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, Vol. X, pages 431--461. Addison-Wesley, 1992.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....the expertise we obtained from the previous model, for learning and optimisation problems. Current work focuses on step one of our study and is described in the next section. Alife Model In order to evaluate Michod s ideas we rebuilt an alife model which is based on the alife model by Packard[Pac88,BP92]. This model contains the essential ingredients of a biological evolutionary system and it was originally introduced to illustrate the di erence between intrinsic and extrinsic adaptation. It consists of organisms which are allowed to traverse a two dimensional world. The elementary actions of the ....

....(g th ) The food distribution is modeled through a eld which di uses over time and where food is added periodically in time and randomly in space. The organisms are able to sense the immediate neighbourhood and to move in the direction of the gradient of the food eld. As in Bedau s model in [BP92], a bug pays both a movement and a metabolic tax. Thus, when a bug is at a location with few resources and does not move then it will die. The size and distribution of the population of organisms depends entirely on the initial con guration of the food eld and the way it is refreshed. Bedau ....

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Mark A. Bedau and Norman H. Packard. Measurement of evolutionary activity, teleology, and life. Articial Life II, SFI Studies in the Sciences of Complexity, X:431-461, 1992.

....expertise we obtained from the previous model, for learning and optimisation problems. Current work focuses on the rst step of our study and is described in the next section. 3 Alife Model In order to evaluate Michod s ideas we rebuilt an Alife model which is based on the Alife model by Packard[7, 1]. This model contains the essential ingredients of a biological evolutionary system and it was originally introduced to illustrate the di erence between intrinsic and extrinsic adaptation. It consists of organisms which are allowed to traverse a two dimensional world. The elementary actions of the ....

....(g off ) and the food threshold required for reproduction (g th ) The size and distribution of the population of organisms depends entirely on the con guration of the food eld and the way it is refreshed. Bedau called these organisms tropic bugs since they invariably climb the food gradient[1]. We extended this model in subsequent steps to model Evolutionary transitions. Step 1 : Group Formation; explicit competition An important requirement for a transition to occur is the emergence of non sel sh behaviour in an evolutionary system. Therefore, in this rst step, we examine whether ....

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Mark A. Bedau and Norman H. Packard. Measurement of evolutionary activity, teleology, and life. Articial Life II, SFI Studies in the Sciences of Complexity, X (1992) 431-461

....for the TSP the meme represented variable local searchers with a probability of being applied xed at 1.0 . 3 EVOLUTIONARY ACTIVITY WAVE AND MEME CONCENTRATION GRAPHS In order to examine the evolutionary and adaptive properties of memes in our system we will use the approach of Bedau et.al. [2]. We are interesting in observing the adaptive signi cance of the search strategies coded by the memes. We de ne the concentration c of meme i at time t as the number of individuals in the population that carry this meme. We denote this value by c i (t) It is hypothesized that since memes are ....

M. Bedau and N.H.Packard. Measurement of Evolutionary Activity, Teleology and Life, volume 9803 -023. Addison-Wesley, 1992.

.... mapping, composite mapping 1 Introduction In the design of an artificial life (alife) system, the system s evolvability , defined as the possibility (potential ability) of evolving a variety of genotypes or phenotypes, is one of the most important properties a designer has to pay attention to [1, 2, 3, 4, 5, 6]. The evolvability determines the system s final performance; hence to design a good alife system, we have to answer the following three primary questions about evolvability. ffl What is an objective measure for evolvability ffl What are the necessary conditions for an alife system to be ....

Bedau, M.A., Packard, N.H.: Measurement of evolutionary activity, teleology, and life. In: Langton, C.G. et al. (eds.): Artificial Life II: Proceedings of an Interdisciplinary Workshop on the Synthesis and Simulation of Living Systems (Santa Fe Institute Studies in the Sciences of Complexity, Vol. 10). Addison-Wesley (1992) 431--461

....genotype space (Assump. 3) the insertion or duplication of alphabets is one of the most important genetic operations for creating a new function. Analyzing a variablelength genotype space is also a future problem to be tackled [15] Evolvability is a major issue in recent Artificial Life studies [1, 2, 16, 10, 14]. The author expects that the present study might provide useful information for optimizing the design of an ALife system [14] Acknowledgements Prof. Nishikawa, National Institute of Genetics at Mishima, and Prof. Iwasa, Kyushu University, provided helpful comments on this study. Dr. K. ....

