Tierra Photoessay

Go to Tom Ray's home page. Go to the Tierra home page.

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What

This project attempts to use evolution by natural selection in the medium of the digital computer to generate complex and intelligent software.

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Evolution by natural selection has generated complex and intelligent life forms in the medium of carbon chemistry.

Evolution is the only process with a proven ability to produce intelligence.

The DNA of living organisms is a genetic ``program''. This is a parallel software of a complexity much greater than any that could be written by humans.

Experiments illustrated here show that evolution by natural selection works very effectively in the medium of computer machine code.

Evolution will find forms and processes that exploit the possibilities inherent in the computational medium.

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Self-replicating machine code programs are introduced to the RAM memory of the computer.

Genetic variation occurs due to ``mutations'' resulting from random flips (between 0 and 1) of bits in the memory.

A ``reaper'' function of the operating system kills old or defective processes in order to make way for newborn programs, once the memory is full.

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The evolutionary process will be introduced into the context of the global computer network, internet. The objective is to evolve complex MIMD distributed processes.

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Evolutionary race between hosts and parasites in a soup of the Tierra Synthetic Life program developed by Tom Ray. Images made using the Artificial Life Monitor (ALmond) program developed by Marc Cygnus (mcygnus@mcs.com). Each image represents a soup of 60,000 bytes, divided into 60 segments of 1000 bytes each. Each individual creature is represented by a colored bar, colors correspond to genome size (e.g., red = 80, yellow = 45, blue = 79).

Hosts, red, are very common. Parasites, yellow, have appeared but are still rare.


Hosts, are now rare because parasites have become very common. Immune hosts, blue, have appeared but are rare.


Immune hosts are increasing in frequency, separating the parasites into the top of memory.


Immune hosts now dominate memory, while parasites and susceptible hosts decline in frequency. The parasites will soon be driven to extinction.

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Images from the Tierra Video

The Digital Environment: Self-replicating computer programs (colored geometric objects) occupy the RAM memory of the computer (orange background). Mutations (lightning) cause random changes in the code. Death (the skull) eliminates old or defective programs.


The Ancestral Program - consists of three ``genes'' (green solid objects). The CPU (green sphere) is executing code in the first gene, which causes the program to measure itself.


A Parasite (blue, two piece object) uses its CPU (blue sphere) to execute the code in the third gene of a neighboring host organism (green) to replicate itself, producing daughter parasite (two-piece wire frame object).


A Hyper-parasite (red, three piece object) steals the CPU from a parasite (blue sphere). Using the stolen CPU, and its own CPU (red sphere) it is able to produce two daughters (wire frame objects on left and right) simultaneously.