Darwin missed a chance

We all know that Darwin missed at least one important finding during his lifetime: the work of Gregor Mendel.  It’s unlikely that he actually knew of it, or that he would have appreciated its significance if he had (it would have solved the dilemma, pointed out by the engineer Fleeming Jenkin, that Darwin’s own theory of blending inheritance inexorably erodes the genetic variation necessary for natural selection to work), but the lack of a Darwin-Mendel conjunction is often mourned by evolutionists.  Now a trio of scholars have found another “missed opportunity” for the Sage of Downe.

In a new communication to Current Biology, Adam Hart et al. report the discovery of a letter written to Darwin by the British entomologist Albert Brydges Farn (1841-1921).  Farn lays out in his letter the evidence that color variation and change in the moth Gnophos (now Charissa) obscurata, called the “annulet,” reflected the action of natural selection.  It’s the peppered-moth story in a different species.  Had Darwin followed this up, say Hart et al., he would have apprehended a crucial piece of evidence missing from his theory: observation of natural selection in action.  Here’s Farn’s letter, sent to Darwin on November 18, 1878.

My dear Sir,
The belief that I am about to relate something which may be of interest to you, must be my excuse for troubling you with a letter.

Perhaps among the whole of the British Lepidoptera, no species varies more, according to the locality in which it is found, than does that Geometer, Gnophos obscurata. They are almost black on the New Forest peat; grey on limestone; almost white on the chalk near Lewes; and brown on clay, and on the red soil of Herefordshire.

Do these variations point to the “survival of the fittest”? I think so. It was, therefore, with some surprise that I took specimens as dark as any of those in the New Forest on a chalk slope; and I have pondered for a solution. Can this
be it?

It is a curious fact, in connexion with these dark specimens, that for the last quarter of a century the chalk slope, on which they occur, has been swept by volumes of black smoke from some lime-kilns situated at the bottom: the herbage, although growing luxuriantly, is blackened by it.

I am told, too, that the very light specimens are now much less common at Lewes than formerly, and that, for some few years, lime-kilns have been in use there.

These are the facts I desire to bring to your notice.

I am, Dear Sir, Yours very faithfully,

A. B. Farn

In fact, the idea of industrial melanism as evidence for natural selection was not explicitly suggested until 1896 (14 years after Darwin’s death) by the British entomologist James William Tutt.

There’s no evidence that Darwin answered Farn’s letter, but of course he had voluminous correspondence with hundreds of people, and it’s too much to fault the old man for failing to follow up on this one suggestion.  And even had he done so, that might not have hastened the general acceptance of natural selection, which after all was not widely embraced by evolutionists until around 1930.  Nevertheless, it’s interesting to contemplate Darwin’s reaction as he read this letter.  Did he blow it off? Or did it simply get lost in the welter of his correspondence?

Hart et al. imply that this is the one crucial missing link in Darwin’s “chain of evidence,” but of course there’s another: the fossil record.  Archaeopteryx, a transitional fossil spanning reptiles and birds, was known in Darwin’s time—and he even mentions it in a later edition of The Origin*—but he didn’t seem to have grasped its significance. However, the evidence for common ancestry that could have been provided by Archaeopteryx was also supplied by several other areas of biology, notably embryology and the study of vestigial features.

Fig. 1.  The annulet, Charissa obscurata. Looks a lot like Biston betularia, no?

*p. 367 of the fourth edition: “Until quite recently these authors might have maintained, and some have maintained, that the whole class of birds came suddenly into existence during the eocene period; but now we know, on the authority of Professor Owen, that a bird certainly lived during the deposition of the upper greensand; and still more recently, that strange bird, the Archeopteryx, with a long lizard-like tail, bearing a pair of feathers on each joint, and with its wings furnished with two free claws, has been discovered in the oolitic slates of Solenhofen. Hardly any recent discovery shows more forcibly than this how little we as yet know of the former inhabitants of the world.”

____

Hart, A. G. R. Stafford, A. L. Smith, and A. E. Goodenough. 2010. Evidence for contemporary evolution during Darwin’s lifetime. Current Biology 20:R95.

h/t: Matthew Cobb

18 thoughts on “Darwin missed a chance

  1. One might be tempted to think that Darwin had perhaps lost his ingenuity in old age, but that isn’t the case; he remained mentally active until the end. See this post for a lint to a paper discussing Darwin’s last paper published in 1882, the year he died.