Bedau, M.A., Packard, N.H.: Measurement of evolutionary activity, teleology, and life. In: Langton, C.G. et al. (eds.): Artificial Life II: Proceedings of an Interdisciplinary Workshop on the Synthesis and Simulation of Living Systems (Santa Fe Institute Studies in the Sciences of Complexity, Vol. 10). Addison-Wesley (1992) 431--461

....switch in defining life as follows: What is life How can it be recognized In an everyday context, these questions seem tantalizingly clear a cat is alive and a rock is not. But formalizing this distinction is difficult, especially if the formalization is to be used in empirical measurements. (Bedau and Packard 1991, 457) Thomas Ray approaches the problem in the same way. He says, Most approaches to defining life involve assembling a short list of properties of life and then testing candidates on the basis of whether or not they exhibit the properties on the list. The main problem with this approach is that ....

....to satisfy the strong demands of such an account has both philosophical and scientific interest. It is plausible, then, to suppose that Aristotle sees no conflict between the goals of arriving at a considered theoretical position which also meets constraints set by our everyday notions 80 See Bedau (1991, 457) Sober (1992, 375 6) Warren (1997, 26) and Harnad (1995, 298) quoted above. 81 We do, after all, find the essentialist account of chemical kinds in terms of their atomic numbers highly intuitively satisfying given that our intuitions indicate that these are compositional kinds whose ....

Bedau, M., and Norman Packard. 1991. Measurement of Evolutionary Activity, Teleology, and Life.

....models and assessed their emergence levels. The other major stream of research is a more statistical approach. This approach is usually related to evolutionary dynamics in an objective model. Bedau et al. devised a way of measuring evolutionary activity from the viewpoint of population genetics (Bedau and Packard 1992), and they then applied their methodology to the fossil data obtained from the real biosphere (Bedau et al. 1997) Their research progressed to the classification of long term evolutionary dynamics (Bedau, Snyder, and Packard 1998) similar to Wolfram s famous work on cellular automata (Wolfram ....

Bedau, M. A. and Packard, N. H. 1992. Measurement of Evolutionary Activity, Teleology, and Life. Artificial Life II, edited by C. G. Langton, C. E. Taylor, J. D.

....switch in defining life as follows: What is life How can it be recognized In an everyday context, these questions seem tantalizingly cleara cat is alive and a rock is not. But formalizing this distinction is difficult, especially if the formalization is to be used in empirical measurements. (Bedau and Packard 1991, 457) Thomas Ray approaches the problem in the same way. He says, Most approaches to defining life involve assembling a short list of properties of life and then testing candidates on the basis of whether or not they exhibit the properties on the list. The main problem with this approach is ....

....on the contemporary scene for offering a nonmechanistic account of life. If this is Aristotle s position, then he occupies an intrinsically interesting and currently unoccupied location in the space of possible accounts of life. Further, Aristotle s acceptance of the empirical 80 See Bedau (1991, 457) Sober (1992, 375 6) Warren (1997, 26) and Harnad (1995, 298) quoted above. 81 We do, after all, find the essentialist account of chemical kinds in terms of their atomic numbers highly intuitively satisfying given that our intuitions indicate that these are compositional kinds whose ....

[Article contains additional citation context not shown here]

Bedau, M., and Norman Packard. 1991. Measurement of Evolutionary Activity, Teleology, and Life. In Artificial Life II, edited by C. Langton, C. Taylor, D. Farmer and S. Rasmussen. Redwood City, CA: Addison Wesley.

....method is Bedau and Packard s evolutionary activity statistics. We also measure system diversity, D, which is simply the number of different genotypes present in a system at a given time. Detailed definitions and motivations for evolutionary activity statistics are readily available elsewhere [2, 1, 3, 4, 13]. Evolutionary activity statistics aim to identify evolutionary innovations (here, new genotypes) that persist and continue to play a significant role in a system because of their adaptive value. These statistics fall into two broad classes: those reflecting evolutionary activity s extent and ....

