measure of energy gone to
waste. The Second Law can be expressed by saying that the entropy of a
closed system tends to increase towards a maximum when all of its energy
will have been dissipated into the chaotic motions of gas molecules;
so if our universe is a closed system, it must eventually 'unwind'
itself from cosmos into chaos. Entropy became a key-concept of physics
-- its alias for Thanatos; it even found its way into Freud's concept
of the death-wish (see
Chapter II
).

 

 

'Negative entropy' (or 'negentropy') is thus a somewhat perverse way
of referring to the power of living organisms to 'build up' instead of
running down, to create complex structures out of simpler elements,
integrated patterns out of shapelessness, order out of disorder. The same
irrepressible building-up tendency is manifested in the progress of
evolution, the emergence of new levels of complexity in the organismic
hierarchy and new methods of functional coordination, resulting in
greater independence from, and mastery of, the environment.