Niles Eldredge - The Darwin Blogs

The Darwin Blogs – October 20, 2006.

Mr. Darwin's Comments on My Answers—and some news.

Oct. 20, 2006

My Dear Eldredge:

I really do not know quite how to respond to the contents of your previous letter. On the one hand, I am grateful for your having taken the trouble to provide such a detailed response to my four queries and statements regarding such issues of species stability (what you—or, I gather, rather your colleague Gould, decided to term "stasis" when you collaborated with him to follow-up on your own initial announcement of "punctuated equilibria"—yet another Gould term as I understand it). I was also concerned with the importance of isolation; whether or not new species always arise by gradual degree; and what my own personal feelings were on the subject of what are now termed "turnovers"—the putative connection between extinction and subsequent bursts of evolutionary change.

On the other hand, I must admit to a degree of exasperation, nay even ire, at being harangued in such a near-belligerent manner. My dear Sir, I am (or at least I was) a human being. In my lifetime I suffered constant assaults from insults thinly disguised as intellectual criticism. I must also say that your American informality (e.g. in addressing me as "Charles"—only my parents, siblings and deepest friends ever addressed me thus) rankles a bit as well—especially when its pretense of friendship veils what strikes me as open disdain for my work. We will need to progress much further in our digital relationship before I shall be comfortable with you addressing me as "Charles"—or before I shall myself feel at ease in calling you "Niles."

That said, I must say I did not find your comments without interest. I had quite forgotten, for example, that I had ever scribbled that sentence that you say my son Francis found in the "fair copy" of my 1844 Essay—the Essay I had set aside for my wife Emma to see through publication in the event of my death. I must have been momentarily troubled afresh by the writings of certain geologists who insisted that extinction occurs in "batches," as it were—with new species arising to take their place—a view, as you correctly state, that takes its origin at least as far back as the writings of the (admittedly great!) Cuvier. And I confess that, regarding things from your vantage point, neither stasis nor turnovers (à la Cuvier) in fact do necessitate abandoning my theory—as you yourself have argued so strenuously.

But I do not appreciate being reminded of that horrid man Wagner, who like a ratting terrier had a stranglehold on the notion of isolation such that he simply would not let go. Sometimes the only way to deal with such a vexatious correspondent as he is simply to turn one's metaphorical back on the man. (Indeed I confess that it did occur to me to do likewise with you upon first reading your last missive—but our correspondence has not proceeded at great enough length for me to conclude that we shall always be hopelessly at odds with one another over our entrenched Views).

On a related matter, my dear Eldredge, I was surprised at something you did NOT mention about my early views: the fact that I, when first openly speculating about the causes of transmutation (in my Red Notebook, completed—as some historians I gather have accurately surmised—after my arrival home in England) was imagining) transmutation to proceed per saltum. (How ironic that my friend and colleague later in life—Thomas Henry Huxley—should have taken me to task for clinging to the old adage "Natura non fecit saltum"—Nature does not take leaps—so unreservedly; he had no way of knowing of my earliest—so unreservedly saltationist—thoughts on transmutation).

This is the more remarkable in that I have seen, in internet articles, how you and Gould were often castigated as "saltationists" yourselves—especially in the early days of battle over your "punctuated equilibria." Were you not struck by my own overt adoption—again, only in MY earliest notes on transmutational causes—of saltationist views? Why not castigate ME for not "sticking to my guns" (a phrase that dates from my days, but I believe is still in use today?).

We shall, no doubt, return to these matters. I confess I find them more interesting than annoying—once the initial shock of such unmitigated criticism passed, and I could bring myself to consider the ideas you broached simply on their own merits.

And I must further say that the paper published by the British geneticist Mark Pagel in Science a few weeks ago now does have the effect of adding convincing results from another domain (the so-called "molecular" level) that seem to bear directly on your thesis that most evolutionary change occurs in conjunction with "speciation" events—i.e. when species divide (through some form of isolation, no doubt)—when in particular new species "bud off" (as you say—I rather like the botanical analogy!) as relatively small isolated populations and go their own separate evolutionary ways. Do I have it right that, were it possible to distinguish between so-called "coding" and "non-coding" changes, a person such as yourself, with your convictions, would expect that the coding changes—those that show up in what I gather is now termed the "phenotype"—will be disproportionately concentrated at the "nodes"—the speciation events? The coding genes would thereby simultaneously be shown to be for the greatest part in stasis during the history of species; and the lack of stasis that Pagel and his team found would thus be explained by the fact that non-coding genes are "neutral"—i.e. invisible to natural selection—and thus open to drift where they may during the lifetime of a species. Am I correct is assuming this—perhaps my first evolutionary hypothesis since returning via the internet ether?

And I must say, as a final comment, that I rather enjoy returning to my very early thoughts that species are like individual organisms. If we can look to natural causes to explain the births and deaths of individuals—including of course human beings; and if (as was common by the time I set sail on the Beagle) we can acknowledge that the extinctions of species occur through natural causes; why not then the births of species as well (as indeed I reasoned as far back as when I was on the Beagle). I had more or less abandoned that line of thought in my later years—though I am anxious to hear your views on some aspects of my "Principle of Divergence"—which does pertain to these issues.

I find my good humour restored simplyin writing these words whilst considering the ideas themselves. That was always the best for me—pure contemplation of Nature the better to understand Her deeper workings. Very Calming, very Engrossing, and how often so very Rewarding!

