alt Hacker NewsI don’t understand the objections:
Most mutations are negative dead-ends, not unlikely DNA now where most pregnancies spontaneously abort due to errors. But life has many, many chances — especially at the molecular scale. So what’s the actual problem?
Similarly, if you have a soup of 10-15 nucleotide sequences, what are the odds actually that they’d link into larger segments?
Let’s suppose that density is a million times lower than blood, so you have one picogram per gram of water. There are 10^24 grams of water on Earth’s surface and 10 base pairs weighs 10^-20 grams, giving us approximately 10^32 segments of that length.
Feel free to play with my numbers, but I’m supposed to believe that with ~10^30 pieces, we can’t have ten of them form the right sequence?
Replies
Your numbers are fine - but RNA is fragile; making one copy of something really rare will not be able to do anything as it will not last long enough to meaningfully contribute.
Interestingly we now are thinking about ways to use mutations in other ways, youve spent a lot of energy making these polymers, so it would be a shame to waste that right? We think that they can be used to assemble larger functional pieces as mutations are mostly deterministic meaning you'll get the same kinds of errors - so why not put them to use!
I also don't understand. Adding billions of years to your numbers probably makes it an even better point.
"Life's first molecule." Take your favorite quantum field theory and consider how it draws a line between a molecule and not a molecule. Consider how it draws a line between life or not. That'd be cool. Consider that it doesn't give a shit who did what first.
"given any word, there's no such thing"
> what’s the actual problem?
A combinatorial explosion. To have mutations you need to have replication first. If a smallest viable self-replicator is, say, 100 nucleotides long, and there's not many other such replicators of the same length, the improbability of its spontaneous formation (~4^-100) dwarfs any amount of material available on Earth.
The researchers have found QT45 replicator. But it replicates other RNA strands, that is it needs another replicator nearby to replicate itself, which brings the probability down to 4^-90 range.
And it's not clear from the article whether QT45 is a viable replicator. That is whether it is stable enough and replicates other RNA strands correctly enough to sustain exponential growth instead of petering out due to filling its surroundings with broken copies that don't perform replication before decaying itself.