Which+code+is+chosen?

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 * TODO List**
 * REF: van Nimwegen 2000
 * Clarify connection matrix (van Nimwegen 2000), but this is not max robustness (WHY?)
 * REF: van Nimwegen 1999

=Which code is chosen?=

Populations evolve to **flatter** parts of the landscape, i.e.:
 * mutational robustness
 * high connectivity of neutral networks
 * max [|eigenvector] of connection matrix (van Nimwegen 2000), but this is not max robustness (WHY?)

It is also interesting to consider the properties of different kinds of coding:
 * with **[|roman numerals]** one needs to add a lot of digits to get new meaning
 * with [|binary code] there are more meanings with fewer digits due to coding
 * in **RNA code** there are 4 bases giving folding, which gives the landscape

van Nimwegen (1999) studied evolution on the neutral network and found that: These results become more intuitively clear if one considers an evolving population as either a **blind ant** or a **[|myopic] ant**. In the case of the blind ant, the ant does steps in arbitrary directions. If it makes a wrong step it must then step back. This ant is on average on an average connectivity of the neutral network. If it is in a highly connected area then it has more chance to leave that area, while in low connected areas it has a harder time leaving! In contrast the myopic ant looks ahead and chooses which direction to step on the neutral path and then always takes a step. This ant more easily finds highly connected nodes in the network because it can observe local landscape properties. This the best analogy of describing how populations evolve on the neutral network.
 * evolution proceeds towards mutational robustness, although not maximal robustness
 * this shows that the walk along a neutral path is not neutral
 * mostly, evolved coding structures are not typical
 * how fast one gets there depends on lambda and the mutation rate
 * population size and mutation rate should be large enough

Next: What special code evolves?


 * References**