[throwup238]

There is tons of concrete evidence, you’re just ignorant of it. Start with Stanley Miller’s seminal 1953 paper “Production of Amino Acids Under Possible Primitive Earth Conditions” and go from there. There’s been a lot of work on the topic since then, several of which have made it to the HN front page.

[ceejayoz]

I'm aware of the Miller-Urey experiment.

It's only one piece of the puzzle, and we're aided significantly in it by knowing what the results are supposed to look like.

[throwup238]

We absolutely know what it’s supposed to look like: monomers. Monomers that can form polymers.

The specific chemical details are irrelevant. We have no evidence of other monomers that could enable non-water based life.

[ceejayoz]

We find polymers outside of Earth-like conditions.

https://en.wikipedia.org/wiki/Hemoglycin

[throwup238]

> Hemoglycin (previously termed hemolithin) is a space polymer that is the first polymer of _amino acids_ found in meteorites.

I’m done, have a great day! (Monomers)

Edit: My apologies for being dismissive. I’d like to get into the specifics of why amino acids (amino and carboxylic groups specifically) are special, and interesting exceptions like hydroxy and alpha-hydroxy acids, but I’ve got to get to work and I could spend an entire year explaining the nuances. The deeper you get into the details, the more the anthropic principle rears its ugly head.