John Von Neumann was the first person that thought about ways of creating artificial life. Artificial Life ("Alife" or "AL") is a field that was officially started in September 1987 at Los Alamos, New Mexico. The study of Artificial Life was first advocated by Christopher Langton of the Santa Fe Institute in the U.S.A. The name "Artificial Life is given to a new discipline that studies "natural" life by attempting to recreate biological phenomena from scratch within computers" and other "artificial" media (1). This field is also referred to as the practice of "synthetic" biology.

Artificial life amounts to the attempt to put together synthetic systems, like automatic robots and organisms within the computer so that they can behave like living organisms. In other words these synthetic systems are designed to exhibit the behavior characteristics of natural living systems, self-organization, adaptation, evolution, co-evolution and metabolism. This is the quest to explain life in any of its possible manifestations, without restriction to the particular examples that have evolved on earth. These include biological and chemical experiments, computer simulations and purely theoretical endeavors. The ultimate goal of the study of artificial life would be to create "life" in some other medium, ideally a virtual medium in which they can implement the extracted logical form of a natural living organism into the computer generated models.

By building new instances or models to represent artificial life, it offers the possibility and the opportunity to observe independent examples of life without leaving the planet. These models of artificial life are tested against a list of characteristics that exists in living organisms only. A problem arises from a lack of agreement on what should be included on the list.

Characteristics common on many lists include the ability to:-

1. Replicate
2. Evolve
3. Metabolize
4. Respond to stimuli
5. Repair damages

Most examples of artificial life fail such tests unless the list is shortened because the models are unable to perform all of the characteristics that are mentioned on the list.

A major step toward the understanding of how artificial creatures might be considered alive, is realizing that the essence of a machine lies in the logic of its organization, the material is not important. One advantage of artificial models is the opportunities they offer in performing in-depth studies of the evolutionary process. This is accomplished by observing not only phenotypic effects but also such measures as fitness, operability, energy and the genescape. "Artificial life research has doubled:-

1. Enhancing our understanding of the functioning of natural systems as well as the manner in which they evolved.
2. Mimicking nature’s achievements by creating artificial systems based on these principles and matching the problem-solving capacities of their natural counterparts" (2).

The field of "artificial life includes the following:-

• simulation of existing life forms and their behaviors
• synthesis of new life forms
• artificial worlds (e.g. Tierra, Avida)
• evolution of cooperation (e.g. prisoners dilemma)
• evolution of communication
• autonomous agents (both mobile robots and software agents)" (3)

Computer Viruses: This is usually one of the simplest levels of artificial life. This model exhibits most of the "required" life signs, such as reproduction, integration of parts, and unpredictability.

"Biomorphs": These are systems that are designed specifically to act in the same manner as real life. These systems are given all the properties of "real" creatures in hopes that they will act the same way. These often use generic algorithms in order to simulate evolutionary processes of creatures.

Robotics: These are physical manifestations of experiments in artificial life. They usually have the property of complexity, integration of parts, irritability, movement but the models lack the ability to reproduce.

Evolving Computer Processes: "These are very similar to computer viruses but are more sophisticated. The main difference between these and the computer viruses is that these tend not to be rogues; they were created with the specific purpose of controlling and observing their behaviors" (5).

The strength of this approach is that you can model not just structures of a specific life, but the entire development process. A major challenge for artificial life is to synthesize the evolutionary transitions that have repeatedly formed differentiated higher level entities from cooperative organizations of low-level entities, producing the nested hierarchical structure of living processes. The success of Artificial life depends on whether it will help solve the conceptual problems of biology.

1. Introduction to Artificial Life by Sipper, Moshe.

Http://alife.santafe.edu/alife/alife-def.html

2. Artificial Life by Levy, Steven.

Http://www.math.tau.ac.il/~hoffman.complexity/6.html

3. What is Artificial Life?

Http://www.wi.leidenuniv.nl/home/gusz/alife.html

4. Computer Virus as Artificial Life by Spafford H. Eugene.

Volume 1, Issue 3, Spring 1994 (pages 249 - 265)

5. Artificial Life used for Artificial Intelligence.

Early Artificial Life ideas.

Current Models used to represent Artificial Life.

by Ofria, Charles.

Http://www.krl.caltech.edu/~charles/stories/alife.html