  2. It is doubtful that either knowledge of Mendel or recognition of Farn’s letter, even with follow up, would have advanced the acceptance of natural selection.

    The information perhaps could have eased any conflicts that Darwin may have had in his own mind.

    1. I remember a comment by Richard Dawkins (but I can’t remember where) about how Darwin would have probably have realised the importance of Mendel’s work immediately had he known of it. The main thing missing in Darwin’s work was a good theory of inheritance, and I’m sure it bothered him immensely.

  3. I recall reading someplace that a copy of Mendels’ paper was actually found among Darwins papers but it was written in German, which Darwin was unable to read. Possibly, if had been written in French or Latin, both languages of which Darwin, like most educated Englishmen of his time was literate in, he would have appreciated the significance and the fact that inheritance is a digital rather then an analog process would have been realized 30 years earlier then it actually was.

    1. The version I’ve heard is that Mendel’s paper was found in Darwin’s library with the pages uncut. Both versions, however, are the history of science equivalent of urban legends. Darwin could read German, but there’s no evidence that Darwin ever had a copy of Mendel’s paper. Mendel, however, did read Darwin. In the Mendel exhibit that was in natural history museums a few years ago, there was one (or two?) of Darwin’s books (don’t recall which offhand– probably the Origin) with some annotations by Mendel.

      1. What is the basis of the claim that Darwin was literate in German? Most educated Englishmen of the time were literate in Latin and French (it is known that Darwin received a copy of a treatise by Lamarck from his professor at Edinburgh which was untranslated) but very few received any instruction in German which was not considered an important language at the time (circa 1830).

      2. A bit of pre-query Googling would have shown you that he could indeed read German. From Darwin: His Life and Letters:
        Much of his scientific reading was in German, and this was a great labour to him; in reading a book after him, I was often struck at seeing, from the pencil-marks made each day where he left off, how little he could read at a time. He used to call German the “Verdammte,” pronounced as if in English. He was especially indignant with Germans, because he was convinced that they could write simply if they chose, and often praised Dr. F. Hildebrand for writing German which was as clear as French. He sometimes gave a German sentence to a friend, a patriotic German lady, and used to laugh at her if she did not translate it fluently. He himself learnt German simply by hammering away with a dictionary; he would say that his only way was to read a sentence a great many times over, and at last the meaning occurred to him. When he began German long ago, he boasted of the fact (as he used to tell) to Sir J. Hooker, who replied, “Ah, my dear fellow, that’s nothing; I’ve begun it many times.”

      3. I suppose I will be accused of moving the goal posts here but being able to struggle through a German text is not exactly the same as being literate in the language. I would argue that that his limited grasp of German could well have made it difficult to appreciate Mendels’ paper, without a considerable effort even if he had had access to it. What are the odds that he would have put forth the effort that would have been required to comprehend a paper written by someone he had never heard of, given the other demands on his time? The same could not be said if it had been written in Latin or French

  4. From all I have read about Darwin and his insatiable interest in biological curiosities, it is quite uncharacteristic of him to overlook this tantalizing observation by Farn. I do not know what volume of correspondence Darwin was managing at the time, but whatever it was, I still think this letter should have caught his attention. I find it mysterious that he seems to have overlooked it.

  5. I asked Dr Hart and he wrote :”It would be fantastic to find a margin note or some reference to Farn’s letter in Darwin’s hand somewhere!”. I thought you might be interested in knowing this.

  6. It’s great to see our article being discussed here. At the moment we have no evidence that Darwin “regarded” this letter in any way – but it is fascinating to contemplate what his reaction may have been. We will continue to dig around and see if we can find some note or other. Farn, the author of the letter, was a rather charasmatic chap by all accounts – a snapshot of his antics is here http://www.canlit.ca/reviews.php?id=11539 – more information is in the book Aurelian Legacy.

  7. I have said it before, but upon reading odds and ends of Darwin I am singularly impressed with his ability to extract and test predictions from a theory. An ability which isn’t exactly common among all life sciences. [Abiogenesis and astrobiology both, I am looking at you!]

    I will grant that any man can make frequent mistakes. But even with hindsight I am suspicious that Darwin would miss out smashing such an easy lob.

  8. I Notice that the reference for the article has been posted incorectly, there is a 4th author in additon to the 3 listed. The corret reference is

    Adam G. Hart, Richard Stafford, Angela L. Smith and Anne E. Goodenough 2010 Evidence for contemporary evolution during Darwin’s lifetime Current Biology 20:R95.

    How can we geth this corrected?

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