You can see these two species coexisting in a long period of stability; then on of the them drops out and all hell breaks loose. Tremendous instabili… - Christopher Langton

Artificial Life (``AL or ``Alife) is the name given to a new discipline that studies "natural" life by attempting to recreate biological phenomena from scratch within computers and other "artificial" media. Alife complements the traditional analytic approach of traditional biology with a synthetic approach in which, rather than studying biological phenomena by taking apart living organisms to see how they work, one attempts to put together systems that behave like living organisms.

Biology is the scientific study of life - in principle, anyway. In practice, biology is the scientific study of life on Earth based on carbon-chain chemistry. There is nothing in its charter that restricts biology to carbon-based life; it is simply that this is the only kind of life that has been available to study. Thus, theoretical biology has long faced the fundamental obstacle that it is impossible to derive general principles from single examples... Without other examples, it is difficult to distinguish essential properties of life - properties that would be shared by any living system - from properties that may be incidental to life in principle, but which happen to be universal to life on Earth due solely to a combination of local historical accident and common genetic descent.

Christopher Langton in: Karl Gerbel, Peter Weibel, Katharina Gsöllpointner (1993) Genetische Kunst--künstliches Leben. p.25