3 ms·

I like that this article mentions the metabolism first hypothesis. It seems less popular, but much more plausible to me then “RNA world.” There are many natural

by _yb2s 3y ago

I like that this article mentions the metabolism first hypothesis. It seems less popular, but much more plausible to me then “RNA world.” There are many natural situations where there is available chemical energy, and reactions very much like central carbon metabolism spontaneously occur. A gradual stepwise process from that to present day metabolism seems fairly straightforward if you also add in isolated units that can be selected for. Importantly, and still relevant to modern day life is the fact that metabolic states contain information and themselves can be heritable.

pfdietz 3y ago
For selection, you need something with "memory", like genes. I've wondered if something like this could work: store information in templates formed in otherwise random organic solids. The idea would be that a molecule adsorbed onto a surface would be most stable if its shape and charge density matched the shape and charges of a hollow in the surface. These charged holes would be a kind of analog memory. They promote formation of the matching chemicals, since they'd make formation of them from precursors more energetically favorable. At the same time, the presence of the small molecules would encourage the formation of matching holes. This mechanism should be testable in small scale systems, forming tars from a mixture of various monomers. RNA/DNA would come later and take over from this primordial mechanism.
ambyra 3y ago
I like the "lipid world" hypothesis over the "RNA world". It reminds me of the chicken or the egg argument. I don't see how life could form outside of a controlled environment, like an egg or a seed. Something forms in a lipid that couldn't form in a harsh nature, the lipid pops, the something gets to hang out with the other somethings that formed in lipids nearby, and they get reabsorbed by lipids. Make sense to me. There are so many specific control mechanisms for getting inside of eggs, seeds, cells, etc. Seems like a fundamental part of life. I remember something from the "your inner fish" book, talking about how all of evolution in a body happens between layers.
- _yb2s 3y ago
  Yes, as I understand it the metabolism first and lipid first ideas are related, in that you have some sort of micelle or vesicle that contains metabolism, and is partitioned off in a way that selection can act on them.

by _yb2s 3y ago

pfdietz 3y ago

For selection, you need something with "memory", like genes. I've wondered if something like this could work: store information in templates formed in otherwise random organic solids. The idea would be that a molecule adsorbed onto a surface would be most stable if its shape and charge density matched the shape and charges of a hollow in the surface. These charged holes would be a kind of analog memory. They promote formation of the matching chemicals, since they'd make formation of them from precursors more energetically favorable. At the same time, the presence of the small molecules would encourage the formation of matching holes. This mechanism should be testable in small scale systems, forming tars from a mixture of various monomers. RNA/DNA would come later and take over from this primordial mechanism.

ambyra 3y ago

I like the "lipid world" hypothesis over the "RNA world". It reminds me of the chicken or the egg argument. I don't see how life could form outside of a controlled environment, like an egg or a seed. Something forms in a lipid that couldn't form in a harsh nature, the lipid pops, the something gets to hang out with the other somethings that formed in lipids nearby, and they get reabsorbed by lipids. Make sense to me. There are so many specific control mechanisms for getting inside of eggs, seeds, cells, etc. Seems like a fundamental part of life. I remember something from the "your inner fish" book, talking about how all of evolution in a body happens between layers.

_yb2s 3y ago
Yes, as I understand it the metabolism first and lipid first ideas are related, in that you have some sort of micelle or vesicle that contains metabolism, and is partitioned off in a way that selection can act on them.