It is fair to say that I was not interested in development per se. That is, I was not going to start a thing which would begin with a fertilised egg and then go through all the steps and ask about the germ layers and so on, which was the classical style of doing that. Nor was I interested in... in relegating myself to a secondary problem such as differentiation and ask questions like, why's a pancreas cell different from a liver cell? Because those were all open possibilities. But I thought that in the nervous system we would embody everything. Because what I clearly had and in fact it's written there, was that we would... one of the things that we... we realised is that the nervous system is an organ. It's an organ built out of cells, and you can ask yourself two questions: how does it work? — which is how does it work to generate behaviour — and then you have to ask how do the genes work to build a nervous system? And the connection between genes and behaviour must go through the construction and performance of a nervous system. So... so developmental biology, or the developmental program, or what I call the construction paradigm — which even at the molecular level is imported — is automatically embedded in this, and I've never seen it as a distinct field. That is, if you're interested in complexity you have to be interested in development. Your solution will be couched in developmental terms. And of course what struck us very... from the little we'd read of the nematodes, the classical work which I read, was that this looked like something that would... in which lineage would be very important. And in which perhaps there was some mechanism here in which when cells divided they actually computed their future fate. And in fact it was seen as being very different to the gradient models as these two lines came, and ought to be made distinctive. And some years later when one tried to explain this as I did through the American plan versus the European plan, it was unclear that this had not been grasped, and I think one should read for this the discussion that I left intact in the... in the Ciba Foundation, because I thought historically it would be important to leave that as a discussion intact. It is a very confused discussion; it is also very remarkable in that most people were wrong in their predictions. There's a rather pessimistic prediction of... by Martin Raff which he himself has proved himself wrong. And there's an interesting discussion there between myself and Lewis Wolpert which... which really tries... in which I try to differentiate between the computation that is performed and the outcome. Because of course everything occupies a position in space, it has to, that's inevitable. But do you calculate, or does each cell calculate its position or it's... it's individuality by looking at its neighbours, or does it do it because it has been put there by its ancestors? And those are two different mechanisms at this level, but of course everybody will say, they will be connected at the molecular level. It is unbelievable that there should be two very distinctive features of organisms that would be unconnected. So that gradients would be the analogue way of doing it, and lineage would be the digital way of doing it, so to speak.
