Vol 25, no 3, October - The Linnean Society of London

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THE LINNEAN 2009 VOLUME 25(3)
discipline of thermodynamics; a discipline which, in the 1980s, began to shed new
light on the organisation of living organisms. The perfection of buildings also had a
mathematical definition. Leon Battista Alberti, in the fifteenth century, defined
perfection in architecture as a geometric construction in which all elements are
proportioned exactly. These proportions could, of course, be expressed mathematically
as Euclidean ratios. On this definition, nothing could be added, diminished, or altered
but for the worse. It could have been George Cuvier defining the body plan of one of
his embranchments and closing the gates on transmutation and, consequently, on
evolution. The problem with the concept of perfection is that it implies stasis; systems
at, or close to, equilibrium. Living organisms are systems very far from equilibrium
and do not behave like perfect engines and, unlike buildings, they have a life cycle.
Jacob’s frog has no option but to be first a tadpole. Perfection, then, faced Darwin
with three problems. First, was there any objective measure of perfection in living
organisms? Second, how could a chancy process, such as Natural Selection, produce
‘organs of extreme perfection’? How could that watchmaker have possibly been blind?
Third, if organisms were indeed perfect, Cuvierian logic tells us that no further change
is possible. Cuvier’s answer was, of course, catastrophism but, wedded as he was to
Lyellian gradualism, this answer would not do for Darwin. How to answer and to
reconcile these conflicts was Darwin’s life’s work and, in the absence of any known
mechanism for heredity, his achievement is no less than breath-taking.
Perfection, as we now realise, does not exist in the way that Paley, the authors of
the Bridgewater Treatises and Darwin himself, at least for a time, believed. The eye,
Darwin’s bete noire, is ‘jury rigged’, so are orchid flowers. Hiccups are the legacy of
our aquatic ancestry, diabetes is a hangover from leaner times and surely a rotary
heart is mechanically preferable to a reciprocating one. Indeed, the whole new discipline
of Darwinian medicine is a scion of Darwin’s realisation that evolution, by Natural
Selection, could not result in perfection but is only a mechanism for tracking
environmental change given its inherited potential; remember those ‘ten thousand
wedges’? Darwin well knew that Natural Selection was ‘Daily and hourly scrutinising,
throughout the world, every variation;’ (Origin p.84). Furthermore those variations,
although their causes were unknown to him, Darwin knew that they were expressed at
all stages in the life cycle of an organism and that, therefore, the scope for Natural
Selection to act was enormous. This resulted in ‘The Struggle for Existence’ being far
more complex than his contemporaries ever realised, preferring, as we still do,
Tennyson’s poetic, if simplistic and wholly misleading, ‘Nature red in tooth and claw’.
.The power of Natural Selection and the resulting evolutionary divergence was very
clear to Darwin but, he lamented, his contemporaries, even his staunchest allies, never
really grasped the significance of it. Asa Gray even congratulated Darwin for
reintroducing teleology and Lyell saw Natural Selection and the Principle of Divergence
as alternatives! It was all too novel. Darwin’s arguments lay outside the accepted
philosophical framework and yet the language available to him was derived from that
very framework. His term ‘Natural Selection’, as Gillian Beer has pointed out was
‘...poised on the edge of metaphor...’ (Beer p.xviii).
Darwin had come a long way from Paley’s watch, whose perfection, or approach
to it, could only be assessed in the final product. When Darlington warned, in 1951,
that something was missing from the ‘New Synthesis’ he was quite right; with