The Science of Discworld II - The Globe tsod-2

by Terry Pratchett

  A faint white ring appeared on the grass, wide enough to hold the wizards.

  'Ah, the ride back,' said the Archchancellor, as the excited Dean was hustled towards the rest of the group. 'Time to—'

  The wizards were suddenly in empty air. They fell. All but one of them were not holding their breath before they hit the river.

  Wizards do, however, have good floating capabilities and a tendency to bob up and down. And the river was in any case rather like a slowly moving swamp. Floating logs and mud banks choked it. Here and there, mud banks had become sufficiently established to sprout a crop of trees. By degrees, and with much arguing about where dry land actually began -it was not very obvious -they splashed their way to the shore. The sun was hot overhead, and clouds of mosquitoes shimmered among the trees.

  'Hex has brought us back to the wrong time,' said Ridcully, wringing out his robe.

  'I don't think he'd do that, Archchancellor,' said Ponder, meekly. 'The wrong place, then. This is not a city, in case you hadn't noticed.'

  Ponder looked around in bewilderment. The landscape around them was not exactly land and not exactly river. Ducks were quacking, somewhere. There were blue hills in the distance.

  'On the upside,' said Rincewind, extracting frogs from a pocket, 'everything smells better.'

  'This is a swamp, Rincewind.'

  'So?'

  'And I can see smoke,' said Ridcully.

  There was a thin grey column in the middle distance.

  Reaching it took a lot longer than the mere distance suggested. Land and water were contesting every step of the way. But, eventually, and with only one sprain and a number of bites, the wizards reached some thick bushes and peered into the clearing beyond.

  There were some houses, but that was stretching the term. They were little more than piles of branches with reed roofs.

  'They could be savages,' said the Lecturer in Recent Runes.

  'Or perhaps someone sent them all out into the country to forge a dynamic team spirit,' said the Dean, who had been badly bitten.

  'Savages would be too much to hope for,' said Rincewind, watching the huts carefully.

  'You want to find savages?' said Ridcully.

  Rincewind sighed. 'I am the Professor of Cruel and Unusual Geography, sir. In an unknown situation, always hope for savages. They tend to be quite polite and hospitable provided you don't make any sudden moves or eat the wrong sort of animal.'

  'Wrong sort of animal?' said Ridcully.

  'Taboo, sir. They tend to be related. Or something.'

  'That sounds rather ... sophisticated,' said Ponder suspiciously.

  'Savages often are,' said Rincewind. 'It's the civilised people that give you trouble. They always want to drag you off somewhere and ask you unsophisticated questions. Edged weapons are often involved. Trust me on this. But these aren't savages, sir.'

  'How can you tell?'

  'Savages build better huts,' said Rincewind firmly. 'These are edge people.'

  'I've never heard of edge people!' said Ridcully.

  'I made it up,' said Rincewind. 'I run into them occasionally. People that live right on the edge, sir. Out on rocks. In the worst kind of desert. No tribe or clan. That takes too much effort. Of course, so does beating up strangers, so they're the best kind of people to meet.'

  Ridcully looked around at the swamp. 'But there's waterfowl everywhere,' he said. 'Birds. Eggs.

  Lots of fish, I'll be bound. Beavers. Animals that come down to drink. I could eat myself greasy to the eyebrows here. This is good country.'

  'Hold on, one of them's coming out.' said the Lecturer in Recent Runes.

  A stooping figure had emerged from a hut. It straightened up, and stared around. Huge nostrils flared.

  'Oh my, look what just fell out of the ugly tree,' said the Dean. 'Is it a troll?'

  'He's certainly a bit rugged,' said Ridcully. 'And why is he wearing boards?'

  'I think he's just not very good at tanning hides,' said Rincewind.

  The enormous shaggy head turned towards the wizards. The nostrils flared again.

  'He smelled us,' said Rincewind, and started to turn. A hand grabbed the back of his robe.

  'This is not a good time to run away, Professor,' said Ridcully, lifting him off the ground in one hand. 'We know you're good at languages. You get on with people. You have been chosen to be our ambassador. Do not scream.'

