What is the biggest change of mind about ecology that any ecologist has ever had?

In an old post, I shared the biggest ecological idea I’ve ever changed my mind about, and invited readers to share theirs. Today’s post is a variant on that: what’s the biggest ecological idea about which any ecologist has ever had a change of mind?

I’m most interested in changes of mind by ecologists who are or were prominent enough to have widely-known views. Has any prominent ecologist ever done the equivalent of philosopher Ludwig Wittgenstein, who famously developed two completely different theories of language and meaning, the second of which refutes the first? I can’t think of any off the top of my head, but that may just show that my memory and/or knowledge of the history of ecology leave something to be desired.

Casual googling reveals various cases of prominent scientists in other fields changing their minds about important topics within their area of expertise. Geologist Wallace Broecker changed his mind about the cause of the Younger Dryas cold spell. Climatologist Stephen Schneider changed his mind about the contribution of human activities to global warming. Astronomer Michael Brown’s own discoveries changed his mind about whether Pluto is a planet. Richard Lewontin dismissed the Price equation as trivial and uninteresting when he first learned about it, then later changed his mind. Further back, Charles Darwin famously changed his mind about the importance of Lamarckian evolution, allowing a greater role for it in the 6th edition of the Origin than the first edition. Years ago The Edge asked prominent scientists what they’d changed their minds about, but many of the responses were about matters outside the respondents’ area of greatest expertise, or stretched the definition of “change of mind”.

There’s a cynical old joke that science advances one death at a time. It would be interesting to try to quantify the extent to which the joke is true. Quantify the extent to which the consensus view on some important scientific topic changed due to scientists changing their minds, vs. scientists with one view dying (or retiring or switching to other areas of research) and being replaced by scientists with other views. Has this been done?

I raise this topic just because I think it’s interesting to think about, not because I think ecologists should change their minds any more or less often than they do. Indeed, I have no idea how often ecologists change their minds, and have no reason to think it’s any more or less often than for other scientists.

28 thoughts on “What is the biggest change of mind about ecology that any ecologist has ever had?

  1. I’m not sure this counts, but in the early 2000s Hubbell was pushing his neutral theory pretty hard but also had his name on quite a few high profile papers showing species-level density dependent and environmental specificity effects which are direct contradictions to neutral theory. I think this was more about the fact that those latter papers used data that he collected though.

    • Yeah, I’m gonna say that doesn’t count. My presumption is the same as yours, that Steve’s name is on those papers because they used the BCI data, not because Steve had changed his mind about neutral theory.

      Which gets back to a question I once posed: should all authors on multi-authored papers agree with everything those papers say? According to the poll we did, ecologists really disagree on this question.
      https://dynamicecology.wordpress.com/2015/04/16/what-happens-if-co-authors-disagree-about-what-their-ms-should-say/
      https://dynamicecology.wordpress.com/2015/04/22/ecologists-disagree-on-whether-co-authors-should-agree/

      • I have some observations about the impact of neutral theory which are partly (though not fully) responsive to this thread, but also to a comments discussion from the past few weeks that you two had under the “controversial ideas” post.

        I think you perhaps undersell the importance of neutral theory in illustrating which community scale patterns are necessary results of ecological drift. It is hard to remember now, but before 2000 it was quite common to publish papers trying to infer information about niches from the shape of species abundance distributions, while not considering the role of drift. And neutral theory rendered much of this work instantly obsolete. I know this is what you mean when you are crediting neutral theory with affecting the null models people choose to use; but discussions of null models often fit into the somewhat technical, “no model is perfect” bucket. And I would argue neutral theory resulted in much more of a categorical change in how people thought about this kind of data.

        As I said, it is not quite responsive to this post, because I do not know if anyone really changed their opinion about the underlying question of the importance of niche dynamics, but it is rare to see a new idea strike such a fatal blow to a previously busy line of research.

