A New Structurally Dissolvable Self-Reproducing Loop Evolving in a Simple Cellular Automata Space

Abstract

We constructed a simple evolutionary system, "evoloop," on a deterministic nine-state five-neighbor cellular automata (CA) space by improving the structurally dissolvable self-reproducing loop we had previously contrived [14] after Langton's self-reproducing loop [7]. The principal role of this improvement is to enhance the adaptability (a degree of the variety of situations in which structures in the CA space can operate regularly) of the self-reproductive mechanism of loops. The experiment with evoloop met with the intriguing result that, though no mechanism was explicitly provided to promote evolution, the loops varied through direct interaction of their phenotypes, smaller individuals were naturally selected thanks to their quicker self-reproductive ability, and the whole population gradually evolved toward the smallest ones. This result gives a unique example of evolution of self-replicators where genotypical variation is caused by precedent phenotypical variation. Such interrelation of genotype and phenotype would be one of the important factors driving the evolutionary process of primitive life forms that might have actually occurred in ancient times.

Dude, where is my sex gene? — Persistence of sex over evolutionary time in cellular automata

“…In either scenario, the sex gene usually persisted in a large fraction of the loops (represented in over 68% of the final population in 4 of the ten 500 x 500 runs, over 67% of the final population in 8 of the ten 1000 x 1000 runs). Although in some stages of the experimental runs the sex gene was present in 100% of individuals, interactions and collisions continued to create individuals not carrying the 2 As in [12] and [6], the "species" of an individual loop is given formally by the number of 7's in its genome (which determines the loop's size). It is not related to the so-called 'biological species' concept, but is only used here as an indication of genetic diversity in the population, since a population with many species (in this sense) will have at least as many different genomes present.…”

“…Nevertheless runs without the sex gene have loops able to reproduce and evolve but in a much smaller numbers: we did experiments using the same environments (500 x 500 and 1000 x 1000) using only one loop without a sex gene (F --sexyloop), and we saw that loops evolved and the dominant species at the end of the runs were of species 4 like in the evoloop [12] but actively reproducing viable loops were much fewer in number since many loops became 'stuck' in collision. Details on such a comparison of these evolutionary dynamics with those of F + -sexyloop will be presented elsewhere 3 .…”

“…Models of selfreproduction have been described in CAs [7,10,11] and Darwinian evolution has been exhibited in populations of self-reproducing loops [6,12,13]. In the sexyloop [6], we managed to allow the transfer of genes from a loop into another one using a simple mechanism with a minimum number of new states, using a mechanism similar to bacterial conjugation [2,3].…”

“…In the sexyloop [6], we managed to allow the transfer of genes from a loop into another one using a simple mechanism with a minimum number of new states, using a mechanism similar to bacterial conjugation [2,3]. The sexyloop work was based on Sayama's evoloop [12] which was transformed by adding a new state and new rules. In the evoloop, all undefined rules create a dissolving state '8'.…”

Codd's Self-Replicating Computer

“…Several attempts have been made to augment the loops with construction or computation capacity [33,20], or to make them more evolvable by ensuring mutated versions have a chance of functioning, with different behaviour [27,26]. In each of these cases the aim is to add back some of the higher functionality that was present in Codd's CA but lost when Langton made his simplification.…”