At a conservative estimate - and assuming we could use every corner of our brain, which we cannot - each of us could store about 5,000 years of continuous conversation, and about five years of continuous video. Well, on one plane, thank God we are analogue and we do forget. Our analogue memory system seems to have evolved to let information fade exponentially, and perhaps this is the stuff of dreams. The problem is, we have new IT-driven demands that mean we have to remember and process more and more information.

I have long considered computers to be my third lobe. They are where I store and process everything with greater precision than nature would normally allow with my carbon-based wetware. So, looking to the future: can these two worlds of analogue and digital forms coexist symbiotically? Could we communicate directly with machines? Perhaps not for a while, it would seem, but all the indications are promising.

There have been more than 1,700 successful cochlea implants, involving chips mounted inside the human head, to restore the hearing of those with severe difficulties. From an engineering perspective, you might suppose that connecting the correct carbon-based nerves to the correct silicon feeds would be a significant problem. But apparently not.

The wife of a friend has been deaf for more than 50 years and recently had cochlea implants. She set about tutoring her brain by using a talking book in conjunction with the printed page. Playing the talking book into her electronic ears while reading the same words helped her to have her first stilted conversations within weeks. After a couple of years, she has become remarkably proficient, and thousands are now emulating this process. Of course, what they hear might not be as good as the real thing, but it works - and it is only a beginning.

Similar experiences are also recorded with prosthetics coupled directly to the human nervous system. There are also serious attempts at nervous-system repair with silicon bypass, and there has been one experiment with an artificial retina. The precise wiring diagram does not seem to matter; we no longer seem to have to obey the engineers' cable colour code. While our electronics are immutable in their configuration, the human system seems able to reprogram the input/output to accommodate this limitation. What a miracle.

It is interesting that recent developments in optical storage and processing technology are seeing a swing back to analogue forms that are more efficient than digital electronics. We should reflect that our biological systems are actually an interesting mix of analogue and digital. Might this be where our true synergy lies, where carbon meets silicon, where the digital meets the analogue . . . where mind meets machine?

Peter Cochrane holds the Collier Chair for the Public Understanding of Science & Technology at the University of Bristol. His home page is:
http://cochrane.org.uk