ZOOL 304

Class Notes

Chapter 13, The History of Life I

Text reading:  Chapter 13.

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• There are several ways to present evolutionary history.
   
  • Perhaps the most common approach is direct description of changing forms over time.  Because this approach can be so rich in fascinating factual detail, some courses in evolution may do little more than this.  (Perhaps this is what you were expecting from ZOOL 304.  But our text provides only an extremely condensed history in Table 13.1, apparently with the expectation that such information is already familiar and thus requires no more than a brief review.)  Unfortunately, "as has often been noted, telling 'the story of life' can give the reader the mistaken impression that it is all laid out along a pre-ordained path, where everything leads inexorably from the slime, through single-celled organisms, to the first vertebrates, the first amphibians on land, the first warm-blooded mammals, and then humans at the peak" (MJBenton, TREE, 18:497).
     
  • Another common approach describes the surprise and intellectual ferment that accompanied discovery of various fossils and interpretation of evidence for shifting continents, seas and climates.  While this can be great fun, and leads to an appreciation for the great effort and talent that has established the field of paleontology, it can also yield a rather fragmented picture of evolution with little connection to evolutionary process.
     
  • Yet another approach attempts to extract from evolutionary history some broad themes or principles.  This is largely the approach in chapter 13 of our text -- but without extensive detail it may appear rather abstract and sterile.
     
  • Finally, as represented in chapter 14, we may be introduced to some key innovations in the history of life, and the persistent challenge of understanding how such innovations emerged.
     
• Chapter 13 contains several rather distinct topics
  • Cosmological origins.
  • Drifting continents.
  • Shifting climates and catastrophes.
  • Mass extinction.
    • Outside links to mass extinction.
      • National Geographic
      • BBC
  • Patterns of stasis, speciation, and change
     
• Each of these several topics raises important issues relevant to the evolutionary history of life.  But all except the last are more-or-less external to evolutionary biology itself .  That is, they represent the stage (or, in terms of the chapter title, the "theater") upon which evolution has occurred (in much the same may that meteorology is outside of ecology)
   
• Discussion:

Notes for chapter 1 / 2 / 3 / 4 / 5 / 6 / 7 / 8 / 9 / 10 / 11 / 12 / 13 / 14 / 15 / 16 / 17

304 index page

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