Today would have been Charles Darwin's 200th birthday. There are those who think that Darwin was the most important scientist ever. That is overstating the case, although in the field of biology it is probably impossible to diminish his importance. Take a moment to think about his ideas, understand what they really were, and the impact that he and his ideas have had on modern science.
It's worth nothing that Darwin was not the author of the theory of evolution. The idea of evolution of species pre-dated Darwin by decades; ever since fossils were subject to study in a systematic way, the idea that species will, over time, evolve into new species was part of established biological fault. Darwin's contribution was not evolution itself, but rather evolution by way of natural selection.
This is what made his idea so subversive and controversial. Nature, acting on its own, is the product of unthinking, blind, unplanned, and fundamentally random forces at work. There is no guiding hand. There is no plan. There is no destination. There is only adaptation to environmental change, extinction as the brutal and deadly consequence for failure to adapt, and the survival of those species that possess the ability to deal with new circumstances. The path towards the diversity of species was littered with the corpses of those who could not survive long enough to breed.
Darwin's idea stood in sharp contrast to two other schools of thought prevailing at the time. One, the school of Lamarckian evolution, held that individuals acquired characteristics through repetitive actions and passed those characteristics down to their offspring. Thus, a deer-like creature that often strained its neck to get at leaves on the top of the bushes would channel "life force" into its neck, and when it reproduced, its offspring would have that extra life force in its neck, too, resulting in the creation of a longer neck -- and thus, over many generations, the deer turns in to a giraffe. Lamarckian thought is much more seductive than it would seem at first glance and even Darwin fell prey to it when attempting to explain racial differences between humans. But it is simply wrong. If I am a ditch digger and use my arms to work all day long, my children are not going to have longer arms.
The other idea was teleological evolution, the idea tha God was guiding the forces of nature in some manner such that the animals of the world, including man, came to their present state, for purposes known to God. This was a common school of thought and remains to this day a "compromise" position for those who have looked into the fossil and biological record but still insist on a role for God in the process. An examination of the evidence reveals that indeed evolution is a fact, a provable phenomenon, as well as a theory; it is worth nothing that gravity is the same sort of thing, and no one doubts that the fact of gravity exists even if there are different ways of explaining how it works. But the problem with divinely-guided evolution is that it explains nothing at all about how evolution works. If God is making species evolove over time, then without God's intervention, they would not evolve over time. So it is really no different than the obviously false concept of spontaneous creation. It also leaves a very substantial issue with extinct species. There is no particular biological reason for God to have created species only to kill them off completely -- why, then do we find dionsaurs? A theologian might simplistically say that Jehovah has His reasons and it is not for us to question them. That, however, is not science -- science is fundamentally about questioning the reason why things happen. So this avenue of analysis eventually leads the scientist to a place that is not science at all; it offers no explanation for the diversity of species in the world.
Darwin's theory does do this. He did not pretend to know what factor within a species caused it to, over many generations, adapt and alter its outward appearance. But it was readily apparent to him that this happens. His theory was that if a species failed to do this, it would eventually be maladapted to changing local environmental conditions, vulnerable to predators, and unable to feed itself. Down that path lay extinction.
As a predicate to this theory, we must note, Darwin had to theorize that environmental conditions in particular areas did indeed change over time. This was the bulk of the insight he offered in his first major work, The Voyage Of The Beagle. This book not contain a word about evolution, although there are some elliptical hints to the concept that we can see now. But the book itself was a combination of a travelogue and a bestiary. It was the heavily-edited memoir of Darwin's travels as the naturalist on the HMS Beagle, whcih had as its mission the geographic exploration of South America.
While exploring the South American coast, Darwin was on several occasions dropped off on the mainland to explore on his own what was there. He took week-long hikes through the Amazon rainforest, the pampas of Patagonia, the deserts and highlands of the middle Andes, and the plains of Uruguay. There, he took note of geological as well as biological evidence. In particular, he noted upwelling in geologically active areas, signs of relatively recent creation of hills, mountains, and escarpments. He also found fossils of animals in the pamapas and in the deserts that appeared to be the sorts of creatures one would expect to find in a forest. So while Voyage of the Beagle can be enjoyed simply for its description of a fascinating journey through the eyes of a keen observer (and a talented write, I would add) it also contains a scientific insight -- the world is not stable, it changes over time, and as it does, different areas have different kinds of environments. This was something of a reach at the time; since geological change is not something that is readily-observable in human time in most instances, many people doubted it happened at all. In particular, those who ascribed a divine role in the creation of the environment and the relatively recent creation of the Earth would have no reason to think that environmental and geological conditions of a particular area had ever changed. (The evidence suggests otherwise, but when dogma and objective evidence conflict, there are those who will sacrifice objective reality in favor of the dogma.)