....evolutionary activity across different systems. We pursue this goal by comparing the generic neutral model with two simple evolutionary systems and their neutral shadows. 2 The Models Packard s Line and Block Models. The Bugs simulation is a series of models originated by Norman Packard [11, 2] and subsequently modified in various ways. Packard s simulation is designed to be a very simple model of the evolution of sensory motor strategies. It consists of agents sensing the resources in their local environment, moving as a function of what they sense, ingesting the resources they find, ....

Bedau, Mark A., and Norman H. Packard. 1992. Measurement of evolutionary activity, teleology, and life. In C. Langton, C. Taylor, D. Farmer, S. Rasmussen, (Eds.), Artificial life II (pp. 431--461). Redwood City CA: Addison-Wesley.

....the dynamics of co evolution. Macroevolutionary theory (e.g. 6] typically treats co evolution as a phenomenon that is hard to observe outside the fossil record. Finally, evolutionary genetics and almost all research in either theoretical biology or artificial life which could be relevant (e.g. [1]) studies (co )evolution at the level of discrete genes for particular traits. W. Hamilton and his associates (e.g. 17] have developed techniques for visualizing and analyzing simplified coevolutionary systems. However, the genetic encoding used in our simulations is sufficiently complex that ....

M. Bedau and N. Packard. Measurement of evolutionary activity, teleology, and life. In C. Langton, C. Taylor, J. D. Farmer, and S. Rasmussen, eds, Artificial Life II, pp.431--461. Addison Wesley, 1992.

....in Section 5 we summarize our observations, draw conclusions and sketch interesting issues for further research. This paper leaves out much of the implementation details of the aegis world. For a more detailed description we refer to (Elia, 1997a) and (Elia, 1997b) Similar work has been done in (Bedau and Packard, 1991), Devine and Paton, 1997) Coderre, 1988) Johnson, 1994) and (Skipper, 1991) 2 AEGIS The arti cial world can be seen as a two dimensional grid wrapped around at the edges (Figure 1) Each grid position corresponds with an area which can contain one animal and one plant. Area plant animal ....

Bedau, M. A. and Packard, N. H. (1991). Measurement of evolutionary activity, teleology, and life.

....of comparison, significant usage is averaged over all generations in a run, and the average of this quantity across multiple runs is presented. For TTT, only those positions with corresponding genes are counted (this brings the measure in closer correspondence with the measure of gene usage in (Bedau and Packard 1991)) Significant usage is substantially higher with sharing and shared sampling. The second aspect analyzed is the loss of potentially important genetic material. As described above, sharing and shared sampling should reduce the extinction of host types that defeat parasites others cannot. Here, ....

Bedau, M.A., and N.H. Packard (1991). Measurement of Evolutionary Activity, Teleology, and Life. In Artificial Life II, Addison-Wesley.

No context found.

Bedau, M.A. N.H. Packard. 1992. Measurement of evolutionary activity, teleology and life, in Langton, C.; C. Taylor, D. Farmer, and S. Rasmussen (eds.), Arti cial Life II, Addison-Wesley.

No context found.

Bedau, M. A., Packard, N. H. (1992). Measurement of Evolutionary Activity, Teleology, and Life. In C. G. Langton, C. E. Taylor, J. D. Farmer, S. Rasmussen, eds., Artificial Life II (pp. 4431--461). Redwood City, Calif.: Addison-Wesley.

....change the relative value of novelty and memory. 2 A Simple Model of Sensorimotor Evolution Our evolutionary system is composed of many agents that could be called organisms, on analogy with biological systems. It has been used in various studies of the evolution of sensory motor functionality [30, 6, 4, 3, 7, 31]. The system consists of many agents that exist together in an environment, in this case a toroidal lattice. The lattice has a real valued field defined on it, E (x) which may be interpreted as an resource field. The resource field is driven by periodically adding resources (from an external ....

