Both Dawkins and Mayhew assert that early life dawned from some sort of entity that was able to replicate. Both pointed out how these “replicators” transitioned from simple forms to sophisticated organisms to a thriving ecosystem, from which advances like communication and behavior emerged. However, how the transition came about is where the two differ.
Dawkins’ gene-centric view suggests that replicators, which emerged from substances of the earth’s primitive environment, became receptacles for genes called “survival machines.” Such machines “fed” on substances available in the “primordial soup”, and gradually developed into organized structures. In this connection, he proposes that these machines were not capable of producing their own “food” and were reliant on the substances available in such pre-biotic broth. In evidence he states how the scarcity of “food” in the soup paved way for a food-producing organism to later arise.
Mayhew holds a different approach. In Brave New Worlds, he stresses the autotrophic theory on the origin of life. To prove the likelihood of an earth consisting initially of food-producing organisms, he emphasizes the difficulties of early cell membranes to have permeability to molecule transport and the fact that metabolic cycles can emerge spontaneously.
There has been much evidence supporting the latter scenario. One is that NH4SCN and H2CO acted as raw materials for the synthesis of bio-organic compounds by photosynthetic structures (Herrera, 2003). Evidence also suggest that photosynthesis was an early acquisition. In evidence, early life used RNA to catalyze reactions due to a lack of sophisticated protein enzymes. As Mayhew pointed out, it isn't a coincidence that chlorophyll synthesis involves molecules bound to RNA. This provided a new abundant energy source, light, which have massively increased potential productivity (Mayhew, 2006).
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There may have been evidence of the second theory however what of the evidence of Dawkins? The primordial soup theory has been laboratory tested and proven to produce something like amino acids. I can't really argue with your writing, however I can show the other side that also has evidence for their argument.
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ReplyDeleteI like that you mention Mayhew's point regarding RNA as a catalyst for early biochemical reactions. It seems logical that use of RNA as a catalyst in modern plants' use of RNA in the synthesis of chlorophyll evolved from these more rudimentary reactions.
ReplyDeletegood post. I like how you went into some detail in the last paragraph about the evidence suggesting photosynthesis being obtained early on and how cholorphyll molecules bound to RNA. That would make some sense since RNA could have possibly been around even before DNA.
ReplyDeleteI like that you correlated specific ideas that both authors bring up. The notion of photosynthesis and when/how it arose is discussed by both authors and each has their own take on the idea. Mayhew brings up the idea of autotrophism first as a reason photosynthesis occurs and Dawkins suggests autotrophism second when food was scarce for heterotrophs.
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