Tierra Photoessay

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

• 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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  Why

• 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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  How

• 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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  Future Work

• 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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  ALmond Overview

  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). Feel free to reproduce or publish these images, make photo credits to: Marc Cygnus
  Hosts, red, are very common. Parasites, yellow, have appeared but are still rare. Medium resolution (33798 bytes). Higher resolution (87505 bytes).
  

  Hosts, are now rare because parasites have become very common. Immune hosts, blue, have appeared but are rare. Medium resolution (39274 bytes). Higher resolution (105636 bytes).
  

  Immune hosts are increasing in frequency, separating the parasites into the top of memory. Medium resolution (38397 bytes). Higher resolution (101459 bytes).
  

  Immune hosts now dominate memory, while parasites and susceptible hosts decline in frequency. The parasites will soon be driven to extinction. Medium resolution (35956 bytes). Higher resolution (91814 bytes).

  
  

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  Anti-Gravity Animation

  Images from the Tierra Video

  Feel free to reproduce or publish these images, make photo credits to: Anti-Gravity Workshop

  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. Medium resolution (29918 bytes, 431x302). Higher resolution (74049 bytes, 864x602).
  

  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. Medium resolution (11169 bytes). Higher resolution (30463 bytes).
  

  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). Medium resolution (18826 bytes). Higher resolution (47741 bytes).
  

  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. Medium resolution (22537 bytes). Higher resolution (57578 bytes).

  
  

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  Visualization of the Tierra Network

  These are two images from the VRML Visualization of Network Tierra. This visualization represents the Tierra network environment though the ``eyes'' of the digital organisms themselves. Digital organisms are able to perceive conditions on the net by using the TPing sensory mechanism (sort of like echo location in bats). These images visualize the data provided by TPing.

  Close up view of Network Tierra visualization. The diameter of the orange sphere is proportional to the amount of memory available to the digital organisms on a node (the soup size); the diameter of the blue sphere (usually) within the orange sphere represents the speed of the processor, measured as virtual machine instructions executed per second; around each blue sphere is a cluster of yellow-green spheres, each of these represents the presence of one hundred digital organisms in that soup. Not that the node represented by the spheres on the lower right of the image has four yellow-green spheres, indicating the presence of four hundred digital organisms on that machine. In the upper left is a machine with a small soup and a fast processor, so the small orange sphere is hidden inside the large blue sphere, and being a small soup, there are only one hundred digital organisms on that machine (note one yellow-green sphere).
  

  Wide view of Network Tierra visualization. This is a view of a medium sized Tierra network, with about one hundred participating machines. The machines are located at ATR in Japan, The University of Delaware, The Santa Fe Institute, The Free University of Brusells, and the Swiss Federal Institute in Lausanne. Each machine is visualized as a set of spheres (one orange, one blue, and a few yellow-green), as described above. The network is represented from the perspective of one digital organism, located on a specific machine (in Santa Fe). The spheres representing the hundred machines are arranged onto the surface of a cone, with the point-of-view machine at the tip of the cone (a little below and left of center). The remaining machines are arranged in spirals on the surface of the cone, but with their distance from the tip proportional to the time that it takes the TPing message to cross the net and return. This network transit time is the most meaningful measure of distance on the network, and it is provided with the TPing data.