A couple of hours ago, I finally finished reading Dov Ospovat’s The Development Of Darwin’s Theory: Natural History, Natural Theology, and Natural Selection, 1838-1859.
I had blogged about this book some weeks ago saying anyone reading The Origin Of Species will be struck by several paragraphs where Darwin describes painstaking experiments he carried out seeking answers to questions that were puzzling him – similar vegetation on far-flung seashores, how did the seeds get there? Or, how did poorly mobile species like snails, etc, manage to spread across the world?
These experiments were largely conducted in the 18 years that passed between Darwin getting off the Beagle and the publication of The Origin Of Species. Which basically suggests that in this period, Darwin was hard at work chasing down hypotheses, testing and proving/disproving them, working on his theory.
And what Dov Ospovat has done, in this book that he finished just before he died at 33, is reconstruct, well, the evolution of Darwin’s theory during that 18 year period.
It has been a mesmerising read. It’s not often that one gets to read about how ideas take shape. And the way the theory of evolution took root in Darwin’s head itself is fascinating.
Why? Because when Darwin left England on the Beagle in 1831, he believed that each species had been independently created with characteristics that suit it admirably for the conditions under which it was destined to live. This was the teleological explanation, which held sway in the mid-nineteenth century. This believed in perfect adaptation. It held that organisms are created, either directly or indirectly, by God. (Cuvier, Paley)
By the time Darwin got off the Beagle, many of the young naturalists were starting to reject the teleological explanation. However, even those who shifted away from teleology continued to believe in perfect adaptation. They too believed that organisms are created by God. But where the teleologists attributed the perfection of organisms to their having been specially adapted for particular conditions of existence, those who rejected the teleological explanation said the perfection of species was the result of harmonious laws established by the creator to achieve his purposes. (Owen, Martin Barry, Bridgewater Treatises, Geoffrey St Hilaire, Carpenter, Whewell)
Similarly, when he wrote the “Essay of 1844” where he put down his evolving thoughts on evolution, this is what Darwin thought as well. He believed that, in general, species are perfectly adapted by God for their conditions of life. This was, admittedly, a different notion of perfect adaptation from what Cuvier and others preached. Darwin and others challenged the notion that there is one form that is better than all others and that is what is chosen by God by pointing at things like vestigial organs, etc. Theirs was the doctrine of limited perfection. Organisms are created by laws and they are only as perfect as they can be within the limits set by the necessity of conforming to these laws. And that organisms are formed with reference to the law of unity of type or of heredity, etc.
He also believed in harmony. That the number of species would remain constant. And that perfectly adapted forms do not vary. That organic change occurs only in response to environmental change.
In the intervening 18 years, his thoughts on all of this changed. He moved from perfect adaptation to relative adaptation. And from a view of nature built around harmony to one built around struggle. As Ospovat writes:
“Rather than a single decisive break we find numerous shifts in emphasis, some obvious, others subtle. In 1844, Darwin supposed that change in the organic world is inherently intermittent; in Natural Selection, he implied that it is potentially – but probably not actually – continuous. In 1844, he supposed that inorganic conditions are the principal determinants of structure; by 1856 he considered them less important than organic conditions. When he wrote the “Essay of 1844”, Darwin assumed that variation occurs only as a result of environmental change; in Natural Selection he assumed it is always occuring because conditions never remain absolutely unchanged. In 1844, an increase in food is allowed to be perhaps a minor cause of variation; in Natural Selection it is said to be an important cause; and by 1868 Darwin called it probably the single most powerful cause… In the “Essay of 1844”, natural selection is supposed to produce perfect adaptation; in Natural Selection it produces forms only as perfect as their competitors. In 1844, Darwin saw nature as a system of inorganic change and organic response; in Natural Selection he saw everywhere organic change and reaction.”
