The Ghost in the Machine (22 page)

 

 

But whatever the beliefs of these men, the concept of homology came to
stay, and became a cornerstone of modern evolutionary theory. Animals
and plants are made out of homologous organelles like the mitochondria,
homologous organs like gills and lungs, homologous limbs such as arms and
wings. They are the stable holons in the evolutionary flux.
The phenomena
of homology implied in fact the hierarchic principle in phylogeny as
well as in ontogeny.
But the point was never made explicit, and the
principles of hierarchic order hardly received a cursory glance. This
may be the reason why the inherent contradictions of the orthodox theory
could pass so long unnoticed.

 

 

 

The Law of Balance

 

 

There are manifestations on still higher levels of what I have called
the stability of evolutionary holons. Such are the geometrical relations
discovered by d'Arcy Thompson, which demonstrate that one species may
become transformed into another and yet preserve its own basic design. The
drawings below show a porcupine fish (Diodon) and the very different
looking sun fish (Orthogoriscus) as they appear in Thompson's classic,
On Growth and Form
, published in 1917.

 

 

I have compared the evolution of homologue organs to the procedure of
motor-car manufacturers when they bring out a new model, which differs
from the previous one merely in some modifications of this or that
component, while the other standardised parts remain unaltered. In the
case of the fish, it is not a particular organ that has been modified,
but the chassis and body-line as a whole. Yet it has not been arbitrarily
re-designed. The pattern has remained the same. It has merely been evenly
distorted according to a simple mathematical equation. Imagine the drawing
of the porcupine fish and its lattice of Cartesian co-ordinates imprinted
on a rubber sheet. The sheet is thicker at the head end, and therefore
more resistant than at the tail end. Now you grip the top and bottom
edges of the rubber sheet and stretch it. The result will be the sun
fish. Corresponding points of the anatomy of the two fishes will have
the same co-ordinates (the eye, for instance, will have 'longitude' 0,5,
and 'latitude' C).

 

 

Thompson found that this phenomenon had general validity. Putting
the outline drawing of an animal on a grid of co-ordinates, and then
drawing another animal belonging to the same zoological group, he found
that he could transform one shape into the other by some simple trick
of rubber-sheet-geometry, which can be expressed by a mathematical
formula. The next drawing, Figure 8, shows the transformation, by means
of a harmoniously deformed grid of Cartesian co-ordinates, of a baboon's
skull into a chimpanzee's and a man's.

 

 

These are not idle mathematical games. They provide a realistic insight
into the evolutionary workshop. Here are d'Arcy Thompson's own comments:

 

We know beforehand that the main difference between the human
and the Simian types depends upon the enlargement or expansion of
the brain and brain case in man, and the relative diminution or
enfeeblement of his jaws. Together with these changes, the facial
angle increases from an oblique angle to nearly a right angle in
man, and the configuration of every constituent bone of the face
and skull undergoes an alteration. We do not know to begin with,
and we are not shewn by the ordinary methods of comparison, how
far these various changes form part of one harmonious and congruent
transformation, or whether we are to look, for instance, upon the
changes undergone by the frontal, the occipital, the maxilliary and
the mandibular regions as a congeries of separate modifications or
independent variables. But as soon as we have marked out a number
of points in the gorilla's or chimpanzee's skull, corresponding with
those which our co-ordinate network intersected in the human skull,
we find that these corresponding points may be at once linked up by
smoothly curved lines of intersection, which form a new system of
co-ordinates and constitute a simple 'projection'* of our human skull
. . . and in short it becomes at once manifest that the modifications
of jaws, brain-case, and the regions between, are all portions of
one continuous and integral process. [10]
* In the sense of Projective Geometry.

 

Surely this process is the exact opposite of evolution through random
changes 'in all and every direction'. If that were the case we should
get what Thompson calls 'a congeries of separate modifications or
independent variables'. In fact, the variations are inter-dependent,
and must be controlled from the apex of the hierarchy which co-ordinates
the pattern of the whole by harmonising the relative growth-rates of
the various parts.

 

 

Thus the rapid expansion of the anthropoid brain was accompanied by
appropriate changes in the other parts of the skull, effected by a
simple and elegant geometrical tramformation. The eighteenth century was
familiar with this kind of phenomenon, which the twentieth took a long
time to re-discover. Goethe called it 'Nature's budgeting law', Geoffroy
St. Hilaire called it
loi du balancement
, the principle of the
equilibrium of organs. From the concept of developmental homeostasis there
is only one logical step to the concept of evolutionary homeostasis --
the
loi du balancement
applied to phylogenetic changes. Faithful to
Goethe, one might call it the preservation of certain basic, archetypal
designs through all changes, combined with the striving towards their
optimal realisation in response to adaptive pressures.

