Darwin's Dangerous Idea - Evolution and the Meaning of Life

136 THREADS OF ACTUALITY IN DESIGN SPACE The Unity of Design Space 137
mechanisms of one sort or another. How many cranes-on-top-of-cranes does
it take to get from the early design explorations of prokaryotic lineages to die
mathematical investigations of Oxford dons? That is the question posed by
Darwinian thinking. The resistance comes from those who think there must
be some discontinuities somewhere, some skyhooks, or moments of Special
Creation, or some other sort of miracles, between the prokaryotes and the
finest treasures in our libraries.
There may be—that will be a question we will look at in many different
ways in the rest of the book. But we have already seen a variety of deep
parallels, instances in which the very same principles, the very same strategies
of analysis or inference, apply in both domains. There are many more
where they came from.
Consider, for instance, Darwin's pioneering use of a certain sort of historical
inference. As Stephen Jay Gould has stressed (e.g., 1977a, 1980a), it
is the imperfections, the curious fallings short of what would seem to be
perfect design, that are the best evidence for a historical process of descent
with modification; they are the best evidence of copying, instead of independent
re-inventing, of the design in question. We can now see better why
this is such good evidence. The odds against two independent processes'
arriving at the same region of Design Space are Vast unless the design
element in question is obviously right, a forced move in Design Space.
Perfection will be independently hit upon again and again, especially if it is
obvious. It is the idiosyncratic versions of near-perfection that are a dead
giveaway of copying. In evolutionary theory, such traits are called homologies:
traits that are similar not because they have to be for functional
reasons, but because of copying. The biologist Mark Ridley observes, "Many
of what are often presented as separate arguments for evolution reduce to the
general form of the argument from homology," and he boils the argument
down to its essence:
The ear-bones of mammals are an example of a homology. They are homologous
with some of the jaw-bones of reptiles. The ear-bones of mammals
did not have to be formed from the same bones as form the jaw of
reptiles; but in fact they are __The fact that species share homologies is
an argument for evolution, for if they had been created separately there
would be no reason why [emphasis added] they should show homologous
similarities. [Mark Ridley 1985, p. 9]
This is how it is in the biosphere, and also how it is in the cultural sphere of
plagiarism, industrial espionage, and the honest work of recension of texts.
Here is a curious historical coincidence: while Darwin was fighting his
way clear to an understanding of this characteristically Darwinian mode of
inference, some of his fellow Victorians, in England and especially in Ger-
many, had already perfected the same bold, ingenious strategy of historical
inference in the domain of paleography or philology. I have several times
alluded to the works of Plato in this book, but it is "a miracle" that Plato's
work survives for us to read today in any version at all. All the texts of his
Dialogues were essentially lost for over a thousand years. When they reemerged
at the dawn of the Renaissance in the form of various tattered,
dubious, partial copies of copies of copies from who knows where, this set in
motion five hundred years of painstaking scholarship, intended to "purify the
text" and establish a proper informational link with the original sources,
which of course would have been in Plato's own hand, or the hand of the
scribe to whom he dictated. The originals had presumably long since turned
to dust. (Today there are some fragments of papyrus with Platonic text on
them, and these bits of text may be roughly contemporaneous with Plato
himself, but they have played no important role in the scholarship, having
been uncovered quite recently.)
The task that faced the scholars was daunting. There were obviously many
"corruptions" in the various nonextinct copies (called "witnesses"), and these
corruptions or errors had to be fixed, but there were also many puzzling—or
exciting—passages of dubious authenticity, and no way of asking the author
which were which. How could they be properly distinguished? The
corruptions could be more or less rank-ordered in obviousness: (1)
typographical errors, (2) grammatical errors, (3) stupid or otherwise baffling
expressions, or ( 4 ) bits that were just not stylistically or doctrinally like the
rest of Plato. By Darwin's day, the philologists who devoted their entire
professional lives to re-creating the genealogy of their witnesses had not only
developed elaborate and—for their day—rigorous methods of comparison,
but had succeeded in extrapolating whole lineages of copies of copies, and
deduced many curious facts about the historical circumstances of their birth,
reproduction, and eventual death. By an analysis of the patterns of shared and
unshared errors in the existing documents (the carefully preserved parchment
treasures in the Bodleian Library at Oxford, in Paris, in the Vienna
Nationalbibliothek, in the Vatican, and elsewhere), they were able to deduce
hypotheses about how many different copyings there had to have been,
roughly when and where some of these must have been made, and which
witnesses had relatively recent shared ancestors and which did not.
Sometimes the deductive boldness of their work is the equal of anything in
Darwin: a particular group of manuscript errors, uncorrected and re-copied in
all the descendants in a particular lineage, was almost certainly due to the
fact that the scribe who took the dictation did not pronounce Greek the same
way the reader did, and consequently misheard a particular phoneme on
many occasions! Such clues, together with evidence from other sources on
the history of the Greek language, might even suggest to the scholars which
monastery, on which Greek island or mountaintop, in