The question is how these changes in his thinking came about. According to Ospovat, these emerged, after 1844, out of “Darwin’s complex, creative response to the thought of the leading naturalists of his day.” Indeed, scientific history too is written by the victors. Darwin has come to appropriate the centrestage in our understanding of how the theory of evolution came about. People like Alfred Russell Wallace, who independently thought up the theory of natural selection while struck down by malaria while collecting specimens and sent the paper he wrote up to Darwin at a time when the latter was still working on his theory have not received their due.
Nor have countless others. How many of the names in the brackets, for instance, can you recognise? Richard Owen, for instance, one of the greatest paleontologists the world has ever seen and the man who set up the Natural History Museum in London, was almost written off as someone who did little more than challenge Darwin. (Only in the 1970s did his rehabilitation start. For a more recent book, see Nicolaas Rupke’s Richard Owen: Biology Without Darwin).
This is one thing that Dov wanted to correct in this book. He wanted to, as Adrian Desmond writes in the foreword, “make Darwin less of a seer, standing out of time, and more a man of his day”.
It is a point that is driven home very successfully. But that said, what makes the book special for me is its detailing of the process through which the idea of evolution came about.
For instance, Lyell, who wrote the Principles Of Geology, the book that so influenced Darwin while he was aboard the Beagle, “argued that the history of the earth is cyclical and when the current cycle of an earlier geological cycle returns, then Iguanadons, Icthyosaurs and Pterodactyls, which were perfectly suited to the ancient climate, will again inhabit the earth. This was the teleological explanation for succession. This also meant that organisms were primarily adapted for inorganic landscape, not to other species around them… This was opposed by Carpenter, Owen and Louis Agassiz, among others. They did think that external conditions were designed with the organic world in mind, but felt that external conditions at any period, though known beforehand by God, were the product of geological forces and laws, not of special adaptation to the living things then or about to be in existence.”
Or take Owen. For him, “There was no strict relationship between external conditions and organic form. He believed that the structure of successively appearing organisms was determined not only by the conditions to which they must be adapted, but also by biological laws, such as unity of type and the law of the succession of the same type in every country. He supposed that new forms were related not only to conditions, but also to their predecessors.”
This, incidentally, qualifies as a real, breakthrough insight. He had identified some of the processes at work!
There are several things that strike me here. First, I cannot but marvel at these hypotheses, all trying to explain what the age of exploration was telling naturalists about species, their distribution, etc. There is an earnest, groping quality to so many of these as they try and make explain the world using the limited information with them.
Or try this. “The problem with advancing such thoughts (challenging perfect adaptation) is they seemed to support transmutation – species changing into another. And naturalists like Owen, Carpenter and Agassiz were anxious to explain that they did not see their viewpoint as tending to denigrate God’s power or to minimise his influence in the creation. Some, like Agassiz held that ‘biologists contribute most effectively to natural theology not by discovering more examples of the adaptation of structure to function and organism to environment, but rather by discovering the laws that constitute the creator’s plan’.
This is how ideas evolve. In the short term at least, the new ideas we get are strongly determined by the ideas we already have. Only if we plug away long enough, and only if we question our assumptions rigorously, might we end up with radically different ideas from what we started out with. Remember, Darwin started with assumptions about harmony and a benevolent creator. It took him 18 years to so utterly recast his views.
But that is also what makes Darwin such a remarkable scientist. He was smart, knew enough to challenge his assumptions, and above all tenacious. Not to mention a keen monitor of how ideas on evolution were, again, evolving and he tried to explain them through his theory.
For a journalist, there are salutary lessons in all of this. We too develop hypotheses in the absence of enough data. And what we resultedly end up with are hypotheses that fare as poorly as MacLeay’s Quinarianism. And we certainly keep writing on the same things over and over again (banking correspondents, financial inclusion, microfinance, yah da, yah da) for the new (story) ideas we get are strongly determined by the ideas we already have.
Anyway. That is how it goes. I should shower and cook now. I am heading out on a long field trip soon and am wondering which books to carry. I think I should get deeper into this fascinating epoch and read Desmond’s Archetypes and Ancestors next. Should be fun.
(A modified version of this review has also been posted on Anomalocaris, my blog for ET)