Aposematism around the world

DSCF5549sThis little chap was climbing the evolutionary ladder to our greenhouse recently. I’m referring to the warningly gaudy (aposematic) caterpillar rather than his cryptic slug friend, destined to be both drab and a toad’s meal. It prompted me to read a little on warning colouration and mimicry, which we debated here a little, some time back. I wasn’t too surprised that it has been a major, and contentious, topic of discussion since Darwin. Ernst Mayr said in 1982 that a biological concept which could clearly and unambiguously explain mimetic phenomena would also solve all other biological problems.

komarek_stanislavI won’t even try and solve it here. I soon stumbled on a link to an entire e-book on the subject in its historical context by a remarkable Czech scientist, Stanislav Komárek, which I’ve been reading with interest (and some difficulty, as the translation dispenses with any hint of paragraphs). It’s more instructive than I could ever need as a non-specialist, let alone a non-biologist. But I’ve persisted mainly because of the author’s valuable perspectives on the philosophy and history of science, which is what I’ll mainly discuss here.

Prominent colouration in plants and animals was a problem for Darwin, but someone suggested asking Alfred Wallace for his views, and the latter quickly came up with a theory – basically a thought experiment – that a distasteful or poisonous species that developed some easily recognisable coloration would have a selective advantage. Predators eating one would avoid doing so again, so the sacrifice would be to the species’ advantage.

Pretty soon, others tried offering such species to captive predators and reported that they did, indeed, hesitate or refuse to eat them. For a while there was an avalanche of papers to this effect. It seems Wallace failed to consider the rather obvious problem that a new trait inviting predation would never get a chance to be selected. It wasn’t until nearly a century later, with the concept of kin-selection, that a population-genetics study showed that such a mechanism could work.

But in the meantime, there were many other objections and alternative theories, especially during the time from c1900-1930 when the whole concept of Darwinism seemed untenable and Neo-Lamarckian, structuralist and other theories (including creationism) vied for dominance in biology.

One example struck me as emblematic. W. L. McAtee, an ornithologist for the Biological Survey Division of the U.S. Department of Agriculture, was a non-Darwinian interested in mimicry, and opposed to Poulton, the champion of adaptationist views on it. Unfortunately for McAtee much of his work was published at the time when Neo-darwinism was beginning to become fashionable again. As part of his studies on the role of birds in agriculture, he examined the stomach-contents of tens of thousands of birds, and found that “the contents of the birds’ stomachs showed a more or less equal representational ratio of aposematic and mimetic insects, as they appear in nature, from which McAtee concluded that these precautions are not effective on predatory birds.”

McAtee also critiqued the subjectivity of the assessments of the behaviour of predators in captivity experiments – asking if a hawk perching with its prey under its talons, or a cat playing with a mouse, should also be interpreted as hesitation over eating something distateful.

Poulton and other critics replied, correctly, that McAtee had done insufficient statistical analysis of insect distributions to prove his case, and thereafter he fell off the publication roundabout. What seems significant is the differential evidential standards required for the two different theories. Wallace’s adaptationist explanation had been accepted initially without a single piece of supportive evidence. Komárek says that analysing the captivity studies in its support shows that in some cases they were based on only ten insects being offered to predators, compared to McAtee’s 80,000 cases from the wild.

This kind of observation forms the background to Komárek’s exhaustive survey. He points out (not in connection with McAtee, incidentally) how non-mainstream research can find publication difficult, or impossible:

…textbook truths, which lie within the general pattern of scientific  disposition, do not require very extensive proofs, while theories well outside of the prevalent scientific outlook do not have a chance even after collecting a large quantity of material.

He shows, for example, how the stream of articles showing the influence of environment on mutations dried up:

[D]uring the twenties, when the general atmosphere was inclined to believe these opinions, these works made up an integral part of the truth of scientific journals and textbooks – editorial staff and later agencies which control research represent something like an internal court, which decides in secret what is and what isn’t true… More in-depth research of these sources would probably bring much new information – if not about the nature of heredity, than at least about the nature of the scientific community.

Most fascinating of all are the accounts he gives of how entire scientific cultures have become extinct for extraneous, political, reasons. For example, we are now completly oblivious to the fact that at one time, “Anglo-Saxon” (British and American) approaches to biology and evolution (including, of course, mimesis and aposematism) differed greatly from European ways of doing science.

For example, much good biology was done in Russia, which became cut off from the west by the Iron Curtain. The infamous Lysenko was not the whole of Russian biology, but became the reason to ignore the rest (and even Lysenko’s moulding by his socio-political environment is instructive in showing how much the same process happened in the west, for example in social Darwinism. Komárek has a long and amusing passage detailing the links of specific biological theories to their social setting – which even explains the different importance Darwin and Wallace placed on sexual selection, given their personal lives!)

