Figure 1
Karl Sims' system for evolving images by aesthetic selection. Left: An array of twenty choices. These are the products of mutations and or recombinations of the previous aesthetic selection(s). The user can choose one or two of these to be the parent(s) of the next generation. Center and Right: Two examples of images evolved through aesthetic selection.
Figure 2
Karl Sims' evolving block creatures. Left: A slightly evolved population of block creatures, which are being selected for swimming velocity. Center: An evolutionary sequence of creatures selected for swimming velocity, eventually leading to a snake-like body. Right: A school of swimming ``water snakes''.
Figure 3
Karl Sims' action sequence of two block creatures competing for possession of a block. Left: Starting positions. Center: Struggling for possession. Right: Finish, the yellow creature on the left wins.
Figure 4
Karl Sims' block creatures struggling for possession of a block.
Figure 5
Screen shot of PolyWorld Ecological Simulator. (from: Yaeger, Larry. 1994. Computational genetics, physiology, metabolism, neural systems, learning, vision, and behavior or PolyWorld: life in a new context. In: Artificial Life III, [Ed.] Christopher G. Langton, SFI Studies in the Sciences of Complexity, Proc. Vol. XVII, Addison-Wesley. Pp. 263--298.)
Figure 6
Implementing the Darwinian scenario in the computer. The orange background circuitry represents the RAM memory chip. The green and blue geometric objects represent self-replicating computer programs which occupy the RAM memory space. The skull represents death, and the lightning bolt represents random mutations.
Figure 7
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.
Figure 8
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 a daughter parasite (two-piece wire frame object).
Figure 9
Evolutionary race between hosts and parasites in a soup of the Tierra program. Left: Hosts, red, are very common. Parasites, yellow, have appeared but are still rare. Left Center: Hosts, are now rare because parasites have become very common. Immune hosts, blue, have appeared but are rare. Right Center: Immune hosts are increasing in frequency, separating the parasites into the top of memory. Right: Immune hosts now dominate memory, while parasites and susceptible hosts decline in frequency. The parasites will soon be driven to extinction. Each image represents a soup of 60,000 bytes, displayed as 60 bars 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).
Figure 10
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.
Figure 11
Complexity increase through evolution on Earth. Most of the increase has occurred in a small number of major transitions, the most significant of which was the Cambrian explosion of diversity, around 600 million years ago.
Figure 12
Two images from the VRML Visualization of Network Tierra (http://vrml.arc.org/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.
Left: 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).
Right: 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.