For the next week or two, I shall remain silent—as I have much to consider from what has occurred already. And I shall be making a private exploration that will occupy my time considerably for the next few instants.

Forgive my initial ill temper. But pardon me also, my dear Eldredge, for not saluting you as "Niles"—nor for signing myself simply as Charles. The habits of a lifetime intrude too deeply, even despite my loss of momentary dyspepsia.

Your correspondent

Charles R. Darwin

My reply was brief:

Oct. 23, 2006

Dear Charles Darwin:

I was appalled to hear from you that my enthusiasm in explaining how my ideas in evolutionary biology have departed at least from some of your own (at least in the form that your own views have actually come down to us) caused you dismay. The very worst thing that could possibly happen would be that I would abuse your kindness in corresponding with me—in the very rude (as I now see it) effort to show that in some points you were wrong and I am right! I apologize, profusely, for any annoyance that I have caused you. And I am vastly relieved that your sheer infectious enthusiasm for considering the works of nature—especially of the evolutionary process—has evidently won out over your initial "dyspepsia" over my last letter.

Well and good. I think for the moment we should leave the scientific issues for another day—beyond my simply saying that I am very impressed with your grasp of the further implications of the Pagel paper. I do expect that most genetic changes involving coding elements will eventually be shown to be concentrated at speciation events (and subsequently in stasis for most of a species' subsequent history)—the non-coding elements producing all the drift, and apparent non-stasis reported by Pagel et al. We shall see what further news such lines of investigation hold in store—but meanwhile kudos to you for having that same old flair for devising intriguing evolutionary hypotheses—now brought very much up-to-date!

You are of course entirely right about your early enthusiasm for saltationism; in my book Darwin. Discovering the Tree of Life (Norton, 2005), I wrote that I nearly had fallen off the very chair on which I am now sitting when I first encountered your words to this effect in the Red Notebook. And you are also of course correct when you say that, at least in your early days (including notes written while you were only partly throughyourBeaglevoyage), you were indeed struck with the analogy between the births and deaths of individuals and those of species. I trust that we will discuss both these issues in greater detail in later correspondence!

I also draw your attention to the news items immediately following this brief reply. It seems that turnovers among Tertiary mammals are not only well-corroborated as basic evolutionary pattern—but in the view of the authors of the paper just published in Nature, apparently correlated with/caused by astronomical periodicities that affect the earth's climate. More food for thought!

I look forward to hearing about your impending explorations, Mr. Darwin—and hope that you shall share your experiences in a future letter. Meanwhile (and again, as briefly noted under "news" below) I shall myself be traveling in your absence.

With all my heartfelt admiration for all you have done for humanity—and for your kindness in writing to me at this website.

Yours,

Niles Eldredge

Some news: As briefly mentioned in my reply to Charles Darwin immediately above, I was delighted to see yet another important publication bearing on the evolutionary issues at hand—this time published by my colleague, the paleontologist Jan van Dam at the University of Utrecht in the Netherlands, and his colleagues, in the journal Nature ("Long-period astronomical forcing of mammal turnover." Nature 443: 687-691, Oct. 12, 2006).

The study focuses on rodent evolutionary patterns in central Spain—and covers the period between 24.5 and 2.5 million years ago. The authors find turnovers in periods of 2.4-2.5 million years, and 1 million years—linked to variations in the Milankovitch cycles (which are caused by the combined effects of earth's tilt, distance from the sun in winter and summer, etc.). The study is very exciting as it corroborates the idea that there ARE turnovers in mammalian evolution (I believe turnovers are absolutely characteristic of the evolutionary history of all of life for at least the last ½ billion years). And their conclusion that astronomical cycles underlying global climate change are the root cause of such turnovers confirms the initial work of paleontologist Elisabeth Vrba—who coined the term "turnovers" in the first place, based on her studies of African mammal evolution. That such turnovers are quite possibly periodic in their nature revives an old idea about periodicity in evolution that was rejected more than a generation ago—adding even more fun to the mix! Congratulations to Jan van Dam and his colleagues for producing such an important study!

Also, two weeks ago our Darwin exhibition (now back up and running to great acclaim at The Franklin Institute in Philadelphia) won an award from the Archivists Round Table of Metropolitan New York for its use of archives (the letters! the manuscripts! the books!—plus everything else—as museum specimens of fossils and living species are also archives!). The Award was presented by Barbara Mathe from the American Museum's library staff—who took note, I am delighted to say, of these very Darwin Blogs—and pointed especially to Darwin's comment (in one of his recent letters to this website) to the effect that emails are the bane of historians—but that, conversely, the reason he remains so prominent in the affairs of the modern world is precisely that he left so many letters for historians to pore over! Thank you ARTS and Barbara!

Finally, while Darwin goes who knows where to check up on things, I shall be in Italy. First off, it’s the Pio Manzù conference in Rimini—named "Life in the Balance" after my book of the very same title. I’ll be speaking about the present day Biodiversity Crisis—and also receiving an award from the Italian government. After a few days back in Milano (including a visit to my favorite restaurant in the entire world—Tagiura), it's on to Genoa and Festival della Scienza for the first meeting of our new Research Group on Hierarchy Theory and a symposium on the same subject to be presented to those attending the Festival. I am really looking forward to these events—and will be posting their results in these blogs when I get back in early November.

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