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Mar. 13th, 2004 12:53 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
baloonworld3Bak Sneppen Model of evolution
Once again this is a cellular autonima, designed to model the evolution of a group of species. The algorithm operates on a grid, each square of which represents a species. The fitness of the species to survive in its current environment is represented by a single number; there is nothing to distinguish between species which fulfil different roles.
To start with each species is assigned a (psudo) random number between 0 and 1 to represent its fitness for survival. From the point, the algorthem operates as follows
1/Select the least fit species (Assumption; species on the brink experience more deaths and hence more intense competition and more rapid evolution than those whose survival is assured)
2/ reassign its fitness randomly.
3/The neighbouring species are those that are have a relationship of some kind. As such the fitness of the neighbouring species is also reassigned at random.
4/ Repeat from 1
Although this model is rather crude and makes some huge assumptions and simplifications, it does produce a rather interesting distribution of fitnesses- no species have less than the critical fitness (which changes with the details of the system) and there is a roughly even distribution of fitnesses amoungst the species above this point. This is shown in fig [BS1]
Fig[BS1] distrubution of fitnesses in a Bak-Sneppen system
Once again this is a cellular autonima, designed to model the evolution of a group of species. The algorithm operates on a grid, each square of which represents a species. The fitness of the species to survive in its current environment is represented by a single number; there is nothing to distinguish between species which fulfil different roles.
To start with each species is assigned a (psudo) random number between 0 and 1 to represent its fitness for survival. From the point, the algorthem operates as follows
1/Select the least fit species (Assumption; species on the brink experience more deaths and hence more intense competition and more rapid evolution than those whose survival is assured)
2/ reassign its fitness randomly.
3/The neighbouring species are those that are have a relationship of some kind. As such the fitness of the neighbouring species is also reassigned at random.
4/ Repeat from 1
Although this model is rather crude and makes some huge assumptions and simplifications, it does produce a rather interesting distribution of fitnesses- no species have less than the critical fitness (which changes with the details of the system) and there is a roughly even distribution of fitnesses amoungst the species above this point. This is shown in fig [BS1]
Fig[BS1] distrubution of fitnesses in a Bak-Sneppen system
