Science of Discworld III

the Narrative of the Surveying Voyages of H.M.S. Adventure and Beagle, Between the Years 1826 and 1836 , with the subtitle Volume 3: Journal and Remarks, 1832–1836 . After a few months the publishers reissued it on its own as Journal of Researches into the Geology and Natural History of the Various Countries Visited by H.M.S. Beagle . It may have been the wrong book,but writing it had one very useful effect on Darwin’s thinking. It forced him to try to make sense of all the things he had seen. Was there some overarching principle that could explain it all?
    Next came his geology book, which eventually turned into three: one on coral reefs, one on volcanic islands, and one on the geology of South America. These established his scientific credentials and led to him winning a major Royal Society prize. Darwin was now recognised as one of the leading scientists in the land.
    He was also making ever more extensive notes on the transmutation of species, but he still was in no hurry to publish. Quite the contrary. Elsewhere, political forces were at work aiming to destroy the influence of the Church, and one of their key points was that living creatures could easily have arisen without the intervention of a creator. Darwin, being (at that point in his life) a good Christian, was totally averse to anything that might seem to ally him with such people. He could not publicly espouse transmutation without risking serious damage to the Anglican Church, and nothing in the world would induce him to contemplate that. But his deep insight about natural selection wouldn’t go away, so he continued developing it as a kind of hobby.
    He did mention the insight to various scientific friends and acquaintances, among them Lyell, and also Joseph Dalton Hooker, who didn’t dismiss the idea out of hand. But he did tell Darwin, ‘I shall be delighted to hear how you think this change may have taken place, as no presently conceived opinions satisfy me on this subject.’ And he later said, rather acerbically, that ‘No one has hardly a right to examine the question of species who has not minutely examined many.’ Darwin took this advice to heart and cast around for new species to become an expert on. In 1846 he sent the final proofs of his geology books back to the printer and celebrated by collecting the last bottle of preserved specimens from the Beagle voyage. At the top of the bottle he noticed a crustacean from the Chonos Archipelago – a barnacle.
    That would do. It was as good as anything else.
    Hooker helped Darwin set up his microscope and make some preliminary anatomical observations. Darwin asked Hooker to name the new beast, and together they decided on Arthrobalanus . 1 ‘Mr Arthrobalanus’, as they privately called it, turned out to be somewhat unusual. ‘I believe Arthrobalanus has no ovisac at all!’ Charles wrote. ‘The appearance of one is entirely owing to the splitting & tucking up of the posterior penis.’ To resolve the mystery he took other barnacles from the bottle and looked at them, too. Now he was doing comparative anatomy of barnacles, and enjoying the hands-on experience immensely. This was better than writing.
    By Christmas he had decided to study every barnacle known to humanity – the entire order of Cirripedia . Which turned out to be rather a lot, so he settled for the British ones. Even these were rather a lot, and in the end the task took eight years.
    He might have finished earlier, but in 1848 he got interested in barnacle sex, and that was very peculiar indeed. Most barnacles were hermaphrodites, able to assume either sex. But some species had good old-fashioned males and females. Except that the males spent much of their lives embedded in the females .
    Not only that: some supposedly hermaphrodite species also had tiny males that somehow assisted in the reproductive process.
    Now Darwin became very excited, because he had convinced himself that what he was observing was a relic of evolution, as a hermaphrodite ancestor gradually developed separate sexes. A ‘missing link’ for barnacle sex. He could reconstruct the barnacles’ family tree, and what he thought he saw reinforced his views on natural selection. So even when he tried to do respectable science, and become a taxonomist, transmutation insisted in getting in on the act. In fact, if anything convinced Darwin he was right about transmutation, it was barnacles.
    He became ill, but continued working on barnacles. In 1851 he