If I told you that evolution was in crisis, what would you think I meant? You would probably think I meant that the theory was on its way out. You would think that new discoveries had shown the untenability of evolution, and that biologists were in despair over their lack of a central organizing principle. You would think that maybe those creationists and ID folks weren’t as crazy as you had been told. If you’re an old hand at this you might even recall Michael Denton’s 1986 book Evolution: A Theory in Crisis, which proved so inspirational to ID folks in the years before Philip Johnson and William Dembski.
You certainly would not think I meant that the entire discipline was being enriched by a variety of new ideas. Nor would you think that the foundational ideas of the subject were as solid as ever, or that evolutionary biologists of old had unnecessarily limited their explanatory options. Those are positive developments, you see, and no one, but no one, uses the word “crisis” to refer to something good.
Why, then, would John Dupre, a prominent philosopher of science, title an essay summarizing some recent developments in evolutionary biology, “Evolutionary Theory’s Welcome Crisis”? And what force on earth could prompt him to write something as foolish as this:
The creationists are right about one thing: contrary to the impression given by much popular writing on the subject, the theory of evolution is in crisis.
Prior to this essay I knew of Dupre only from his book Darwin’s Legacy: What Evolution Means Today. I liked that book quite a lot, not least because it pulls no punches about the serious challenges evolution poses for traditional religion. I cite the book favorably in Among the Creationists. So it was especially disappointing that he would hand the creationists such a huge propaganda victory.
The substance of his essay, minus the absurdly hyperbolic language, seems fine to me. He writes things like this:
The current crisis in evolutionary science does not imply complete rejection of this paradigm. Rather, it entails a major, progressive reorganization of existing knowledge, without undermining the fundamental tenets of evolutionary theory: organisms alive today developed from significantly different organisms in the distant past; dissimilar organisms may share common ancestors; and natural selection has played a crucial role in this process.
Other assumptions, however, are under threat. For example, in the traditional “tree of life” representation of evolution, the branches always move apart, never merging, implying that species’ ancestry follows a linear path, and that all evolutionary changes along this path occur within the lineage being traced. But examination of genomes – particularly microbes – has shown that genes moving between distantly related organisms are an important catalyst of evolutionary change.
Moreover, the new synthesis assumes that the main drivers of evolution are small mutations generated by chance within a species. But recent evidence suggests that large changes, caused by the absorption of a chunk of alien genetic material, may be just as significant. Indeed, the absorption of entire organisms – such as the two bacteria that formed the first eukaryotic cell (the more complex cell type found in multicellular animals) – can generate large and crucial evolutionary change.
I could nitpick, but that seems basically fine to me. Likewise for Dupre’s other points. So why not write a headline like, “New Developments Show Evolution is More Interesting Than We Thought”? Unlike the actual title, that one would be accurate.
Mind you, the problem is not simply that it is politically unwise to phrase things as Dupre has done. It is that Dupre’s statement is completely false, and not at all supported by anything that comes after it. When creationists tell their flock that evolution is a theory in crisis — and I can tell you from personal experience that they use that phrasing routinely — do you think they have in mind any of the esoteric points Dupre is discussing? Of course not. They are saying that the whole theory is ridiculous. They are saying that the three points that Dupre describes as the solid foundation of the theory are being soundly rejected by more and more scientists. The creationists are not right, about anything, even granting every point that Dupre makes.
I have no doubt that Dupre will think I quoted him out of context. For the record, here’s the text surrounding the one sentence I quoted earlier:
Those who believe that a supernatural being created the universe have never posed an intellectual challenge to evolutionary theory. But creationists, whether biblical fundamentalists or believers in “intelligent design,” do pose a threat to scientific thinking. Indeed, creationism’s insidious genius lies in its ability to reinvent evolution in its own image as a dogmatic belief system – and thus the antithesis of science.
The creationists are right about one thing: contrary to the impression given by much popular writing on the subject, the theory of evolution is in crisis. But this is a positive development, because it reflects the non-linear progress of scientific knowledge, characterized by what Thomas Kuhn described in his influential book The Structure of Scientific Revolutions as “paradigm shifts.”
Dupre concludes his essay with this:
This brings us back to where we started. Radically rethinking evolutionary theory invariably attracts the attention of creationists, who gleefully announce that if professional advocates of Darwinism cannot agree, the concept must be in retreat. And, evolutionists, confronted with this response, tend to circle the wagons and insist that everyone is in agreement.
But nothing more clearly demonstrates that science and creationism are polar opposites than the latter’s assumption that disagreement signals failure. In fact, disagreement – and the deeper insights that result from it – enables new approaches to scientific understanding. For science, unlike for dogmatic belief systems, disagreement is to be encouraged.
Evolutionary theory’s current contretemps – and our inability to predict where the field will be in 50 years – are a cause for celebration. We should leave the creationists to their hollow convictions and happily embrace the uncertainties inherent in a truly empirical approach to understanding the world.
It’s great that he includes all that nuance, but no one can be so naive as to think the creationists will care in the slightest. They will happily quote that one sentence, and their audiences will lap it up.
This whole thing is reminiscent of that appalling New Scientist cover, the one that breathlessly announced, in enormous type, “Darwin Was Wrong.” The magazine was quite properly excoriated for putting sensationalism ahead of accuracy. It took about ninety minutes for a picture of that cover to become slide number one in every creationists presentation I subsequently attended. And why not? Why shouldn’t they crow that a major popular science magazine was using precisely their language to describe the state of evolution? Dupre’s essay is in the same mold. It’s a scientifically interesting commentary buried under a cover of silly, unhelpful sensationalism.
It’s really very frustrating. Why this endless desire to present every two-bit discovery in biology as prompting a revolution? Why the endless language of crisis, radical rethinking and paradigm shifts? It is not a radical rethinking of the subject to say that horizontal gene transfer shows that a tree isn’t always the best metaphor for evolution, especially in the earliest stages of the process. It is not a paradigm shift to go from thinking that genes alone determine the physical structure of an organism to thinking that it’s actually an interaction between genes and environment that does that.
And is Dupre serious that we can’t predict where the field will be in fifty years? I think we can make some pretty strong predictions about where evolution will be. Fifty years from now it will still be true that modern organisms are related by common descent, it will still be true that naturalistic mechanisms are entirely sufficient to explain that descent, and it will still be true that complex adaptations evolve gradually by natural selection. Those are mighty big things. In fact, they are precisely the claims that cause evolutionary theory to have cultural relevance beyond the esoteric questions studied by scientists.
At any rate, Jerry Coyne also takes Dupre to task for his hyperbolic rhetoric.
Massimo Pigliucci plays mediator in this post. I was pleased that he said this, early in the post:
As it turns out, Jerry had a point in chastising John: contra the latter, there is no “crisis” in evolutionary theory.
Later on, Massimo points out that Dupre should not have used the word, “Radically,” when “Significantly” would have been more measured and reasonable. Alas, Massimo somewhat spoils the effect by concluding his post with this:
Jerry concludes his critique of John’s essay thusly: “As an evolutionary biologist — which Dupré is not — I think I’d know if my field was in crisis.” No Jerry, plenty of us have been telling you, you just haven’t been listening.
Hmmm. That makes it sound like Massimo really does think the theory is in crisis. I wish he would get his story straight…