Avida
From Free net encyclopedia
Avida is an artificial life 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.
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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.
Use in research, and its criticism
Adami and Ofria, in collaboration with others, have used Avida to conduct research in digital evolution, and the scientific journals Nature and Science have published several of their papers. Most controversially, it has been used in an attempt to demonstrate that Darwinian evolution can produce complexity. Nature' published "The Evolutionary Origin of Complex Features" in 2003, in which the evolution of a mathematical equals operation is constructed of at least 19 simpler, precisely ordered logical operations. Some claim that this proves that irreducible complexity can evolve, while proponents of irreducible complexity claim this only shows it for simple instances, which irreducible complexity already admits can evolve.
See also
Other ALife platforms
Other Digital Organism Simulators
References
- "Testing Darwin", Discover Magazine, February 2005.
- "Computer Speeds Up Evolution, Produces Complexity"
- "Vignere Encoded Text Evolution" from ISCID
External links
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.
- Eric Anderson, (2004). Bits, Bytes and Biology: What Evolutionary Algorithms (Don't) Teach Us About Biology pdf