The Science of Discworld Revised Edition

looked like – maybe it was
all
shorter in those days, maybe today’s frogs and newts have much more extensive recipes than ancient ones. But on balance it seems more likely that mammals just eliminated a lot of surplus instructions.
    Modern technology uses the same trick. Because the machinery that makes today’s consumer goods is extremely precise and accurate, those goods can be
simpler
than they were in the past. A soft drinks can, for example, is little more than a piece of aluminium that has been formed into a cylinder, with another flat bit on top to act as a lid, a weak line for the tab to tear along, and a ring (or nowadays a lever) attached to the tab. It replaces the bottle, which consisted of two or more bits of moulded glass ‘welded’ together, a metal cap, and a slice of cork. The simplicity of the can comes at a price:
very
careful control of the forming process.
    There are many scientists who insist that an organism’s DNA determines everything about it – even though it manifestly does not – and they argue that the mother’s temperature-control system is included in
her
DNA recipe. This may well be true, but even if it is, ‘this organism’s’ DNA has somehow migrated to another organism (mother, not her offspring). As soon as two generations are involved in implementing the genetic blueprint, a gap opens up into which things can be inserted that are not genetic at all. We’ve already mentioned several, for example prions in the reproduction of yeast.
    Our mammalian ancestry may even be responsible for one of the more bizarre modern myths, persistent tales of people being abducted by aliens. Ufologists allege that one American in twenty now claims to have undergone such an experience (but they would, wouldn’t they?). If true, this figure would be a remarkable and not very happy comment either on the critical faculties of that great nation or on the habits of an unknown spacefaring species.
    As it happens, the figure is bogus. It originates in a Roper poll of 1994, which revealed that one American in fifty had undergone such an experience. But, as Joel Best pointed out in his book
Damned Lies and Statistics
in 2001, the number of people who claimed to have been abducted by aliens was actually
zero
. The pollsters, worried that a direct question about aliens would put people off, used five ‘symptoms’ of abduction instead. Anyone who scored sufficiently highly on those symptoms was
deemed
to have undergone an abduction experience.
    The questions were things like ‘Have you ever woken up paralysed with the sense of some strange presence in the room?’ This sensation is typical of ‘sleep paralysis’, the most obvious rational explanation of abduction experiences, which we describe shortly. So really the Roper poll was a survey about sleep paralysis. Only the researchers thought that it had anything to do with alien abduction. The subjects had more sense.
    Be that as it may, a lot of people are convinced that strange aliens, usually with big black eyes and pear-shaped heads like the ones in
Close Encounters of the Third Kind
, landed a UFO near them, loaded them on board, and took them for a flight round the solar system while carrying out weird experiments, often of a sexual nature, on them. After which they were calmly returned to the very spot from which they had been abducted, as if absolutely nothing had happened.
    The first thing to say is that without doubt many of these experiences are false. Ian once did a radio broadcast which included a woman who had undergone a convincing experience of being abducted – except that she knew she hadn’t really been, because her family told her she’d been asleep beside the fire the whole time. Jack once met a woman who claimed that the aliens abducted her and took away her baby. So he asked a question that nobody else had thought to ask, the woman included: ‘Were you pregnant?’
    ‘No.’
    The point is that to the victims, the experience
felt
real. Even though logic told them it couldn’t have happened, they either didn’t apply the logic, or they did but still remembered the experience vividly. We deduce that the human mind sometimes has vivid memories that do not correspond to real events. Of course we must also observe that just because some alien abductions aren’t real, that doesn’t imply they all aren’t. However, if we can find a sensible mechanism for otherwise reasonable people
believing
that they really were