The Science of Discworld III - Darwin's Watch

10. WATCH-22

IN THE STANDARD VERSION OF Roundworld history, Charles Darwin's presence on the Beagle came about only because of a highly improbable series of coincidences - so improbable that it is tempting to view them as wizardly intervention. What Darwin expected to become was not a globetrotting naturalist who revolutionised humanity's view of living creatures, but a country vicar.

And it was all Paley's fault.

Natural Theologys seductive and beautifully argued line of reasoning found considerable favour with the devout people of Georgian (III and IV) England, and after them, the equally devout subjects of William IV and Victoria. By the time Victoria ascended to the throne, in 1837, it was indeed almost compulsory for country vicars to become experts in some local moth, or bird, or flower, and the Church actively encouraged such activities because they were continuing revelations of the glory of God. The Suffolk rector William Kirby was co-author, with the businessman William Spence, of a lavish four-volume treatise An Introduction to Entomology, for example. It was fine for a clergyman to interest himself in beetles. Or geology, a relatively new branch of science that had grabbed the young Charles Darwin's attention.

The big breakthrough in geology, which turned it into a fully fledged science, was Charles Lyell's discovery of Deep Time - the idea that the Earth is enormously older than Ussher's 6000 years. Lyell argued that the rocks that we find at the Earth's surface are the product of an ongoing sequence of physical, chemical, and biological processes. By measuring the thickness of the rock layers, and estimating the rate at which those layers can form, he deduced that the Earth must be extraordinarily ancient.

Darwin had a passion for geology, and absorbed Lyell's ideas like a sponge. However, Charles was basically rather lazy, and his father knew it. He also knew, to quote Adrian Desmond and James Moore's biography Darwin, that: The Anglican Church, fat, complacent, and corrupt, lived luxuriously on tithes and endowments, as it had for a century. Desirable parishes were routinely auctioned to the highest bidder. A fine rural `living' with a commodious rectory, a few acres to rent or farm, and perhaps a tithe barn to hold the local levy worth hundreds of pounds a year, could easily be bought as an investment by a gentleman of Dr. Darwin's means and held for his son.

That, at least, was the plan.

And at first, the plan seemed to be working. In 1828 Charles was admitted to the University of Cambridge, taking his oath of matriculation one cold January morning, swearing to uphold the university's ancient statutes and customs, `so help me God and his holy Gospels'. He was enrolled at Christ's College for a degree in theology, alongside his cousin William Darwin Fox who had started the previous year. (Charles had previously attempted medicine in Edinburgh, following in the footsteps of his father and grandfather, but he became disillusioned and left without a degree.) After getting his Batchelor of Arts degree, he might spend a further year reading theology, ready to be ordained in the, Anglican Church. He could become a curate, marry, and take up a rural position near Shrewsbury.

It was all arranged.

Shortly after starting at Christ's, Charles was bitten by the beetle bug, as it were. An Introduction to Entomology sparked off an intense interest in beetles, when seemingly half the nation was out searching the woods and hedgerows to find new species. Since there were more species of beetle in the world than anything else, this was a serious prospect. Charles and his cousin scoured the byways of rural Cambridgeshire, pinning their catches in neat rows on large sheets of cardboard. He didn't find a new species of beetle, but he found a rare German one, seen only twice before in the whole of England.

Towards the end of his second year at university, exams loomed. Darwin had been too intent on beetles and a young lady named Fanny Owen and had neglected his academic studies. Now he had a mere two months left to do the work of two years. In particular, there would be ten questions on the book Evidences of Christianity, by one William Paley. Darwin had already read the book, but now he read it again with new attention - and loved it. He found the logic fascinating. Moreover, Paley's political leanings were distinctly leftwing, which appealed to Charles's innate sense of social justice. Bolstered by his studies of Paley, Darwin scraped through.

