Went to a talk by ex-BBC producer Roy Davies today, about his new book The Darwin Conspiracy, which supposedly proves that Darwin stole Alfred Russel Wallace's ideas rather than coming up with them independently. Davies' argument in the talk was three-pronged: (1) Darwin was provably mendacious, (2) Darwin's 1840s work on evolution was entirely wrongheaded, and there's no reason to believe that he was on the right track before Wallace's letters reached him, and (3) Darwin lied about when Wallace's letters reached him, on the evidence of a bunch of 1850s Indonesian naval timetables that show when the mailboats came and went from wherever Wallace was at the time. Davies' work seems either comprehensively false or largely correct, as his story hangs together quite well. I have no idea of how sound the detective work on (3) is, but if (1) and (2) are true then (3) is plausible anyway. The main evidence for (1) is that Darwin silently edited his Beagle diaries between the 1839 edition and the 1844 edition to insert a bunch of material semi-plagiarized from Edward Blyth and possibly Vestiges of Creation. As for (2), Davies claims that Darwin's 1840s work on evolution was mostly based on the idea that species swam across the sea and found themselves in new surroundings where they had "somehow" to adapt to survive; and that Darwin hadn't thought of survival of the fittest at this point. As someone who's utterly unfamiliar with 19th-century biology, I'm curious to know if Davies is entirely making this up.
As for how this fits into the larger picture, it's of no consequence whether Darwin or Wallace came up with the theory of evolution, or whether Darwin was a crook. But it's always seemed to me -- and here of course I differ from Davies -- that Darwin/Wallace get way too much relative credit for their contributions to evolutionary theory. The story as I see it goes something like this:
1. Early 1800s geologists find out that the geography of the earth changes over time, sometimes relatively fast. The earth appears to be pretty old. Native species seem well-adapted to their changing environments; this is implausible in the extreme if everything was created at once. Therefore, some sort of adaptation must happen. Also, there are fossils.
2. The species native to some (old) islands are highly distinctive, whereas those from recently isolated islands are similar to the mainland varieties. The pattern of similarities in archipelagoes, in particular, -- Indonesia, the Galapagos -- seems strongly suggestive of a common ancestor from whom the varieties diverged over time because they were isolated. This gets you the "descent with modification" part.
3. A half-assed analogy with Malthus leads to the claim that descent with modification is due to "survival of the fittest" while competing for scarce resources. This claim was largely unsubstantiated (it's more a conjecture than anything else) and had huge problems, e.g., that with "blending inheritance" -- the naive belief that characteristics "blend" during reproduction, which I think everyone believed at the time -- mutations are unlikely to survive.
4. Gregor Mendel discovers that inheritance is particulate rather than blending, i.e., that black + black = white 1/4 of the time, and basically invents genetics. I don't know if Mendel thought about the implications for evolution, but this is really the key point that makes natural selection work.
5. 20th-century geneticists -- people like Morgan, Fisher, and Haldane -- turn genetics into a proper experimental science and construct the theory of evolution through natural selection, or, if you like, prove Darwin's conjecture using Mendel's theory.
In terms of importance I would rank these 4-1-5=2-3 -- and that's without discounting 3. as derivative of Malthus. First of all, 3. is conceptually shaky without 4., and vague besides; this is evident from e.g., the fact that the next major advances in evolutionary theory came through 4. via 5. This is rarely the case with true scientific breakthroughs. Second, I feel like 4. would have led immediately to 3. once people started taking Mendel seriously. This is because 1. and 2. had opened up the question of the variation of species (which is why they are important advances).
It would be a gross exaggeration to say that Darwin discovered evolution like Democritus discovered atoms, but not, I suspect, a complete falsehood.
PS Wallace was a spiritualist and a teleologically minded type so it's probably a good thing he didn't grow too influential. Besides, he was no Marsellus Wallace.