  'Besides, the thing looks like cruel and unusual geography,' said the Dean, as Rincewind was thrust out of the bushes.

  The big man watched him, but made no attempt to attack.

  'Go on!' hissed the bushes. 'We need to find out when we are!'

  'Oh, right,' said Rincewind, eyeing the giant cautiously. 'And he's going to tell me, is he? He's got a calendar, has he?'

  He advanced carefully, hands up to show that he didn't have a weapon. Rincewind was a great believer in not being armed. It made you a target.

  The man had obviously seen him. But he didn't seem very excited about it. He watched Rincewind as someone might watch a passing cloud.

  'Er ... hello,' said Rincewind, stopping just out of range. 'Me big fella Professor of Cruel and Unusual Geography belong Unseen University, you ... oh dear, you haven't even discovered washing, have you? Either that or it's the clothes belong you. Still, no obvious weapons. Er ...'

  The man took a few steps forward and tugged the hat off Rincewind's head in one quick movement.

  'Hey—!'

  What was visible of the big face broke into a grin. The man turned the hat this way and that.

  Sunlight sparkled off the word 'Wizzard' in cheap sequins.

  'Oh, I see,' said Rincewind. 'Pretty glitter. Well, that's a start ...'

  10. BLIND MAN WITH LANTERN

  The wizards are now beginning to understand that, while you can eliminate evil by eliminating extelligence, the result can be about as interesting as watching daytime television. Their plan to stop the elves interfering with human evolution has worked, but they don't like the result. It is bland and unintelligent. It has no spark of creativity.

  How did human creativity arise? By now you won't be surprised to learn that it came from stories. Let's take a closer look at the current scientific view of human evolution, and fill in that gap between R-O-C-K and the space elevator.

  An elf, observing Earth's landmasses 25 million years ago, would have seen vast areas of forest.

  From the hills of northern India to Tibet and China, and down into Africa, these forests held a great variety of small apes, ranging from about half the size of chimpanzees to the size of gorillas. The apes were at home on the ground and in the lower branches of the forest, and they were so common that today we have many fossils of them. In addition, the Old World monkeys were starting to diversify in the upper levels of the forest. Earth was a Monkey Planet.

  But also a Snake Planet, a Big Cat Planet, a Nematode Planet, an Alga Planet and a Grass Planet.

  Not to mention Plankton Planet, Bacterium Planet and Virus Planet. The elf might not have noticed that the African apes had produced several ground-dwelling kinds, not very different from the monkey-derived baboons. And it might also have failed to spot the presence of gibbons in the high branches, alongside the monkeys. These creatures were not particularly remarkable against a background of spectacular large mammals like rhinoceroses, a variety of forest elephants, bears. But we humans are interested in them, because they were our ancestors.

  We call them 'woods-apes', dryopithecines. Some, known as Ramapithecus, were of lighter build

  -the jargon is 'gracile'. Others, such as Sivapithecus, were big and strong -'robust'. The lineage of Sivapithecus was the one that led to orangutans. These early apes would have been shy, morose creatures like today's wild apes, occasionally playful, but the adults would have been very belligerent and conscious of status within the group.

  The forests inhabited by the woods-apes slowly dwindled as the climate cooled and dried, and grasslands -savannah cou
ntry -took over. There were ice ages, but in the region of the tropics these did not reduce temperatures severely. However, they did change the patterns of rainfall.

  The monkeys thrived, producing many ground-living kinds like baboons and vervets, and the ape populations got smaller.

  By ten million years ago, there were few apes left. There are almost no fossil apes from that period. It seems plausible that, as now and as previously, those apes that did still exist were forest creatures. Some, like today's chimpanzees, gorillas and orangutans, were probably common in a few locations in the forests, but you'd have needed a lot of luck to find them. The observing elf might, even then, have put all of these apes on its Endangered List of Earth Mammals. Like very nearly all animal groups that had evolved, the forest apes were soon to be history rather than ecology. The common ancestor of humans and chimpanzees was, then, a not very remarkable ape that probably lived much as the different chimpanzees do now: some in flooded forest like today's bonobos, some in rain-forest, and some in fairly open woodland grading into grasslands. The gorilla lineage separated from the other apes around this time.