German biology all but perished (as an original contribution) after World War II:

It is a world which today is for a large part filed away, much like the works and questions of later Antiquity or of the Middle Ages – the shift of accent and of the primary language of mainstream science towards the comprehensive and lucid Anglo-Saxon way of thinking after 1945 (even in Germany) leaves these studies to be buried in the depths of libraries, perhaps for future historians of biology. This shift of accent, among other things, shows that a new biological paradigm always appears on the shoulders of the winners (a similar shift took place in Japan), but it also shows that it is impossible to discard from a compact national intellectual heritage only those parts which directly gave rise to a historical catastrophe and humiliation and to keep intact the parts which did not play a part.

In fact, the “German” way of understanding the world, at once complicated and cumbersome, and on the other hand deep and penetrating, understands man’s nature and the nature of other organisms in such depth, that the possibility of  misuse (even unconscious) is really great,  therefore the conscious shift away at that time in history is quite understandable even in people with a profound ability of reflection and self-reflection (the Anglo-Saxon model of thinking, which only skims the surface of the object of study, on the one hand provides less information, but on the other hand it does less damage).

French biology (remember, the term biologie was coined in eighteenth century France) diminished in importance with the decline of French as a language. Accordingly, what we see now as the “objective findings of Science™” is what Komárek, from a broader, external perspective, sees as an “Anglo-Saxon monoculture” taking over the world. In fact, one of his themes is the myth of science as an ever expanding and progessing system of truth. Rather, much real knowledge gets buried in the back-rooms of libraries, perhaps in languages most people can’t read (oh for the days when the entire academic world wrote in Latin!). Worse still, when those libraries need to clear out their shelves of what is “no longer relevant”, which books will go to the skip and be forever lost?

The author, therefore, has deliberately sought out those forgotten pieces of research, and as a result not only provides an astonishingly comprehensive view of the problems and proposed solutions for what has been an important biological phenomenon over the entire history of science, but gives all of us a timely reminder of how little we actually know and how much we take for granted on poor evidence.

At the same time he gives us several completely new sets of spectacles with which to view biology – which is pretty scary, but to me deeply educational.

Another distasteful friend of Potiphar

Another distasteful friend of Potiphar

Jon Garvey

About Jon Garvey

Training in medicine (which was my career), social psychology and theology. Interests in most things, but especially the science-faith interface. The rest of my time, though, is spent writing, playing and recording music.
This entry was posted in History, Politics and sociology, Science. Bookmark the permalink.

14 Responses to Aposematism around the world

  1. Merv Bitikofer Merv Bitikofer says:

    Okay –so help me out on the personal histories of Wallace and Darwin here. Was one of them known to have a more robust libido, thereby influencing their approach to sexual selection in their studies?

    Regarding your lament for days gone by of more-or-less universal Latin: perhaps we have a repeat of the time when Latin came to dominate, and so other cultures or works felt squeezed out. I guess the Arabic world stood on its own without succumbing and so the west could enjoy the benefits of Islamic scholarship. But how many other minor cultures and languages may have had lost contributions at that time? If English (largely courtesy of the internet and other mass media) is recognized as a/the dominating language of academia, can we imagine some future scholar pining for the days when it was “all English”? Not to detract from your point of regrettable and substantial losses of knowledge. I’m just pointing out that perhaps Latin could have an heir of sorts in a (hopefully!) ongoing cycle.

    Thanks for this piece (and your last one too!). My vocabulary continues to grow.

    • Jon Garvey Jon Garvey says:

      Hi Merv

      The author’s comparison is based on Darwin’s happy marriage into a wealthy family, the pleasures of family life (lots of kids) and so on; and Wallace’s life of largely impoverished bachelorhood and sojourns in tropical solitude.

      The more serious point about Latin is that the whole Western tradition of the University arose with a Latin academic lingua franca. The separation from the Greek East had already happened, and the Islamic empire was another world – though of course it was the universities that encouraged the import and translation of classical Greek texts (and also Arabic and Hebrew) and their translation into Latin.

      But in mediaeval and early modern times, you could read work from a Bohemian, French, German or Spanish scholar and immediately incorporate it into your programme at Oxford or Cambridge. And being a dead language it privileged no one nation’s agenda… though it did keep the proletarians out of the loop.

  2. Jon Garvey Jon Garvey says:

    Here’s a timely link confirming Komárek’s stuff about language and science (pointed out to me by my brother).

  3. Lou Jost says:

    This is very interesting indeed, and a good lesson for biologists. I’d only add that for the particular question of aposematic colors, and for most other questions, it is understandable that results which match theoretical expectations are less subject to scrutiny than results which violate them. This does pose the danger of self-reinforcing science, or confirmation bias. But there is still plenty of diversity in science, and there has always been a strong incentive to overthrow accepted theory. Yes, the barriers to success in overthrowing a successful theory are high, and are partly sociological and political, but history shows that such revolutions still happen regularly.

    So yes, science has a large social and political component, but it is nothing compared to the influence of culture and politics on religion. And unlike science, fundamental revolutions rarely happen in religions. Is there any chance that someone will come along and convince all Christians that they were wrong and should all become Hindi, or should all follow Joseph Smith, or a new prophet? Won’t ever happen.