So, confronted with evidence of geological change causing local conditions to alter, in areas that appeared to have isolated populations of creatures, Darwin found species alive and thriving in areas that were unlike any he had seen elsewhere. It was in the Galapagos Islands that he finally reached his conclusion that adaptive species, which could change over time, would survive while non-adaptive species died out. "Survival of the fittest" was not a concept Darwin embraced, "survival of the most adaptable" is much closer to the mark. The Galapagos, in particular the finches and tortoises of the area, were powerful demonstraters of this concept, because environmental conditions on the various islands in the archipalego were so different from one another. The Galapagos provided a world in miniature, isolated by a thousand miles of ocean from the South American mainland, and with more than a dozen local micro-environments to see, hopping from one island to another quickly. Here the tortoises had pointy shells; here they were rounded. Here the finches had large, squat beaks and there, they were narrow and pointy. The prevalence of different kinds of food sources was the answer; some islands had one kind of food and others had different kinds of food, and the species, which all started out with a common kind of ancestor, changed over time so that they could get at their food and survive.
Having had this epiphany, Darwin realized its explosive nature and kept it to himself. He spent many years writing conventional biology textbooks, teaching, and otherwise establishing his reputation in the scientific community, without breathing a word of his theory to anyone. By the time Origin of Species was published, Darwin was a major figure within the scientific establishment. But he had sat on the idea and the book for tens of years, developing arguments and marshalling evidence to back them up, trying to anticipate every sort of serious objection that could be raised against the idea of evolution by natural selection.
As is well-known now, though, his hand was eventually forced. Another naturalist, Alfred Russell Wallace, had gathered a significant amount of evidence from his work in Borneo. He developed his own theory that natural selection in response to environmental change caused the evolution and resulting diversity of species, and he sent a draft of a paper to that effect to Darwin with a request for Darwin's input and editing. Realizing that he was about to be upstaged by this newcomer to the field, Darwin rushed to publish. He gave Wallace credit in his book for the work Wallace had done and for independently coming up with the idea, which was a reasonably classy thing to have done under the circumstances, but he still claimed to have derived the theory first.
The book was an immediate bombshell dropped on the scientific establishment of the world. The power and effectiveness of the concept quickly gained adherence, and the necessity of excluding a guiding divine hand from the process was almost as immediately recognized as a threat to religion and a refutation of even an allegorical interpretation of the Genesis myth. Darwin spent thehttp://www.blogger.com/ rest of his life seeing the forces of religion attacking him and his theories. Indeed, that intellectual battle still rages today.
This was a matter that did not pain Darwin overmuch. He had been raised as a nonconformist Unitarian by freethinking parents; he openly questioned why one religion should be deemed superior to another. He resisted characterizing himself as an atheist, preferring to say he was an agnostic. He participated in the charitable and community activities of his church but skipped the religious services (which his family attended; during the sermons he would take long walks and then meet up with his family later in the day for meals).
His observations of episodes of astonishing pain the the natural world left him comfortable with the concept that there had been no guidance in that process by a benevolent God; he wrote on this subject "I cannot persuade myself that a beneficent and omnipotent God would have designedly created parasitic wasps with the express intention of their feeding within the living bodies of Caterpillars." The digger wasp implanting its larvae in the living body of a caterpillar so that the young wasps have fresh, living meat to eat while being born seems cruel, but it is more accurate to call it unthinkingly pitiless. There was simply no role for God in such a vision of nature.
Darwin was not well aware of the internal mechanism of how species adapt and change over time. We know now, of course, that the foundations of that branch of science were being laid by a contemporary of Darwin's, Gregor Mendel, in experiments with pea plants and fruit flies, explored the mechanisms of inherited traits and gene theory. Mendel's work went unnoticed for much of his lifetime (and Darwin's) but the two theories were synthesized in the 1930's and 1940's by a variety of scientists working two generations after Darwin's death. It is difficult to imagine Darwin being displeased with this discovery, as well as the subsequent vindication of it by the accumulated weight of two more generations' worth of observations, experimentations, and the use of progressively more and more powerful instruments.
There are those who insist that Darwin recanted of evolution completely on his deathbed, or that Augustine-like, he converted to some kind of Christianity on his deathbead. This is utter and complete bullshit and Darwin would have considered it slander, although he would probably have been too polite to actually say so or do anything about it, given that a minor noblewoman was the author of this fiction.
But if modern genetic science has accomplished miracles -- and there is little doubt that it has; you and I probably both owe our lives to its accomplishments -- it is because the miracle workers have stood on the shoulders of a giant, and that giant was Charles Darwin. The power and scope of Darwin's theory are so great that the concept of evolution by way of natural selection is as fundamental to the concept of biology as the Copernican theory of heliocentricity is the field of astronomy. It is, perhaps, "only a theory," but a proven theory, the only theory that has ever been offered that makes observable facts fall into place and harmoniously make sense of the world. Professor Theodosius Dobzhansky, an acclaimed Ukranian-American genecicist (and a devout Eastern Orthodox Christian), famously wrote in 1973 that "Nothing in biology makes sense except in the light of evolution." It is ultimately to Charles Darwin that we owe this remarkable and powerful idea, which has been responsible for so much life and healing ever since.
Happy Darwin Day, everyone.