      • Andrew – I totally agree with you that a lot of patterns used to be explained as highly adaptive and niche based and now we know they’re not. Neutral theory certainly gets some of the credit for that. But: a) we knew that long before – there is a 1968 paper by Joel Cohen making the same point, and b) I tend to think it was not just nuetral theory but an onslaught of other theories including MaxEnt that all ended up the same place that really hammered home a point that was/should have been known for 50 years before that.

  2. Here’s a candidate: John Lawton famously deciding near the end of his career that community ecology (which he’d spent his career doing) is a waste of time because it’s too idiosyncratic.

  3. E. O. Wilson seems to have changed his mind about the value of kin selection / inclusive fitness theory. (Too evolutionary, insufficiently ecological to go on this list?)

  4. I have another example involving Stephen Hubbell.
    He worked on competition theory and lab experiments before moving to what would become neutral theory and the BCI FDP
    I wouldn’t say that this is exactly Hubbell going from believing P to not-P, but it is certainly a change of mind about what is important.
    References:
    Hsu, SB, SP Hubbell, and Paul Waltman. 1978. “A contribution to the theory of competing predators.” Ecological Monographs:337-349.
    Hsu, Sze-Bi, S Hubbell, and Paul Waltman. 1977. “A mathematical theory for single-nutrient competition in continuous cultures of micro-organisms.” SIAM Journal on Applied Mathematics 32 (2):366-383.
    Hubbell, Stephen P. 1979. “Tree Dispersion, Abundance, and Diversity in a Tropical Dry Forest.” Science 203 (4387):1299-1309.
    Hubbell, Stephen P. 1984. “Methodologies for the study of the origin and maintenance of tree diversity in tropical rainforest.” In The Significance of Species Diversity in Tropical Forest Ecosystems, edited by Gema Maury-Lechon, Malcom Hadley and Talal Younes, 8-17. International Union of Biological Sciences.

    • Hmm, don’t know that I buy that one. Hsu and Hubbell also have a Science paper from around that time in which they show experimentally that, if you equalize the R* values of two bacteria competing for a single limiting resource in a well-mixed chemostat, the two microbes coexist indefinitely at their initial relative abundances (it’s microbes, so population sizes are huge and drift is extremely slow). I’ve always assumed that that result was what started Hubbell down the neutral theory road.

      • Oh, interesting. Do you have the reference?
        But doesn’t it still stand that he was working on resource competition theory and then switched to neutral theory?
        Also, studying microbes to tropical forests also seems like a big change of mind, albeit not a theoretical one. I’ve always wondered what led him to make this change.

      • Pedantic response :-): resource competition theory *is* neutral theory if you set the R* values of the competitors equal. It’s neutral theory without drift (if you’re using a deterministic model), but it’s still neutral theory.

        I wouldn’t count changes of study system as changes of mind. At least, they aren’t the sort of changes of mind I had in mind. But yes, Hubbell is among those who have made a big change of study system. Dave Tilman did too, from algal chemostats to grasslands. My understanding (which might be wrong; it’s n-th hand) is that he switched at least in part because many ecologists didn’t think algae were “real” organisms or that chemostats were a “real” study system.

        EDIT: Sorry, hit “post” too soon. The reference I was thinking of is actually Hansen and Hubbell 1980 Science. It’s a very Tilmanesque paper, and came out around the time that Tilman was developing resource competition theory and testing it in chemostats. It’s amusing to imagine an alternate universe in which Steve Hubbell goes down the path David Tilman went down, and David Tilman goes down the path Steve Hubbell went down. 🙂

  5. Dropping a central assumption, changing the mathematics used, and adding other processes seems like it would be more than enough count as a big change, even if there is a continuity.
    The lab systems not being real systems seems like part of the answer for sure.

    • By “changing your mind”, I mean “reversing your view on something”. You once thought X was true, now you think not-X is true. Not “adding in other processes to your model” or “changing the type of mathematics you use to build your models” or etc.

