We can now apply the same metaphor to the alert guardians who protect the
gates of heredity against the chaos that would ensue if random mutations
'in all and every direction' were given free access. We must assume
that mutations -- that is, 'changes' in the original sense of the word
-- on the elementary quantum level are occurring constantly under the
impact of radiations and other factors impinging on the gene-complex. The
giant molecules of the chromosome chains consisting of millions of atoms
must also be surrounded by a 'blooming, buzzing confusion' of their own
sub-microscopic universe. Most of these changes would be transitory,
quickly rectified by self-regulatory devices of the gene-complex,
or without noticeable effect on its functioning. The relatively few
mutations potentially capable of affecting heredity would be submitted to
sifting and processing at the gates of successively higher levels of the
hierarchy. I have mentioned several stages of this processing, for which
there is solid evidence: the elimination of 'mis-spelt' syllables in the
genetic code; 'developmental homeostasis' which ensures that mutations
should affect a whole organ in a harmonious way; similar processes
on higher levels (Thompson's transformations,
loi du balancement
)
which preserve the proper equilibrium between organs; the evolution of
homologous organs from different combinations of genes (drosophila-eye),
and of similar species of independent evolutionary origin (marsupials).*
* I shall not bother the reader with technical terms like
'homeoplasy', 'convergence', 'parallelism', which are merely
descriptive, but not explanatory.
The conclusion which emerges from all this is that there must be unitary
laws underlying evolutionary variety, permitting unlimited variations
on a limited number of themes. Translated into our terminology, this
means that the evolutionary process, like all hierarchic operations,
is governed by fixed canons, and guided by adaptable strategies. The
latter are partly (see below) accounted for by the selective pressures
of the environment -- predators, competitors, etc.; but the laws which
confine possible evolutionary advances to certain main avenues cannot
be defined in terms of these external factors which only enter into
action after a change proposed by mutating genes has been approved and
passed muster at the successive Kremlin gates of the organism's internal
controls. These internal controls define the 'evolutionary canon'.
Several eminent biologists have in recent years toyed with this idea,
but without spelling out its profound implications.* Thus von Bertalanffy
wrote: 'While fully appreciating modern selection theory, we nevertheless
arrive at an essentially different view of evolution. It appears to be
not a series of accidents, the course of which is determined only by the
change of environments during earth history and the resulting struggle
for existence, which leads to selection within a chaotic material of
mutations . . . but is governed by definite laws, and we believe that the
discovery of these laws constitutes one of the most important tasks of
the future.' [13] Waddington and Hardy have both rediscovered Goethe's
notion of archetypal forms; Helen Spurway concluded from the evidence
of homology that the organism has only 'a restricted mutation spectrum'
which 'determines its possibilities of evolution'. [14]
* For an excellent short critical discussion see L.L. Whyte's
Internal Factors in Evolution, and W.H. Thorpe's review of
the book in Nature, May 14, 1966.
But what exactly do these authors mean by expressions like 'archetypal
selection', 'organic laws co-determining evolution', 'mutation
spectrum', or 'moulding influences guiding evolutionary change along
certain avenues'? [15] They seem to mean in fact, without saying it in
as many words, that given the conditions on our particular planet, the
chemistry and temperature of its atmosphere, and the available energies
and building materials, life from its inception in the first blob of
living slime could only progress in a limited number of directions in
a limited number of ways. But this implies that just as the Australian
and European wolf were both potentially foreshadowed in the ancestral
mouse-like creature, that creature in turn was foreshadowed in the
ancestral chordate, and so on back to the ancestral protist, and the
first, self-replicating strand of nucleic acid.
If this conclusion is correct, it sheds some additional light on man's
status in this universe. It puts an end to the fantasies of science
fiction regarding future forms of life on earth. But it does not mean
the opposite either: it emphatically does not mean a rigidly determined
universe which unwinds like a mechanical clockwork. It means, to revert
to one of the leitmotivs of this book, that the evolution of life is a
game played according to fixed rules which limit its possibilities but
leave sufficient scope for a limitless number of variations. The rules
are inherent in the basic structure of living matter; the variations
derive from adaptive strategies.
In other words, evolution is neither a free-for-all, nor the execution
of a rigidly predetermined computer programme. It could be compared to
a musical composition whose possibilities are limited by the rules of
harmony and the structure of the diatonic scales which, however, permit
an inexhaustible number of original creations. Or it could be compared
to the game of chess obeying fixed rules but with equally inexhaustible
variations. Lastly, the vast number of existing animal species (about
one million) and the small number of major classes (about fifty) and of
major phyla or divisions (about ten), could be compared with the vast
number of works of literature and the small number of basic themes or
plots. All works of literature are variations on a limited number of
leitmotivs, derived from man's archetypal experiences and conflicts, but
adapted each time to a new environment -- the costumes, conventions and
language of the period. Not even Shakespeare could invent an original
plot. Goethe quoted with approval the Italian dramatist Carlo Gozzi,*
according to whom there are only thirty-six tragic situations. Goethe
himself thought that there were probably even less; but their exact number
is a well-kept secret among writers of fiction. A work of literature
is constructed out of thematic holons -- which, like homologue organs,
need not even have a common ancestor.
* Author of Turandot and many other successful works.
