“It seemed obvious to me that there were double inheritance systems with cells inside of cells.”
She delved deeply into the work of Tracy Sonneborn on cytoplasmic inheritance in paramecia, Ryan writes, “grasping at once that his experiments had confirmed that characteristics acquired by the organism in its lifetime could be passed on: ‘They confirmed a kind of neo-Lamarckian inheritance.’” (Ryan, 87)
Ryan notes that cellular mitochondria, which enable the use of oxygen in respiration, and chloroplasts, which enable photosynthesis to take place, resemble bacteria in their behavior and metabolism. For Margulis, he continues, “there seemed little difference between a bacterium newly trapped within a cell and a mitochondria inherited as part of cell evolution. What everybody called a chloroplast was simply a blue-green bacterium.… that had shed its cell wall to reside inside the cytoplasm of a plant cell.” (Ryan, 87-88)
Margulis hypothesized that if mitochondria and chloroplasts had once been free-living bacteria, they might still retain their bacterial DNA. The hypothesis was subsequently confirmed, and this confirmation, Ryan suggests, marked the “coming of age” of symbiogenesis. (Ryan, 88)
Summarizing Margulis’ The Symbiotic Planet—A New Look at Evolution, an anonymous reviewer writes: “We are all symbionts, creatures linked in vast re-cycling circuits of matter and energy. In turn, we contain multitudes of symbionts, from the tiny bacteria that live in our gut and help us digest food to the even smaller remnant organisms that power our very cells. These mitochondria were once free-living microbes that long ago entered a pact with larger cells, and now dwell inside the enormous multi-cellular animals that roam the world and sometimes dream up science and art.” (Anon)
The Marriage of Darwinism and Symbiotic Theory?
“The world is a wedding,” the poet-essayist Delmore Schwartz once wrote. There is great truth in this metaphor, on all levels, from microscopic to macroscopic. Symbionts are married couples. Some of their marriages are for better, some for worse, but they all bear witness to the fact of there having been “natural marital selections” somewhere back down the line.
Is it possible that Darwinism and symbiotic theory may enter into marriage? Yes. It is not only possible, it is inevitable. Symbiosis is ready and willing, and Darwinism is three-fifths of the way to saying “I do.”
“Three-fifths of the way? What is meant by that?” Ryan indicates that three out of five of Darwinism’s major tenets are already compatible with symbiosis. The three compatible tenets are: (1) “Evolution is the explanation of the origin of life” [sic]; (2) “life arose through common descent from a simple ancestor;” and (3) “new species [arise] from old.” (Ryan, 262)
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