Janus (29 page)

 

 

Jacques Monod was confronted with the same dilemma. His brave attempt in
Chance and Necessity
to defend the beleaguered citadel could be compared
to Custer's Last Stand. Though he keeps repeating that 'chance alone is
at the source of all creation in the biosphere', etc., he is compelled
by the evidence derived from his own field to acknowledge the existence
of the 'great central something' by postulating a second basic principle
of evolution besides chance, which he calls
teleonomy
(his italics):

 

One of the fundamental characteristics common to all living beings
without exception [is] that of being objects endowed with a purpose
or project, which at the same time they exhibit in their structure
and carry out through their performances . . . [53]

 

The cornerstone of the scientific method is . . . the
systematic
denial
that 'true' knowledge can be got at by interpreting phenomena in terms of
final causes -- that is to say, of 'purpose' . . . Objectivity nevertheless
obliges us to recognize the teleonomic character of living organisms,
to admit that in their structure and performance they act projectively --
realise and pursue a purpose. .. [54]

 

 

But what, one might ask, is the difference between Monod's 'teleonomy'
and the good old Aristotelian teleology, defined by the
Concise Oxford
Dictionary
as the 'doctrine of final causes, view that developments
are due to the purpose or design that is served by them'? And even more
shockingly, does not the passage quoted remind one of the Lamarckian
heresy, according to which evolution is nature's reponse to the organisms'
needs? Grassé commented:

 

The Darwinians have coined the words pseudo-teleology and teleonomy to
refer to final causes whose existence at the same time they deny. They
say that the appearances are deceptive, that the constituents of
life are all products of chance; and that what we take for finality*
is nothing but the ordering of haphazard building blocks by natural
selection . . . As a matter of fact, the terms pseudo-teleology and
teleonomy pay tribute to finality, as hypocrisy pays homage to virtue
. . . [55]
* 'Finality': principle of final cause, i.e., purpose viewed as
operative in the universe. 'Teleology': view that developments
are due to the purpose or design served by them (Concise
Oxford Dictionary).

 

Yet Jacques Monod was not a hypocrite. He was brilliant in his specialized
field, but disarmingly naive concerning the theoretical implications of it
-- what his compatriots call a 'terrible generalisateur'. This, of course,
applies to many of his eminent colleagues in the neo-Darwinian establishment.
Guided -- perhaps unconsciously -- by the maxim that a bad theory is better
than no theory, they are unable or unwilling to realize that the citadel
they are defending lies in ruins.

 

 

 

 

 

X

 

 

LAMARCK REVISITED

 

 

 

1

 

 

Genetic atomism is dead. As dead as the atomism of nineteenth-century
physics, which regarded atoms as hard little indivisible marbles. The
living organism is not a mosaic, where each bit is governed by a separate
gene, and evolution does not proceed by replacing individual bits in a
haphazard fashion until, lo and behold, the image of a fish is replaced
by that of an amphibian. In
The Ghost in the Machine
I compared the
present crisis in evolutionary theory with the falling apart of medieval
cosmology. The pages that follow carry the argument one step further.

 

 

 

2

 

 

In his
Evolution Old and New
, published in 1879, Samuel Butler wrote:
'Lamarck has been so systematically laughed at that it amounts to
little less than philosophical suicide for anyone to stand up on his
behalf.' Nearly half a century later, Paul Kammerer, the most brilliant
Lamarckian of his time, was driven into bodily suicide by the laughter
and hostility of his fellow biologists.* At the time of writing, another
fifty years later, Lamarckism is still an emotional minefield, which
academics may enter only at the risk of having their reputations and
careers blown to bits.**

 

* The Case of the Midwife Toad is an account of his life and the
controversy surrounding his work.
** In France there is more tolerance in this respect; after all,
Lamarck was French, Darwin British.

 

The explosive core of the argument was -- and still is -- a seemingly
innocuous postulate: 'the inheritance of acquired characteristics',
which Lamarck formulated at the beginning of the nineteenth century,
in his
Philosophie Zoologique
. The term 'acquired characteristics'
refers to improvements in physique, skills, or ways of life, which
individuals acquire through their efforts to cope with the environment
and to exploit the opportunities it offers; in other words, progressive
changes
which correspond to the vital needs of the species
and which --
here's the rub -- are transmitted, according to Lamarck, from parents
to offspring through the channels of heredity. Successive generations
would thus benefit from the struggles and exertions of their forebears
by direct bodily inheritance (and not only indirectly through imitative
learning from their elders).

 

 

Some early Lamarckians actually believed that a blacksmith's son
would be born with stronger than average biceps, without having to
develop them by repeating his father's efforts all over again, and
that a concert pianist's offspring would inherit some of his father's
acquired skill. But neo-Lamarckians abandoned these naive views a long
time ago; they hold that only biologically vital characteristics which
are acquired in response to intense and persistent pressures of the
environment
over many generations
become eventually hereditary, that
is, incorporated into the gene-complex. In spite of this qualification,
the essence of Lamarckism is the belief that the efforts of the parents
are not entirely wasted, that some of the benefits derived from their
experiences and labours are transmitted to their offspring, and that
this is the principal active cause of evolution 'from amoeba to man'.

