Science of Discworld III

by Terry Pratchett

  An unexpected name is that of the Reverend Baden Powell, whose 1855 ‘Essays on the Unity of Worlds’ states that the introduction of new species is a natural process, not a miracle. Credit for mutability of species is also given to Karl Ernst von Baer, Huxley, and Hooker.

  Darwin was determined not to miss out anyone with a legitimate claim, and in all he lists more than twenty people who in various ways anticipated parts of this theory. He is absolutely explicit that he is not claiming credit for the idea that species can change, which was common currency in scientific circles – and, as Baden Powell shows, beyond. What Darwin is laying claim to is not the idea of evolution, but that of natural selection as an evolutionary mechanism.

  So … we come full circle. Does an innovative idea change the world, or does a changing world generate the idea?

  Yes.

  It’s complicity. Both of these things happen – not once, but over and over again, each progressively altering the other. Innovations redirect the course of human civilisation. New social directions encourage further innovation. The world of human ideas, and the world of things, recursively modify each other.

  That is what happens to a planet when a species evolves that is not merely intelligent, but what we like to call extelligent. One that can store its cultural capital outside individual minds. Which lets that capital grow virtually without limit, and be accessible to almost anybody in any succeeding generation.

  Extelligent species take new ideas and run with them. Before the ink was dry on Origin, biologists and laymen were already trying to test its ideas, shoot them down, push them further. If Darwin had written Ology, and if nobody else had written something like Origin, then Victorian extelligence would have been enfeebled, and perhaps the modern world would have taken longer to arrive.

  But it was evolution time. Somebody would have written such a book, and soon. And in that alternat(iv)e world of if, he or she would have got the credit instead.

  So it’s only fair to give Darwin the credit in this world. Steam engine time notwithstanding.

  1 Dry grass and drops of water are not commonly associated, but perhaps a damp elephant had just emerged from a river crossing on to dry savannah … Oh, invent your own explanation.

  2 See The Science of Discworld.

  3 What would have happened if Darwin had gone back in time and killed his own grandfather?

  NINETEEN

  LIES TO DARWIN

  ARCHCHANCELLOR RIDCULLY’S MOUTH DROPPED OPEN.

  ‘You mean killed?’ he said.

  +++ No +++, Hex wrote, +++ I mean vanished. Darwin disappears from Roundworld in 1850. This is a new development. That is to say, it has always happened, but has always happened only for the last two minutes +++

  ‘I really hate time travel,’ sighed the Dean.

  ‘Kidnapped?’ said Ponder, hurrying across the hall.

  +++ Unknown. Phase space currently contains proto-histories in which he reappears after a fraction of one second and others where he never reappears at all. Clarity must be restored to this new node +++

  ‘And you only tell us this now?’ said the Dean.

  +++ It has only just happened +++

  ‘But,’ the Dean attempted, ‘when you looked at this … history before, this wasn’t happening!’

  +++ Correct. But that was then then, this is then now. Something has been changed. I surmise that this is as a result of our activities. And, having happened, it has always happened, from the point of view of an observer in Roundworld +++

  ‘It’s like a play, Dean,’ said Ponder Stibbons. ‘The characters just see the act they’re in. They don’t see the scenery being shifted because that’s not part of the play.’

  +++ Despite being wrong in every important respect, that is a very, good analogy +++ Hex wrote.

  ‘Have you any idea where he is?’ said Ridcully.

  +++ No +++

  ‘Well, don’t just sit there, man, find him!’

  Rincewind reappeared above the lawn, and rolled expertly when he hit the ground. Other wizards, nothing like so experienced at dealing with the vicissitudes of the world, lay about groaning or staggered around uncertainly.

  ‘It wears off,’ he said, as he stepped over them. ‘You might throw up a bit at first. Other symptoms of rapid cross-dimensional travel are short-term memory loss, ringing in the ears, constipation, diarrhoea, hot flushes, confusion, bewilderment, a morbid dread of feet, disorientation, nose bleeds, ear twinges, grumbling of the spleen, widgeons, and short-term memory loss.’