Next in line were the final exams. Another of Paley's books was on the syllabus: Principles of Moral and Political Philosophy. The book was outdated, and sailed close to the wind of (political) heresy and well into the shallows of unorthodoxy; that was why it was on the syllabus. You had to be able to argue the case against it, where applicable. It said, for example, that an established Church formed no part of Christianity. Darwin, then a very conventional Christian, wasn't sure what to think. He needed to broaden his reading, and in so doing he selected yet another book by his idol Paley: Natural Theology. He knew that many intellectuals derided Paley's stance on design as naive. He knew that his own grandfather, Erasmus Darwin, had held a radically different view, speculating about spontaneous changes in organisms in his own book Zoonomia. Darwin's sympathies were with Paley, but he started wondering how scientific laws were established, and what kind of evidence was acceptable, a quest that led him to a book by Sir John Herschel with the mind-numbing title Preliminary Discourse on the Study of Natural Philosophy. He also picked up a copy of Alexander von Humboldt's Personal Narrative, a 3754-page blockbuster about the intrepid explorer's trip to South America.

Darwin was entranced. Herschel stimulated his interest in science, and Humboldt showed him how exciting scientific discoveries could be. He determined, then and there, to visit the volcanoes of the Canary Islands and see for himself the Great Dragon Tree. His friend Marmaduke Ramsay agreed to accompany him. They would leave for the tropics once Darwin had signed the 39 Articles of the Anglican Church at his degree ceremony. To prepare for the journey, Charles went to Wales to carry out geological fieldwork. He discovered that there was no Old Red Sandstone in the Vale of Clwyd, contrary to the current national geological map. He had won his geologists' spurs.

Then a message arrived. Ramsay had died. The Canary scheme shuddered to a halt. The tropics seemed further away than ever. Could Charles go it alone? He was still trying to decide when a bulky package arrived from London. Inside was a letter, offering him the opportunity to join a voyage round the world. The ship would sail in a month.

The British Navy was planning to explore and map the coast of South America. It was to be a chronometric survey, meaning that all navigation would be done using the relatively new and not fully trusted technique of finding longitude with the aid of a very accurate watch or chronometer. A 26-year-old sea captain, Robert FitzRoy, would head the expedition; his ship would be the Beagle.

FitzRoy was worried that the solitude of his command might drive him to suicide. The risk was not far-fetched: the Beagle's former captain Pringle Stokes had shot himself while mapping a particularly convoluted bit of the coast of South America. Further, one of FitzRoy's uncles had slit his own throat in a fit of depression.'[27] So he had decided that he needed someone to talk to, to keep him sane. It was this position that was now being offered to Darwin. The job would be especially suitable for someone with an interest in natural history, and the ship had the necessary scientific equipment. Technically, Darwin would not be `ship's naturalist', as later he sometimes claimed, and that presumption would eventually lead to an almighty row with the Beagle's surgeon Robert McCormick, because by tradition the surgeon did the job of naturalist in his spare time. Darwin was being hired as a `gentleman companion' for the captain.

Charles decided to accept the offer, but his father, forewarned by Charles's sisters, refused permission. Darwin could have gone against his father's wishes, but the thought made him feel very uncomfortable, so he wrote to the Navy and turned the job down. Then, uncharacteristically, his father opened a loophole - our first example of what looks suspiciously like wizardly interference. Charles might yet be allowed to go, he said, provided `some person of good standing' recommended it. Both Charles and his father knew who was meant: Uncle Jos (Wedgwood, grandson of the founder of the pottery company). Jos was an industrialist, and Dr Darwin trusted his judgement. So Charles and his uncle sat up very late, composing a suitable letter. Jos told Dr. Darwin that such a voyage would be the making of the young man. And, slyly, he added that it would improve his knowledge of natural history, which would be very useful for a subsequent career in the clergy.

Darwin Senior relented (score one to the wizards). Excited beyond measure, Charles hurriedly wrote another letter to the Navy, this time accepting. But then he heard from FitzRoy, who told him that the post was no longer vacant. The captain had given it to a friend.

