sampling of underlying programs—without any systematic effect of natural selection.

For the more superficial aspects of organisms—such as pigmentation patterns—it seems likely that among programs sampled at random a fair fraction will produce results that are not disastrous for the organism. But when one is dealing with the basic structure of organisms, the vast majority of programs sampled at random will no doubt have immediate disastrous consequences. And in a sense it is natural selection that is responsible for the fact that such programs do not survive.

But the point is that in such a case its effect is not systematic or cumulative. And indeed it is my strong suspicion that for essentially all purposes the only reasonable model for important new features of organisms is that they come from programs selected purely at random.

So does this then mean that there can never be any kind of general theory for all the features of higher organisms? Presumably the pattern of exactly which new features were added when in the history of biological evolution is no more amenable to general theory than the specific course of events in human history. But I strongly suspect that the vast majority of significant new features that appear in organisms are at least at first associated with fairly short underlying programs. And insofar as this is the case the results of this book should allow one to develop some fairly general characterizations of what can happen.

So what all this means is that much of what we see in biology should correspond quite closely to the typical behavior of simple programs as we have studied them in this book—with the main caveat being just that certain aspects will be smoothed and simplified by the effects of natural selection. Seeing in earlier chapters of this book all the diverse things that simple programs can do, it is easy to be struck by analogies to books of biological flora and fauna. Yet what we now see is that in fact such analogies may be quite direct—and that many of the most obvious features of actual biological organisms may in effect be direct reflections of typical behavior that one sees in simple programs.