Three times at least, but probably much more often, eyes with lenses
have evolved independently in animals as widely different as molluscs,
spiders and vertebrates. Most insects have, unlike the spider, compound
eyes, but these are merely modifications of the same optical principle:
the smooth-curved surface of the camera lens is broken up into a honeycomb
of small corneal lenses, each with its own light-sensitive tube. These
are the only two basic types of image-forming eyes* throughout the animal
kingdom. But again there are countless variations and refinements, from
the 'pinhole eye' of the nautilus which functions on the principle of
the camera obscura, without lens, through the rudimentary lenses of
starfish, up to the precision mechanisms by which various groups of
animals achieve accommodation and focussing of the eye on objects of
varying distance. Fishes, perhaps because they have more time on their
fins, move the whole lens closer to the retina when focussing on distant
objects. Mammals, including man, have evolved a more elegant method of
focussing by altering the curvature of the lens -- flattening it for
close objects, thickening it for distant vision. Predatory birds have
developed an even more effective strategy for keeping the prey in focus
while sweeping down on it: instead of adjusting the relatively inert lens,
they quickly change the curvature of the more flexible cornea. Another
essential refinement, colour vision, also evolved independently several
times. Lastly, the gradual shifting of the position of the eyes from the
side to the front of the head led to binocular vision -- the fusion of
the images in each separate eye into a single three-dimensional image
in the brain.
* As distinct from primitive, light-sensitive units which respond
to differences in light intensity, but do not provide pattern-vision.
The purpose of the preceding paragraph was not to praise the glories of
vision, but to point to the remarkable achievements of adaptive strategies
making the best of the organism's limited possibilities. The limitations
are inherent in the physico-chemical structure of living matter as it
exists on earth -- and presumably on any planet whose conditions are
remotely similar to those on earth. But there is no limit to what an
artist can do with Gozzi's meagre list of thirty-six themes.
XI
EVOLUTION CTD: PROGRESS BY INITIATIVE
When you don't know where a road leads, it sure as hell will take
you there.
Leo Rosten
Expressions like 'adaptive strategy' or 'exploiting opportunities' imply
an active striving towards an optimal realisation of the evolutionary
potential.
In recent years it has become once more scientifically respectable to
speak of goal-directedness in
ontogeny
-- from the canalisation of
embryonic development to the purposiveness of instinctive and learned
behaviour. But not so in
phytogeny
. There the official attitude may
still be fairly summarised by the following quotation from G.G. Simpson:
'It does seem that the problem [of evolution] is now essentially
solved and that the mechanism of adaptation is known. It turns out
to be basically materialistic, with no sign of purpose as a working
variable in life history, and with any possible Purposer pushed back to
the incomprehensible position of First Cause.' And later on: 'Man is the
result of a purposeless and materialistic process that did not have him
in mind. He was not planned.' [1]
However, there is no need to engage in philosophical debate over this kind
of pronouncement, because it is based on spurious alternatives. According
to Simpson, evolution is either 'basically materialistic' (whatever that
means in this context) -- or else there must be a Purposer, a god; man
is either the result of a purposeless process or else he must have been
'planned' from the beginning. But the term 'purpose' in its biological
context implies neither a Purposer nor a cut-and-dried image of the
ultimate goal to be achieved. The predator setting out on its nightly
round does not look for a particular rabbit or hare, he looks for a likely
prey; the chess-player cannot generally foresee or plan the ultimate mate
situation: he uses his skill to take advantage of the opportunities on
the board. Purposiveness means goal-directed instead of random activity,
flexible strategies instead of rigid mechanisms, and adaptive behaviour
-- but on the organism's own terms: it does not 'adapt' to a freezing
environment by lowering its body temperature, but by burning up more
fuel. In a word, as E.W. Sinnott wrote, purpose is 'the directive activity
shown by individual organisms that distinguishes living things from
inanimate objects'. [2] Or, to quote the Nobel Laureate H.J. Muller,
'purpose is not imported into nature, and need not be puzzled over as
a strange or divine something else that gets inside and makes life go
. . . it is simply implicit in the fact of biological organisation,
and it is to be studied rather than admired or "explained" '. [3]
Let me repeat: to talk of 'directiveness', or purpose in this limited
sense, in ontogeny, has become respectable once more; but to apply
these terms to phylogeny is still considered heretical (or at least
in bad taste). But phylogeny is an abstraction, which only acquires a
concrete meaning when we realise that 'phylogeny, evolutionary descent,
is a sequence of ontogenies', and that 'the course of evolution is through
changes in ontogeny'. The quotations in the previous sentence are actually
also by Simpson [4], and contain the answer to his own conundrum about the
Purposer behind the purpose.
The Purposer is each and every individual
organism, from the inception of life, which struggled and strove to make
the best of its limited opportunities.
Acting Before Reacting
When orthodox evolutionists speak of 'adaptations' they mean, as
Behaviourists do when they speak of 'responses', an essentially passive
process or mechanism, controlled by the environment. This view may be in
keeping with their philosophy, but it is certainly not in keeping with
the evidence which shows, to quote G.E. Coghill once more, that 'the
organism acts on the environment before it reacts to it'. [5] Coghill
has demonstrated that in the embryo the motor-nerve tracts become active,
and movements make their appearance, before the sensory nerves become
functional. And the moment it is hatched or born the creature lashes
out at the environment, be it liquid or solid, with cilia, flagellae, or
contractile muscle fibre; it crawls, swims, glides, pulsates; it kicks,
yells, breathes, feeds on its surroundings for all it is worth. It
does not merely adapt to the environment, but constantly adapts the
environment to itself -- it eats and drinks its environment, fights and
mates with it, burrows and builds in it; it does not merely respond to the
environment, but asks questions by exploring it. The 'exploratory drive'
is now recognised by the younger generation of animal psychologists to
be a primary biological instinct, as basic as the instincts of hunger
and sex; it can on occasion be even more powerful than these. Countless
experimenters* -- starting with Darwin himself have shown that curiosity,
and the 'seeking out of thrills', is an instinctual urge in rats, birds,
dolphins, chimpanzees and man; and so is what Behaviourists call 'ludic
behaviour' known to ordinary mortals as playfulness.