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I became interesting in this book because of Lynn Margulis's theory called symbiogenesis. This evolutionary term refers the origin of tissues, organisms and even species through a long-term form of symbiosis. After describing her early start in the subject matter, she notes that she has always felt that genetics was the key to evolutionary history. She observed that three classes of organelles located outside of the nucleus of a cell (plastids, mitochondria, cilia) "resembled bacteria in their behavior and metabolism."
In the chapter on Individuality by Incorporation, she tries to make the case for the symbiotic process. For example, an archaebacterium merges with a swimming bacterium, which subsequently merges with an oxygen-breathing bacterium, which subsequently engulfs, but fails to digest, a photosynthetic bacterium ultimately evolving into a swimming green algae. It is believed that our mitochondria in our cells and the chloroplasts in plant cells are of bacteriological origin. These processes are part of the theory called Serial Endosymbiosis Theory or SET. Margulis next delves into the problems with taxonomy or the classification of life. She discusses Robert Whittaker's (1924-1980) five-kingdom classification, but then goes on to develop a modified version that she feels more accurately "reflects the evolution of protoctists from symbiotic bacteria, and of animals, plants and fungi from protoctists."
In discussing evolution, the author notes that the bacterial cell is the minimal unit of life, and this is where one must begin. These organisms are like more advanced life; they use energy to take up food, have DNA and RNA and proteins, and use chemical reactions to keep themselves going. It is interesting to note that "no life-form exists outside a self-maintaining, self-reproducing cell." She spends a chapter discussing the possible origins of sex which I found interesting. Moving on to the evolving of life on land, Margulis feels strongly that symbiogenesis is what made habitation on land possible. She concludes the book with a chapter on Gaia, which she defines as the physiologically regulated Earth, or the "system that emerges from ten million or more connected living species that form its incessantly active body."
I found the book fairly readable for the layperson; however, you may have to research some terminology. In one chapter, for example, I came across a few undefined words or expressions, such as photosynthate food, fungal hyphal networks, and chitinase enzymes to name a few. The concept of SET is very interesting, and it appears to be another facet in our quest to understand the process of evolution.
- Paperback: 176 pages
- Publisher: Basic Books; Revised ed. edition (October 8, 1999)
- Language: English
- ISBN-10: 0465072720
- ISBN-13: 978-0465072729
- Product Dimensions: 5 x 0.4 x 8 inches
- Shipping Weight: 5.6 ounces (View shipping rates and policies)
- Average Customer Review: 35 customer reviews
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Amazon Best Sellers Rank:
#151,689 in Books (See Top 100 in Books)
- #55 in Microbiology (Books)
- #1246 in Evolution (Books)
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