Science of Discworld III

The ‘canals’ died in the public mind, replaced by craters and gigantic volcanoes.
    We have now visited again, and it seems that ancient, wet Mars may have been a reality, there may be at least bacterial life forms under the sand … Much is not yet clear, but what is clear is that our image of Mars has changed yet again.
    Each of us has a variety of associations with Mars. When we weave these many different interpretations and imaginations together, webecome a different, wiser kind of creature. As for all of our different Marses … well, those are toys of our imaginations, as we grok the red planet’s fullness.
    If Mars seems a bit of a digression, consider those twin icons of evolution, the archaeopteryx and the dodo. In folk-evolutionary thinking, the archaeopteryx is the ancestor of all the birds, and the dodo is the bird that went extinct about 400 years ago. ‘As dead as a dodo.’ Again, our thinking about these iconic creatures is heavily daubed with unchallenged assumptions, myths, and fictional associations.
    We mentioned archaeopteryx in Chapter 36 (‘Running from Dinosaurs’) of The Science of Discworld , second edition. We think of it as the ancestral bird because it is a dinosaur-like animal with birdlike feathers … and it was the first one to be found . However, by the time of archaeopteryx there were plenty of genuine birds around, among them the diving bird Ichthyornis . Poor old archaeopteryx arrived on the scene far too late to be ‘the’ bird ancestor.
    The recent amazing ‘dinobird’ discoveries in China – transitional creatures part way between dinosaurs and birds – have totally changed scientists’ view of bird evolution. At some stage some dinosaurs started to develop feathers, though they couldn’t then fly. The feathers had some other function, probably keeping the animal warm. Later, they turned out to be useful in wings. Some dinobirds effectively had four wings – two at the front, two at the back. It took a while before the standard ‘bird’ body-plan settled down.
    As for the dodo – we all know what it looked like, right? Fat little thing with a big hooked beak … Such a famously extinct creature must be well documented in the scientific literature.
    No, it’s not. What we have is about ten paintings and half a stuffed specimen. 5 We have more specimens of the archaeopteryx than wedo of the dodo. Why? The dodo went extinct , remember? And it did so before science really got interested in it. So few people recorded it, or studied it. It was there , not requiring special attention, and then it wasn’t, and it was too late to start studying it. It isn’t even certain what colour it was – many books say ‘grey’, but it was more likely brown.
    Yet, we all know exactly what it looked like. How come? Because we all saw it illustrated by Sir John Tenniel in Alice’s Adventures in Wonderland .
    Say no more.
    The great strength of Discworld narrative is that it makes fun of just those places where ‘education’ has left us feeling a bit vulnerable: where we change the subject in the pub, or when our five-year-old asks us those probing questions. A running joke throughout the Science of Discworld series is what grammarians call ‘privatives’. These are concepts that our minds seem quite happy with, even though a moment’s thought shows that they’re complete nonsense. Chapter 22 of The Science of Discworld discussed this notion, and we recap briefly.
    It is entirely normal to speak of ‘cold coming in the window’ or ‘ignorance spreading among the masses’. The opposites of these concepts, heat and knowledge, are real, but we’ve dignified their absence with words that do not correspond to actual things. In Discworld, we find ‘knurd’, which is super-sober, as far from ordinary sober as drunk is in the alcoholic direction. There are jokes about the speed of dark, which must be faster than the speed of light because dark has to get out of the way. On Discworld, Death exists as a (perhaps the ) major character, but on Roundworld that word refers only to the absence of life.
    People habitually label the absence of something with a word, instead of (or as well as) its presence: such words are the aforementioned privatives.
    Sometimes this habit leads to mistakes. The classic case was the label ‘phlogiston’, the substance that appears to be emitted by burning materials. You can see it coming out as smoke, flame, foam … It took many years to