.... by each trait (where, in this study, each strategy entry b = is is considered a trait for the i agent) We consider a trait s adaptive significance to be the positive contribution it has made to the ongoing existence of its host agent (further discussion of this suggestion occurs elsewhere [6, 7, 8, 31]. We judge such a contribution to be indicated by the degree to which the trait has been well tested by natural selection, with the trait persisting through repeated use and, in particular, accumulating more usage than would be expected a priori. Measuring a trait s adaptive significance, then, ....

[Article contains additional citation context not shown here]

Bedau, M. A. and Packard, N. H. 1992. Measurement of evolutionary activity, teleology, and life. In: C. G. Langton, C. E. Taylor, J. D. Farmer, and S. Rasmussen (Eds.), Artificial Life II, Addison-Wesley, Redwood City, CA, pp. 431--461.

....real world financial markets [4, 12] we hope that our results are also a step toward explaining the complexity of real world financial markets. Current and future work in this area includes quantifying evolutionary activity in this model using neutral models and evolutionary activity statistics [5, 6], and also studying the 13 emergence of technical trading in financial markets[11] Acknowledgments. Thanks to the authors of the Santa Fe Artificial Stock Market, especially Richard Palmer and Blake LeBaron, for making their source code available to us and helping us to use it productively. For ....

Bedau, M.A. N.H. Packard. 1992. Measurement of evolutionary activity, teleology and life, in Langton, C.; C. Taylor, D. Farmer, and S. Rasmussen (eds.), Artificial Life II, Addison-Wesley.

....directly change the physical properties of their environment, that is, directly construct their environment. One common form of direct environmental construction occurs when organisms change the spatial distribution of food in their environment by eating it; see, for example, Packard (1989) Bedau and Packard (1992), and Todd, Wilson, Somayaji, and Yanco (1994) Organisms can directly construct their environments in other ways, of course; see, for example, Kirsh, this issue. Bedau (1994) has proposed one general method for measuring the extent to which an adapting population changes the structure of its ....

Bedau, M. A., & Packard, N. H. (1992). Measurement of evolutionary activity, teleology, and life. In C. Langton, C. Taylor, J. D. Farmer, & S.

....level of supple adaptation can smoothly drop to nothing or smoothly rise from nothing. It is obvious enough that evolving systems level of supple adaptation can rise or fall continuously. In fact, there are methods for quantifying various aspects of an evolving system s level of supple adaptation (Bedau and Packard 1992; Bedau 1995) and this enables the dynamics of supple adaptation in artificial and natural systems to be compared directly (Bedau, Snyder, Brown and Packard 1997; Bedau, Snyder, and Packard 1998) Thus, if we view life as supple adaptation, then being alive is a matter of degree. In addition to ....

....cut off point. Thus, the continuum is the truth underlying the dichotomies which it can be used to define. There is a pragmatic dimension of the issue whether life at bottom is boolean or continuous. If we quantify a system s level of supple adaptation in the way proposed by Bedau and Packard (Bedau and Packard 1992; Bedau 1995; Bedau 1996; Bedau, Snyder and Packard 1998) then one needs a certain amount of data, and so a certain amount of time to gather the data, in order to determine (to within a certain level of statistical confidence) whether a system has a given level of supple adaptation. So, a system ....

Bedau, M. A., and Packard, N. H. 1992. Measurement of Evolutionary Activity, Teleology, and Life. In Langton et al. (1992), 431-461.

....make an analogy with flight simulators, and these are used to build quite realistic intuitions about flying specific airplanes. I view unrealistic models as thought experiments, intended to capture the essential properties of some kind of complex adaptive system. One can view Packard s Bugs model [3] and Ray s Tierra model [15] as embodiments of two related but different pictures of the essential core of living evolving systems. The goal of capturing the essential properties of a complex adaptive systems is typically to discern the essential mechanisms underlying certain interesting kinds of ....

