150 years ago on November 24th a naturalist born 50 years earlier named Charles Darwin published a book with a rather long and cumbersome title. It was called On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life (for its sixth edition in 1872, the title was cut short to simply The Origin of Species, which was found to be much more manageable to say in conversation). It was inspired by an almost five year journey around the world on a ship named for a small, floppy eared canine during which Darwin did his best to catalog and understand geology and the diversity of life he found.
It's incomprehensible, now, to think of someone writing a single volume that could equally change science as we know it. The two simple ideas that Darwin fleshed out in his first publication were earth shattering at the time. He has since been called both a genius and a heretic for these two theories - both titles equally deserved. But whatever you call him, his vision has changed the world irrevocably. Indeed, you do not hear of people calling anyone "Newtonists" or "Einsteinists". He is alone among scientists to have spurred an "-ism" with "-ists" for followers. Even still, I am not a Darwinist.
In On the Origin of Species (for short), Darwin proposed two related but different scientific theories. The first is generally referred to as Common Descent, which asserts that organisms are related through a single ancestor, like branches of a tree which all erupt from a solitary trunk - indeed, the metaphor of a "tree of life" is often how such relationships are depicted. In modern science, common descent is generally taken as fact with overwhelming support. Even when first proposed, the idea was quickly accepted among the scientific community. The evidence was everywhere, and it was like someone had finally produced the key to a locked door in scientific thought. It was already known by those who bred domesticated animals that two very different looking and behaving creatures could come from specific breeding for certain traits. There was no doubt, then, that two similar beasts could be pulled from one - the only question was how much had this occurred in the past, and how.
To some of the religious, Common Descent only supported their beliefs in God. It seemed the perfect blend of what they could see and what they believed. God, thus, acted upon nature how we do with dogs, picking and choosing which to breed with what to produce the fantastic variety of animals on the planet. How many initial "ancestors" he started with might be up for debate, but the idea that he fine-tuned a generic "cat" to become tigers, leopards and irritable house pets suited most of them just fine. If anything, it seemed to elegantly explain how God might have created life.
No, Darwin was not a heretic for asserting that animals could have evolved from distinct ancestors. He was labeled a heretic because of his second proposal - that of the means.
The second theory in his book was far more controversial and, initially, garnished far less acceptance. This was the theory of Natural Selection. Darwin proposed that the variation between animals, when not intentionally bred by humans, was due to favorable traits being passed down from generation to generation via the individuals interaction with its enviroment. In his own words, he described natural selection as thus:
Owing to this struggle for life, any variation, however slight and from whatever cause proceeding, if it be in any degree profitable to an individual of any species, in its infinitely complex relations to other organic beings and to external nature, will tend to the preservation of that individual, and will generally be inherited by its offspring. The offspring, also, will thus have a better chance of surviving, for, of the many individuals of any species which are periodically born, but a small number can survive. I have called this principle, by which each slight variation, if useful, is preserved, by the term of Natural Selection, in order to mark its relation to man's power of selection. We have seen that man by selection can certainly produce great results, and can adapt organic beings to his own uses, through the accumulation of slight but useful variations, given to him by the hand of Nature. But Natural Selection, as we shall hereafter see, is a power incessantly ready for action, and is as immeasurably superior to man's feeble efforts, as the works of Nature are to those of Art.
At the time, the idea that species could change without some kind of input similar to that of man was not only impossible, it was heresy. Even some of Darwin's staunchest supporters viewed the idea that natural variation could cause the dramatic diversity of life as highly unlikely. To have such changes occur with no "guidance" and so slowly was just not believable. It wasn't until the 1930s, with the integration of Mendelian genetics that the scientific community fully realized the accuracy and feasibility of Darwin's mechanism.
However, the final result of the two theories, now known together as "Evolution", has come a long way since Darwin. Indeed, Evolution by Darwinian Natural Selection only begins to touch on what is meant to most by the term Evolution. It is for this reason, you see, that I am not a Darwinist.
It's not that Darwin was wrong, as some feeble-minded magazine cover designers have purported. It's that he wasn't complete. And how could he have been? He had no understanding of how traits were passed down between generations or how, even, those traits were stored as information. Even more, his theory lacked the ability to explain how negative traits survive and flourish in populations, or how seemingly neutral ones change in frequency.
Darwinism, in the sense it was first coined and indeed how it is often used today, is strictly the belief that Darwin's theories are a sufficient explanation of the origins and diversification of life. It is the assertion that Natural Selection is the mechanism by which one common ancestor became a vast array of species. And, simply put, I don't agree.
While Natural Selection is clearly a viable, true mechanism for evolution, it's hardly the only one. To assume that a trait must be favorable in some way to be passed down and increase in frequency is simply inaccurate. Evolution, as it now has come to mean, is the change in alleles (those little bits of information that store traits that Darwin didn't know about) in a population. So to say that the only way the relative frequency of a trait can change is by it allowing an individual to survive and breed more than others is silly. Genetic Drift, Gene Flow and Mutation all cause changes in allele frequency, and not necessarily making the individuals or the group more "fit". There is a clear role for chance - for example, if a hurricane suddenly wiped out the entire population of Florida, we would not say that the resulting change in allele frequency in the U.S.A. was due to them being "less fit"; they were simply in the wrong place at the wrong time. Similarly, alleles which affect an organism after its ability to reproduce are not subjectable to Natural Selection, but, I would argue,certainly are a part of evolution. And where does horizontal gene transfer fit into "Darwinian" theory? Short answer, it doesn't - not easily, anyhow.
Darwin began a movement and an understanding of life that we have only begun to appreciate. But to call evolution "Darwinian" is to dismiss all the work that has been done since his time and all that we have learned from it. Darwin was a scientific pioneer who laid the groundwork for modern evolutionary theory, but he was no singular hero. Thus I find it at best inaccurate, and at worst perhaps insulting, that having even a slight grasp of evolution and support for its mechanisms is often singularly called "Darwinism". Not only does it belittle the countless others who have aided to and complimented the theory, it makes it sounds like evolution is just another ideology, like "Marxism" or "Communism". Evolution is not a belief - it's a scientifically tested theory. No one claims that the "belief" in Gravitational Theory is some form of "-ism" like "Newtonism", with those that say objects do obey given laws of gravity labeled "Newtonists". So while I have an astounding amount of admiration and respect for the Darwin and the incredible discoveries and insights he provided, I am not, nor will ever be, a "Darwinist".
I am a Scientist who finds Evolution to be the most scientifically accurate and clear explanation for the diversification of life from one or more entities that formed from a chemical base. Evolution is no longer simple, linear Darwinism, where the toughest and fittest survive. Evolution is a fine web of connections and adaptations with ever increasing complexity and elegance. We have yet to fully unravel the mysteries surrounding how genes originated, moved and diversified, not just vertically but horizontally, between related and distant species, in entirely un-"Darwinian" ways. But, like we credit Newton for Gravity despite gaping flaws in his assumptions and exact calculations of the force, so too should we celebrate Darwin on this year, the 150th anniversary of The Origin of Species and his 200th birthday, as the grandfather of Evolution. So while I am not a Darwinist, as I have explained, I might just let it slide if you call me one - for now - because I appreciate the legacy that he has given us all. And, in the end, I guess it is somewhat of an honor to be lumped in with the likes of him, even if the grouping is not entirely accurate.
**UPDATE: This post is up as a nominee for the 3 Quark's Daily Top Quark: Science! Go Vote For It Here!! (scroll down to the Os)