  At first, the elf would probably not have been very interested as -according to one of the two popular theories of human origins - a new kind of ape began to evolve a more upright stance than those of its relatives, lost its hair, and moved out on to the savannah. Many other mammals did the same; there was a new kind of living to be made on the great grass plains. Giant hyenas, massive wild dogs, lions and cheetahs made a good living from the vast herds of herbivores that lived on the productive savannah grasses; the giant pythons were probably originally savannah animals, too.

  The story has been told many times, in many versions. And that's just the point: we understand our ancestry through story. We wouldn't be able to work out our ancestry from the fossils that we have discovered unless we'd learned just what clues to look for, especially since few fossil sites have enough evidence left.

  The new ancestral plains ape saw the world differently. Judging from the behaviour of today's chimpanzees, especially bonobos, it was a highly intelligent animal. We call their fossils southern apes, australopithecines, and there are hundreds of books that tell stories about them.

  They may have sojourned by the sea, doing clever things on beaches. Some certainly lived on lake margins. Today's chimpanzees use stones to smash hard nuts open, and sticks to extract ants from nests; the australopithecines also used stones and sticks as tools, rather more so than their cousins the chimpanzees now do. They may have killed small game, as chimpanzees do. They probably used sexual behaviour to hang much of their pleasure on, like today's bonobos, but most likely they were more gender-conscious and male-dominant. Like previous apes, they diverged into gracile and robust lines. The robust ones, called Anthropithecus boisi, or even a different genus Zinjanthropus ('nutcracker man') and other defamatory names, were vegetarians like today's gorillas, and probably left no descendants in modern times.

  This kind of split into gracile and robust forms, by the way, seems to be one of the standard patterns of evolution. Mathematical models suggest that it probably happens when a mixed population of big and small creatures can exploit the environment more effectively than a single population of medium-sized ones, but this idea has to be considered highly speculative until more evidence comes in. The zoological world was recently given a reminder of how common such a split is, and of how little we really know about the creatures of our own planet.

  The animal involved could not have been better known, nor more appropriate to Discworld: the elephant[34]. As every child learns at an early age, there are two kinds of elephant, two distinct species: the African elephant and the Indian elephant.

  Not so. There are three species. Zoologists have been arguing for at least a century about what they thought was at most a subspecies of 'the' African elephant Loxodonta africana. The typical big, burly African elephant lives on the savannah. The elephants that live in the forest are shy, and difficult to spot: there is just one of them in the Paris zoo, for example. Biologists had assumed that because the forest elephants and the savannah elephants can interbreed at the edges of the forest, they could not be separate species. After all, the standard definition of a species, promoted by the evolutionary biologist Ernst Mayr, is 'able to interbreed'. So they either insisted that there was just one species, or that 'African elephant' had a distinguished subspecies, the forest elephant Loxodonta africana cyclotis. On the other hand, zoologists who have had the good fortune to see forest elephants are in no doubt that they look very different from the savannah ones: they are smaller, with straighter, longer tusks, and round ears, not pointed ones.

  Nicholas Georgiadis, a biologist at the Mpala Research Centre in Kenya, has said: 'If you see a forest elephant for the first time, you think, "Wow, what is that?'" But because biologists knew, on theoretical grounds, that the animals had to be all the same species, the observational evidence was rejected as inconclusive.

  However, in August 2001 a team of four biologists - Georgiadis, Alfred Roca, Jill Pecon-Slattery and Stephen O'Brien -reported in the journal Science their 'Genetic evidence for two species of elephant in Africa'. Their DNA analysis makes it absolutely clear that the African elephant really does come in two distinct forms: the usual robust form, and a separate gracile form. Moreover, the gracile African elephants really are a different species from the robust ones. As different, in fact, as either African species is from the Indian one. So now we have the robust African plains elephant Loxodonta africana and the gracile African forest elephant Loxodonta cyclotis.

