The Science of Discworld Revised Edition

place to another. Once you’ve got nerve cells you can have networks of nerve cells; and once you’ve got networks, then a whole pile of stuff comes along free of charge. For example, there is an area of complexity theory called ‘emergent computation’. It turns out that when you evolve a network – randomly chosen networks, arbitrary networks, not constructed with specific purposes – they do things. They do
something
, which may or may not seem meaningful; they do whatever it is that that network does. But you can often look at what that network does, and spot emergent features. You discover that even though its architecture was random, it evolved the ability to compute things. It carries out algorithmic processes (or something close to algorithmic processes). The ability to do calculations, computations, algorithms seems to come
free of charge
once you’ve invented devices that send signals from one place to another and react to those signals to send new signals. If you allow evolution you don’t have to work hard to create the ability to do some kind of processing.
    Once you’ve got that facility, it’s a relatively short step to the ability to do specific kinds of processing that happen to be useful – that happen to offer survival value. All you need is the standard Darwinian selection procedure. Anything that’s got that ability survives, anything that hasn’t, doesn’t. The ability to process incoming information in ways that extract an interesting feature of the outside world, react to it, and thereby make it easier to evade a predator or to spot food, gets reinforced. The brain’s internal architecture comes from a phase space of possible structures, and evolution selects from that phase space. Put those two together and you can evolve structures in the brain that have specific functions. The brain’s surroundings certainly influence the development of the brain.
    Do animals have minds? They do to some extent, depending on the animal. Even simple animals can have surprisingly sophisticated mental abilities. One of the most surprising is a funny creature called a mantis shrimp.
    It’s like the shrimps you put inside a sandwich and eat, except that it’s about 5 inches (12 cm) long and it’s more complex. You can keep a mantis shrimp in a tank, as part of a miniature marine ecology. If you do, you’ll find that mantis shrimps cause havoc. They tend to destroy things – but they also build things. One thing they love building is tunnels, which they then live in. The mantis shrimp is a bit of an architect, and it decorates the front of its tunnel with bits and pieces of things – especially bits and pieces of what it has just killed. Hunting trophies. It doesn’t like to have just one tunnel – it’s discovered that if you have one tunnel with one entrance, that’s more correctly known as a ‘trap’. So it likes to have a back entrance too – and more. By the time it’s been in the tank for about two months, it’s riddled the entire tank with tunnels, and you find it sticking its head out at one end or the other without seeing it pass between.
    Years ago, Jack used to have a mantis shrimp called Dougal. 1 Jack and his students discovered that they could set Dougal puzzles. They would feed it shrimps and it would come out and grab the shrimp. Then they would put the shrimp inside a plastic container with a lid and after a little while Dougal would like to take the lid off the container and eat the shrimp. And then they put an elastic band around the container to hold the lid on, and Dougal would learn to take the band off and open the container and eat the shrimp. And after a while if they stuck a shrimp in on its own, you could almost see the mantis shrimp coming out and looking disappointed: ‘They haven’t set me a puzzle, this is no fun, I don’t want to play this game!’ And it would take a long look at the shrimp and then go back into its tunnel without grabbing it.
    Although we can think of no way to
prove
this, everyone got the strong impression that the shrimp was developing a little bit of a mind. Its brain had the potential to do so, and humans had provided it with the kind of context that would help it develop that potential. Wild mantis shrimps
don’t go
out and play with elastic bands, because those aren’t part of their environment, but if you give them that kind of stimulus, you change them. Because
we’ve
got minds, we also have the capacity to create a