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Artificial Life:An Overview

Cover Image Copyright Year: 1997
Author(s): Langton, C.
Publisher: MIT Press
Content Type : Books & eBooks
Topics: Computing & Processing (Hardware/Software)
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Abstract

Artificial life, a field that seeks to increase the role of synthesis in the study of biological phenomena, has great potential, both for unlocking the secrets of life and for raising a host of disturbing issues -- scientific and technical as well as philosophical and ethical. This book brings together a series of overview articles that appeared in the first three issues of the groundbreaking journal Artificial Life, along with a new introduction by Christopher Langton, Editor-in-Chief of Artificial Life, founder of the discipline, and Director of the Artificial Life Program at the Santa Fe Institute.

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      Front Matter

      Langton, C.
      Artificial Life:An Overview

      Page(s): i - xi
      Copyright Year: 1997

      MIT Press eBook Chapters

      This chapter contains sections titled: Half Title, Complex Adaptive Systems, Title, Copyright, Contents, Foreword, Editor's Introduction View full abstract»

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      Artificial Life as a Tool for Biological Inquiry

      Langton, C.
      Artificial Life:An Overview

      Page(s): 1 - 13
      Copyright Year: 1997

      MIT Press eBook Chapters

      Artificial life embraces those human-made systems that possess some of the key properties of natural life. We are specifically interested in artificial systems that serve as models of living systems for the investigation of open questions in biology. First we review some of the artificial life models that have been constructed with biological problems in mind, and classify them by mediurp (hardware, software, or “wetware”) and by level of organization (molecular, cellular, organismal, or population). We then describe several “grand challenge” open problems in biology that seem especially good candidates to benefit from artificial life studies, including the origin of life and self-organization, cultural evolution, origin and maintenance of sex, shifting balance in evolution, the relation between fitness and adaptedness, the structure of ecosystems, and the nature of mind. View full abstract»

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      Cooperation and Community Structure in Artificial Ecosystems

      Langton, C.
      Artificial Life:An Overview

      Page(s): 15 - 37
      Copyright Year: 1997

      MIT Press eBook Chapters

      We review results on the evolution of cooperation based on the iterated Prisoner's Dilemma. Coevolution of strategies is discussed both in situations where everyone plays against everyone, and for spatial games. Simple artificial ecologies are constructed by incorporating an explicit resource flow and predatory interactions into models of coevolving strategies. Properties of food webs are reviewed, and we discuss what artificial ecologies can teach us about community structure. View full abstract»

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      Extended Molecular Evolutionary Biology: Artificial Life Bridging the Gap Between Chemistry and Biology

      Langton, C.
      Artificial Life:An Overview

      Page(s): 39 - 60
      Copyright Year: 1997

      MIT Press eBook Chapters

      Molecular evolution provides an ample field for the extension of Nature's principles towards novel applications. Several examples are discussed here, among them are evolution in the test tube, nucleotide chemistry with new base pairs and new backbones, enzyme-free replication of polynucleotides and template chemistry aiming at replicating structures that have nothing in common with the molecules from nature. Molecular evolution in the test tube provides a uniquely simple system for the study of evolutionary phenomena: genotype and phenotype are two features of one and the same RNA molecule. Then fitness landscapes are nothing more than combined mappings from sequences to structures and from structures to functions, the latter being expressed in terms of rate constants. RNA landscapes are presented as examples for which an access to phenomena in reality by mathematical analysis and computer simulations is feasible. New questions concerning stability of structures in evolution can be raised and quantitative answers are given. Evolutionary biotechnology is a spin-off from molecular evolution. Darwin's principle of variation and selection is applied to design novel biopolymers with predetermined functions. Different approaches to achieve this goal are discussed and a survey of the current state of the art is given. View full abstract»

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      Visual Models of Morphogenesis

      Langton, C.
      Artificial Life:An Overview

      Page(s): 61 - 74
      Copyright Year: 1997

      MIT Press eBook Chapters

      Rapid progress in the modeling of biological structures and simulation of their development has occurred over the last few years. It has been coupled with the visualization of simulation results, which has led to a better understanding of morphogenesis and given rise to new procedural techniques for realistic image synthesis. This paper reviews selected models of morphogenesis with a significant visual component. View full abstract»

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      The Artificial Life Roots of Artificial Intelligence

      Langton, C.
      Artificial Life:An Overview

      Page(s): 75 - 110
      Copyright Year: 1997

      MIT Press eBook Chapters

      Behavior-oriented Artificial Intelligence (AI) is a scientific discipline that studies how behavior of agents emerges and becomes intelligent and adaptive. Success of the field is defined in terms of success in building physical agents that are capable of maximizing their own self-preservation in interaction with a dynamically changing environment. The paper addresses this Artificial Life route toward AI and reviews some of the results obtained so far. View full abstract»

