Artiicial Biology

Artiicial Life spans a continuum from engineering to biology. Biological organisms are inspiring both as existence proofs for the tractability of many engineering problems and as testaments to the innovation and power of evolution as a sort of \blind" engineer. The middle of the continuum is occupied by researchers trying to synthesize life in novel substrates. Far from the nightmares of Frankenstein, theoretical biologists are beginning to open up some of the most intractable problems of biology through the use of new computer modeling techniques. Artiicial Biology is this approach of using computer models to simulate biological systems. These simulations allow us to gain experimental control over biological systems that are beyond direct empirical method-ologies. The models also allow us to address systems with complexities that would make an analytical model intractable. In this way, Artiicial Biology complements the traditional elds of empirical and theoretical biology. 1 The Structure of Artiicial Life We have only one example of how life can work. All of life, as we know it, is based on a genetic code of four nucleic acids and their translation into proteins. Yet, we have begun to suspect that perhaps \life" is a more general phenomenon and so might be found in unfamiliar substrates. It is almost as if we were stuck in the middle ages when our only experience of light was that it came from re. It is diicult to understand any complex phenomenon when you cannot abstract the concept from its implementation. This is the raison d'etre for the eld of Artiicial Life..13, 15, 14, 3, 23] In the long view, researchers in Artiicial Life seek to simulate and even synthesize life in novel media in order to understand the phenomenon of life itself. Only then can we hope to separate the historical accidents that led to life on Earth from the systematic constraints that shaped it. Artiicial Life can be understood as the froth that is thrown up when the waves of engineering hubris crash upon the shores of organismal biology. It is the intersection of 1