The difference between a brain and a computer can be expressed in a single word, that is, complexity. The large mammalian brain is the most complicated thing, for its size, known to us. The human brain weights 3 ponds, but in that 3 ponds are 10 billion neurons and a hundred billion smaller cells.// Even the most complicated computer man has yet built can't compare in intricacy with the brain. Computer switches and components number in the thousands rather than in the billions. What's more, the computer switch is just an on-off device, whereas the brain cell is itself possessed of a tremendously complex inner structure.// It is frequently said that computers solve problems only because they are “programmed” to do so. They can only do what men have them do. One must remember that human beings also can only do what they are “programmed” to do. Our genes “program” us and our potentialities are limited by that “program”.// Our “program” is so much more enormously complex, though, that we might like to define “thinking” in terms of our creativity in literature, art, science and technology. In that sense, computers certainly can't think.//

In his book Brave New World, published in 1932, Aldous Huxley predicted a big biotechnological revolution about to take place: the hatching of people not in wombs but in test tubes; the drug which gave people instant happiness; the sensation which was simulated by implanted electrodes; and modification of behavior through the administration of various artificial hormones.// With 70 years of separating us from the publication of this book, we can see that Huxley's technological predictions are surprisingly accurate. Many of the technologies that Huxley envisioned are already here or just over the horizon. But this revolution has only just begun.// According to Huxley, the most significant threat posed by contemporary biotechnology is the possibility that it will alter human nature and thereby move us into a “posthuman” stage of history. This is important because human nature exists and defines us as a species with a stable continuity. It is what defines our most basic values.// Medical technology offers us in many cases a devil's bargain: longer life, but with reduced mental capacity; freedom from depression, together with freedom form creativity or spirit. It will blur the line between what we achieve on our own and what we achieve because of the levels of various chemicals in our brains.//