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Life Cycles: Reflections of an Evolutionary Biologist

Life Cycles: Reflections of an Evolutionary Biologist

Copyright Date: 1993
Pages: 222
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  • Book Info
    Life Cycles: Reflections of an Evolutionary Biologist
    Book Description:

    Within a single captivating narrative, John Bonner combines an intensely personal memoir of scientific progress and an overview of what we now know about living things. Bonner, a major participant in the development of biology as an experimental science, draws on his life-long study of slime molds for an understanding of the life cycle-the foundation of all biology. In an age of increasing specialization and fragmentation among subfields of biology, this is a unique work of reflection and integration.

    Originally published in 1995.

    ThePrinceton Legacy Libraryuses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These paperback editions preserve the original texts of these important books while presenting them in durable paperback editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.

    eISBN: 978-1-4008-7277-0
    Subjects: Biological Sciences

Table of Contents

  1. Front Matter
    (pp. i-vi)
  2. Table of Contents
    (pp. vii-viii)
    (pp. ix-xii)

    • Chapter 1 BEGINNINGS
      (pp. 3-14)

      I have devoted my life to slime molds. This may seem a peculiar occupation—narrow at best, slightly revolting at its worst—but let me explain why they captivated me and how they opened my eyes so that I wanted to understand not only what made them tick, but how they fit into the general pattern of living things and what the principles are that integrate all of life.

      Slime molds are an extremely common organism, widespread all over the world. Yet because they are microscopic and live mostly in the darkness of the soil, they are hard to see,...

    • Chapter 2 THE LIFE CYCLE
      (pp. 15-36)

      Working on slime molds at such an early age had an unexpected salutary effect on me. I was very conscious of the fact that my favorite organisms were different, and for that reason alone I should continuously pay attention to other organisms and look for similarities and differences. This led me, with the help of some gifted students, to small skirmishes on other “lower forms” such as colonial algae, fungi of various sorts, and protozoa. Unconsciously I suspect there was something else influencing me. Slime molds had such an obvious life cycle, from germination to the final fruiting body, that...


      (pp. 39-67)

      The conventional wisdom has always been that there was one origin of multicellular animals that gave rise to the invertebrates and another that gave rise to plants. This hypothesis might even be true, but it ignores a host primitive multicellular organisms that certainly did not arise from one multicellular ancestor. Again the obviousness of this point thrust itself on my mind because I could not argue, even with the wildest stretch of the imagination, that slime molds are in any way ancestral to higher animals or plants.

      When I give lectures people often ask me, “Are slime molds animals or...

      (pp. 68-92)

      My plan in this book is to dissect the different phases of the life cycle and discuss them separately. In this chapter I shall concentrate on the period of size increase in any one cycle; in other words, the period of development. In the next chapter I will consider how that period of size increase can change and become progressively longer (or shorter) during the course of evolution; it will be a consideration of how the period of development can evolve over large periods of time and in many successive life cycles. Finally, in the remaining chapters, I will consider...

      (pp. 93-120)

      The great lesson that comes from thinking of organisms as life cycles is that it is the life cycle, not just the adult, that evolves. In particular, it is the building period of the life cycle—the period of development—that is over time by natural selection. It is obvious that the only way to change the characters of an adult is to change its development.

      Let me now examine the way natural selection operates on development at a deeper level. I have already made clear that selection acts on the system of inheritance, namely the genes; they are the...


    • Chapter 6 BECOMING AWARE
      (pp. 123-157)

      With respect to the increase in the range of sizes of organisms during the course of evolution, one particular part of an animal has had an enormous influence. It is the brain, for the brain is responsible for behavior, which, as we will see, can do things that affect evolution in a unique way. At first it would appear strange that this major invention is something confined to animals, for certainly plants are without brains. On the other hand, brains did not burst forth in one great leap: their makings are found in properties of all organisms. The range in...

    • Chapter 7 BECOMING SOCIAL
      (pp. 158-178)

      One of the interesting things about life cycles is that they can combine in a way to form a social group which itself can cycle. Some have called such societies “superorganisms” to show the cohesiveness of the individual life cycles that come together in groups.

      The study of social animals is called sociobiology, though it is difficult to define a social animal. We mean by “social” that individual animals interact behaviorally with one another, but all animals, especially vertebrates, do this to some degree. Consider, for instance, a grizzly bear or a tiger: it spends most of its life as...

      (pp. 179-200)

      Finally, we come to the ultimate achievement of the adult stage of the life cycle. It is the advent of culture. As we shall see, this involves a different kind of evolution than the one we have discussed so far.

      With time, everything evolves, but the changes are not always caused by the same forces. The shape of a boulder is determined by the elements; the shape of animals and plants is changed because of natural selection; our customs and manners change in what is called cultural evolution, which is achieved in a quite different way from the evolution of...

    (pp. 201-204)
  8. INDEX
    (pp. 205-209)