Zombie ideas in ecology: textbooks now teach the controversy on the IDH

How did I not know about this until now?!wp-1471365580601.jpg

The above is from the 3rd (2014) Canadian edition of Manuel Molles & James Cahill’s Ecology textbook. “Zombie ideas”! In a textbook!

A while back I asked how you teach controversial scientific ideas to undergrads. I really like the Molles & Cahill approach. They use my 2013 paper critiquing the intermediate disturbance hypothesis to kick of a really nice discussion of how ongoing debate and lack of final resolution are normal parts of science. They also talk about how the intermediate disturbance hypothesis shouldn’t be treated as a universal law–that’s not how hypotheses and hypothesis testing contribute to scientific progress. Finally, I think the term “zombie ideas” is a good way to get students to sit up and pay attention. And although there’s a part of me that wishes their discussion were pitched slightly differently, honestly I think what they wrote works better for an undergrad text than what my inner zombie-slayer would’ve written.*

My only quibble: Fox (2013) doesn’t actually use the term “zombie idea”, so I suggest that the 4th edition cite the original blog post as well. Yes, you can cite blog posts. Indeed, that one’s already been cited.

I’m unreasonably proud that a Canadian textbook cites three other Canadians in the passage critiquing the IDH. Canada: where zombie ideas go to die.🙂

I know JC, I’ll have to buy him a beer next time I see him. And give him a hard time for not telling me about this! HT to my Calgary colleague Kyla Flanagan for pointing this out to me.

After I saw this, I went and checked another new ecology textbook, Markus Eichhorn’s (2016) Natural Systems. Markus has commented approvingly on some of my zombie ideas posts, so I was curious to see how he’d treat the IDH. It’s a much briefer treatment than Molles & Cahill, and sadly (well, sadly to me) he doesn’t use the phrase “zombie idea”. But lo and behold:


I’ll be very interested to see how the treatment of the IDH changes over time in other ecology textbooks. Down the road, will we set textbooks increasing the space given over to critiques of the IDH? Just cutting back on all discussion of it? Swapping out discussion of the IDH for discussion of, say, the storage effect?

I’m also very curious to hear from folks who teach or have learned from these new textbooks exactly how the IDH was taught in class and what if anything was asked about it on exams.

*On the page following the one pictured above, Molles and Cahill analogize the intermediate disturbance hypothesis to the Lotka-Volterra model: a simple limiting case useful for generating hypotheses and sharpening intuitions. I’d quibble with that, since in its canonical textbook form the IDH isn’t mathematical, it’s a verbal argument along with a sketch illustrating its conclusion. That doesn’t sharpen intuition so much as enshrine faulty intuition. And I question whether “testing” vaguely-defined hypotheses is scientifically useful. But even I recognize that a debate about the value of verbal vs. mathematical models isn’t the sort of thing you should try to cram into a brief passage in an undergrad ecology textbook.

10 thoughts on “Zombie ideas in ecology: textbooks now teach the controversy on the IDH

  1. Prof. Pedant writes: “I believe that there is a ‘not’ missing in your opening sentence”.

    Seriously though, this is an interesting illustration of an important point: how often do (more senior) ecologists read text books? We recommend them to our students, but do we sit down and read them cover-to-cover ourselves? I certainly don’t; much as I’d love to read Markus’s book, I just don’t have the time. It’s hard enough to keep up with the primary literature (and I don’t do a very good job of that either!)

    • Typo fixed, thanks.

      I don’t know that senior ecologists *should* read textbooks, I didn’t mean to imply that. I ask “How did I not know about this?” because you’d have thought JC would’ve told me that he was revising his textbook to mention zombie ideas. Or that Kyla or someone else who teaches intro ecology at Calgary would’ve told me about it sooner, since we teach intro ecology from Molles & Cahill. Or that some reader aware of my interest in zombie ideas would’ve passed on this news before now.

      • Well then, how do we know that what we are recommending is any good?

        But taking your point of what you meant, perhaps it’s symptomatic of a more general issue. We _think_ we are communicating to one another because we do so damn much of it, but in fact we’re not really doing it very effectively because we miss out on telling one another so much. Or perhaps it’s just that what is important to one person is less so to another?

      • ” Or perhaps it’s just that what is important to one person is less so to another?”

        We have a winner! At least, that’s probably the answer to the question with which I opened the post.

    • Cheers for this!

      Our of curiosity, did you try to cite the blog post only for the editor to nix it?

      Clearly I need to do a full-text search of the entire ecological literature since my original post, looking for occurrences of the phrase “zombie idea”.

  2. Thanks for mentioning Natural Systems :o) This section went through a major revision while I was writing the book, partly in response to your blog post and the subsequent paper. I did toy with the idea of removing the IDH altogether; after all, one of my aims was to focus positively on ideas with ongoing potential rather than write another history of the development of thinking in ecology. In the end, however, I decided that its ongoing presence in the literature (especially in applied fields) meant that I would be doing a disservice to students if I didn’t at least mention it. Some other ideas were deliberately left out, but I’m not going to start pointing fingers and shouting ‘zombie’ at them. I’d rather let silence speak for itself, at least in print, but I’ll happily name names over a beer.

    As for Jeff’s comment on whether academics have time to read textbooks, I couldn’t agree more. It’s already impossible to keep up with new research, and textbooks are by default several years out of date by the time they hit the shelves, so why would we invest scarce time and effort. Nowadays the only times I look at undergraduate textbooks are when (a) I’m writing a new module (mercifully seldom), (b) I need a clear definition of a concept, in which case I’m only taking a few sentences, or (c) when I’m trying to develop my understanding of an area outside my usual field. The latter is most common, but doesn’t help with policing accuracy. I would love to receive constructive, thoughtful feedback from other academics on my book, but realise that it’s hard to come by.

    • Cheers for this Markus, interesting to hear your thinking. I can only imagine how many difficult choices of topic coverage must go into writing a textbook!

      I confess I’ve only glanced through Natural Systems so far, but my first reaction is that it’s very much to your credit that you managed to come up with a textbook that’s quite differently structured than those following the Ricklefs/Begon-Harper-Townsend template.

      • Thanks, I’m flattered whenever anyone looks at it :o) If you ever get the chance to give it a look through, however thorough, I’d really appreciate your thoughts. Or those of anyone else reading this, whether a student or a senior academic.

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