Unbounded evolutionary dynamics in a system of agents that actively process and transform their environment

Abstract

Abstract. Bedau et al.'s statistical classification system for long-term evolutionary dynamics provides a test for open-ended evolution. Making this test more rigorous, and passing it, are two of the most important open problems for research into systems of agents that actively process and transform their environment. This paper presents a detailed description of the application of this test to 'Geb', a system designed to verify and extend theories behind the generation of evolutionarily emergent systems. The result is that, according to these statistics, Geb exhibits unbounded evolutionary dynamics, making it the first autonomous artificial system to pass this test. However, having passed it, the most prudent course of action is to look for weaknesses in the test. The test is criticized, most significantly with regard to its normalization method for artificial systems. Furthermore, this paper presents a modified normalization method, based on component activity normalization, that overcomes these criticisms. The results of the revised test, when applied to Geb, indicate that this system does indeed exhibit open-ended evolution.

Open-Ended Evolution: Perspectives from the OEE Workshop in York

“…Bedau and colleagues analyzed the dynamics of a Tierra-like system named Evita (but not Tierra itself), and found it to have qualitatively different evolutionary dynamics from those displayed in biological evolution as evidenced by the fossil record [6]. 15 • Avida (Ofria et al). Avida [32] is currently the most widely used digital evolution system, and is used to study a wide range of evolutionary and ecological dynamics in populations of self-replicating computer programs.…”

“…Geb was the first ALife system to be classified as exhibiting openended evolutionary dynamics according to Bedau and Packardʼs evolutionary activity measures [7] and is the only one to have been classified as such according to an enhanced version of these measures developed by Channon [14,15]. 16 Novel adaptations reported in Geb include behaviors such as following, fighting, fleeing, mimicking, and novel artifacts such as matching I&O channels in agentsʼ neurocontrollers.…”

“…However, he questioned the inclusion of increasing complexity as a hallmark of OEE, as this would preclude the possibility of addressing important questions such as whether or not OEE can be the cause of increasing maximal complexity (whether individual, group, or system complexity) or what conditions might be necessary or sufficient for this. Channon then described his Geb system [15], based upon Harveyʼs SAGA principles [19] with the addition of coevolutionary feedback arising via biotic selection rather than being specified by abiotic fitness functions, followed by a description of Bedau et alʼs work on evolutionary activity statistics [4,14]. Two useful features of these measures, he suggested, were that they are widely applicable, and that the key metric (cumulative evolutionary activity, based on adaptive persistence) is "a measure of the continual adaptive success of the components in the system" [7], that is a measure of accumulated adaptive success.…”

Long-term evolutionary dynamics in heterogeneous cellular automata

“…Several researchers [8,21,14] claim that ecosystemic models are well suited to the generation of life-like behaviours, and perhaps even creativity. Further, an artificial system shown to pass Bedau et al's test for unbounded evolutionary activity had its success attributed to ecosystemic interactions [5].…”

Open-ended evolution in cellular automata worlds

“…Since then several systems have been built that aimed to provide a platform for developing systems with open-ended evolution, these include the Tierra (Ray, 1991;Shao and Ray, 2010), Geb (Channon and Damper, 1998;Channon, 2006), PolyWorld (Yaeger, 1994;Yaeger and Sporns, 2006), Avida (Ofria and Wilke, 2006;Fortuna et al, 2017), Aevol (Knibbe et al, 2007), Chromaria (Soros and Stanley, 2014) and others. Among these, it has been shown, for example, that the evolutionary process supported by the Geb system satisfies the criteria of open-ended evolution (Channon and Damper, 1998) laid down by Bedau (1992;Bedau et al, 1998) and also a further modified criterion proposed by Channon (2006). Cellular automata based simulations of evolution have been used since the beginning of artificial life research (Langton, 1984).…”