    • Jon Garvey Jon Garvey says:

      Actually, Lou, I’d say was a great deal like the influence of culture and politics on religion. So it’s a lesson for both science and religion (and any other source of knowledge and truth).

      The problem is simply that, unless one becomes globally agnostic, one simply has to do ones best with the biases that inevitably exist. It’s only a huge problem if one is convinced that knowledge must be entirely objective to be true knowledge, in which case one is scuppered.

      I do recommend the book, though, simply as an exhaustive review of a perennially interesting subject (from an unusual perspective).

      • Lou Jost says:

        The book really does sound interesting, thanks for bringing it to our attention.

        But I have to disagree that science and religion are in the same ballpark when it comes to cultural influence. When relativity or quantum mechanics were proposed, in a matter of decades virtually all physicists worldwide, regardless of their cultures, accepted the new theories. That happens all the time in science. It never happens with religions. After millenia of bickering there is still not even rough global agreement on even the most basic questions of religion, such as whether there is one god or many (though the “one god” team is currently winning).

  4. Merv Bitikofer Merv Bitikofer says:

    You bring up an interesting point, Lou — a lack of revolutions in religion.

    I’m not sure that would be exactly true, though. The reformation comes to mind as a “recent” example. And major shakeups would have happened before that too — a particular one a couple thousand years ago comes to mind. True, we don’t find everybody suddenly unified on the after-side (nor does science for that matter), but we do find forced changes. The Catholic church changed many of its practices as a result of many felt reformational pressures.

    Perhaps the scientific revolutions are more concentrated into the last bit of history with the large religious examples more spread out. But the religious ones, for better or worse, seem to give birth to the greater lasting impacts (with even modern science itself arguably being the offspring of those impacts.)

    • Lou Jost says:

      Merv, to me those “revolutions” you mentioned are minor tweaks, compared to many of the revolutions in science (eg QM, relativity, evolution). And yet even those minor tweaks were too much for many followers (Protestants and Catholics still can’t agree on central issues), while the really gigantic changes brought about by at least the three scientific revolutions I mentioned were quickly accepted worldwide (with a caveat for evolution in cases where it conflicts with a person’s religion).

      Religious revolutions comparable to the three scientific revolutions I mentioned are, for example, the rise of Christianity, or Mormonism, or Islam, or Scientology. In contrast to the success of scientific theories, I think you could model the growth and decay of religions as a sort of neutral genetic drift…

  5. Merv Bitikofer Merv Bitikofer says:

    I amend my last parenthetical addition to read: “with even modern science itself being *one of* the offspring …”

    It would be a dismal world indeed if the whole point of prior religions was to produce nothing more than what is now called science. But science enlisted as a team member along with religious identity and communities to breath life into otherwise vacuous endeavors –God may have something good in mind for that. But the jury is still out (from our perspective) on how and for whom the roles of villainy and chivalry will unfold.

  6. Lou Jost says:

    I’ve been looking at Komarek’s book, and I can see why Jon likes it….it echos some of Jon’s anti-Darwinian comments in his post on mimicry. For example, K says that sometimes mimicry is more detailed than necessary, while evolutionary biologists would argue that this is not likely to evolve. K says “The fact that this belief [that unnecessary detail cannot evolve) is a thing of faith and by definition circular reasoning is something that its believers did not and do not realize.”

    That is wrong, of course, for at least two reasons. First, we have an independently-tested theory of population genetics that should apply in this case because it has been shown to apply in other similar cases. Second, it is testable; one could in some cases make models with different levels of mimicry detail and compare their predation rates to see whether, given the population size and structure, selection was strong enough to drive the evolution of these details. In fact biologists do make and test models of this kind.

    K’s or Jon’s assessment of what constitutes unnecessary detail is subjective, and is not backed up with any kind of quantitative consideration of selection strength in relation to population size and available time for evolution. A detail that saved the life of a bug one time in a thousand predation attempts could easily become fixed in the population, because bug populations are typically very large. The degree of detail achievable by natural selection should depend on population size and generation time; hence bugs should exhibit more detailed mimicry than mammals, and small bugs should exhibit more detail than large, slow-growing ones. This kind of pattern-prediction provides yet another way to test the theory, which does seem broadly confirmed in this regard by simple observation.

  7. Merv Bitikofer Merv Bitikofer says:

    Lou wrote: …(Protestants and Catholics still can’t agree on central issues)

    I think it more accurate to say that Protestants and Catholics would disagree on what all gets to qualify *as* a central issue — though even here all would agree that Jesus’ identity qualifies. And on that there is remarkable unity among these groups, and regarding his life, death, and resurrection … the unity extends there too, though fringe groups can always be found.

    And if the significance of Jesus’ life and teachings were no more than a minor tweak to the religious establishment, then somebody forgot to tell that to the Pharisees of his day and to all the Christians ever since.

    • Lou Jost says:

      I don’t understand your last sentence, if it was directed at mine. I said the rise of Christianity was indeed a revolution comparable to the scientific ones I mentioned. The split between Catholics and Protestants is not.

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