3 comments

  1. You wrote: “If you go on the internet, your research will show that a simple cell is an amazingly complex molecular machine. So the first cell wasn’t just some micro-blob of a few simple ingredients: it was a molecular information system of mind-boggling proportions.”

    This looks like a non sequitur to me. Why would the complexity of present day cells mean that the first cell must have been complex?

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    1. KR,
      But in response to your anticipated objection the following statement appears just a few lines down:
      “And even if the primordial cell is hypothesized to have been more simple and primitive, it had by necessity the sophistication and complexity of a DNA (or RNA) existence in order to be able to replicate itself and, crucially, to sustain its own life. “The simplest form of life [such as bacteria] requires millions of parts at the atomic level, and the higher life forms require trillions” (J. Bergman). Biochemist Michael Denton adds: “Molecular biology has shown that even the simplest of all living systems on Earth today, bacterial cells, are exceedingly complex objects…far more complicated than any machine built by man and absolutely without parallel in the non-living world.”
      Tom

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      1. Abiogenesis (the study of the origin of life) is all about finding the simplest possible structure that could have started the evolutionary process. The simpler, the more likely that it could have formed spontaneously. This is where I think you go wrong – you’re still looking at the sophistication of a modern cell and concluding that nothing that complex could just self-assemble. Well, I’m with you that far but if you take this as evidence that the first cell couldn’t have formed spontaneously, I think you’re making an unwarranted leap.

        You mention the complexity of RNA but that complexity only comes into play in a cell that has a system for protein synthesis – something which is very unlikely to have existed in the first cell. Without the role as template for protein synthesis, RNA is just a linear polymer made up of four different monomers (A, U, G and C) – not very complex at all. All that the first cell would have needed was the capacity to self-replicate. Pretty much any old RNA sequence would have been good enough to get the process started as long as the only requirement was self-replication.

        So far, abiogenesis researchers have been able to show that all the important basic molecules (like RNA nucleotides, amino acids and lipids) can form non-enzymatically in plausible pre-biotic conditions. RNA has been shown to polymerize and also self-replicate without any help from protein enzymes. Lipids dissolved in water will spontaneously form bilayer vesicles which have the same basic structure as a cell membrane. They’re still far from having a complete sequence from basic chemicals to a self-replicating cell but I see no reason to think that it’s impossible.

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