However, Darwin was top of the list if his friend changed his mind.

Darwin went to London, to make contingency plans in case he got lucky, and to keep an appointment with FitzRoy. He arrived to be told that the captain's friend had changed his mind, not five minutes earlier. (Wizards again?) His wife had objected to the length of the voyage, then planned to be three years. Did Darwin still want the job?

Lost for words, Charles nodded.

Darwin's heart sank when he saw the ship. The Beagle was a rotting, eleven-year-old brig, with ten guns. It was being rebuilt, partly at FitzRoy's own expense, so it would be seaworthy enough. But the ship was cramped, a mere 90 feet (30m) long by 24 feet (8m) wide. Could his companionship with the captain survive such a lengthy voyage in such close contact? Fortunately, he was allocated one of the larger cabins.

The Beagle's assignment was to survey the southern end of South America, in particular the complicated islands around Tierra del Fuego. The Admiralty had provided 11 chronometers for navigation, because the trip would be the first attempt to circumnavigate the Globe using marine chronometers to find longitude. FitzRoy borrowed five more, then bought six himself. So the Beagle sailed with a massive 22 chronometers on board.

The voyage started badly. Darwin was sick as a dog, crossing the Bay of Biscay, and had to endure the sound of sailors being flogged as he lay nauseated in his hammock. FitzRoy was hot on discipline, especially at the beginning of a voyage. Privately, the captain expected his `companion' to jump ship the moment it touched land, and hotfoot it back to England. The ship was supposed to put in at Madeira to take on fresh food, which would be the perfect opportunity. But the Madeira landing was cancelled because the sea was too heavy and there was no pressing need (score 3 to the wizards?).

Instead, the Beagle headed for Tenerife in the Canaries. If Charles jumped ship there, he could see the volcanoes and the Great Dragon Tree. But the consul in Santa Cruz was scared that visitors from England might introduce cholera to his islands, and he refused the Beagle permission to put into port without undergoing quarantine (score 4? We'll see). Unwilling to wait off land for the required two weeks, FitzRoy ordered the Beagle south, to the Cape Verde Islands.

It may not have been the wizards at work, but something was determined that Charles should stay on the Beagle. And now, a fifth coincidence, involving his great love, geology, made it impossible for him to do anything else. As the Beagle sailed westward, the ocean grew calm, the air warm. Darwin could trawl for plankton and jellyfish with home-made gauze nets. Things were looking up. And when they finally touched land, the island of St Jago in the Cape Verde Islands, Darwin found it hard to believe his luck. St Jago was a rugged volcanic outcrop, with conical volcanoes and lush valleys. Charles could do geology. And natural history.

He collected everything. He noticed that an octopus can change colour, and mistakenly thought this was a new discovery. After two days, he had worked out the geological history of the island, using the principles he had learned from Lyell. Lava had flowed over the seabed, trapping shells and other debris, and had later been raised to the surface. All of this must have happened relatively recently, because the shells were just like the fresh ones lying on the beach. This was not the conventional theory of the day, which held that volcanic structures were incredibly old.

The young man was coming into his own.

In the end, the voyage lasted five years, and in the whole of that time, poor Darwin never found his sea-legs. Even on the final run home, he was still seasick. But he contrived to spend most of the voyage on land, and only 18 months at sea. And while on land, he made discovery after discovery. He found fifteen new species of flatworm in Brazil. He studied rheas, giant flightless birds related to the ostrich, in Argentina. There, too, he found fossils, including the head of a giant armadillo-like glyptodont. In Tierra del Fuego he turned anthropologist, and studied the people. `I shall never forget how savage & wild one group was,' he wrote, on encountering `naked savages'. He found more fossils, among them bones of the groundsloth Megatherium and the llama-like Macrauchenia. In Chile, he studied the geology of the Andes and decided that they, and the plains beyond, had been thrust skyward in some gigantic geological upheaval.

