Niles Eldredge - The Darwin Blogs

The Darwin Blogs – June 12, 2006.

A Tale of Two Charles’: Lyell’s Influence on Darwin.

Charles Lyell richly deserves the credit he has garnered over the years for influencing the young Charles Darwin so deeply. Lyell, of course, is the one who developed the modern science of geology by shaping, applying and extending James Hutton’s concept of “uniformitarianism” into a recipe for deciphering and understanding the sequence of historical events that have shaped the earth through geological time.

Darwin’s first scientific goal was to become a geologist; later in life, in his Autobiography, Darwin made it clear that he still thought of himself primarily as a geologist. His first scientific paper when he arrived back in England in 1836, after nearly five years voyaging around the world on the Beagle, was on the step-by-step uplift of the Andes: Darwin had experienced a severe earthquake while in Chile in early 1835, and realized that it was through a long series of such abrupt shocks that the Andes had risen from the ocean floor.

But it is Lyell’s impact on the genesis and development of Darwin’s ideas on biological evolution that have captured most of the interest in Lyell’s influence on the young Darwin’s mind. Darwin’s insistence—at least by the time he published his On the Origin of Species in 1859 (over twenty years after he first harbored the conviction that life had evolved)—that life evolves slowly and gradually, has always struck historians as the perfect mirror of Lyell’s insistence that changes in the earth through time are likewise slow, steady and gradual: however joltingly abrupt any earthquake may be, it takes a lot of them regularly interspersed through lots of geological time to make a mountain chain out of a seafloor.

On the Beagle voyage Darwin hit the geological ground running: at the very first stop—the volcanic island of St. Jago in the Atlantic—Darwin found upraised sediments bearing the young fossils shells of species of mollusks still living, judging form their fresh shells cast up onto the beach. Darwin’s one week sojourn with the Reverend Adam Sedgwick, Professor of Geology at Cambridge, had taught him the ropes of deciphering the stratigraphic sequence of layered sedimentary rocks in a region. He had the sense that earth history is both intelligible and dynamic: careful observation allows you to figure out the sequence of events that determined the deposition, hardening and eventual uplift of sedimentary rocks. Darwin learned that the earth has had an active history—and it is no huge surprise that he eventually applied that percept to the fossils he was digging out of some of the sedimentary layers he encountered on his journey.

Important as Darwin’s field experience with Sedgwick proved to be, Darwin had another source for his geological education—albeit somewhat less direct: he had Lyell’s three volumes of the Principles of Geology with him on the Beagle. Lyell published his first volume in 1830; I have held in my hands the copy that was given to Darwin just before the Beagle left England in the final days of December, 1831. The pencil inscription on the fly-leaf reads “Gift of Capt. Fitz-Roy.” Volumes 2 (1832) and 3 (1833) reached Darwin on the voyage; they were sent by his mentor the Reverend John Stevens Henslow, who had told Darwin not to believe every word that Lyell had written.

I had long heard that Volume 2 of Lyell’s Principles was a diatribe against evolution (or “transmutationism” as it was then commonly called)—especially the version of evolution espoused by the French naturalist Lamarck. But I hadn’t really read the Principles until recently, when curiosity finally got the better of me.

I bought James Secord’s abridged version (Penguin Classics, 1997) of all three volumes on Amazon (it’s really cheap in paperback!). I skimmed through Volume 1—anxious as I was to get to the evolution part. In a sense, Lyell does not disappoint: for here, in Volume 2, was a ringingly clear exposition of the failings of those poor misguided naturalists—chief among them M. Lamarck—who dared suggest that the diversity of life on earth reflects the outcome of a long process of evolution.

Lyell sounds much like a modern creationist when he flings down the gauntlet, saying, for example, that Lamarck’s theory never really touches on the origin of completely new organs. And he has an easy time poking holes in Lamarck’s suggested mechanism of evolution: “use and disuse” or the inheritance of acquired characteristics.

I found myself growing deeply annoyed with Lyell—just as I do with a modern creationist. I reminded myself that Lyell was originally a barrister—and I found myself thinking that I was actually reading a lawyer’s brief arguing against an opponent’s position—rather than an original scientific argument in favor of something. Secord’s introduction helped me out—though it only confirmed my worst feelings on Lyell’s text: according to Secord, Lyell was hoping to get a Chair in geology at King’s College; one of the “electors” was the Dean of St Paul’s—who had said that geologists “undermined beliefs concerning the creation of man and the reality of a universal Deluge” (Secord, 1997, p. xxxii). Legal brief indeed! Lyell was looking for work.

I hated to feel this way about Lyell. The man had, after all, founded the modern science of geology—the field in which I hold my own Ph. D. But there it was.

In particular, I felt that Lyell was not dealing out all the cards in his hand. Lyell talked openly about extinction of species—and the fact that new species appear, in a very real sense, to take their place. He estimated that, the world over, on land and sea, on average one species goes extinct each year. And one species comes along to takes its place—also, on average, once a year.

Darwin’s Beagle notes—and all of his later writings—makes it clear that Darwin saw extinction, and replacement, of species—though he questions Lyell’s intransigent uniformitarianism of one species loss/creation per year. But Darwin saw these replacements in what we would now called a phylogenetic sense. What got to Darwin first and foremost was that new species seemed to belong to the same group as the extinct species: he saw modern armadillos (there are nine species alive in South America) as replacements for the giant extinct armadillos (“glyptodonts”) he was collecting in early 1832—only a few months after the Beagle had left England.

Not so Lyell. I was angry at Lyell for not seeing/stressing this point (a great argument in favor of transmutationism—thus I felt as I read that Lyell was deliberately holding back in his anti-evolution polemic!). Rather, Lyell said that replacements of species was dictated (in the orderly mind of the Creator) by other considerations: the Creator, for example, could hardly create a new species of carnivore unless the appropriate prey species was already created!

But this story has a happy ending after all. I was delighted when I started reading Lyell’s discussions on the causes of extinctions. He sees that whole biotas can be overwhelmed by physical environmental change. He sees that some species, faced with environmental change, can move and find familiar habitat elsewhere—and thus for awhile evade the scythe of extinction. This is the “habitat tracking” I have been stressing so much these last twenty years. I never thought that I was the first to have thought it up—but few if any evolutionary biologists to my knowledge have been discussing habitat tracking in the past sixty years or so.

So I was delighted to find Lyell speaking in these terms. Lyell might have been an anti-evolution polemicist looking for a job when he wrote Volume 2 of his Principles. But he is also one of history’s first ecologists. He was a better ecologist than Darwin ever was—and the disconnect between Lyell and Darwin on the subject of evolution in part reflects the simple fact that Lyell thought of the world differently than did Darwin.

To this day, ecology and evolution have yet to be fully integrated. Lyell and Darwin together form a dialectic that demands closer scrutiny!

Niles Eldredge

Previous Blog ::: Blog Index (main) ::: Next Blog