Niles Eldredge - The Darwin Blogs

The Darwin Blogs – January 18, 2007.

Galapagos Blog

January 12, 2007

My DearEldredge—

My salutations to you for the New Year.

I write to enquire whether your plans to visit the Galapagos Islands are still in place. I truly hope so, as I am as anxious to see through your eyes the Islands as they now exist as you appear to be to have my advice on what to look for whilst you are there.

As you know, I was there for some 5 weeks or so—from Sept. 15-Oct. 20, 1835. This period, of course, came rather late in the nearly five year course of the Beagle's journey—and I suppose it fair to say that I had become by then a considerably more confident, and perhaps more skilled, naturalist through all my labours in South America preceding our arrival, than I had been when first we set sail in latest December 1831.

Having already encountered, time and again, a common phenomenon—viz. the fauna and flora on islands just off the coast of South America oft-times including distinct species which nevertheless bear a peculiarly American aspect, I was to some extent prepared to observe similar phenomena on the Galapagos Islands. Nor was I disappointed in this regard—the Galapagos flycatchers, mockingbirds etc etc, for example, are in general native to the Americas. Yet—and again, unsurprisingly given my experiences up to that time on other islands—the species seemed quite distinct from those closely allied forms I had observed previously on the South American mainland.

Indeed, though, I was not prepared to find so high a proportion of the plant and animal species I observed while there (and collected and had studied by various experts in England after my arrival home a year later) to be peculiar to those islands—as if created there. Indeed, some plants and animals (for example, the land and marine iguana species—like iguanas found nowhere else) seemed to bespeak a profound separation from their natal stocks of the mainland. And yet, as I wrote in my notes and in my Journal of Researches (my first book—soon to be called by its informal name The Voyage of the Beagle) the volcanic islands of the Galapagos appeared to me to be rather young geologically (a point, I believe, that has been confirmed by subsequent geological researches). But, then again, the Galapagos Islands lie some 600 miles from the South American coast—far further removed from the mainland than any islands I had previously visited on my journey thus far.

I was also astounded that, notwithstanding the position of the islands directly over the Equator, the aspect of each island was notably bleak. No profusion of tropical greenery here! The volcanic rocks of course accounted for much of the barrenness—especially in parts where lava had recently flowed. But the plants themselves—mostly stunted bushes and a variety of weedy-looking productions—contributed to the barren aspect of the islands—as at first glance they appeared to be like trees in my homeland in wintertime—devoid of leaves (and, of course, flowers). It was only after being there several days that I came to realize that the plants were in fact in full leaf—and many were in full bloom! Their leaves and flowers being of such modest size, I had initially failed to observe them. Only the Opuntia cactus—favoured food of the giant tortoises and (especially their flowers) of the terrestrial iguana, provided a consistently green appearance that we quite naturally expect of plant life!

But my prior experience left me unprepared to discover that the species on each island were often quite distinct from those on other islands—in some cases islands so close that they were in sight of one another. It was very much as if the Galapagos records in microcosm the story with which I was already so familiar—the differentiation of species on islands from those on the mainland. Here, in the Galapagos, that phenomenon (as I have said) was immediately and abundantly evident. What I almost failed to notice, however, was this smaller-scale pattern of differences between the islands themselves. As it was, my failure to collect assiduously especially the animals of each separate island we visited during our brief stay became my greatest regret of the entire 5 year voyage.

To my great good fortune, however, I had taken notice of the mocking-birds (a term I learned from Mr. Gould when I returned home—birds I had called Thenca while on the Beagle—having seen similar species on the South American mainland). Mocking-birds are bold birds, unafraid of humans (true, of course, of virtually all birds on these islands—but true of mocking-birds wherever found in the Americas)—thus rather easily observed and captured. I concluded while there that there are three species of mocking-birds present—with distinct forms especially to be seen on the southern-most islands of the archipelago. I was unsure whether they represented simple varieties, or perhaps fully distinct species; upon my return, Mr. Gould confirmed their status as fully distinct species. As you well know, my speculations on these birds in my notes written near the end of the journey (i.e. many months after leaving the Galapagos) was my most overtly "transmutational" thought I allowed myself to record in my notes while still aboard ship (I had carefully avoided committing such speculations to paper, as Capt. FitzRoy had the authority to read all diaries and notes recorded during the voyage; indeed, he did ask to read a portion of my diary early on in the trip—to my relief and satisfaction pronouncing them excellent and worthy of publication!).