  ‘I think I’d like to … thing … end of your life thing …’ murmured a young wizard, crawling across the damp grass. Nearby, another wizard had pulled off his boots and was screaming at his toes.

  Rincewind sighed and made a grab at an elderly wizard, who was staring around like a lost lamb. He was also soaking wet, having apparently also landed in the fountain.

  He looked familiar. It was impossible to know all the wizards in UU, of course, but this one he had definitely seen before.

  ‘Are you the Chair of Oblique Frogs?’ he said.

  The man blinked at him. ‘I … don’t know,’ he said. ‘Am I?’

  ‘Or the Professor of Revolvings?’ said Rincewind. ‘I used to write down my name on a piece of paper before this sort of thing. That’s always a help. You look a bit like the Professor of Revolvings.’

  ‘Do I?’ said the man.

  This looked like a very bad case. ‘Let’s find you your pointy hat and some cocoa, shall we? You’ll soon feel—’

  The Luggage landed with a thump, raised itself on its legs, and trotted away. The possible Professor of Revolvings stared at it.

  ‘That? Oh, it’s just the Luggage,’ said Rincewind. The man didn’t move. ‘Sapient pearwood, you know?’ Rincewind carried on, watching him anxiously. ‘It’s very clever wood. You can’t get the very clever wood any more, not around here.’

  ‘It moves about?’ said the possible professor.

  ‘Oh, yes. Everywhere,’ said Rincewind.

  ‘I know of no plant life that moves about!’

  ‘Really? I wish I didn’t,’ said Rincewind, fervently, gripping the man a little tighter. ‘Come on, after a nice warm drink you’ll—’

  I must examine it closely! I am aware, of course of the so-called Venus Fly—’

  ‘Please don’t!’ Rincewind pleaded, pulling the man back. ‘You cannot botanise the Luggage!’

  The bewildered man looked around with a desperation that was shading into anger.

  ‘Who are you, sir? Where is this place? Why are all these people wearing pointy hats? Is this Oxford? What has happened to me!’

  A chilly feeling was creeping over Rincewind. Quite probably, he alone of all the wizards had read Ponder’s briefings as they arrived by surly porter; it paid to know what you might have to run away from. One had included a picture of a man who looked as if he was evolving all by himself, an effect caused by the riot of facial hair. This man was not that man. Not yet. But Rincewind could see that he would be.

  ‘Um,’ he said, ‘I think you should come and meet people.’

  It seemed to the wizards that Mr Darwin took it all very well, after the initial and quite understandable screaming.

  It helped that they told him quite a lot of lies. No one would like to be told that they came from a universe created quite by accident and, moreover, by the Dean. It could only cause bad feeling. If you were told you were meeting your maker, you’d want something better.

  It was Ponder and Hex who solved that. Roundworld’s history offered a lot of opportunities, after all.

  ‘I didn’t feel any lightning strike,’ Darwin said, looking around the Uncommon Room.

  ‘Ah, you wouldn’t have done,’ said Ponder. ‘The whole force of it threw you here.’

  ‘Another world …’ said Darwin. He looked at the wizards. ‘And you are … magical practitioners …’

  ‘Do have a little more sherry,’ said the Chair of Indefinite Studies. T
he sherry glass in Darwin’s hand filled up again.

  ‘You create sherry?’ he said, aghast.

  ‘Oh no, that’s done by grapes and sunshine and so on,’ said Ridcully. ‘My colleague just moved it from the decanter over there. It’s a simple trick.’

  ‘We’re all very good at it,’ said the Dean cheerfully.

  ‘Magic is basically just movin’ stuff around,’ said Ridcully, but Darwin was looking past him. The Librarian had just knuckled into the room, wearing the old green robe he wore for important occasions or when he’d had a bath. He climbed into a chair and held up a glass; it filled instantly, and a banana dropped into it.

  ‘That is Pongo pongo!’ said Darwin, pointing a shaking finger. ‘An ape!’

