The Science of Discworld II - The Globe tsod-2

by Terry Pratchett

  This looks like a very nice story, with the DNA evidence supporting the expected history. But science is the best guard against believing things because you want to. There is a factor that Moses and his colleagues didn't explicitly consider, and it needs to be explained away, because it makes those figures much too good.

  Most human groups pretend to practise monogamy, but like swans and gibbons and other creatures that we thought were faithful for life, there are plenty of adulterous relationships and children 'whose legal and biological parentage differ'. In English society, about one child in seven is in that position, and the proportion doesn't differ much between the slums of Liverpool and the stockbroker belt of Maidenhead[45].

  The most restrained people that we know, in this regard, are the Amish of Eastern Pennsylvania and other parts of the United States, for whom the figure is a mere one in twenty. So, to err on the safe side, let's assume that all of the Mrs Cohens, from the present day back 100 generations to the sons of Aaron, were as well behaved as the Amish. Then the proportion of Cohen males with Aaron's Y-chromo-some should be 0.95100, which is considerably less than one in a hundred. So how can it be as high as one in two?

  There is a possible explanation, consonant with what we know about human sexuality, or at least with what John Symons, an expert on human sexual practices, says in his books. According to many surveys of sexual behaviour, going right back to Alfred Kinsey around 1950, women practise adultery with men of both higher and lower status. The two situations frequently occur in different social contexts, with women 'doing favours for' higher status men (think Clinton), but going down-market for 'a bit of rough'. Overwhelmingly often, however, when a baby results the father is of higher status than the woman's husband or regular partner.

  This implies that if Mrs Cohen, living in a ghetto or any other predominantly Jewish society, wants to go up-market, her only choices are other Cohens. So the maintenance of the Aaron Y- chromosome may have been assured by sexual snobbery rather than amazing fidelity, and that's a much more likely story.

  13. STATUS QUO

  The breeze shook the willows. And, in the centre of the willows, the lightning-struck tree spoke, in a very faint voice. The Ugs had seen lightning strike the same tree three times. It was the highest point in the area, thanks to the shell mounds.

  Even for creatures so preternaturally against thinking any kind of new thoughts, this made an impression. In some way, they'd felt, the tree had importance. It was an important thing. The place of the tree was an important place, where the sky touched the ground.

  It wasn't much of an opening, it was a story without a plot and it barely amounted to a belief, but Hex had to make do with what could be found.

  Now the wizards were considering the future, or futures.

  'Nothing changes?' said the Dean.

  'No, sir,' said Ponder, for the fourth time. 'And, yes, this is indeed the same time as the city we were in. But things are different.'

  'The city was almost modern!'

  'Yes, it had heads on spikes,' said Rincewind.

  'It was a bit backward, admittedly,' said Ridcully. 'And the beer was foul. But it had possibilities.'

  'But I don't understand! We stopped the elves,' said the Dean.

  'And now we've got thousands and thousands of years of this,' said Ponder. 'That's what Hex says. These people won't even have learned how to make fire before the big rock hits. Rincewind is right. They're not exactly stupid, they just don't ... progress. Remember the crab civilisation we found?'

  'But they had wars and took prisoners and slaves!' said the Lecturer in Recent Runes.

  'Yes. Progress,' said Ponder.

  'Heads on spikes,' said Rincewind.

  'Do stop going on about that, it was only two heads,' snapped Ponder.

  'Perhaps we did something else that changed history,' said the Chair of Indefinite Studies. 'Maybe we trod on the wrong insect or something? Only a thought,' he added, when they glared at him.

  'We just saw off the elves, that's all we did,' said Ridcully. 'Elves cause exactly the sort of things we've seen here. Superstition and—'

  'The Ugs aren't superstitious,' said Rincewind.

  'They didn't like it when I struck that match!'

  'They didn't start worshipping you, either. They just don't like things that happen too quickly. But I told you, they don't draw pictures, they don't use body paint, they don't make things ... I asked Ug about the sky and the moon, and as far as I can tell they don't think about them. They're just things in the sky.'