From the South American mainland, the Beagle went north-west to the Galapagos, a tight group of a dozen or so islands, far out into the Pacific ocean. The islands had fascinating geology, mainly volcanic, and a great variety of animals that were not found anywhere else. There were the spectacular giant tortoises that had given the islands their name. Darwin measured the circumference of one as seven feet (2m). There were iguanas, and birds - boobies, warblers, finches. The finches had beaks of different shapes and sizes, depending on the food they ate, and Darwin divided them up into a series of subfamilies. He did not notice that different types of animals occurred on different islands, until Nicholas Lawson pointed this out. (The wizards again? Oh yes, this will have happened soon ...) But he did notice that the mockingbirds of Charles and Chatham islands (now Santa Maria and San Cristobal) were different species, and when, now alerted, he looked on James Island (San Salvador), he found yet a third species. But Darwin was not greatly interested in small variations in species, or how those variations corresponded to the local geography. He was vaguely aware of some theorising about species change, or `transmutation', if only from his grandfather Erasmus, but the topic didn't interest him and he saw no reason to collect evidence for or, against it.

And so the Beagle continued to Tahiti, New Zealand, and Australia.

Darwin had seen wonders that would shortly revolutionise the world. But he did not yet understand what he had seen.

In Tahiti, though, he glimpsed his first coral reef. Before leaving Australia, he was determined to find out how coral islands came into being. Lyell had suggested that because the coral animals live only in shallow waters, with ample sunlight, the reefs must be built on top of submerged volcanoes. This also explained their ringed shape. Darwin didn't believe Lyell's theory. `The idea of a lagoon island, 30 miles in diameter being based on a submarine crater of equal dimensions, has always appeared to me to be a monstrous hypothesis.' Instead, he had his own theory. He already knew that land could rise, he'd seen that in the Andes. He reasoned that if some land went up, then other land ought to go down, to maintain the balance of the Earth's crust. Suppose that when the reef started to form, the water was shallow, but then the ocean floor started descending slowly, while the coral polyps at the surface continued building the reef. Then eventually you would get a huge mountain of coral rising from what was now the ocean depths - all built by tiny creatures, always in shallow water while the building was going on. The shape? That was the result of an island with a fringing reef collapsing. The island would sink, leaving a hole in the middle, but the reef would continue to grow.

Five years and three days after the Beagle set sail from Plymouth, Darwin walked into the family home. His father glanced up from his breakfast. `Why,' he said, `the shape of his head is quite altered.'

Darwin did not come up with the concept of evolution during his Beagle voyage. He was too busy amassing specimens, mapping geology, taking notes, and being seasick, to have time to organise his observations into a coherent theory. But when the voyage was over, he was promptly elected to the Royal Geological Society. In January 1837 he presented his inaugural paper, on the geology of Chile's coast. He suggested that the Andes mountains had originally been the ocean floor, but had later been uplifted. His diary records amazement at `the wonderful force which has upheaved these mountains, & even more so the countless ages needed to have broken through, removed & levelled whole masses of them'. Much later, the Chilean coast became part of the evidence for `continental drift': we now think that these mountains result from subduction, as the Nazca tectonic plate slides underneath the South American plate.

Darwin could certainly spot them.

His interest in geology had other, less obvious, implications. He was starting to wonder about the finches of the Galapagos. They seemed to contradict Lyell's view that local geological conditions determined what species were created. It was a puzzle.

In fact, it was more of a puzzle than Darwin thought, because he had misunderstood the finches completely. He thought they all fed on the same food, in big flocks. He had not noticed important differences among their beaks, and he even had trouble identifying different species. Some, he believed, were not finches at all, but wrens and blackbirds. He was so baffled by the birds, and so indifferent to the specimens he had collected, that he donated the lot to the Zoological Society. Within ten days the Society's bird expert John Gould had worked out that they were all finches, all very closely related, forming a tightly knit grouping that nonetheless contained twelve[28] distinct species. This number was surprisingly large for such a small group of tiny islands. What had caused such diversity? Gould wanted to know, but Darwin didn't care.

