Darwin Day 2008

199 years ago today, Charles Robert Darwin was born in Shrewsbury, Shropshire, England at the home of his family (known as the Mount). By pure coincidence, Charles would have published one of the most important books ever written 50 years later in 1859, and next year will mark not only the bicentennial of Darwin's birth but also the 150th anniversary of On the Origin of Species by Natural Selection. Indeed, next year will give us cause for raucous celebration, but this year I have been asking myself why Darwin's work is important enough to still get excited about it nearly a century and a half after his "dangerous idea" was first introduced to the public.

Understanding Darwin & his legacy is a complex task, especially at a time when everyone knows his name yet might entertain entirely divergent ideas about his work. When I was first introduced to evolution in elementary school, Darwin was like a colossus whose shadow was cast over the subject (and this remains true); he devised a theory of evolution as we know it today, the idea popping into his mind virtually out of thin air and revolutionizing science. Such is the "textbook cardboard," anyway, but in recent years I've attained a more complex & nuanced understanding of who Darwin was and why evolution by natural selection is so powerful a concept.

It had always seemed strange to me that no one had recognized natural selection before Darwin, and the truth of the matter is that Darwin was certainly not the first to propose the idea. It's well understood that Darwin was not the first to propose that creatures might change over the course of time, either (although many early ideas of "transmutation" were hardly scientific). Adding to what some may think is a case against Darwin are a number of his incorrect ideas (most notably his thoughts on heredity) that were rejected soon after he proposed them, so at an extremely superficial level someone might wonder why we are spending so much time talking about a 19th century naturalist who had no concept of genetics.

It would be irresponsible and overly harsh to relegate Darwin to the intellectual dustbin because some of his ideas were found to be wrong or because other people had arrived at similar conclusions about the reality of natural selection. What is truly significant about Darwin is that he recognized the true significance of natural selection to evolution. He worked on his theory of evolution for years, accumulating masses of evidence to support his theory, and through this work he was able to produce an abstract that would change what we think about who we are.

Darwin stuck to his theory of an unguided, branching process of evolution driven by natural selection even when it involved our own species. Alfred Wallace, often cited as the "co-discoverer" of natural selection, folded on this point, but Darwin saw no reason to make special allowances so that our own species could be exempt. This is even more admirable considering the opposition that Darwin faced, and even though some scientists were willing to concede the reality evolution, the mechanism of natural selection was seen by some as a "negative" force that destroyed & degenerated rather than built-up. In the conclusion of Animals and Plants Under Domestication (Vol. II, 2nd ed.), however, Darwin makes it clear that the power of natural selection cannot be denied;

Some authors have declared that natural selection explains nothing, unless the precise cause of each slight individual difference be made clear. If it were explained to a savage utterly ignorant of the art of building, how the edifice had been raised stone upon stone, and why wedge-formed fragments were used for the arches, flat-stones for the roof, &c.; and if the use of each part and of the whole building were pointed out, it would be unreasonable if he declared that nothing had been made clear to him, because the precise cause of the shape of each fragment could not be told. But this is a nearly parallel case with the objection that selection explains nothing, because we know not the cause of each individual difference in the structure of each being.

Opposition did not come only from other naturalists, though, and Darwin had to contend with those who rejected evolution because of their religious beliefs (or even tried to cram theism into the natural system that Darwin had illuminated). A few lines after the passage I just copied, Darwin wrote;

An omniscient Creator must have foreseen every consequence which results from the laws imposed by Him. But can it be reasonably maintained that the Creator intentionally ordered, if we use the words in any ordinary sense, that certain fragments of rock should assume certain shapes so that the builder might erect his edifice? If the various laws which have determined the shape of each fragment were not predetermined for the builder's sake, can it be maintained with any greater probability that He specially ordained for the sake of the breeder each of the innumerable variations in domestic animals and plants; - many of these variations being of no service to man, and not beneficial, far more often injurious, to the creatures themselves? Did He ordain that the crop and tail-feathers of the pigeon should vary in order that the fancier might make his grotesque pouter and fantail breeds? Did He cause the frame and mental qualities of the dog to vary in order that a breed might be formed of indomitable ferocity, with jaws fitted to pin down the bull for man's brutal sport? But if we give up the principle in one case, - if we do not admit that the variations of the primeval dog were intentionally guided in order that the greyhound, for instance, that perfect image of symmetry and vigour, might be formed, - no shadow of reason can be assigned for the belief the variations, alike in nature and the result of the same general laws, which have been the groundwork through natural selection of the formation of the most perfectly adapted animals in the world, man included, were intentionally and specially guided. [emphasis mine]

Indeed, Darwin knew that his theory was going to be controversial, but rather than ignoring his opponents he studied their arguments and addressed them in his work (even if not explicitly). William Paley's Natural Theology was a book that Darwin much admired, and his familiarity with Paley's arguments for design allowed him to come up with better counter-arguments and examples when carefully piecing together his own theory. Sadly, almost 150 years after the publication of On the Origin of Species by Natural Selection, scientists still have to continue to keep up with the rhetoric of creationists (many of whom, from what I can tell, have only a very superficial understanding of Darwin & his work), but such is a tradition that was started with Darwin himself.

Despite the misgivings of creationists, Neo-Lamarckians, & others, Darwin's theory of natural selection was vindicated in the 20th century with the development of the Modern Synthesis. On the Origin of Species by Natural Selection did not install a scientific dogma that everyone agreed upon and did not question; the mechanisms of evolution were hotly debated for some time. Rather than crumbling when the science of genetics was pioneered, though, Darwin's theory of natural selection was strengthened. Things have certainly changed since Darwin's time (and even since the development of the Modern Synthesis) and new theories have been added to natural selection within evolutionary science, but natural selection remains the most powerful mechanism that makes sense of both the fact and theory of evolutionary change.

I could go on about the intellectual significance of Darwin, but there is a more personal, subjective aspect to why so many of us are writing about him today (and almost every day, for that matter). Speaking for myself, much of my own appreciation comes from the fact that Darwin's writings are open to anyone that is curious enough to read them. Darwin's diary, notebooks, and letters reflect the thoughts and worries of a naturalist who spent most of his life contemplating the natural world, his writing recording his intellectual journey from a young creationist to a brilliant evolutionary theorist. We can thus trace the evolution of the evolution idea, the material available to do so being virtually unsurpassed for any of science's other "big ideas." It is of little surprise, then, that so much has been written about one man.

Charles Darwin made sense of one of the most complex problems in all of science with a simple and elegant theory, a concept that is within the grasp of nearly anyone willing to listen. Say what you like about the "originality" of the key components of the theory of evolution by natural selection, but no other naturalist was so elegantly able to unite them and reveal how the unity & diversity of life on earth came to be. Science will continue to produce new hypotheses and theories, but I surmise that 101 years from now evolutionary scientists will be just as enthused over the tricentennial of Darwin's birth (if not more) as we are on the eve of the bicentennial.