Is Evolution the Cornerstone of Biology?
In response to yesterday's post my frequent commenter and occasional sparring partner Salvador Cordova left the following remarks:
I do like your blog and your insights and your concerns, but I have to comment on this claim by Lynn:
“we cannot ignore this cornerstone of science”.
I keep hearing that repeated, but I just don't see that evolutionary theory is a cornerstone of science. Biology can be understood well without traditional evolutionary biology.
The few creationist biologists and physcians in the world are counter-examples to that claim. There is hardly a physicst who would deny the existence of gravity, but there have always been a minority of first rate scientists who doubt evolutionary theory (whatever evolutionary theory really is, the vague definition of the term “evolutionary theory” is suggestive it's no cornerstone of science at all).
The great Columbia University genetecist Theodosious Dobzhansky famously said “Nothing in biology makes sense except in the light of evolution.” What did he mean by that?
In a trivial sort of way there are many things in biology that make perfect sense even without evolution. The structure of DNA, the mechanics of the Krebs cycle, the skeletal structure of the water buffalo, all of these facts can be understood without any reference to Darwin or his theories.
But of course, the same could be said for any branch of science. Brute facts can be learned and understood without any reference to theory at all. Plainly, this is not what Dobzhansky had in mind.
What he intended was that evolution is what transforms biology from a chaotic menagerie of unrelated facts into an actual science. For example, the fossil record shows a clear pattern to life's history. We begin with the simplest sort of one-celled organisms around 3.5 billion years ago, and move gradually through more complex single-celled organisms, simple multicellular organisms, and on and on through fish, amphibians, reptiles and humans. Along the way we find numerous examples of transitional series in which, for example, the reptilian skull seems to transform itself gradually into the mammalian skull. Without evolution we must simply accept this history as a brute fact. Intelligent Design offers no explanation of it, and the Young-Earth Creationists offer an explanation (that the patterns in the fossil record represent the different abilities of animals to escape the rising waters of Noah's flood) so clearly at odds with the facts that it can't be taken seriously. Salvador, if you reject evolution, tell me how I am to understand the fossil record.
And that is just one example. I could take any other line of evidence and ask the same question. Evolution lets me take a mass of disconnected facts and see them as the consequence of one simple idea. There is no rival theory with the same explanatory power. And, creationist distortions notwithstanding, there is no data that speaks against the idea. That is what Dobzhansky had in mind with his statement.
So the idea that “Biology can be understood well without traditional evolutionary biology,” is true only if by “understand” you mean, “absorb a mass of unrelated facts”.
Salvador points out that there have always been a handful of scientists who reject evolutionary theory. To which I reply, “So what?” Logic and set theory are cornerstones of mathematics, but you can have a nice long career in the field without knowing very much about either one. Saying that evolution is the cornerstone of biology does not mean that every biologist spends every moment of his working life thinking about deep evolutionary questions. Rejecting evolutionary theory will not prevent you, at least in principle, from discovering ineresting biological facts. But it will prevent you from making sense of those facts, and it will prevent you from putting those facts in any sort of larger context. And that is why no creationist has made any significant contribution to biology in the past century.
I would also point out something rather obvious. Browse through the biology journals in any university science library and you will find dozens that deal specifically with evolution. And the journals that don't mention evolution explicitly still invariably treat evolutionary questions. I have not looked at any statistics, but I suspect that academic book publishers put out far more books about evolution than on any other area of biology. The fact that every once in a while someone with a PhD, nearly always in some field of science not related to evolution in any way, will reject evolution has nothing to do with whether evolution is the cornerstone of modern biology. I need only look at what biologists do when they enter the laboratory to see that it is.
The remark about evolutionary theory being vaguely defined is precisely the sort of silly nonsense that gets scientists so irate when dealing with creationists. It sure seems to me that biologists know what mean when they talk about evolution, and the better informed creationists seem to know what they are railing against. Have you, uh, tried reading a book on the subject?
To seal the deal Salvador offers the following quote from biologist Lynn Margulis:
The practicing neo-Darwinists lack relevant knowledge in, for example, microbiology, cell biology, biochemistry, molecular biology, and cytoplasmic genetics. They avoid biochemical cytology and microbial ecology. This is comparable to attempting a critical analysis of Shakespeare's Elizabethan phraseology and idiomatic expression in Chinese, while ignoring the relevance of the English language!
Now, Lynn Margulis is as hard-core a defender of evolution as you will find. Leaving aside, for the moment, the more florid aspects of this quote, what she is criticizing is the Neo-Darwinian interpretation of evolution, not evolution itself. Anyone familiar with Margulis' work knows that what she objects to is the overemphasis (in her view) of natural selection acting on small genetic variations. She believes that symbiosis is a more important mechanism of evolution than Neo-Darwinism acknowledges. She has done some fine work in this regard, though most scientists believe that while symbiolsis is certainly important, especially in the earliest stages of evolution, it is she who is overstating her case. Since symbiosis is yet another method by which biological complexity can increase through natural mechanisms, her work is one more blow against intelligent design.
As for the business about Neo-Darwinists simply ignoring vast swathes of biology, I'm afraid Ms. Margulis can go climb a tree. That statement is both false and obnoxious. The fact that she often makes such hyperbolic statements is a large part of the reason she finds it difficult to get other scientists to take her seriously anymore.
Reject evolutionary theory if you want to, but at least try to get an accurate picture of the role it plays in modern biology. And when pulling out dramatic quotes, take a moment first to understand the point the person was actually making.