  'Oh, come now,' said Ridcully, 'everyone tells stories about the moon.'

  'They don't. They don't have any stories at all,' said Rincewind.

  There was silence as this sank in.

  'Oh dear,' said Ponder.

  'No narrativium,' said the Dean. 'Remember? That's what this universe lacks. We never found a trace of it. Nothing knows what it's supposed to be.'

  'There must be something like it, surely?' said Ridcully. 'The place looks normal, after all. Seeds grow up into trees and grass, by the look of it. Clouds know they have to stay up in the sky.'

  'If you remember, sir,' said Ponder, using the tone that meant I know you've forgotten, sir, 'we found that this universe has things that work instead of narrativium.'

  'Then why are these people just sittin' about?'

  'Because that's all they have to do!' said Rincewind. There doesn't seem to be much around that can hurt them, there's enough food, the sun is shining ... it's all gravy! They're like ... lions. Lions don't need stories. Eat when you're hungry, sleep when you're tired. That's all they need to know.

  What else do they need?'

  'But it must get cold in the winter, surely?'

  'So? It gets warmer in the spring! It's just like the moon and the stars! Things happen!'

  'And they've been like this for hundreds of thousands of years,' said Ponder.

  There was some more silence.

  'Remember those stupid big lizards?' said the Dean. 'They lasted for more than a hundred million years, I remember. I suppose they were quite successful, in their way.'

  'Successful?' said Ridcully.

  'I mean they lasted a long time.'

  'Really? And did they build a single university?'

  'Well, no—'

  'Did they draw a single picture? Invent writing? Offer even small classes of elementary tuition?'

  'Not that I know—'

  'And they all got killed off by a yet another big rock,' said Ridcully. 'They really did not know what hit them. Bein' around for millions of years is not an achievement. Even lumps of stone can manage that.'

  The circle of wizards was sunk in gloom.

  'And Dee's people were doin' quite well,' muttered Ridcully. 'Terrible beer, of course.'

  'I suppose ...' Rincewind began.

  'Yes?' said the Archchancellor.

  'Well ... how about if we went back and stopped us from stopping the elves? And least we'd be back among people more interesting than cows.'

  'Could we do that?' said Ridcully to Ponder.

  'I suppose so,' said Ponder. 'Technically, if we stop ourselves, then nothing will change, I assume. All this won't have happened ... I think. That is to say, it will have happened, because we'll remember it, but then it won't have happened.'

  'Fair enough,' said Ridcully. Wizards do not have a lot of patience with temporal paradoxes.

  'Can we stop ourselves?' said the Dean. 'I mean, how do we do it?'

  'We'll just explain the situation to us,' said Ridcully. 'We're reasonable men.'

  'Hah!' said Ponder, and then looked up. 'Oh, sorry, Archchancellor. I must have been thinking about something else. Do go on.'

  'Ahem. If I was just about to fight elves, and someone who looked very much like me came up and told me not to, I'd assume it was an elvish trick,' said the Lecturer in Recent Runes. 'They can make you think they look like someone else, you know.'

  'I'd know me if I saw me!' said the D
ean.

  'Look, it's easy,' said Rincewind. 'Trust me. Just tell yourself something about yourself that no one else could possibly know.'

  A worried look crossed the Dean's face.

  'Would that be wise?' he said. Like many people, wizards often have secrets they don't want themselves to know.

  Ridcully stood up. 'We know it'll work,' he said, 'because it's already happened to us. Think about it. We must succeed in the end, because we know a species like this gets off the planet.'

  'Yes,' said Ponder, slowly, 'and, then again, no.'

  'What the hell does that mean?' Ridcully demanded.