  6. “There’s a cynical old joke that science advances one death at a time. It would be interesting to try to quantify the extent to which the joke is true.”

    It appears that you now have a fairly clear answer to this!

    But I am not at all sure if that is a good or bad thing.

  7. My guess is that a whole suite of theoreticians, including Hastings and Ellner, have changed their minds about the importance of chaos in ecology. As one can see from this paper https://www.jstor.org/stable/2097171, they once thought it was quite important and likely common. If you pressed them for what they thought now, I’d be willing to bet they don’t think chaos is all that common in ecological systems. I think some of the authors have publicly said this.

    • Ooh, good one. Although I don’t actually know if the excitement about chaos was more “excitement about the mere possibility that it might occur at all” or “excitement borne from the belief that chaos is probably common and important”. Only in the latter case would waning of enthusiasm for chaos be a symptom of a collective change of mind.

      And yes, I agree that probably very few people would argue that chaos is common and important in natural systems. Maybe Jeff Huisman would? (note: I’m totally speculating just based on my recollection of his recent-ish papers). And maybe some people would say the jury’s still out because chaos is so hard to detect and distinguish from noisy limit cycles.

  8. Edward O. Wilson (1977, Biology and the social sciences. Daedalus 106(4):27-140, p.136) embraced the use of neoclassical economic theory/models for ecology. In a book with Oster (Oster, George F., and Edward O. Wilson. 1978. Caste and ecology in social insects. NJ: Princeton University Press, p. 294) they mentioned operations research as a particular source of inspiration for their theoretical treatment of insect states. In Consilience (1998, ch. 9), however, Wilson recanted calling economic theory “Newtonian” (too simple) and “hermetic” (sealed off from reality).

    The most radical recantation of the economic models used for studying optimal foraging theory, however, seems to have been by Rapport (1991. Myths in the foundations of economics and ecology. Biological Journal of the Linnean Society 44: 185-202). The guy who was formerly most upfront about economics as a source of inspiration for optimal foraging theory radically denied the use of any such economic models.

    Prichard’s “Researches into the physical history of man” (1813, not to be mistaken with his later multi-volume work “The natural history of man”) was advanced in terms of evolutionary thinking. E.g., he stated the mechanism of artificial selection quite clearly (p. 38):

    “The power which human art possesses of modifying the individual is very limited indeed; but by diligently taking advantage of the natural tendency to transmit any qualities which happen to arise, a very considerable influence is exercised over the race. Different breeds are thus formed endowed with divers properties, which render them useful in various ways to their owners. The process consists in a careful selection of those individual animals, which happen to be possessed in a more remarkable degree than the generality, of the characters which it is desirable to perpetuate. These are kept for the future propagation of the stock, and a repeated attention is paid to the same circumstances, till the effect continually increasing a particular figure, colour, proportion of limbs or any other attainable quality, is established in the race, and the conformity is afterwards maintained by removing from the breed any new variety which may casually spring up in it.”

    While the second edition only changed the title from “… man” to “… mankind,” the evolutionary thrust got lost from later editions and works.

    • Forgot to mention that Prichard added the word “artificial” in the second edition (1826, Researches into the physical history of mankind, vol. 2, p. 557) to read: “The artificial process consists in careful selection …”
      That already implied a natural process of selection as well.

  9. Tansley’s (1935. The use and abuse of vegetational concepts and terms. Ecology 16: 284 307) was, IMHO, due to his change of mind to no longer tolerate organismic analogies as heuristics for ecosystems (prompted by Philips overloading the analogy). He had previously tolerated Clements’s use of the organism analogy.

  10. In evolutionary biology, Simon Conway Morris changed his mind about contingency vs. repeatability in evolution. He started out seeing the Burgess Shale fossils as evidence of the idiosyncratic non-repeatability of evolution, but later changed his mind and emphasized the ubiquity of convergent evolution.

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