By 1837, Paley's logic was no longer in vogue. The scientifically literate theist now believed that God had set up the laws of nature at the time of Creation, and that those laws included not just the `background' laws of physics, to which Paley subscribed, but also the development of living creatures, which Paley had denied. The laws of the universe were fixed for all eternity. They had to be, otherwise God's creation was flawed. Paley's analogies were used against him. What kind of artificer made such bad machinery that He had to keep tinkering with it all the time to keep it working?

Science and theology were ripping asunder. The political corruption of the Church was becoming undeniable; now its intellectual claims were also coming under fire. And some radical thinkers, often medics who had studied comparative anatomy and noticed remarkable similarities between the bones of entirely different animals, were engaged in speculation that changed the view of creation itself. According to the Bible, God had created each type of animal as a one-off item - whales and winged fowl on the fifth day, cattle and creeping things and humans on the sixth. But these medical types were starting to think that species could change, `transmute'. Species were not fixed for all time. They realised that there was a rather big gap between, say, a banana and a fish. You couldn't cross that gap in one step. But given enough time, and enough steps ...

Darwin slowly became caught up in the flow. His Red Notebook, where he recorded anything that he saw or that came to mind, began to hint at the `mutability of species'. The hints were incomplete and ill-assorted. Deformed babies resembled new species. The beaks of Galapagos finches were of different shapes and sizes. Rheas were a puzzle, though: two distinct species of the giant birds had overlapping ranges in Patagonia. Why didn't they merge into a single species?

By July, he had secretly started a new notebook, his B Notebook.

It was on the transmutation of species.

By 1839 Darwin was building up a complete picture, and he wrote a 35-page summary of his thinking. A crucial influence was Thomas Malthus, whose 1826 Essay on the Principle of Population pointed out that the unchecked growth of organisms is exponential (or 'geometric', in the old-fashioned phrase of the time), whereas that of resources is linear (`arithmetic'). Exponential growth occurs when each step multiplies the size by some fixed amount, for example 1, 2, 4, 8, 16, 32, where each number is twice the previous one. Linear growth adds some fixed amount at each step, for instance 2, 4, 6, 8, 10, where each number exceeds the previous one by 2. However small the multiplier is in exponential growth, provided it is bigger than 1, and however large the number added in linear growth may be, it turns out that in the long run exponential growth always beats linear. Though it does take some time if the multiplier is close to 1 and the number being added is huge.

Darwin had taken on board Malthus's argument, and he had realised that in practice what keeps populations down is competition for resources, such as food and a place to live. This competition, he wrote, leads to `natural selection', in which those creatures that are victorious in the `war of nature' are the ones that produce the next generation. Individual creatures within a species are not exactly identical; those differences make it possible for the force of natural selection to produce slow, gradual changes. How far might such changes go? In Darwin's view, very far indeed. Far enough to lead to entirely new species, given enough time. And thanks to geology, scientists now knew that the Earth was very, very old.

Darwin, following family tradition, was a Unitarian. This particular branch of Christianity has been aptly described as `people who believe in at most one God'. As a sound Unitarian, he believed that the Deity must work on the grandest of scales. So he finished his summary with a powerful appeal to the Unitarian view of the Deity: It is derogatory that the Creator of countless systems of worlds should have created each of the myriads of creeping parasites and slimy worms which have swarmed each day of life on land and water on this one globe. We cease being astonished, however much we may deplore, that a group of animals should have been directly created to lay their eggs in bowels and flesh of others - that some organisms should delight in cruelty ... From death, famine, rapine, and the concealed war of nature we can see that the highest good, which we can conceive, the creation of the higher animals has directly come.

God surely has better taste than to create nasty parasites directly. They exist only because they are a necessary step along the path that leads to cats, dogs, and us.

Darwin had his hypothesis.

Now he began to agonise about how to bring it to the waiting world.