On Charles Island (Floreana as it is now apparently usually called), the governor of the penal colony remarked that he could easily tell from the slight differences of shape of the carapace the island that any particular tortoise came from. Though I paid little attention to the remark at that point, by voyage's end, when reflecting on the differences between the mocking-birds on the various islands, I considered the tortoises as possibly constituting a further example; and I remembered that I had detected in the fox native to the Falkland Islands some slight differences between the individuals on North and South Falkland Islands. A general phenomenon seemed to emerge—and thus my remark to the effect that, if such observations could be confirmed to be generally true (i.e. with further examples recorded on archipelagoes elsewhere around the world), they would undermine the doctrine of the stability of species.

So I had not missed the phenomenon of inter-island variation completely. Mr. Gould, of course (and quite famously—my face is still, albeit metaphorically, red over this!) pronounced the entire panoply of those vexatious little black and greenish birds, as constituting a group of closely allied species of finches derived from a single common stock—not long after I arrived home and placed my bird specimens in his hands. And later, when Dr. Hooker had the opportunity to study my plant collections from the Galapagos, the plants abundantly confirmed the pattern first glimpsed with the mocking-birds. So many species are confined to single islands that the plants provide the very best examples of inter-island differentiation into peculiar varieties and species.

Enough. Of course I am curious to hear of other examples no doubt recorded by naturalists who have come after me to these "Islas Encantadas." I predict that what I saw myself pertaining to the mocking-birds—and later seen by Gould for the finches, Hooker for the plants—will have been seen time and again in virtually all the other groups. I am reasonably certain, as well, that others will have recorded many other examples from archipelagoes the world over (Indeed, that was already well under way during my own lifetime).

And I am concerned to hear of current state of these delicate productions—these trusting species of birds, these species of plants eking out an existence in these bleak rocky islands. As you are aware, I have encountered on the internet ether some ominous accounts of the current state of the Galapagos and its native flora and fauna. I do hope that you might relieve some of my growing anxiety over these matters.

My dear Eldredge, I frankly envy you your opportunity to observe first hand the Galapagos Islands as they exist today. I eagerly await your account of your current travels there!

Yours most sincerely,

Ch. Darwin

Floreana Island, The Galapagos—January 18, 2007

Dear Charles Darwin:

Greetings, my dear Sir, from the Island of Floreana—the very place where the Governor first told you how different the tortoises are on each of the islands.

We are here at the very onset of the rainy season—somewhat uncomfortable and inconvenient for human visitors, but a welcome relief for the inhabitants of these islands, as there has been very little rain for the past several years. There is some thought that the present rain—a true deluge this morning that knocked out our satellite-fed internet service—is a reflection of the El Niño phenomenon.

And of course we are here in relative comfort—luxury, really—when compared with the circumstances you faced in your cramped living quarters aboard the Beagle. Hot and cold running water, indoor lighting and plumbing—all the appurtenances of modern life. Email allowing me to blog directly from this remote spot. And even Powerpoint for our lectures: I am here with the noted Darwin historian Dr. David Kohn—with whom I have been delivering a series of lectures about you—your life and work, using images of the American Museum's exhibition Darwin. Our audience consists of some 27 travelers on a special American Museum program that takes us to nearly all the islands on the Galapagos archipelago—including many not on the usual tourist route. And though we are visiting these islands in a different order than you followed on your visit, nonetheless we will be seeing most of the places you stopped at—and many more.