 

 

 

The Doppelgängers

 

 

The last phenomenon to be mentioned in this context is an enigma wrapped
in a puzzle. The enigma concerns the marsupials -- the class of pouched
animals living in Australia. The puzzle is that evolutionists refuse to
see the enigma.

 

 

Nearly all mammalians are either marsupials or placentaIs. (The 'nearly'
refers to the near-extinct monotremes, such as the duck-billed platypus,
a kind of living fossil which lays eggs as reptiles do, but suckles its
young.) The marsupials could be called the poor relatives of us 'normal',
that is, placental, mammals; they have evolved along a parallel branch of
the evolutionary tree. The marsupial embryo, while in the womb, receives
hardly any nourishment from its mother. It is born in a very immature
state of development, and is reared in an elastic pouch, or bag of skin,
on the mother's belly. A newborn kangaroo is really a half-finished job
-- about an inch long, naked, blind, with hind-legs that are no more
than embryonic buds. One might speculate whether the human infant, more
developed but still helpless at birth, would be better off in a maternal
pouch than in a cot; and also whether this would increase its oedipal
inclinations. But whether the marsupial's method of reproduction is better
or worse than the placental's, the point is that it is fundamentally
different.

 

 

The two lines split up at the very beginning of mammalian evolution,
in the Age of Reptiles, and have evolved separately, out of some
small mouse-like common ancestral creature, over some hundred and
fifty million years. The enigma is, why so many species produced by
the independent evolutionary line of the marsupials are so startlingly
similar to placentaIs. It is almost as if two artists who had never met,
never heard of each other, and never had the same model, had painted
a parallel series of nearly identical portraits. Figure 9 shows on the
left side a series of placental mammals, and on the right their opposite
numbers among marsupials.

 

 

 

A. Marsupial jerboa and placental jerboa.
B. Marsupial flying phalanger and placental flying squirrel (after Hardy).
C. Skull of marsupial Tasmanian wolf compared to skull of placental wolf
(after Hardy).

 

Let me repeat: we know that, contrary to all appearances, the two series
of animals have evolved independently from each other. Australia was
cut off from the Asiatic mainland some time during the late Cretaceous,
when the only existing mammals were unpromising-looking tiny creatures,
hanging precariously on to existence. The marsupials seem to have evolved
earlier than the placentaIs from a common egg-laying ancestor with
part-reptilian, part-mammalian features; at any rate, the marsupials got
to Australia before it was cut off, and the placentals did not. These
immigrants were, as already said, mouse-like creatures, probably not
unlike the still surviving, yellow-footed pouched mouse, but much more
primitive. And yet these mice, confined to their island continent,
branched out and gave rise to pouched versions of moles, ant-eaters,
flying squirrels, cats and wolves -- each like a somewhat clumsy copy
of the corresponding placentals.* Why, if evolution were a free-for-all,
restrained only by selection for fitness, why did Australia not produce
some of the bug-eyed monsters of science fiction? The only moderately
unorthodox creation of that isolated island in a hundred million years
are the kangaroos and wallabies; the rest of its fauna consists of
rather poor replicas of more efficient placental types -- variations on
a limited number of archetypal themes. **

 

* Marsupials have also evolved, again independently, in South America.
** The reasons for the inferiority of marsupials compared to
placentals will be discussed in Chapter XVI.

 

How is the enigma to be explained? The explanation offered by the orthodox
theory is summed up in the following passage from an otherwise excellent
textbook, that I have repeatedly quoted: 'Tasmanian [i.e., marsupial]
and true wolves are both running predators, preying on other animals of
about the same size and habits. Adaptive similarity [i.e., adaptation
to similar environments] involves similarity also of structure and
function. The mechanism of such evolution is natural selection.' [11]
And G.G. Simpson, a leading Harvard authority, discussing the same
problem, concludes that the explanation is 'selection of random
mutations'. [12]

 

 

Once more the
deus ex machina
. Are we really to believe that
the condition described by the vague terms 'preying on animals of
approximately the same size and habits' -- which could be applied to
hundreds of different species -- sufficiently explains the emergence,
twice over, independently from each other, of the almost identical two
skulls in Figure 9? One might as well say, with the wisdom of hindsight,
that there is only one way of making a wolf, which is to make it look
like a wolf.

 

 

 

The Thirty-six Plots

 

 

In
Chapter VI
, I compared the series of scanning
and filtering mechanisms through which the intake of our sense-organs must
pass before it is admitted to awareness and found worthy to be preserved
by memory, to the seventeen gates of the Kremlin. The sense-receptors
of eye, ear and skin are exposed (in a famous phrase of William James')
to a continuous bombardment by the 'blooming, buzzing confusion' of
the outside world; without careful scrutiny by the sentries guarding
the gates, we should be at the mercy of all random intruders, and our
minds and memories would be all confusion, unable to make sense of our
chaotic sensations.