Selective variety

Although this principle is again self-evident or tautologous, it leads to a number of useful and far from trivial conclusions. For example, the less numerous or the farther apart potential stable configurations are, the more variation (passing through a variety of configurations) the system will have to undergo in order to maintain its chances to find a stable configuration. In cases where selection criteria, determining which configurations are stable and which are not, can change, it is better to dispose of a large variety of possible configurations. If under a new selective regime configurations lose their stability, a large initial variety will make it probable that at least some configurations will retain their stability. A classic example is the danger of monoculture with genetically similar or identical plants: a single disease or parasite invasion can be sufficient to destroy all crops. If there is variety, on the other hand, there will always be some crops that survive the invasion.

Another special case is the "order from noise" principle ( fromulated by von Foerster), related to "order out of chaos". Noise or chaos can here be interpreted as rapid and blind variation. The principle states that addition of such noise makes it more likely for a system to evolve to an ordered (stable) configuration. A practical application is the technique of (simulated) annealing, where noise or variation is applied in stepwise decreasing amounts, in order to reach a maximally stable configuration.

Mis à jour le 01/04/2016 pratclif.com