A comparison between developmental and direct encodings

In this paper we compare the evolutionary and run time behaviours of two forms of indirect encoding and a direct encoding. The indirect encodings are comparable to approaches used in the emerging field of developmental systems. We evolve a developmental encoding based on a cellular automaton to grow bit patterns of predefined complexities (in the Kolmogorov sense), and compare its behaviour to the evolution of a direct encoding on the same task. We find that the developmental encodings perform worse at high complexities than the direct encodings, and suggest that this is an artefact from using cell overwriting. Our findings suggest that developmental approaches may scale better for tasks that have complexities below a certain threshold. In this updated version of the paper, we also compare the difference in behaviour of the two approaches for short and long bit strings, and observe that again cell overwriting is detrimental to performance.