Thoughts on the Synthesis of Life

One of the most challenging problems in Artiicial Life remains the creation of open ended evolution. A number of current eeorts are directed at this problem. One characteristic that these eeorts generally share is that they parallel the origin of life event, in that they attempt to create pre-biotic conditions from which Artiicial Life may emerge spontaneously and evolve in an open ended fashion. While the origin of life is generally recognized as an event of the rst order, there is another event in the history of life that is less well known but of comparable signiicance. The origin of biological diversity and at the same time of macroscopic multi-cellular life, occurred abruptly in the Cambrian explosion 600 million years ago. This event involved a riotous diversiication of life forms. Dozens of phyla appeared suddenly, many existing only eetingly, as diverse and sometimes bizarre ways of life were explored in a relative ecological void. I discuss an approach to AL that parallels this second major event in the history of life, the origin of diversity. Rather than attempting to create pre-biotic conditions from which life may emerge, this approach involves engineering over the rst 3 billion years of life's history to design complex evolvable artiicial organisms, and attempting to create the biological conditions that will set oo a spontaneous evolutionary process of increasing diversity and complexity of organisms. This is a very diicult undertaking, because in the midst of the Cambrian explosion, life had evolved to a level of complexity in which emergent properties existed at many hierarchical levels: molecular, cellular, organismal, populational and community. In order to deene an approach to the synthesis of Artiicial Life paralleling this historical stage of organic life, we must examine each of the fundamental hierarchical levels and abstract the principal biological properties from their physical representation, and determine how they can be represented in our chosen artiicial media. I will discuss some of the outstanding biological properties of several of these levels, in the context of Artiicial Life. This is an exercise in considering the extension of biological properties to life forms beyond the organic.