  'Well ... we've been to a future where it happens, certainly,' said Ponder, twiddling his pencil nervously. 'But there are other futures. The multiplex nature of the universe that allows it to absorb and cushion the effects of apparent paradoxes also means that nothing is certain, even if you know it is.' He tried to avoid Ridcully's stare. 'We went to a future. At the moment, it exists only in our memories. Then, it was real. Now, it may never be. Look, Rincewind was telling me about some play writer he's found, born around about Dee's time but not in this branch of the universe. Yet we know he has an existence, because L-space contains all possible books in all possible histories. Do you see what I mean? Nothing is certain.'

  After a while, the Chair of Indefinite Studies said, 'You know, I think I prefer the kind of universal law that says the third son of a king always gets the princess. They make sense.'

  'The universe is so big, sir, that it obeys all possible laws,' said Ponder. 'For a given value of

  "teapot".'

  'Look, if we go back in time and talk to ourselves, why don't we remember it?' said the Lecturer in Recent Runes.

  Ponder sighed. 'Because although it has already happened to us, it hasn't yet happened to us.'

  'I, er, tried something like that,' said Rincewind. 'While you were having your mussel soup just now I got Hex to send me back in time to warn myself to hold my breath when we landed in the river. It worked.'

  'Did you hold your breath?' 'Yes, because I've warned myself.'

  'So ... was there any time anywhere where you didn't hold your breath, thus giving yourself a mouthful of river water and causing you to go back to make sure you did?'

  'Probably there was, I think, but there isn't now.' 'Oh, I see,' said the Lecturer in Recent Runes.

  'You know, it's a good job we're wizards, otherwise this time travel business could really be confusing ...'

  'At least we know that Hex can still make contact with us,' said Ponder. 'I'll ask him to move us back again.' The Librarian watched them go. A moment later, the rest of everywhere went with them.

  14. FOURTEEN

  The Ugs have no real stories, hence no sense of their place in time. They have no conception of the future, and therefore no wish to change it.

  We know that there are other futures ... As Ponder Stibbons remarks, we live in a multiplex universe. We look at the past and we see times and places where things could have been different, and we wonder whether we could have ended up in a different present. By analogy, we look at the present and imagine many different futures. And we wonder which of them will happen, and what we can do now to affect the choice.

  We could be wrong. Maybe the fatalist view, 'it is written', is right. Maybe we are all automata, working out the deterministic future of a clockwork universe. Or maybe the Quantum philosophers are right, and all possible futures (and pasts) coexist. Or maybe everything that exists is just one point in a multiplex phase space of universes, a single card dealt from Fate's deck.

  How did we acquire this sense of ourselves as beings who exist in time? Who remember their past, and use it to try (usually unsuccessfully) to control their future?

  It all goes back a long, long way.

  Watch a proto-human watching a zebra watching a lioness. The three mammalian brains are doing very different things. The herbivore brain has seen the lioness, is barely conscious (we guess, watch some horses in a field) of the whole 360 degrees of his environment, and has marked some things, like that tuft of grass over there, that female over there who could just be in heat, that male who's giving her the right signals, the three bushes that could have a surprise behind them .. the lioness moves, she suddenly gets priority, but not totally because there are other considerations. Another lioness could well be behind those bushes, and I'd better move up on that nice grass before Nigella does ... Looking at that grass makes me think of the taste of that long grass ... THE LIONESS IS MOVING.

  The lioness is thinking: that's a nice zebra stallion, won't go for him he's too strong (memory of a previous eye injury from a zebra kick) but if I get him running, Dora behind those bushes can probably jump on the young female over there who is trying to attract the male, then I can run after it with her ...

  There is probably no more of a plan than that in the zebra's brain but it does foresee a little bit of the future and plug memories into present planning. If I stand up now ...

  The human is looking at the lioness and the zebra. Even if it's a Homo erectus, we bet it had stories in its head: that lioness will run out, the zebra will startle, the other lioness will go for ...

  ah, that young female. Then I can run out there and get in front of the young male; I see myself running at him and hitting him with this stone. Homo sapiens may well have done better from the beginning; his brain was bigger and probably better. He may, from the beginning, have had room for several alternative, thought about 'or' scenarios and probably the 'and' one which goes

  'and I will be a big hunter and meet interesting women'. 'If' probably came along later, perhaps with cave paintings, but making predictions put our ancestors way ahead of their predators and their prey.

