Experimental Evolution, Ecology and Behaviour (EXEB)

What happens when eight researchers suggest there is value in multiple, alternative conceptual frameworks in evolutionary biology?

Posted by Tobias Uller

A few weeks ago EXEB discussed a commentary about the structure of evolutionary theory that I was a co-author on. I listened to the discussion and a lot of insightful things were said. Unfortunately, Erik was not able to attend but he has now shared his perspective online instead; all in friendly disagreement. Erik’s comments are quite similar to several other reactions we have had so I will highlight a few things that I think are worth noting. But if you are interested in my opinion it is no doubt more informative to simply come and discuss with me in person.

What did we publish?

The paper was an invited popular science commentary in a magazine called Nature. The editors of Nature knew we were writing a detailed academic paper (10,000 words, 250 references, currently in review). This paper attempts to explain how some critiques of contemporary evolutionary biology are conceptually aligned. Nature asked us to write a popular summary arguing that these perspectives may stimulate a rethink of certain aspects of evolutionary theory. Another team were asked to argue against this notion.

Our instructions were to write for a general audience and make it understandable and appealing to – as roughly stated by the editor - astronomers and others with a limited knowledge of evolutionary biology. We think it worked reasonably well overall, but the rhetoric on both sides naturally reflects Nature’s aim with the commentary and hence should be taken lightly. We did not know the author list of the other team (and only saw their response as it was published), but I assume they had similar instructions.

Erik thinks that this type of popular science should not be published in scientific magazines but instead posted on blogs. I do not read blogs much, but they are a good source of information about what people like about themselves and dislikes about others. Sometimes posts also help to interpret and understand science (e.g., Arild Stoltzfus' comment here). Similarly, glossy science magazines can be entertaining and informative and the many private and public responses to our commentary show that Nature indeed has a large and diverse readership. 

The main aim with this Yes/No piece was to encourage debate across disciplines about what counts as evolutionarily relevant causes and processes. This appears to have worked. So I think it is ok for Nature to publish these more informal pieces if they want. After all, magazines do not have the same aims as specialist academic journals, which may be good to remember also when we read scientific articles that are published in Nature.

Rethinking what?

Rethinking theory can mean a number of different things. Interpretation varies somewhat even among the authors of the ‘Yes’ comment. But many evolutionary biologists seem to think that as long as variation, heredity, and differential reproductive success remain central to evolutionary theory there is no such thing as a rethink.

I find this a pretty drab view of our field since it implies that we are only adding footnotes to the Origin of Species.  Indeed, this is pretty much the impression one gets from the ‘No’ comment – although their extensive Darwin references are likely there for rhetoric and journalistic effect and not because the authors think that evolutionary theory lacks progress.

Thinking about the structure and content of theory is healthy and something that all scientists should do regularly even if core aspects of our theories remain the same. The ‘Yes’ authors think that there are some important features of contemporary evolutionary biology that are problematic, including the proximate/ultimate distinction, the separation of heredity and development, and neglect of attention to the developmental origin of innovations. 

If we are to change this situation we need to rethink. But we have never claimed that this should be described in terms of revolution or a paradigm shift. Indeed, it is unlikely that fundamental insights from what we call standard evolutionary theory will be proven false. We think we can understand things even better. That is why we advocate an expansion of what counts as relevant causes of evolution – by shifting our perspective we can see things clearer.

We too have our reservations about the use of the term Extended Evolutionary Synthesis, which undoubtedly comes with some unwanted baggage. Nevertheless, naming a putative conceptual framework as it is being formulated can help to see how it differs from others. But it should not be interpreted as meaning something more than an attempt to provide a coherent perspective that differs from the prevailing view (as opposed to add-ons as the ‘No’ side and Erik appear to view things).

At the end of the day, the usefulness of a conceptual framework is measured by the extent to which it stimulates useful research. I, and my co-authors, fully agree with Erik that we need much more empirical work. But we also need ideas to guide us. We said: “We believe that a plurality of perspectives in science encourages development of alternative hypotheses, and stimulates empirical work”. 

In contrast, the ‘No’ authors appear to reverse the order and ask that empirical support precedes consideration of alternative perspectives (last page of their comment).  Because one of our main points is that conceptual frameworks channel thinking – and hence affect not only our interpretation of data but also what data we collect – this appears to be a major difference in philosophy of science between the two sides.

History Lessons and the Straw Man

Nevertheless, Erik is surely right that evolutionary biologists have not prevented him from studying how learning shapes mate choice. But on a more positive note, he also appears to have been inspired to do so by people like Mary-Jane West-Eberhard, who have argued that plasticity plays important roles in evolution. 

This theory may seem uncontroversial to some today, with the leading journal in organismal evolution recently publishing a review on the topic (which clearly shows we need more explicit empirical testing). But the idea certainly represents a, possibly incomplete, rethinking of evolutionary theory that was not very welcomed when it arrived, and is still poorly understood. If you have forgotten the discussions in coffee rooms following publication of Developmental Plasticity and Evolution, or if you have entered science more recently, it may be useful to read how the Nature reviewers of the book reacted to these ideas when they were published in 2003. Would we have vibrant work on plasticity and evolution without West-Eberhard's and others’ outspoken efforts to outline alternative conceptualizations of how evolution works?

The straw man is a helpful fellow. In a single stroke he lets you dismiss someone’s argument simply by inferring that that you understand the topic better. What is frustrating for both the ‘Yes’ and ‘No’ authors is that straw-man advocates imply that a 1700 word popular commentary written for a general audience is all that either side has to back up their points. How else could one know that these are straw man arguments?

Given that there are some quite intelligent, experienced, and well-respected researchers in both camps, assuming they got it wrong because of major gaps in their knowledge of evolutionary theory strikes me as somewhat arrogant. Admittedly, the Nature commentary is not overly helpful for evolutionary biologists, who would of course like to see the arguments fully fleshed out (as, of course, would we).

But the details of how our examples are unified conceptually, and how this differs from standard evolutionary theory, were deemed too complicated for the average reader of Nature (remember that this is not an evolutionary biology journal and that the comment was written with a very different audience in mind). Similarly, the ‘No’ response does not attempt to explain why no conceptual change is needed, presumably for the same reasons. 

This is no doubt frustrating for us all, but hardly a reason to conclude that there is no substance to the claims of either side. To avoid this situation Kevin Laland asked the ‘No’ authors if we should provide a more informative joint analysis elsewhere, but they declined.

Erik’s diagnosis is that if we would properly understand adaptive landscapes we would not have been misled to believe that new insights flow from the research fields we highlight in our commentary. It is true that the adaptive landscape is helpful for thinking about, for example, the evolutionary implications of plasticity (see e.g., Frank 2011,who also includes a personal reflection on why he was slow to appreciate the idea). We have never claimed anything else. In fact, I use this approach in my lectures on plasticity and evolution for third-year Oxford undergraduates. 

The Arnold paper Erik refers to is interesting and I encourage people to read it alongside our own contribution when it eventually becomes available. There are substantial differences in aims, approaches, and conclusions – it will be useful to examine these if you want to make up your mind on what questions are urgent to answer in evolutionary biology (through models, experiments, comparative tests and so on). I find that I learn more from people with alternative views, even if I disagree with what they say.

Evolution is a simple idea but actually quite difficult to understand in any detail. Trying to formulate an alternative perspective is, in my opinion, the best way to see if we are missing something. If you want pointers to the large literature that can provide useful insights into what this 'something' may be please do not hesitate to ask.