Evolution of Heterogeneous Cellular Automata in Fluctuating Environments

Abstract

The importance of environmental fluctuations in the evolution of living organisms by natural selection has been widely noted by biologists and linked to many important characteristics of life such as modularity, plasticity, genotype size, mutation rate, learning, or epigenetic adaptations. In artificial-life simulations, however, environmental fluctuations are usually seen as a nuisance rather than an essential characteristic of evolution. HetCA is a heterogeneous cellular automata characterized by its ability to generate open-ended long-term evolution and "evolutionary progress". In this paper, we propose to measure the impact of different types of environmental fluctuations in HetCA. Our results indicate that environmental changes induce mechanisms analogous to epigenetic adaptation or multilevel selection. This is particularly prevalent in two of the tested fluctuation schemes, which involve a round-robin inhibition of certain cell types, where phenotypic selection seems to occur.

Evolutionary Progress in Heterogenous Cellular Automata (HetCA)

“…As described by Medernach et al (2013), HetCA is designed as a heterogenous cellular automata, using several cell categories: Living cells, decay cells and quiescent cells. Every living cell has, in addition to its state, a genotype that determines its transition rules.…”

“…The possible genotypes of an individual are its transition rules encoded with CA-LGP using the function set depicted in Table 2. Mutation of genotypes is enabled and we use the Micro/Marco-mutation of CA-LGP described in Medernach et al (2013). For each simulation we saved the most common genotype (most frequently occurring) in iterations 5, 1000, 5000, 50000, 300000 and 500000.…”

“…But the existence of EP is much less obvious in biology which evolves in an open ended evolutionary process. HetCA, Medernach et al (2013), is a heterogenous cellular automata (CA) evolutionary simulation which represents a version of open-ended evolution.…”

“…Copying its genotype into a nearby quiescent and then committing "cellular suicide", changing to quiescent state and therefore rebooting its life counter.5 Parameters are identical to HetCA-a7 inMedernach et al (2013).…”