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Abiogenesis

A friendly creationist left a comment on one of the old posts. I thought I’d respond to him or her in more detail here. Here’s what he or she said:

“Am I missing something? This article said nothing about how all life on earth could have evolved in only 4 billions years… NOTHING! But hey, if you want to believe everything arranged itself from a goo or a rock – GO AHEAD!”

That sounds to me like a CHALLENGE!

I certainly don’t believe “everything arranged itself” from a rock, and I’m pretty sure “goo” is only a singular noun in World Of Goo (worth taking a look at)… but I’ll try to explain what I accept as the most likely hypothesis about abiogenesis (which I guess is a synonym for “believe”? eh, close enough).

I’ll also try and simplify it as best I can, but I’m no expert so everyone else can feel free to correct me on this if/when I get it wrong.

Y’see, young earth was a very active place. Volcano’s and meteorites and lots and lots and lots of rain. Imagine the plot of Armageddon combined with the Yellowstone caldera erupting combined with a British Public Holiday, but everywhere.

Anyway, all this activity meant that pretty much every body of water, especially the shallow ones, would have been filled to the brim with volatile chemicals and minerals, like the floor of a chem lab after a shrapnel grenade. And combine a situation like that with an energy source (the sun) and earth would have been home to a whole host of interesting chemical reactions, including those that result in organic compounds.

Note that this isn’t speculation. The famous Urey/Miller experiment might not have been a particularly good simulation of early-earthian conditions, but it demonstrated that if you dump a load of inorganic components together and apply energy, you can get organic compounds easily enough. Besides, it’s successors have done a far better job of simulating early-earthian conditions, with even better results.

But back to early earth. This mix of organic compounds in shallow water, across an entire planet (that’s a lot of space for a microscopic experiment) provides the perfect environment for the formation of more complex chemical reactions, including those involved in abiogenesis.

Now, the exact mechanism of abiogenesis isn’t known, but this isn’t because it’s difficult to make happen. Turns out there’s loads of ways to make a self-replicating molecule. We’re spoiled for choice: there’s so many that it’s hard to pick a “most likely” option. Personally, I like the idea of catalytic cycles.

A catalytic cycle isn’t a self-replicating molecule. A self-replicating molecule is something that builds copies of itself out of whatever molecules exist in it’s environment: so Molecule A takes 2 Molecule B’s and combines them into another Molecule A. A catalytic cycle, on the other hand, is a molecule that builds another molecule, which in turn builds the first molecule. So A builds copies of B, and B builds copies of A. It’s chemical symbiosis, and the component molecules can be even simpler than self-replicating molecules (which are already fairly simple).

Anyway, once you’ve got reproduction, these molecules quickly take over their environment, converting all the “building block” molecules. If one of these cycles changes slightly to use a different mineral to make itself, it will be able to spread further than the original and become dominant where there’s none of the original food. This process can then continue until all the worlds oceans are teeming with catalytic cycles or another variety of chemical self-replicator. From there they become more and more complex, to use more and more ‘food sources’ and fill more and more niches. This is the base for evolution: random mutation + natural selection. It leads to more versatile molecules, to RNA and to DNA, and later to single celled organisms. Since you’re all undoubtedly familiar with evolution, I’ll skip that for now.

As you can see, this process isn’t the creationist misrepresentation of “the components of a cell rolled together by chance”. You might be able to say “the components of a catalytic cycle rolled together by chance”, but that wasn’t so much chance as chemistry.

Of course, the biggest stumbling block for public acceptance of the science behind abiogenesis (well, apart from people desperate to believe the universe as a whole cares about them) is that all this would have happened nearly 4 billions years ago. We don’t even have many *rocks* that old, and even if we did it’s not like molecules fossilize  So there’s no way to know what the exact structure of the early self-replicator/catalytic cycles may have been. Maybe aliens did seed the planet with their dandruff, maybe God did look at a barren rock and think “you know what this needs? SINGLE CELLED ORGANISMS!”, maybe space bacteria from Mars surfed an asteroid here. Maybe all of these things happened at once and God got smacked in the face by an asteroid carrying martian head-lice  We’ll never know for certain. All we can do is try to work out what the most likely scientific hypothesis option is. And that’s abiogenesis.

This isn’t enough for IDists and creationists, though: for some reason (I’ll avoid speculating on motives) they can’t accept that abiogenesis is even a possibility. But since it obviously is (and the research in that area just keeps on confirming this), they need to misrepresent it as something absurd in order to make their arguments from incredulity.

Which brings us back to the comment that sparked this post.

But hey, if you want to believe everything arranged itself from a goo or a rock – GO AHEAD

I don’t want to believe that because it’s a ridiculous misrepresentation. But hey, if you want to believe that the scientific alternative to your own beliefs is blatantly stupid, a fact which has somehow miraculously escaped the attention of every atheist chemist, biochemist and biologist on earth despite them spending their lives researching this stuff… go ahead.

“Or maybe it’s a CONSPIRACY!”

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