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Randomness in Evolution

Randomness in Evolution

John Tyler Bonner
Copyright Date: 2013
Pages: 152
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  • Book Info
    Randomness in Evolution
    Book Description:

    John Tyler Bonner, one of our most distinguished and insightful biologists, here challenges a central tenet of evolutionary biology. In this concise, elegantly written book, he makes the bold and provocative claim that some biological diversity may be explained by something other than natural selection.

    With his customary wit and accessible style, Bonner makes an argument for the underappreciated role that randomness--or chance--plays in evolution. Due to the tremendous and enduring influence of Darwin's natural selection, the importance of randomness has been to some extent overshadowed. Bonner shows how the effects of randomness differ for organisms of different sizes, and how the smaller an organism is, the more likely it is that morphological differences will be random and selection may not be involved to any degree. He traces the increase in size and complexity of organisms over geological time, and looks at the varying significance of randomness at different size levels, from microorganisms to large mammals. Bonner also discusses how sexual cycles vary depending on size and complexity, and how the trend away from randomness in higher forms has even been reversed in some social organisms.

    Certain to provoke lively discussion,Randomness in Evolutionis a book that may fundamentally change our understanding of evolution and the history of life.

    eISBN: 978-1-4008-4642-9
    Subjects: Ecology & Evolutionary Biology, Biological Sciences

Table of Contents

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  1. Front Matter
    (pp. i-iv)
  2. Table of Contents
    (pp. v-vi)
    (pp. vii-viii)
    (pp. ix-xiv)
  5. CHAPTER 1 Life and the Riddle of Randomness
    (pp. 1-16)

    As biologists our great aim is to find order in all the diversity and complexity of the living world. This is something we all strive for: it is what gives us a feeling of fulfillment and satisfaction. We seek the rules that underlie living phenomena to make ignorance and confusion turn into clarity and order. This is what Linnaeus did by finding a way to classify the vast numbers of different kinds of animals and plants: he brought order out of chaos. And this is what Mendel did with crossing his peas to reveal the basic rules of inheritance, a...

  6. CHAPTER 2 Time, Size, and Complexity
    (pp. 17-39)

    Since the argument of this book frames evolution in terms of size, it is important to look closely at that evolution of size. It is essential to understand how it occurred, and in particular why it occurred.

    We are all brought up with the idea that life on Earth began over three billion years ago, and the first real organisms were prokaryotes. As life progressed since then, some organisms became larger while others remained small, giving us the incredible array of living creatures that exist today: from bacteria to whales, elephants, and giant sequoias, and all those plants and animals...

  7. CHAPTER 3 Small Organisms and Neutral Morphologies
    (pp. 40-62)

    The possibility is raised here that microorganisms might in some circumstances haveneutral morphologies. By that I mean that there are significant differences between individual morphologies, but natural selection is blind to them. I will suggest candidates for this unconventional condition for both aquatic and terrestrial forms. In particular, I will be considering eukaryotic microorganisms, and not bacteria and archaea. The concern here is with morphology and the degree to which it is adaptive, and bacteria and archaea have very limited morphologies; their variation exists mostly in the form of multitudinous biochemical differences.

    Let me preface the discussion by pointing...

  8. CHAPTER 4 The Evolution of the Decrease of Randomness
    (pp. 63-92)

    An important way of reducing the effect of randomness is to become bigger, as have all large multicellular organisms. The results of random mutations are filtered by the vast number of steps they go through to produce an adult animal or plant. Each step goes under the absolute scrutiny of “internal selection”; there are virtually no opportunities for any deleterious change to survive this sequence of steps that we know as development.

    This does not mean that every step, every final morphology is determined genetically, nor is it determined by chance. As D’Arcy Thompson28and some current authors29have pointed...

  9. CHAPTER 5 An Exception: Where Small Organisms Suppress Randomness
    (pp. 93-100)

    The point has already been made that the sexual system has been burnished by natural selection so that in each generation the degree of variation in the off-spring is optimal—not too little and not too much—which allows natural selection to take place and makes evolutionary progress possible. An important size-related phenomenon is that in many simpler, small organisms this sexual variation-control mechanism can be turned on and off: periods of sexual reproduction will be interspersed with periods of asexual reproduction. In larger forms (with some rare exceptions) only the sexual route is possible. And it is only in...

  10. CHAPTER 6 The Division of Labor: Two Cases of the Return of Randomness in Higher Forms
    (pp. 101-117)

    The division of labor has arisen a number of times during the course of evolution, and it is determined in different ways. First there is the conventional method associated with organisms that develop from a single cell, such as an egg that undergoes repeated cleavages with the increase in size. Then there are those cases where the division of labor arises in separate units, be they cells, as in cellular slime molds, or whole organisms, as in insect societies. What will be novel here is that in these latter cases there can be specially engineered periods of nongenetic or phenotypic...

  11. CHAPTER 7 Envoi
    (pp. 118-120)

    The purpose of this essay has been to give a balanced view of evolution by showing how big a role randomness plays. I think randomness is necessary to counteract the tremendous power of natural selection that to some degree blinds our vision. Selection is the supreme mechanism that brings order out of chaos, and for that reason it is quite rightly foremost in our minds in all matters concerning evolution. It is for this reason that randomness is often ignored and sometimes rejected because of our natural selection mind-set. But, as I have pointed out, there could be no natural...

    (pp. 121-124)
    (pp. 125-130)
  14. INDEX
    (pp. 131-134)