  There has been a variety of suggestions about why our brains suddenly grew to nearly double their previous size, from the need to keep the faces of our social group in mind while gossiping about them, to the need to compete with other hunter-gatherers, to the competitive nature of language and its structuring of the brain so that lying could be successful for the li-ar, but then the li-ee got better at detecting lies. Such escalations all have an attraction to them. They make good stories, ones that we can easily imagine, filling in the background just as we do with hearing sentences or enjoying pictures. That doesn't make them true, of course, just as our attraction to the supposed seashore phase of our history doesn't make 'aquatic apes' true either.

  The stories serve as placeholders for whatever the real pressures were: the meta-explanation of why our brain growth took off is that competitive advantage was to be won by All Of The Above routes, and many more.

  Perhaps the human viewer of that wildlife scene is a cameraman for a natural history TV series.

  Even a mere 15 years ago, he would have had an Arriflex (or if he was paying for it himself, perhaps just a Bolex H16) 16mm film camera with a very precious 800 feet (260 metres) of film loaded, and perhaps another dozen film packs in his rucksack (800 feet gives about 40 minutes of filming: if you're very good, or very lucky, five minutes of useful stuff). Now he has a video camera that would have seemed miraculous then, which can reuse and reuse a length of tape until it's full of five-minute sequences, end to end. All the things he wished for, then, are in the apparatus in his hand now: it stays in focus, it compensates for a bit of wobble, it goes down to unbelievably low light levels (for those of us who grew up with photographic film) and it zooms over a range much wider than we ever had before.

  It's magic, in fact.

  And in his head are a dozen alternative scenarios for the lions and zebras, which he'll flick to instantly as the animals act to constrain their futures. He's actually thinking about other things altogether, letting the experienced professional part of his brain do the work while he daydreams

  ('I'll get an award for this and meet interesting women'). It's like driving on a quiet motorway: a lot of the thinking has been taken out of it.

  Our ancestors honed that ability, to cons
ider alternative scenarios. And within any of those scenarios, the ability to make a story of what was happening was a very powerful way to remember it and to communicate it. And, particularly, to employ it as a parable, to direct your future action or that of your children. Human beings need a very long time to get that brain upand- running, at least twice as long as their brother and sister chimpanzees. That is why threeyear- old chimps are nearly adult in chimp behaviour, and can do some of the mental tricks of six- or seven-year-old children.

  But the young chimps don't hear stories. Our children have been hearing stories since they recognised any words at all, and by three years old they are making up their own stories about what is happening around them. We are all impressed by their vocabulary skills, and by their acquisition of syntax and semantics; but we should also note how good they are at making narratives out of events. From about five years old, they get their parents to do things for them by placing those things in narrative context. And most of their games with peers have a context, within which stories are played out. The context they create is just like that of the animal and fairy stories we tell them. The parents don't instruct the child how to do this, nor do the children have to elicit the 'right' storytelling behaviours from their parents. This is an evolutionary complicity. It seems very natural -after all, we are Pan narrans -that we tell stories to children, and that children and parents enjoy the activity. We learn about 'narrativium' very early in our development, and we use it and promote it for the whole of our lives.

  Human development is a complex, recursive behaviour. It is not simply reading out DNA

  'blueprints' and making another working part (contrary to the new folk-biology of genes). To show you how truly remarkable our development is, despite seeming so simple and so natural, let's have a look at some earlier parent-child behaviour.

  Keep in mind a distinction that is being imported into more and more scientific thinking, that between 'complicated' and 'complex'. 'Complicated' means a whole set of simple things working together to produce some effect, like a clock or an automobile: each of the components -brakes, engine, body-shell, steering - contributes to what the car does by doing its own thing, pretty well.