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The Plausibility of Life

The Plausibility of Life: Resolving Darwin’s Dilemma

Marc W. Kirschner
John C. Gerhart
Illustrated by John Norton
Copyright Date: 2005
Published by: Yale University Press
Pages: 336
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  • Book Info
    The Plausibility of Life
    Book Description:

    In the 150 years since Darwin, the field of evolutionary biology has left a glaring gap in understanding how animals developed their astounding variety and complexity. The standard answer has been that small genetic mutations accumulate over time to produce wondrous innovations such as eyes and wings. Drawing on cutting-edge research across the spectrum of modern biology, Marc Kirschner and John Gerhart demonstrate how this stock answer is woefully inadequate. Rather they offer an original solution to the longstanding puzzle of how small random genetic change can be converted into complex, useful innovations.In a new theory they call "facilitated variation," Kirschner and Gerhart elevate the individual organism from a passive target of natural selection to a central player in the 3-billion-year history of evolution. In clear, accessible language, the authors invite every reader to contemplate daring new ideas about evolution. By closing the major gap in Darwin's theory Kirschner and Gerhart also provide a timely scientific rebuttal to modern critics of evolution who champion "intelligent design."

    eISBN: 978-0-300-12867-3
    Subjects: Ecology & Evolutionary Biology

Table of Contents

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  1. Front Matter
    (pp. i-vi)
  2. Table of Contents
    (pp. vii-viii)
  3. Preface
    (pp. ix-xvi)
  4. INTRODUCTION A Clock on the Heath
    (pp. 1-9)

    In 1802 the Reverend William Paley expressed his faith that life, full as it is of intricate design, must be the work of a Supreme and Intelligent Creator. In his now-famous metaphor, the minister wanders on the heath and stumbles across a brass watch. Plunged into thought, he asks how the watch came into being and reflects that his explanations are entirely different from those brought to mind when his boot hit a stone. The stone might have “lain there for-ever,” demanding no explanation. But the watch, with its carefully constructed wheels, teeth, springs, pointers, and oval glass face, each...

  5. ONE The Sources of Variation
    (pp. 10-37)

    Physical scientists in the nineteenth and early twentieth centuries had astounding success in formulating very general yet predictive theories in thermodynamics, electricity and magnetism, and atomic structure. Biology sought a similar level of generalization and had signal success in the cell theory, the germ theory of disease, metabolism, and heredity. Darwin’s theory of evolution was perhaps the most ambitious effort to understand the living world, but unlike the others it was historically based and hard to test experimentally. Even to be comprehensible, it required an accumulation of knowledge from natural history, genetics, and paleontology. Biology differed from physics in that...

  6. TWO Conserved Cells, Divergent Organisms
    (pp. 38-70)

    Sewall Wright, who with J. B. S. Haldane and R. A. Fisher established population genetics in the early twentieth century, asserted that beneath the anatomical changes in evolution are changes in what he called adaptive cell behavior. He thereby alleviated some of the difficulties of imagining the evolution of complex organisms. Yet his assertion avoids the obvious next question: What is “adaptive cell behavior”? We now know that the cell has hundreds of behaviors or activities that involve conserved core processes. When a significant change occurs in evolution, do radically new behaviors develop or does the cell use its existing...

  7. THREE Physiological Adaptability and Evolution
    (pp. 71-108)

    Evolution, as we have seen, is framed by two features: conservation on a cellular level and diversity on an anatomical and physiological level. How does diversification occur despite so much conservation? In this chapter we examine a few examples that reveal how conservation actually enables variation. The connection between the two is at the level of mechanisms; those that are exploited for evolution are the very ones that the organism uses day to day to vary its phenotype to meet new physiological demands. Such mechanisms can be easily modified in evolution to yield new phenotypes.

    The potential relationship between physiological...

  8. FOUR Weak Regulatory Linkage
    (pp. 109-142)

    Let us now delve directly into the conserved core processes that are responsible for generating most of the anatomy, physiology, and behavior of the organism. These are the processes that evolved between three billion and a half billion years ago (Chapter 2). They include metabolism, gene expression, and signaling between cells.

    In deepening the inquiry, we introduce the fact that all the conserved core processes possess adaptability, which they use in response to varying conditions inside the organism rather than to identifiable external conditions, although they can do that as well. We ask the same question as before: How can...

  9. FIVE Exploratory Behavior
    (pp. 143-176)

    We have seen that existing somatic adaptations can be a ready and available source for new variation when genetic change stabilizes adaptive processes at different points along their ranges. This application of the Baldwin effect has not been widely endorsed as a panacea for explaining novelty in evolution, because the kind of variation that seems most interesting in evolution is not that which causes small quantitative perturbations of existing systems. Certainly, in anatomical novelty it is hard to imagine how an organism could store within itself the capacity for forming novel structures in the future, such as the first wing...

  10. SIX Invisible Anatomy
    (pp. 177-218)

    If one looks at animals as one of the various life forms, and asks what is unique about them, it would have to be their large size and the varied anatomy by which their physiology and behavior are conveyed. It is not their chemistry or efficiency or resistance to harsh conditions, all of which are exceeded by bacteria, protists, fungi, and plants. Complex anatomy has not been achieved on the level of the single cell and hence emerged only with multicellularity, that is, in the last 600 million years. While relying on the conserved cellular processes brought forth from the...

  11. SEVEN Facilitated Variation
    (pp. 219-243)

    We summarize here in explicit terms our theory of facilitated variation, distinguishing it from other theories and providing evidence for it. The theory rests on molecular knowledge of a host of conserved cellular and developmental processes, which underlie and connect both somatic adaptation and phenotypic variation. Many evolutionary biologists do not see a need to connect somatic adaptability to the generation of variation, and some see a need to keep them separate. For them, it is sufficient to say that random mutation is required and that phenotypic variation arises haphazardly from it as random damage; the organism’s current phenotype does...

  12. EIGHT Is Life Plausible?
    (pp. 244-274)

    We now take a perspective outside the theory of facilitated variation to measure its explanatory power. Having asserted that facilitated variation is consistent with neo-Darwinian theory, we ask, To what extent is evolutionary theory now a complete theory? To incorporate facilitated variation fully into the neo-Darwinian theory, we have to understand why it should be selected and maintained in populations. Many evolutionary biologists believe that any process that provides a future benefit must have an immediate benefit in each generation, or it will be lost. Whether or not such a stringent view is required, we still must evaluate the conditions...

  13. Glossary
    (pp. 275-292)
  14. Notes
    (pp. 293-302)
  15. Index
    (pp. 303-314)