Looking back along this chain of evolution, this incredibly detailed chain of many steps, I am overwhelmingly impressed by the way in which chemistry has gradually given way to electronics. It is not unreasonable to describe the first living creatures as entirely chemical in character. Although electrochemical processes are important in plants, organized electronics, in the sense of data processing, does not enter or operate in the plant world. But primitive electronics begins to assume importance as soon as we have a creature that moves around, instead of being rooted in a particular spot, as a plant is. This is surely what we mean by an animal, a creature that moves around. In order to move in any purposeful way a system capable of analyzing and processing information about the external world, about the lay of the land as one might say, becomes necessary. The first electronic systems possessed by primitive animals were essentially guidance systems, analogous logically to sonar or radar. As we pass to more developed animals we find electronic systems being used not merely for guidance but for directing the animal toward food, particularly toward food in the form of another animal. First we have animals eating plants, then animals eating animals, a second order effect. The situation is analogous to a guided missile, the job of which is to intercept and destroy another missile. Just as in our modern world attack and defense become more and more subtle in their methods, so it was the case with animals. And with increasing subtlety, better and better systems of electronics become necessary. What happened in nature has a close parallel with the development of electronics in modern military applications.
I find it a sobering thought that but for the tooth-and-claw existence of the jungle we should not possess our intellectual capabilities, we should not be able to inquire into the structure of the Universe, or to be able to appreciate a symphony of Beethoven. What happened was that electronic systems gradually outran their original purposes. At first they existed to guide animals with powerful weapons, teeth and claws, toward their victims. The astonishing thing, however, was that at a certain stage of subtlety the teeth and claws became unnecessary. Creatures began to emerge in which the original roles of chemistry and electronics were reversed. Instead of the electronics being servant to the chemistry, the reverse became the case. By the time we reach the human, the body has become the servant of the head, existing very largely to supply the brain with appropriate materials for its operation. In us, the computer in our heads, the computer that we call our brain, has entirely taken control. The same I think is true of most of the higher animals, indeed I think this is how one really defines a higher animal. Viewed in this light, the question that is sometimes asked—can computers think?—is somewhat ironic. Here of course I mean the computers that we ourselves make out of inorganic materials. What on earth do those who ask such a question think they themselves are? Simply computers, but vastly more complicated ones than anything we have yet learned to make. Remember that our man-made computer industry is a mere two or three decades old, whereas we ourselves are the products of an evolution that has operated over hundreds of millions of years.