Complexity_ A Guided Tour - Melanie Mitchell [38]
Lyell agreed that, in order to solve the priority problem, Darwin and Wallace should publish their work together. This joint work was read to the Linnean Society in the summer of 1858. By the end of 1859, Darwin had published his 400-plus-page book On the Origin of Species.
It turns out that the priority issue was not fully solved. Unbeknown to Darwin, twenty-eight years before the publication of the Origin, a little-known Scot named Patrick Matthew had published an obscure book with an equally obscure title, On Naval Timber and Arboriculture, in whose appendix he proposed something very much like Darwin’s evolution by natural selection. In 1860, Matthew read about Darwin’s ideas in the periodical Gardiner’s Chronicle and wrote a letter to the publication citing his priority. Darwin, ever anxious to do the right thing, responded with his own letter: “I freely acknowledge that Mr. Matthew has anticipated by many years the explanation which I have offered of the origin of species, under the name of natural selection…I can do no more than offer my apologies to Mr. Matthew for my entire ignorance of his publication.”
So who actually is responsible for the idea of evolution by natural selection? Evidently, this is another example of an idea that was “in the air” at the time, an idea that someone would inevitably come up with. Darwin’s colleague Thomas Huxley realized this and chided himself: “How extremely stupid not to have thought of that!”
Why does Darwin get all the credit? There are several reasons, including the fact that he was at that time a more famous and respected scientist than the others, but the most important reason is that Darwin’s book, unlike the works of Wallace and Matthew, contained a more coherent set of ideas and a tremendous amount of evidence supporting those ideas. Darwin was the person who turned natural selection from an interesting and plausible speculation into an extremely well-supported theory.
To summarize the major ideas of Darwin’s theory:
Evolution has occurred; that is, all species descend from a common ancestor. The history of life is a branching tree of species.
Natural selection occurs when the number of births is greater than existing resources can support so that individuals undergo competition for resources.
Traits of organisms are inherited with variation. The variation is in some sense random—that is, there is no force or bias leading to variations that increase fitness (though, as I mentioned previously, Darwin himself accepted Lamarck’s view that there are such forces). Variations that turn out to be adaptive in the current environment are likely to be selected, meaning that organisms with those variations are more likely to survive and thus pass on the new traits to their offspring, causing the number of organisms with those traits to increase over subsequent generations.
Evolutionary change is constant and gradual via the accumulation of small, favorable variations.
According to this view, the result of evolution by natural selection is the appearance of “design” but with no designer. The appearance of design comes from chance, natural selection, and long periods of time. Entropy decreases (living systems become more organized, seemingly more designed) as a result of the work done by natural selection. The energy for this work comes from the ability of individual organisms to metabolize energy from their environments (e.g., sunlight and food).
Mendel and