  ‘Well done that man!’ said Ridcully. ‘You’d be amazed at how many people get that wrong! He’s our Librarian. Very good at it, too. Now, Mr Darwin, there’s a delicate matter we—’

  ‘It’s another vision, isn’t it?’ said Darwin. ‘It’s my health, I know it. I have been working too hard.’ He tapped the chair. ‘But this wood feels solid. This sherry is quite passable. But magic, I must tell you, does not exist!’ Beside him, with a little gurgle, his glass refilled.

  ‘Just one moment, sir, please,’ said Ponder. ‘Did you say another vision?’

  Darwin put his head in his hands. ‘I though it was an epiphany,’ he groaned. ‘I thought that God himself appeared unto me and explained His design. It made so much sense. I had relegated Him to the status of Prime Mover, but now I see that He is immanent in His creation, constantly imparting direction and meaning to it all … or,’ he looked up, blinking, ‘so I thought …’

  The wizards stood frozen. Then, very carefully, Ridcully said: ‘Divine visitation, eh? And when was this, exactly?’

  ‘It would have been after breakfast,’ moaned Darwin. ‘It was raining, and then I saw this strange beetle on the window. The room filled up with beetles—’

  He stopped, mouth open; a thin blue haze surrounded him.

  Ridcully lowered his hand.

  ‘Well, well,’ he said. ‘What about that, Mr Stibbons?’

  Ponder was scrabbling desperately at the paper on his clipboard.

  ‘I’ve no idea!’ he said. ‘Hex hasn’t mentioned it!’

  The Archchancellor grinned the grim little grin of someone sensing that the game, at last, was afoot.

  ‘Mono Island, remember?’ said Ridcully, while Darwin stared blankly at nothing. ‘A god with a thing about beetles?’

  ‘I’d rather forget,’ Ponder shuddered. ‘But, but … no, it couldn’t be him. How could the God of Evolution get into Roundworld?’

  ‘Same way the Auditors did?’ said Ridcully. ‘All the spacetime continuumuum stuff we’re doing, who’s to say we aren’t leaving a few doors ajar? Well, we can’t let the barmy old boy run around there! You and Rincewind, meet me in the Great Hall in one hour!’

  Ponder remembered the God of Evolution, who had been so proud of developing a creature even better fitted to survive than mankind. It had been a cockroach.

  ‘We should go right away,’ he said; firmly.

  ‘Why? We can move in time!’ said Ridcully. ‘The hour, Mr Stibbons, is for you to come up with some way to kill Auditors!’

  ‘They’re indestructible, sir!’

  ‘All right – ninety minutes!’

  TWENTY

  THE SECRETS OF LIFE

  THE DISCWORLD VERSION OF DARWIN’S vision may not be quite what Roundworld’s historians of science like to tell us, but the two will have been done converged on to the same timeline if the wizards manage to have will defeated the Auditors, so we can concentrate on the after-effects of that convergence. In any case some features are common to both versions of Darwinian history, including apes, beetles, and parasitic wasps. By contemplating these organisms, and many others – especially those confounded barnacles, of course – Darwin was led to his grand synthesis.

  Today, no area of biology remains unaffected by the discovery of evolution. The evidence that today’s species evolved from different ones, and that this process still continues, is overwhelming. Very little modern biology would make sense without the over-arching framework of evolution. If Darwin were reincarnated today, he would recognise many of his ideas, perhaps slightly reformulated, in the conventional scientific wisdom. The big principle of natural selection would be one of them. But he would also observe debate, perhaps even controversy, about this fundamental pillar of his thinking. Not whether natural selection happens, not whether it drives much of evolution; but whether it is the only driving force.

  He would also find many new layers of detail filling some of the gaps in his theories. The most important and far-reaching of these is DNA, the magic molecule that carries genetic ‘information’, the physical form of heredity. Darwin was sure that organisms could pass on their characteristics to their offspring, but he had no idea how this process was implemented, and what physical form it took. Today we are so familiar with the role of genes, and their chemical structure, that any discussion of evolution is likely to focus mainly on DNA chemistry. The role of natural selection, indeed the role of organisms, has been downgraded: the molecule has triumphed.

