184 D. M. Walsh
survive at the expense of others. Vehicle selection is the process by
which some vehicles are more successful than others in ensuring the
survival of their replicators [1982, 82].Dawkins serves up a particularly strongly distilled version of replicator biology,
but it is the same in spirit as almost any orthodox account of evolutionary expla-
nation. Perhaps replicator biology deserves its privileged status. It provides us
with a powerful explanation of biology’s dual problematic — fit and diversity. The
marvellous fit of organisms to the conditions of their existence is achieved by the
gradual accretion of selected (adapted) replicators. Fitness-promoting replicators
are assembled and recombined by inheritance and selection into integrated suites
of traits [Ayala, 1970].
The success of replicator biology has allowed evolutionists not merely to ‘black
box’ development, but to see right through it; the organism becomes diaphanous.
Dawkins drives home the point with great ́elan; watching through his window as
a large willow tree sheds its seeds, he proclaims...
It is raining DNA outside.... Up and down the canal, the water is
white with cottony flecks.... The cotton wool is mostly made of cel-
lulose, and it dwarfs the tiny capsule of that contains the DNA, the
genetic information. The DNA content must be a small proportion of
the total, so why did I say it was raining DNA rather than cellulose?
The answer is that it is the DNA that matters.... The whole perfor-
mance, cotton wool, catkins, tree and all, is in aid of one thing and
one thing only, the spreading of DNA around the countryside. Not
just any DNA, but DNA whose coded characters spell out specific in-
structions for building willow trees that will shed a new generation of
downy seeds. Those fluffy specks are literally spreading instructions for
making themselves. They are there because their ancestors succeeded
in doing the same. It is raining instructions out there; it’s raining tree-
growing, fluff-spreading algorithms. That is not a metaphor, it is the
plain truth. [Dawkins, 1987, 111]Evolutionary biology is not about organisms, it would seem. Where organisms
are of such minimal theoretical significance, their development is too. Development
is merely an intra-organismal process. What really matters to evolution are the
inter-organismal process of transmission of replicators and thesupra-organismal
process of selection. Small wonder, then, that as Hamburger notes, developmental
biology was left out of the modern synthesis.
No one, not even the most ardent acolyte of the modern synthesis, denies that
development has an explanatory role to play in evolutionary biology. Quite what
that role might be, however, is a matter of some dispute. There are various
attitudes we might take to the significance of development to the explanation of
adaptive evolution. I attempt to outline a range of them in the next section. As I
see it, it is not just the place of development in the sub-organismal reading of the