Читать книгу Noises from the Darkroom: The Science and Mystery of the Mind - Guy Claxton - Страница 23

One of the evolutionary moves that must have stimulated the development of the first brains was mobility: the discovery of the advantages of being able to get about. Couple mobility with a sensory system, and you are able not just to close your mouth and hold your breath when something nasty comes along, but to get out of the way. You are not dependent on what the stream happens to be serving that day; if you don’t like it you can go and see what is available at the restaurant across the road. But there are also inherent questions and problems associated with being mobile. Do you become nomadic, of no fixed abode, or do you have a home that you return to each evening after a hard day running about chasing things? Either way there are pros and cons.

If you were a tunicate – a sea squirt – for example, you would have opted for an interim solution. The young sea squirt is a tadpole-like larva that possesses a primitive brain, which can be informed about what is going on by an organ of balance (such as we humans have in the middle ear), and a simple eye. It is equipped to navigate its way through changing aquatic conditions whilst engaged in a process of once-and-for-all house-hunting. When it finds its ideal home, the sea squirt gratefully settles down for life, and turns itself back into a plant by the simple expedient of eating its now redundant brain. (It has been suggested that this behaviour parallels that of university academics on finally obtaining a tenured appointment.)¹⁸ We might also note, to anticipate later discussions, that the issue of what to do with a brain that has evolved to a level of power that is out of all proportion to the current survival demands – when a species finds that, for a while, it has ‘got it made’ – is one that bears on the contemporary situation of homo sapiens. Eating a good chunk of the brain seems a solution to the problem that it might pay us to consider.