  We want to convince you that it won’t stay that way.

  Evolution by natural selection, the great advance that Darwin and Wallace brought to public attention, is nowadays considered to be ‘obvious’ by scientists of most persuasions and by most non-specialists outside the US Bible Belt. This consensus has arisen partly because of a general perception that biology is ‘easy’, it isn’t a real, hard-to-understand science like chemistry or physics, and most people think that they know enough about it by a kind of osmosis from the general folk information. This assumption showed up amusingly at the Cheltenham Science Festival in 2001, when the Astronomer Royal Sir Martin Rees and two other eminent astronomers gave talks on ‘Life Out There’.

  The talks were sensible and interesting, but they made no contact with real modern biology. They were based on the kind of biology that is currently taught in schools, most of which is about thirty years out of date. Like almost everything in school science, because it takes at least that long for ideas to ‘trickle down’ from the research frontiers to the classroom. Most ‘modern mathematics’ is at least 150 years old, so thirty-year-old biology is pretty good. But it’s not what you should base your thinking on when discussing cutting-edge science.

  Jack, in the audience, asked: ‘What would you think of three biologists discussing the physics of the black hole at the centre of the galaxy?’ The audience applauded, seeing the point, but it took a couple of minutes for the scientists on the platform to understand the symmetry. They were then as contrite as they could be without losing their dignity.

  This kind of thing happens a lot, because we are all so familiar with evolution that we think we understand it. We devote the rest of this section to a reasonable account of what the average person thinks about evolution. It goes like this.

  Once upon a time there was a little warm pond full of chemicals, and they messed about a bit and came up with an amoeba. The amoeba’s progeny multiplied (because it was a good amoeba) and some of them had more babies (something funny here …) and some had fewer, and some of them invented sex and had a much better time after that. Because biological copying wasn’t very good in those days, all of their progeny were different from each other, carrying various copying mistakes called mutations.

  Nearly all mutations were bad, on the principle that putting a bullet randomly through a piece of complex machinery is unlikely to improve its performance, but a few were good. Animals with good mutations had many more babies, and those had the good mutation too, so they thrived and bred. Their progeny carried the good mutation into the future. However, many more bad mutations accumulated, so natural selection killed those off. Luckily, another new mutation appeared, which made a new character for a new species (better eyes, or swimming fins, or scales), which was altoget
her better and took over.

  These later species were fishes, and one of them came out on land, growing legs and lungs to do so. From these first amphibians arose the reptiles, especially the dinosaurs (while the unadventurous fishes were presumably just messing about in the sea for millions of years, waiting to be fish and chips). There were some small, obscure mammals, who survived by coming out at night and eating dinosaur eggs. When the dinosaurs died, the mammals took over the planet, and some evolved into monkeys, then apes, then Stone Age people.

  Then evolution stopped, with amoebas in ponds content to remain amoebas and not wanting to be fishes, fishes not wanting to be dinosaurs but just living their little fishy lives, the dinosaurs wiped out by a meteorite. The monkeys and apes, having seen what it was like to be at the peak of evolution, are now just slowly dying out – except in zoos, where they are kept to show us what our progenitors used to be like. Humans now occupy the top branch of the tree of life: since we are perfect, there’s nowhere for evolution to go any more, which is why it has stopped.

  If pressed for more detail, we dredge up various things we’ve learned, mostly from newspapers, about things called genes. Genes are made from a molecule called DNA, which takes the form of a double helix and contains a kind of code. The code specifies how to make that kind of organism, so human DNA contains the information needed to make a human, whereas cat DNA contains the information for a cat, and so on. Because the DNA helix is double, it can be split apart, and the separate parts can easily be copied, which is how living creatures reproduce. DNA is the molecule of life, and without it, life would not exist. Mutations are mistakes in the DNA copying process – typos in the messages of life.