This will be, I think, just about the last post on Darwin’s attempt to ease his way into his subject. After all, it’s been almost a month since the birthday, and we, like Charles, must eventually come to grips with the meat of the matter. More posts from other contributors are on the way to move the matter forward.
Here I just want to draw attention to one seemingly minor transposition Darwin wrote into the introduction to The Origin. If you look into the table of contents, you see a very clear sequence of ideas: geology first, important enough to be broken into two chapters — ten and eleven — after which comes Darwin’s treatment of the importance of geography for his theory, also very important, also weighty enough to require two chapters of explication (out of a total of only fourteen).
At first glance, this seems reasonable, and in fact, it plays into something of the current furore over evolution. Many of the anti-evolutionists fix on the very problem Darwin addresses in The Origin — the imperfection of the geological record, the fact that so much of the information one could want about the change in biological form and function over time is missing from the rock record.
So, placing the geology chapters first seems to match their importance to the underlying idea Darwin is trying to advance. The theory, after all, posits a process that generates change over time — lots of time. That time is frozen into the accumulation of strata, and so an examination of what the rock record does and does not tell us would seem to take pride of place on a book considering the origin of species.
And of course, the gaps in this story told in stone were then and are now ripe fodder for those who choose not to come to grips with the theory as Darwin advanced it and subsequent work has informed and extended it. So, as we will see later in this tour through the ur-text, Darwin took pains to begin as the field would mean to go on: by emphasizing both what the geological record could not tell the patient (and honest) observer, and then what it could.
The geographical chapters that immediately follow the two geological ones seem to follow in priority too, in the sense that they return to the what will become the exhaustive (exhausting?) accumulation of facts placed in a highly structured order. Here Darwin offers a kind of answer to the broad charge of missing links in the geological record. He does so by looking at how the distribution of species in space provides one way of filling in the gaps in the historical sequence. All in all, the sequence of logic is clear: the same idea that could explain a sequence of events in time also explains the distribution of outcomes in space, thus reinforcing the argument for the truth of that underlying idea’s.
And yet…in the introduction, in Darwin’s brief summary of what is to come, he momentarily reverses this sequence. He writes on page 6:
Who can explain why one species ranges widely and is very numerous, and why another allied species has a narrow range and is rare? Yet these relations are of the highest importance, for they determine the present welfare, and, as I believe, the future success and modification of every inhabitant of this world. Still less do we know of the mutual relations of the innumerable inhabitants of the world during the many past geological epochs in its history.
Why time before space in this disarming confession of incomplete understanding? In part because Darwin’s claimed uncertainty is at least partly that useful ignorance Socrates wielded with such devastating effect. Darwin does not know why a particular species may claim a wide range or not, but he does know the form of the theory that accounts for the fact that some species do and do not wander all over the lot.
But there is more here than yet another instance of Darwin’s attempts to disarm critics before they can recognize how hard pressed their cherished assumptions have become. It is a striking fact of current creationism that you very rarely find someone in the anti-evolution game making the kind of detailed critique of evolutionary explanations for the geographical distribution of species that are commonplace amongst those who follow such pseudo fields as Flood geology or other attempts to exploit gaps in the fossil record to decry evolutionary explanations.
Why might this be so?
Because, as Darwin was certainly aware, the geographical argument was and is a truly powerful one. The question of why species are distributed the way they are is one that was recognized as significant well before Darwin, by amateurs as well as the small but growing tribe of professionals — and this at a time when the general argument that the species existed as and where they did because God created them that way. Take, for example, this stray comment in one of the classics of eighteenth century nature writing, The Natural History of Selbourne. In Letter XXIV, Gilbert White wonders:
The question you put with regard to those genera of animals that are peculiar to America, viz., how they came there and whence? is too puzzling for me to answer, and yet so obvious as often to have struck me with wonder.
White puts his finger on it there, as he so often did, as one of the best pure observers of the natural world of his day (or probably any other): how to explain the similarities and differences in the biospheres of distant regions is the question that any theory that attempts to account for the diversity of life on earth must answer. Darwin’s did, economically and powerfully by demonstrating that inherited variation combined with natural selection could produce the observered results. That theoretical understanding, now vastly enriched and deepened by 150 years advance on a whole zoo of scientific pursuits, remains amongst the hardest of nuts for critics of evolutionary thought to crack.
Darwin himself surely knew that the elegance with which his theory answered the essence of White’s awed inquiry, was one of its most powerful pillars. The plan of the book may have required that geology, with its study of change over time, precede the excitement of geography, with its exuberant display of variation over space. But at least once (actually at least twice — see page three of the introduction) Darwin allowed space to take precedence over time. To this day Darwin’s would-be opponents, fighting their battles a century and a half late, still shy away from engaging the old man, (and his heirs) on this ground.
More to come on the nitty gritty of all this when we reach chapters nine through twelve. Which is as good a cue as any to come to grips with Chapter one, which I and friends will do beginning later this week.