 

 

Thus in the Lamarckian view, evolution is a
cumulative
process,
the outcome of the purposeful striving of living organisms (not very
different from Monod's teleonomy), whereas in the neo-Darwinian view
evolution is an
accidental
process, in the course of which the
parents can transmit through the channels of heredity only what they
have inherited themselves, plus some (mostly harmful) aberrations in
the genetic material. Thus from the point of view of the offspring, the
struggles and achievements of their ancestors were wasted, and amounted,
in the words of
Ecclesiastes
, to mere 'vanity - and chasing the
wind'. The two contrasting attitudes can be summed up by two quotations:
the first is from Kammerer, the Lamarckian:

 

It is not merciless selection that shapes and perfects the machinery
of life; it is not the desperate struggle for survival alone which
governs the world, but rather out of its own strength everything that
has been created strives upwards towards light and the joy of life,
burying only that which is useless in the graveyard of selection. [1]

 

The second quotation is from Simpson of Harvard, an eminent neo-Darwinian:

 

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 . . . Man is the result of a purposeless
and materialistic process . . . [2]

 

It is not surprising that such diametrically opposed attitudes became
fraught with emotion, comparable to the theological disputes of the past.
As Sir J. A. Thomson wrote in 1908:

 

The question as to the transmissibility of characters acquired during
life by the body of the parent . . . is much more than a technical
problem for biologists. Our decision in regard to it affects not
only our whole theory of organic evolution, but even our every-day
conduct. The question should be of interest to the parent, the
physician, the teacher, the moralist, and the social reformer --
in short, to us all. [3]

 

It is not only of historical interest that Darwin himself remained all
his life half a Darwinist and half a Lamarckist. In his
The Variation
of Animals and Plants under Domestication
, published in 1868, and in his
notebooks, he gave a whole series of spurious examples of the inheritance
of acquired characteristics: 'the cat had its tail cut off at Shrewsbury,
and its kittens had all short tails', or 'a man losing part of his
little finger and all his sons being born with deformed little fingers',
and many similar old wives' tales in which he earnestly believed; and in
1875, towards the end of his life, he wrote to Galton that each year he
found himself more compelled to revert to the inheritance of acquired
characteristics because chance variations and natural selection alone
were apparently insufficient to explain the phenomena of evolution. The
examples he quoted were no doubt apocryphal, but they prove that if
Lamarckism was 'a disreputable ancient superstition' (as Professor
Darlington called it), Darwin himself shared it.
^[4]
And so
did Herbert Spencer, the great apostle of Darwinism, who wrote in his
Principles of Biology
(1893):

 

Close contemplation of the facts impresses me more strongly than ever
with the two alternatives -- either there has been inheritance of
acquired characters, or there has been no evolution.
[Italics in the original. [5]

 

Thus in that early period it was possible, and even usual among
evolutionists, to be both a Lamarckian and a Darwinian at the same
time. With the advent of neo-Darwinism this peaceful coexistence came
to an end, Lamarck was excommunicated, and the eclecticism of the early
evolutionists was transformed into an attitude of sectarian intolerance.

 

 

The ostensible cause of the schism was a doctrine, propounded in 1885,
three years after Darwin's death, by the German zoologist August Weismann
-- the doctrine of the 'continuity and unalterability of the germ-plasm'.
Weismann's 'germ-plasm' is the carrier of the hereditary endowment (today
called the 'genetic blueprint'); it is located in the sex-cells -- sperm
and ovum -- which are set aside at an early stage in the development
of the embryo, isolated from the soma-cells that will give rise to the
rest of the body; and is transmitted to the next generation along the
'continuous germ-tract', unaltered and unaffected by anything that
happened to the transient individuals which harboured the immortal
plasm in their ovaries and testicles. The doctrine that no 'acquired
characteristic' can penetrate the barrier protecting the germ-plasm
and alter the hereditary endowment became an integral part of the
neo-Darwinist creed, and still is -- brought up to date in Crick and
Watson's provocatively named 'central dogma'. It tells us that the DNA
chains of heredity in the chromosomes are kept in splendid isolation
from the rest of the body, that they are potentially immortal molecular
structures, protected from the hazards of life, and passed on, unaltered,
from generation to generation, ad infinitum, unless some nasty radiation
intervenes. It is a depressing doctrine, whether true or not. The
indications are that it is not.

 

 

Neo-Darwinism did indeed carry the nineteenth-century brand of materialism
to its extreme limits by proclaiming the evolution of man to be the result
of 'a purposeless materialistic process', ruled by 'blind chance'.
And therein, precisely, lay its perverse philosophical attraction --
in its uncompromising rejection of any trace of purpose in the manifestations
of life; in its grim determination to reduce ethical values and mental
phenomena to the elementary laws of physics; and to brand those aspects of
biology which cannot be thus reduced, as unworthy of scientific attention.

 

 

How this metaphysical bias influenced and distorted scientific methodology
is illustrated by a hilarious episode rarely mentioned in the textbooks.
In order to prove his doctrine that the 'germ-plasm' remained unaffected
by acquired characteristics, Weismann amputated the tails of twenty-two
successive generations of rats to see whether eventually a tail-less rat
would be born. No such rat was born, so Lamarck was refuted. However,
as one unrepentant Lamarckian remarked, Weismann might as well have
studied the inheritance of a wooden leg. For Lamarck's thesis was that
only such acquired characteristics become inheritable which an animal
develops as a result of its natural, vital needs -- and having its tail
chopped off can hardly be called a vital need of the rat.

 

 

 

3

 

 

Neither Weismann, nor anybody else, has been able to disprove
Lamarckian inheritance, because of the inherent difficulty of
proving a negative: the Lamarckians could always argue, with
perfect justification, that evolution works on an incomparably
larger time-scale than a research team, however patient. This was
admitted even by staunch Darwinians, such as J. B. S. Haldane:

 

It must be remembered that however many experiments fail, it is always
possible that the effects of acquired characters may be impressed
on a species at a rate not susceptible to experimental verification,
yet rapid enough to be of importance in geological time.

 

It is rather amusing to note that Sir Julian Huxley, as we have seen,
used exactly the same argument in defence of Darwinian inheritance against
its critics: the '"hoary objection" of the improbability of an eye or
a hand or a brain being evolved by blind chance has "lost its force"
because natural selection is "operating over the stretches of geological
time".' [7]