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      Toward Synthesizing Artificial Neural Networks that Exhibit Cooperative Intelligent Behavior: Some Open Issues in Artificial Life

      Langton, C.
      Artificial Life:An Overview

      Page(s): 111 - 134
      Copyright Year: 1997

      MIT Press eBook Chapters

      The tasks that animals perform require a high degree of intelligence. Animals forage for food, migrate, navigate, court mates, rear offspring, defend against predators, construct nests, and so on. These tasks commonly require social interaction/cooperation and are accomplished by animal nervous systems, which are the result of billions of years of evolution and complex developmental/learning processes. The Artificial Life (AL) approach to synthesizing intelligent behavior is guided by this biological perspective. In this article we examine some of the numerous open problems in synthesizing intelligent animal behavior (especially cooperative behavior involving communication) that face the field of AL, a discipline still in its infancy. View full abstract»

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      Modeling Adaptive Autonomous Agents

      Langton, C.
      Artificial Life:An Overview

      Page(s): 135 - 162
      Copyright Year: 1997

      MIT Press eBook Chapters

      One category of research in Artificial Life is concerned with modeling and building so-called adaptive autonomous agents, which are systems that inhabit a dynamic, unpredictable environment in which they try to satisfy a set of time-dependent goals or motivations. Agents are said to be adaptive if they improve their competence at dealing with these goals. based on experience. Autonomous agents constitute a new approach to the study of Artificial Intelligence (AI), which is highly inspired by biology, in particular ethology, the study of animal behavior. Research in autonomous agents has brought about a new wave of excitement into the field of AI. This paper reflects on the state of the art of this new approach. It attempts to extract its main ideas, evaluates what contributions have been made so far, and identifies its current limitations and open problems. View full abstract»

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      Chaos as a Source of Complexity and Diversity in Evolution

      Langton, C.
      Artificial Life:An Overview

      Page(s): 163 - 177
      Copyright Year: 1997

      MIT Press eBook Chapters

      The relevance of chaos to evolution is discussed in the context of the origin and maintenance of diversity and complexity. Evolution to the edge of chaos is demonstrated in an imitation game. As an origin of diversity, dynamic clustering of identical chaotic elements, globally coupled each to the other, is briefly reviewed. The clustering is extended to nonlinear dynamics on hypercubic lattices, which enables us to construct a self-organizing genetic algorithm. A mechanism of maintenance of diversity, “homeochaos,” is given in an ecological system with interaction among many species. Homeochaos provides a dynamic stability sustained by high-dimensional weak chaos. A novel mechanism of cell differentiation is presented, based on dynamic clustering. Here, a new concept—“open chaos”—is proposed for the instability in a dynamical system with growing degrees of freedom. It is suggested that studies based on interacting chaotic elements can replace both top-down and bottom-up approaches. View full abstract»

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      An Evolutionary Approach to Synthetic Biology: Zen and the Art of Creating Life

      Langton, C.
      Artificial Life:An Overview

      Page(s): 179 - 209
      Copyright Year: 1997

      MIT Press eBook Chapters

      Our concepts of biology, evolution, and complexity are constrained by having observed only a single instance of life, life on earth. A truly comparative biology is needed to extend these concepts. Because we cannot observe life on other planets, we are left with the alternative of creating Artificial Life forms on earth. I will discuss the approach of inoculating evolution by natural selection into the medium of the digital computer. This is not a physical/chemical medium; it is a logical/informational medium. Thus, these new instances of evolution are not subject to the same physical laws as organic evolution (e.g., the laws of thermodynamics) and exist in what amounts to another universe, governed by the “physical laws” of the logic of the computer. This exercise gives us a broader perspective on what evolution is and what it does. An evolutionary approach to synthetic biology consists of inoculating the process of evolution by natural selection into an artificial medium. Evolution is then allowed to find the natural forms of living organisms in the artificial medium. These are not models of life, but independent instances of life. This essay is intended to communicate a way of thinking about synthetic biology that leads to a particular approach: to understand and respect the natural form of the artificial medium, to facilitate the process of evolution in generating forms that are adapted to the medium, and to let evolution find forms and processes that naturally exploit the possibilities inherent in the medium. Examples are cited of synthetic biology embedded in the computational medium, where in addition to being an exercise in experimental comparative evolutionary biology, it is also a possible means of harnessing the evolutionary process for the production of complex computer software. View full abstract»

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      Beyond Digital Naturalism

      Langton, C.
      Artificial Life:An Overview

      Page(s): 211 - 227
      Copyright Year: 1997

      MIT Press eBook Chapters

      The success of Artificial Life (ALife) depends on whether it will help solve the conceptual problems of biology. Biology may be viewed as the science of the transformation of organizations. Yet biology lacks a theory of organization. We use this as an example of the challenge that ALife must meet. View full abstract»

