Avida is a software platform to study the evolutionary biology of self-replicating and evolving computer programs (digital organisms). Avida was originally developed by Chris Adami, Titus Brown, and Charles Ofria, and was inspired by and inherits several of its properties from the Tierra system.

Design principles

The main difference between Avida and Tierra is that in Avida, every digital organism (that is, self-replicating computer program) lives in its own protected region of memory, and is executed by its own virtual CPU. By default, other digital organisms cannot access this memory space, neither for reading nor for writing, and cannot execute code that is not in their own memory space.

A second major difference is that the virtual CPUs of different organisms can run at different speeds, such that one organism executes for example twice as many instructions in the same time interval than another organism. The speed at which a virtual CPU runs is determined by a number of factors, but most importantly, by the tasks that the organism performs: Tasks are logical computations that the organisms can carry out to reap extra CPU speed as bonus.

See also

• Tierra

Scientific publications featuring Avida

• R.E. Lenski, C. Ofria, T. C. Collier, C. Adami (1999). Genomic Complexity, Robustness, and Genetic Interactions in Digital Organisms. Nature 400:661-664. abstract of this article
• C.O. Wilke, J.L. Wang, C. Ofria, R.E. Lenski, and C. Adami (2001). Evolution of Digital Organisms at High Mutation Rate Leads To Survial of the Flattest. Nature 412:331-333.
• R.E. Lenski, C. Ofria, R.T. Pennock, and C. Adami (2003). The Evolutionary Origin of Complex Features. Nature 423:139-145.
• S.S. Chow, C.O. Wilke, C. Ofria, R.E. Lenski, and C. Adami (2004). Adaptive Radiation from Resource Competition in Digital Organims. Science 305:84-86.

Popular science publications on Avida

• Testing Darwin Discover Magazine Vol. 26 No. 02 | February 2005

External links

• Project homepage
• Avida-ED Project - Robert T. Pennock