  What of the belief that there could be only one species because of the potential for interbreeding?

  This particular definition of species is taking a hammering at the moment, and deservedly so.

  The main reason is a growing realisation that even when animals can interbreed, they may decide not to.

  The story of the Third Elephant is not new: only the names have been changed. Before 1929 every zoologist 'knew' there was only one species of chimpanzee; after 1929, when the bonobos of the inaccessible swamps of Zaire were recognised as a second species[35], it became obvious to many zoos that they had possessed two distinct chimpanzee species for years, but not realised it.

  Exactly the same story is now being played out with elephants.

  As we've mentioned, Discworld recently revived interest in its fifth elephant, a story told, you will be surprised to hear, in The Fifth Elephant. According to legend, there were originally five elephants standing on Great A'Tuin and supporting the Disc, but one slipped, fell off the turtle, and crashed into a remote region of Discworld: They say that the fifth elephant came screaming and trumpeting through the atmosphere in the young world all those years ago and landed hard enough to split continents and raise mountains.

  No one actually saw it land, which raised the interesting philosophical question: when millions of tons of angry elephant come spinning through the sky, and there is no one to hear it, does it philosophically speaking - make a noise?

  And if there was no one to see it hit, did it actually hit?

  There is evidence, in the form of vast deposits of fat and gold (the great elephants that support the world do not have ordinary bones), deep underground in the Schmaltzberg mines. However, there is a more down-to-Disc theory: some catastrophe killed off millions of mammoths, bison and giant shrews, and then covered them over. On Roundworld, there would be a good scientific test to distinguish the two theories: are the deposits of fat shaped like a crash-landed elephant?

  But there's no point even in looking, on Discworld, because narrative imperative will ensure that they are, even if they were formed by millions of mammoths, bison and giant shrews. Reality has to follow the legend.

  Roundworld has so far reached only its third elephant, although Jack hopes that some careful selective breeding might yet bring back a fourth: the pygmy elephant, which lived in Malta and was about the size of a Shetland pony. It would make a marvellous p
et -except that, like many diminutive creatures, it would probably be rather bad-tempered. And the very devil to discourage from getting on the settee.

  We are a gracile ape (not that you'd notice in some parts of the world, where many of us more closely resemble a robust hippopotamus). About four million years ago one gracile lineage of apes started to get bigger brains and better tools. Against all the rules of taxonomy we call this lineage, our lineage, Homo: it really should be Pan, because we are the third chimpanzee. We use this name because it is certainly our own lineage, and we prefer to think of ourselves as being enormously different from the apes. In this we could be right: we may indeed share 98 per cent of our genes with chimpanzees, but then, we share 47 per cent with cabbages. Our big difference from the apes is cultural, not genetic. Anyway, within the Homo lineage we again find gracile and robust stocks. Homo habilis was our gracile tool-making ancestor, but Homo ergaster and others went the vegetarian, robust way. If there actually is a yeti or a bigfoot, the best bet is a robust Homo. From Homo habilis's success, a larger-brained Homo spread out over Africa, into Asia (as Peking Man) and Eastern Europe about 700 million years ago.

  We have labelled one variety of these fossils Homo erectus. The visiting elf would certainly have noticed this fellow. He had several kinds of tools, and he used fire. He may even have possessed language, of a kind. What we have every reason to suspect that he did, that his ancestors and cousins only occasionally achieved, was to 'understand' his world and change it. Chimpanzees engage in quite a lot of 'if ... then' activities, including lying: 'if I pretend not to have seen that banana, I can come back and get it later when that big male won't steal it from me'.

  The young of this early hominid grew up in family groups where things were happening that were unlike anything anywhere else on the planet. Sure, there were lots of other mammal nests, packs and troupes, where the young were playing at being adult or just fooling around; nests were safe, and trial-and-error was rarely lethal, so the young could learn safely. But in the human lineage, father was making stone tools, grunting at his women about the children, about the cave, about putting more wood on the fire. There would be favourite gourds for banging, perhaps for fetching water, spears for hunting, lots of stones for tools.