Validation of evolutionary activity metrics for long-term evolutionary dynamics

ABSTRACT

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.

REFERENCES

• 1: J. C. Avise. Phylogeography: The History and Formation of Species. Harvard University Press, 2000.
• 2: M. A. Bedau and N. H. Packard. Measurement of evolutionary activity, teleology, and life. In C. Langton, C. Taylor, D. Farmer, and S. Rasmussen, editors, Artificial Life II, Santa Fe Institute Studies in the Sciences of Complexity, Volume X, pages 431--461, 1992.
• 3: M. A. Bedau, E. Snyder, C. T. Brown, and N. H. Packard. A comparison of evolutionary activity in artificial evolving systems and in the biosphere. In P. Husbands and I. Harvey, editors, Proceedings of the Fourth European Conference on Artificial Life, pages 125--134. MIT Press, 1997.
• 4: Mark A. Bedau , Emile Snyder , Norman H. Packard, A classification of long-term evolutionary dynamics, Proceedings of the sixth international conference on Artificial life, p.228-237, August 1998, Madison, Wisconsin, United States
• 5: Alastair Channon, Passing the ALife Test: Activity Statistics Classify Evolution in Geb as Unbounded, Proceedings of the 6th European Conference on Advances in Artificial Life, p.417-426, September 10-14, 2001
• 6: Alastair Channon, Improving and still passing the ALife test: component-normalised activity statistics classify evolution in geb as unbounded, Proceedings of the eighth international conference on Artificial life, p.173-181, December 09-13, 2002
• 7: S. J. Gould. The Structure of Evolutionary Theory. Belknap Press, 2002.

INDEX TERMS

Primary Classification:
  I. Computing Methodologies
  I.6 SIMULATION AND MODELING
      I.6.1 Simulation Theory
          Subjects: Model classification

Additional Classification:
  J. Computer Applications
  J.3 LIFE AND MEDICAL SCIENCES
      Subjects: Biology and genetics

General Terms:
Experimentation, Measurement, Theory

Keywords:
artificial life, evolutionary activity metrics, long-term evolutionary dynamics