....means of certain macro level statistics. Thermodynamic analogues are statistics like pressure and temperature. Some examples of such statistics are diversity of genotypes [2] or species [13] or complexity of taxa (see Ref. 14] and references cited therein) or adaptive evolutionary activity [3, 5]. A statistic enables you to see a model s macro scale forest in the face of all the micro scale trees. In addition, these statistics are what allow you to compare the behavior of the model with the behavior of the natural systems you seek to understand. For this reason, it is typically in terms ....

Bedau, M. A. and N. H. Packard. 1992. Measurement of evolutionary activity, teleology, and life. In C. Langton, C. Taylor, J. D. Farmer, S. Rasmussen, eds., Artificial Life II (pp. 431--461). Redwood City, CA: Addison-Wesley.

....evolution. Part of what makes this especially interesting is that evolutionary activity statistics apply to myriad evolutionary systems at myriad levels of analysis, so we can investigate whether the same regulatities hold in evolving systems in general. We use the approach of Bedau and Packard [1, 2] to identify the extent to which a system s evolutionary dynamics depend on adaptation rather than other evolutionary forces like chance and necessity. That is, we screen off the effect of non adaptive evolutionary forces by comparing the evolutionary dynamics observed in target evolutionary ....

....current activity as the component persists. If the components are passed along during reproduction, the corresponding counters are inherited with the components, maintaining an increasing count for an entire lineage. Previous work has studied components on the level of individual alleles [1] as well as genotypes [2] and taxonomic families [2] For simplicity, here we restrict our attention to entire genotypes. To measure activity contributions we attach a counter to each component of the system, a i (t) where i labels the component and t labels time. A component s activity increases ....

[Article contains additional citation context not shown here]

Bedau, M. A. and N. H. Packard. 1992. Measurement of evolutionary activity, teleology, and life. In C. Langton, C. Taylor, J. D. Farmer, S. Rasmussen, eds., Artificial Life II (pp. 431--461). Redwood City, Calif.: Addison-Wesley.

....evolution and then outlines how the method can be applied in the study of evolvability. 2 The Extent and Intensity of Evolutionary Activity The method for quantifying adaptive evolution presented here involves using the evolutionary activity statistics originally devised by Bedau and Packard [1]. These statistics have been applied to a variety of evolving systems for a variety of purposes, including visualizing adaptive evolutionary phenomena [1, 2, 3] studying punctuated equilibrium dynamics in evolution [8] identifying long term evolutionary trends [4, 6] and classifying ....

.... for quantifying adaptive evolution presented here involves using the evolutionary activity statistics originally devised by Bedau and Packard [1] These statistics have been applied to a variety of evolving systems for a variety of purposes, including visualizing adaptive evolutionary phenomena [1, 2, 3], studying punctuated equilibrium dynamics in evolution [8] identifying long term evolutionary trends [4, 6] and classifying evolutionary dynamics [5] Evolutionary activity statistics are computed from data obtained by observing an evolving system, where an evolving system as a population of ....

[Article contains additional citation context not shown here]

Bedau, M. A. and N. H. Packard. 1992. Measurement of evolutionary activity, teleology, and life. In C. Langton, C. Taylor, J. D. Farmer, S. Rasmussen, eds., Artificial Life II (pp. 431--461). Redwood City, CA: Addison-Wesley.

No context found.

Bedau, M. A., Packard, N. H. (1992). Measurement of Evolutionary Activity, Teleology, and Life. In C. G. Langton, C. E. Taylor, J. D. Farmer, S. Rasmussen (Eds.), Artificial Life II (pp. 431--461). Redwood City, CA: Addison-Wesley.

No context found.

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, Vol. X, pages 431--461. Addison-Wesley, 1992.

No context found.

M. A. Bedau and N. H. Packard. Measurement of evolutionary activity, teleology, and life. In C. G. Langton, C. Taylor, J. D. Farmer, and S. Rasmussen, editors, Artificial Life II, pages 431--461, Reading, MA, 1992. Addison-Wesley.

No context found.

M. A. Bedau and N. H Packard. Measurement of evolutionary activity, teleology, and life. In C. G. Langton, C. Taylor, J. D. Farmer, and S. Rasmussen, editors, Artificial Life II, pages 431--461, Reading, MA, 1992. Addison-Wesley.

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