Your visit was indeed brief—and in an interesting way rather incomplete, for you did not report seeing the native penguin nor flamingoes—both of which can be seen a mere mile away from one another here at Floreana. Imagine that! No bird more symbolizes the tropics than do flamingoes, nor do any birds symbolize the frozen high latitudes (i.e. of the southern hemisphere) than penguins. And yet here both are, within a mile of one another. For the sun is hot, but the waters washing the shores of the Galapagos are often quite cold—when the Humboldt current is dominating conditions here. (There are several currents—cold and hot—converging here, dominating the climate—and accounting for the scarcity of rain, hence the bleak look to the islands that you mention in your letter).

Our trip is all about you and your ideas—or at least, so it seems to me. I remain obsessed by what I think of as the logic underlying your coming to transmutationalism; and of course the Galapagos remain in nearly everyone's mind the linchpin of your early thoughts on evolution. That you were already pretty much there as a result of your earlier experiences on mainland South America remains a conviction of mine; certainly there is no doubt that your prior experiences—as you in part have mentioned in your letter, gave you what we call these days a "prepared mind" for what you were to see on the Galapagos. Though of course you are right to say that you almost missed the most important point of all—that species differ from island to island—in many cases to the point where skilled systematists, following in the footsteps of your ornithologist, Mr. Gould—classify them as distinct species on the islands.

Modern ornithologists recognize five species of mockingbirds (though the Charles mockingbird of Floreana is nearly extinct—surviving on only two small islands of the coast of the main island). And you are of course correct when you say that naturalists coming to these islands after you have documented many more such examples of closely related, yet distinct, species living on different islands. We ourselves have already seen distinct species of lava lizards living on different islands (so far in the past three days we have visited North Seymour Island; Española (known to you as Hood Island—your first sighting of the Galapagos). This island is home to a breeding population of Waved Albatross and other splendors; and today Floreana (formerly Charles, and also known as Santa Maria).

It is an absolute thrill to walk in your footsteps, to see what you saw, and to see and learn more than was accessible to you so long ago. But is doesn't take much experience here to see, hear and feel that you were absolutely right in your basic take on the structure of biological variation within and between these islands. And you managed to get it basically right without knowing anything whatsoever about those (as you say) "vexatious" Darwin's finches!

One more thing in this report of progress so far: we spent a day traveling from Quito to Antisana National Park—at one point reaching an altitude of 13,000' (respect again to you for going by pack train through the Portillo Pass—though your youth and vigorous good health when you did that undoubtedly was a key to the evident ease with which this passage was accomplished; as a 63 year-old out-of-shape and overweight paleontologist, I have to say that the altitude was not easy for me to tolerate).

But this outing of ours to Antisana had two distinct and unexpected Darwinian themes to it: first, we saw many Bar-winged Cinclodes—oven-birds singing in the dense brush at some spots, and hopping about in plain sight in others. I remembered reading in your various zoological diaries (and later in your Red Notebook) about your accounts of these birds—replacing one another in disjunct geographic settings throughout the regions you visited while you were in mainland South America. You would note the variation you saw geographically, sometimes wondering in your notes whether or not these were varieties or separate species—the very same question you posed for the Galapagos mockingbirds later on. You learned your lessons on collecting and observation from Professor Henslow very well indeed!

Secondly, nearby the house where we had a delightful lunch, nestled in the flanks of the fog-enshrouded magnificent volcano Antisana, was a thatched hut said to be the resting place of Humboldt while he was in the vicinity exploring Antisana. Wow! I thought—Humboldt was your original inspiration to visit the tropics, and surely one of the main reasons you were so eager to accept the invitation to join in on the Beagle voyage!

So everywhere we have been we have felt your presence. Any thoughts you might have on these observations—or anything else pertaining to the Galapagos, would of course be gratefully received. Meanwhile, I shall blog soon again from these Islas Encantadas.

Professor Kohn sends his regards.

All the best,

Niles (Eldredge)

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