To: All Msg #277, Jul1593 10:07AM Subject: Evolution simulator available Fellow t.o reader

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From: Alan Geist To: All Msg #277, Jul-15-93 10:07AM Subject: Evolution simulator available Organization: Supercomputer Systems Division (SSD), Intel From: alang@ssd.intel.com (Alan Geist) Message-ID: Newsgroups: talk.origins Fellow t.o readers, I have uploaded a program for PCs that while simple, illustrates some of the basic concepts of evolution. The ftp site is wuarchive.wustl.edu, and the path and name are pub/goe.tar.Z. Not being a biologist, parts of it are certainly going to be innacurate. Hopefully, as many parts are at least somewhat accurate. The reason I am posting notice here is that I am interested in feedback from those who are far more knowing in the subjects of evolution and biology than I am. So if you have a PC and some time, give it a try, and let me know what you think. My email address appears in the 'about' file, which is part of the game. The about file is also included below so you can see what it's all about before bothering to download it. Thanks in advance, Alan Geist "Why do today what you can put off again tomorrow?" ================================================================= The Game of Evolution Copyright 1991, 1992, 1993 Alan Geist Permission for reproduction or distribution is granted to all provided that the files 'goe.hlp' and 'goe.abo' always accompany the compiled code. Disclaimer: The opinions expressed in this file, the 'goe.hlp' file, and the game are accidental, and thus are not those of either the author, or any employer, past, present, or future. Furthermore, this game is not meant to either support or discredit any scientific, political, or social theory whatsoever. About GOE: The Game of Evolution (GOE) is a highly modified version of the familiar Game of Life (GOL). The screen is made up of a grid of "sites", each of which may be occupied by a living, but non-mobile "cell". In GOE, like GOL, the cells survive and reproduce according to certain rules. The first difference between GOE and GOL is that in GOE the rules of survival and reproduction are specified in probabilities instead of absolutes. The probability is specified for each number of neighbors a site can have. For example, if a 50% probability is specified for a birth into an empty site with three neighbors, then about 50% of the empty sites with three neighbors on the screen will have new cells in them in a given generation. Each site is evaluated randomly according to the probability, and independant of the evaluation of all other sites on the screen. The user may specify those probabilities, or use the defaults. In addition, GOE has different species groups, and different environments. Species group 1 is said to represent all species whose relative success rate is "good" in environment 1. (For the purposes of this game and description, consider the word "species" to mean species group). Likewise, species 2 is said to represent all species whose relative success rate is good in environment 2, and so on up to species 4. Each of species 1 through 4 has a "good" success rate in the environment by the same name, a "fair" success rate in the two adjacent environments, and a "poor" success rate in the environment which is diagonally opposite on the screen. Species 5 is said to have a "poor" success rate in any environment, and is thus considered to be a non-viable species. Reproduction of one species over another is decided by the neighbors of the empty site. For any given empty site, each neighbor is given the opportunity to reproduce into that empty site in a random order. So in an empty site with a variety of species of neighbors, each neighbor gets a turn to give birth into that site, until a birth occurs, or until all neighbors have had their opportunity. The probability that a particular neighbor will give birth depends on the success rate for that species, given the number of neighbors of the empty site, and the environment that the particular neighbor is in. Also, for the purposes of birth only, the probability is "degraded" such that after checking all neighbors of an empty site, the probability that a birth occured is equal to the number specified for that species (assuming all neighbors were of the same species). In other words, if an empty site has a 50% chance of getting a birth in it for three neighbors, the chance for each of the three individuals to give birth there is degraded such that the chance for a birth after all three have been checked is 50%. If the chance wasn't degraded, the chance after all three have been checked would be 87.5%. (To understand this, flip a coin. The chance that the coin came up heads is 50%. Flip it again. The chance that one of the two flips was heads is 75%. Flip it again. The chance that one of the three flips was heads is 87.5%. Etcetera. In the birth example above, the coin has been weighted, such that after three flips, the chance that one of the three flips was heads is 50%.) Birth chance degredation depends only on the total number of neighbors, and the relative success rate of the species trying to give birth. It does not depend on the species of the other neighbors. The last difference between GOE and GOL is that GOE has evolution. On a random basis, mutations will occur during the birth of a new cell. A mutation will result in the "child" cell being of a different species than the "parent" cell. To aid in telling the difference between different mutations to the same species group, the color rotates through a series of nine different colors each time a new mutation occurs into a given species group. Thus, a blue species 1 and a green species 1 are said to be different species, but with the same relative success rate in environment one. Both the rate of mutation, and the chance that a given mutation will be viable can be specified by the user. Non-viable mutations automatically result in species 5. A viable mutation results in species 1 through 4, and is independant of the environment. That is, a mutation is considered viable, even if it has a poor success rate in the environment into which it was born. To see how species concentrate in their best environments, initialize the screen with a variety of species scattered across the entire screen. Within 100 generations or so (with default parameters), you will see this happen. I recommend this your first time, as it shows some of the effects that happen aside from evolution. To actually watch evolution in action (other than watching bungie jumping of course), intialize the whole screen with just one species. After an unpredictable number of generations (but usually less than 1000), at least one of the environments will probably have a species that evolved especially for it. There is one extremely interesting phenomenon which I have yet to be able to explain. It seems that different species with identical characteristics seem to segregate from one another, simply by being labeled differently. This occurs independantly of evolution, and is readily replicable with the probability of mutation equal to zero. Further, there is nothing I know of in the program to cause this effect other than a species only gives birth to an exact copy of itself (assuming no mutation). To observe this phenomenon, enter identical reproduction and sustaining characteristics for each of the three success levels. When prompted for the chance of a birth being a mutant, enter zero. At this point all species should have identical characteristics regardless of where they are located. Now initialize the screen with a random mix of species. Within 100 generations or so, they will have segregated into colonies, and even appear to sort of war against each other. Comments, suggestions, and explanations for the above phenomenon are encouraged via email. The author's email address, as of July, 1993, is alang@ssd.intel.com. goe.exe is a PC executable file, though admittedly, it has not been tried on a wide variety of machines prior to distribution. Executables for other machines are not available, so please don't ask. Enjoy your game. If you are viewing this from within the game, the help file is automatically displayed next.

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