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      Learning About Life

      Langton, C.
      Artificial Life:An Overview

      Page(s): 229 - 241
      Copyright Year: 1997

      MIT Press eBook Chapters

      The growing interest in Artificial Life is part of a broader intellectual movement toward decentralized models and metaphors. But even as decentralized ideas spread through the culture, there is a deep-seated resistance to these ideas. People have strong attachments to centralized ways of thinking: they often assume centralized control where none exists. New types of computational tools and construction kits are needed to help people move beyond this “centralized mindset.” Perhaps most important are new tools and activities for children, to help them develop new ways of looking at the world. View full abstract»

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      Book Reviews

      Langton, C.
      Artificial Life:An Overview

      Page(s): 243 - 247
      Copyright Year: 1997

      MIT Press eBook Chapters

      This chapter contains section titled: Books on Artifical Life and Related Topics View full abstract»

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      Computer Viruses as Artificial Life

      Langton, C.
      Artificial Life:An Overview

      Page(s): 249 - 265
      Copyright Year: 1997

      MIT Press eBook Chapters

      There has been considerable interest in computer viruses since they first appeared in 1981, and especially in the past few years as they have reached epidemic numbers in many personal computer environments. Viruses have been written about as a security problem, as a social problem, and as a possible means of performing useful tasks in a distributed computing environment. However, only recently have some scientists begun to ask if computer viruses are not a form of artificial life—a self-replicating organism. Simply because computer viruses do not exist as organic molecules may not be sufficient reason to dismiss the classification of this form of “vandalware” as a form of life. This paper begins with a description of how computer viruses operate and their history, and of the various ways computer viruses are structured. It then examines how viruses meet properties associated with life as defined by some researchers in the area of artificial life and self-organizing systems. The paper concludes with some comments directed toward the definition of artificially “alive” systems and experimentation. View full abstract»

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      Genetic Algorithms and Artificial Life

      Langton, C.
      Artificial Life:An Overview

      Page(s): 267 - 289
      Copyright Year: 1997

      MIT Press eBook Chapters

      Genetic algorithms are computational models of evolution that play a central role in many artificial-life models. We review the history and current scope of research on genetic algorithms in artificial life, giving illustrative examples in which the genetic algorithm is used to study how learning and evolution interact, and to model ecosystems, immune system, cognitive systems, and social systems. We also outline a number of open questions and future directions for genetic algorithms in artificial-life research. View full abstract»

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      Artificial Life as Philosophy

      Langton, C.
      Artificial Life:An Overview

      Page(s): 291 - 292
      Copyright Year: 1997

      MIT Press eBook Chapters

      This chapter contains sections titled: References View full abstract»

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      Levels of Functional Equivalence in Reverse Bioengineering

      Langton, C.
      Artificial Life:An Overview

      Page(s): 293 - 301
      Copyright Year: 1997

      MIT Press eBook Chapters

      Both Artificial Life and Artificial Mind are branches of what Dennett has called “reverse engineering”: Ordinary engineering attempts to build systems to meet certain functional specifications; reverse bioengineering attempts to understand how systems that have already been built by the Blind Watchmaker work. Computational modeling (virtual life) can capture the foonal principles of life, perhaps predict and explain it completely, but it can no more be alive than a virtual forest fire can be hot. In itself, a computational model is just an ungrounded symbol system; no matter how closely it matches the properties of what is being modeled, it matches them only formally, with the mediation of an interpretation. Synthetic life is not open to this objection, but it is still an open question how close a functional equivalence is needed in order to capture life. Close enough to fool the Blind Watchmaker is probably close enough, but would that require molecular indistinguishability, and if so, do we really need to go that far? View full abstract»

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      Why Do We Need Artificial Life?

      Langton, C.
      Artificial Life:An Overview

      Page(s): 303 - 325
      Copyright Year: 1997

      MIT Press eBook Chapters

      In this paper, we ask the question of whether we need artificial life (AL) at all. We find a lot of convincing arguments in favor of AL, but we also point out some dangers AL is exposed to. This careful epistemological review reveals the potential richness of AL without being either too reductionist or too holistic. We give some examples showing how this can be done in practice, and conclude that almost everybody needs AL. View full abstract»

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      Index

      Langton, C.
      Artificial Life:An Overview

      Page(s): 327 - 340
      Copyright Year: 1997

      MIT Press eBook Chapters

      Artificial life, a field that seeks to increase the role of synthesis in the study of biological phenomena, has great potential, both for unlocking the secrets of life and for raising a host of disturbing issues -- scientific and technical as well as philosophical and ethical. This book brings together a series of overview articles that appeared in the first three issues of the groundbreaking journal Artificial Life, along with a new introduction by Christopher Langton, Editor-in-Chief of Artificial Life, founder of the discipline, and Director of the Artificial Life Program at the Santa Fe Institute. View full abstract»