Validation of evolutionary activity metrics for long-term evolutionary dynamics

As artificial life systems grow in number and sophistication, it is becoming increasingly important that the field agree on principled metrics for evaluating them. This report describes a series of experiments validating the evolutionary activity statistics developed by Bedau and his colleagues [2, 3, 4]. The work described herein was motivated by a feeling that the 'null hypothesis'-that is, that the evolutionary activity statistics fail to exclude intuitively unlifelike systems from Class 3 dynamics [3]-had not been sufficiently disproved in the existing literature. We conducted a series of experiments applying the statistics to such systems, attempting to 'break' the scheme by measuring Class 3 dynamics in an intuitively unlifelike system. The evolutionary activity measurement scheme has so far proved robust to our attempts to break it, but we believe that this work is still valuable in advancing the validity of the scheme, and that this does not mean the scheme is without shortcomings.