The Science of Discworld Revised Edition

also pave the way to radically new lifeforms …
    It’s all rather confusing.
    Life is resilient, but any particular species may not be. Life is constantly devising new tricks. The one with eggs is brilliant: provide the developing embryo with its own personal life-support machine. Inside, the environment is tailored to the needs of that species – and what’s outside doesn’t matter much, because there’s a barrier to keep it out.
    Life is adaptable. It changes the rules of its own game. As soon as eggs make their appearance, the stage is set for the evolution of egg-eaters …
    Life is diverse. The more players there are, the more ways there are to make a living by taking in each others’ washing.
    Life is repetitious. When it finds a trick that works, it churns out thousands of variations on the same basic theme. The great biologist John (J.B.S.) Haldane was once asked what question he would like to pose to God, and replied that he’d like to know why He has such an inordinate fondness for beetles. 1
    There are a third of a million beetle species today – far more than in any other plant or animal group. In 1998 Brian Farrell came up with a possible answer to Haldane’s query. Beetles appeared about 250 million years ago, but the number of species didn’t explode until about 100 million years ago. That happens to be just when flowering plants came into existence. The ‘phase space’ available for organisms suddenly acquired a new dimension – a new resource became available for exploitation. The beetles were beautifully poised to take advantage by eating the new plants, especially their leaves. It used to be thought that flowering plants and pollinating insects drove each other to wilder and wilder diversity, but that’s not true. However, it
is
true for beetles. Nearly half of today’s beetle species are leaf-eaters. It’s
still
an effective tactic.
    Sometimes natural disasters don’t just eliminate a species or two. The fossil record contains a number of ‘mass extinctions’ in which a substantial proportion of all life on Earth disappeared. The best-known mass extinction is the death of the dinosaurs, 65 million years ago.
    In order not to mislead you, we should point out at once that there is no scientific evidence for the existence of any dinosaur
civilization
, no matter what events are going on in the Roundworld Project. But … whenever a scientist says ‘there is no scientific evidence for’, there are three important questions you should ask – especially if it’s a government scientist. These are: ‘Is there any evidence
against
?, ‘Has anyone looked?’, and ‘If they did, would they expect to find anything?’ 2
    The answers here are ‘no,’ ‘no’, and ‘no’. Deep Time hides a lot, especially when it’s assisted by continental movement, the bulldozing ice sheets, volcanic action and the occasional doomed asteroid. There are few surviving
human
artefacts more than ten thousand years old, and if we died out today, the only evidence of our civilization that might survive for a million years would be a few dead probes in deep space and various bits of debris on the Moon.
Sixty
- five million? Not a chance. So although a dinosaurian civilization is pure fantasy – or, rather, pure speculation – we can’t rule it out
absolutely
. As for dinosaurs who were sufficiently advanced to use tools, herd other dinosaurs … well, Deep Time would wash over them without a ripple.
    Dinosaurs are always among the most popular exhibits at museums. They remind us that the world wasn’t always like it is now; and they remind us that humans have been on this planet for a very short time, geologically speaking. Basically, dinosaurs
are
ancient lizards. The ones whose bones we all go to gawp at in museums are rather
big
lizards, but many were much smaller. The name means ‘terrible lizard’, and anyone who watched
Jurassic Park
will understand why.
    An Italian fossil collector who watched the Spielberg movie suddenly realized that a perplexing fossil, filed away for years in his basement, might well be a bit of a dinosaur. He then sent it to a nearby university, where it was found not just to be a dinosaur, but a new species. It was a young therapod – small flesh-eating dinosaurs that are the closest relatives of birds. Interestingly, it didn’t have any feathers. A story straight out of the movies: narrative imperative at work in our own world … traceable, as always, to