The
Star Larvae Hypothesis
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"Lichens are also clearly metabolically integrated. The products of photosynthesis flow from bluegreen or green to the translucent partner. What is seldom realized is that in tight associations the metabolites flow in both directions. The animal or fungal partner also releases materials to the photosynthesizer. Symbioses are two-way exchanges. The kindness of strangers, the metabolic flow of gifts, makes them less strange and, ultimately, part of a single, co-dependent biological self."
-- Lynn Margulis and Dorion Sagan |
"Indeed the lower we go in the scale of being, the more necessary is geographical unity for that close interaction of individuals which constitutes society. Societies of the higher animals, of insects, of molecules, all possess geographical unity. A rock is nothing else than a society of molecules, indulging in every species of activity open to molecules. I draw attention to this lowly form of society in order to dispel the notion that social life is a peculiarity of the higher organisms. The contrary is the case. So far as survival value is concerned, a piece of rock, with its past history of some eight hundred millions of years, far outstrips the short span attained by any nation."
-- Alfred North Whitehead |
A mutually beneficial relationship among organisms is called symbiosis. This concept can make it hard to distinguish between organisms and their environments. For example, if a plant requires the participation of an organism of a different type, a bee, say, to reproduce, then the bee is a part of the plant’s reproductive process. And if the bee requires the pollen from the plant to feed its larvae, then the plant participates in the bee’s reproductive cycle. The organism is the beeplant. To where the bee flies, the plant might expand its range. To where the plant’s seeds light, perhaps due to the intervention of a bird, a new beehive might be established. The bird further complicates the boundaries of the organisms. Symbiotic organisms function simultaneously as extensions of one another's metabolisms and as components of their environments.
A lichen appears to be a single type of organism, but the lichens are actually integrated symbiotic communities of cyanobacteria and fungi.
An enzyme produced by a micro-organism that lives in the gut of the termite enables the insect to digest cellulose (wood fiber). By mass, the human body consists mostly of symbiotic bacteria. Whose metabolism is whose?
The ambiguities encountered when trying to delineate biological "units" is a problem for evolution generally, because evolution theory needs to define something discrete for nature to "select", from among her integrated metabolic processes. Which is a discrete unit of evolutionary selection, a gene, a trait, an individual organism, a species? This "granularity problem" plagues the Darwinian model.
The ambiguities take a dramatic turn in the more complicated mechanism of endosymbiosis. This process occurs when different types of unicellular organisms merge to form a new kind of cell, which, being a conglomerate of symbionts, has a more complicated structure than its formerly independent constituents. According to normal evolution theory, various species of bacteria, or prokaryotes, merged to create the more complex, eukaryotic, cells that make up the bodies of multicellular plants and animals. The notion that this is how complex cells arose, through a communal pooling of resources on the part of bacteria, was greeted with scorn when researcher Lynn Margulis proposed the idea in the 1960s. She since has enjoyed the last laugh, however. Endosymbiosis generally is accepted today by evolutionary theorists as the most plausible evolutionary path to eukaryotic cells.
Tightly coupled anabolic and catabolic subprocesses create the illusion that bodies are fundamentally discrete biological units. But the metabolic process per se is the fundamental structuring pattern. Organism is a conceptual convenience that designates a relatively stable cross-section of overlapping interdependent metabolisms. Organisms make their ways among other organisms, making and breaking bonds of various kinds, forming new organisms in their combinations and recombinations of metabolic overlappings. Gene, organism, and species each can be regarded as a discrete biological unit, subject to evolutionary selection.
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The concept of symbiosis can be abstracted further to include all social behaviors, as forms of intraspecific symbiosis. Microbiologist Bonnie Bassler describes symbiotic/social behaviors among bacteria and the chemical signalling involved. |
Is the coral of the reef distinct from, or part of, the living organism, the polyp, that excretes the coral? Is the coral an artifact of polyp technology, just another component of the polyp's physical environment, or the true skin of its body? Can the reef's coral be part of the organism and itself not be living? If so, it suggests that an organism can have two parts, one possessed of livingness and one not, the two interwoven in the body of the thing. But are the molecules themselves possessed of livingness? Are the iron atoms that ride along in the hemoglobin molecule that keeps animals alive, alive?
Something as intuitively nonliving as iron is essential to keeping certain organisms alive, but it seems doubtful that any iron atom feels a distinction between participating in living processes and nonliving ones. During its lifetime an iron atom will make and break bonds with countless other atoms, in hemoglobin molecules and rusty nails. Matter and energy exchanges within nature crisscross back and forth between the organic and the inorganic seemlessly. Nature seems uninterested in maintaining walls of separation between the two domains of the organic and the inorganic. This observation raises questions about the character of manufactured (organic and inorganic) artifacts and the potential range of their impressions on humankind.
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Think
you're Bright?
Rise and Shine at http://starlarvae.blogspot.com/ |
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