Reddit reviews Evolution of Hydrothermal Ecosystems on Earth (and Mars?) (Novartis Foundation Symposia)

Glad I could answer your question. To answer your next one, just because Miller's hypothesis was later proven to be 'improbable', it still forms the foundation for solid experimentation. It was a milestone Miller happened upon, partially due to luck. The kid was a student when he did this. He had a pretty awesome advisor since Urey didn't take sole ownership of the study.

There are many other fields of study that compliments the basic principles of Miller's but are 'tweaked'. One in particular is 'hydrothermal environments'. Essentially, deep-underwater hydrothermal vent systems are known today to have the ability to produce amino acid oligomers (1 AA + 1 AA -> dipeptide). These vent systems are believed to have existed on a primitive earth. For this type of condensation mechanism to occur (where two amino acids form a dipeptide), a lot of energy is required. Why? A condensation reaction is the following, A1+A2 -> B1 + H2O (where A1 and A2 are amino acids and B is the dipeptide). Notice how a water is in the products of reaction. If you have two amino acids in the ocean (a ton of waters) and you want to combine these amino acids, a water is produced in an environment where water concentration >> amino acid concentration (so, it is unlikely a water will 'form' in this environment because water is in great excess). Hydrothermal environments are perfect because they are high energy environments consisting of high temperatures (180-300C) and pressures. This type of condensation reaction has been repeatedly achieved in experimental labs (see E. Imai in Google Scholar for starters). The one problem people have with this is, amino acid chains (oligomers) decompose to their basic amino acid units at temperatures this high. I have personally faced opposition at conferences when promoting this idea from organic chemists who claim there is no possible way it could work because of the temperatures involved. So we're stuck between a rock and a hard place right? Wrong.

Here's the workaround. Hydrothermal environments constantly circulate water deep under the ocean. At that elevation, water is very very cold. The water seeps into the ground and enters hydrothermal channels where it is rapidly heated. After an amount of time, the water is expelled back into the cold waters of the ocean (the water is quenched). This quenching process gives amino acid oligomers the stability it needs to remain in complex chains. The process is pretty rapid so the oligomer retention time needs to be short. One of my favorite books (which is actually sitting right here on my shelf) has a lot of information on this. Its expensive so I suggest you borrow it from a university library if you're interested. Dr. Everett Shock (I believe it works out in Arizona or something?) is my idol when it comes to this school of thought.

Preemptive "I may edit this post" since it was a stream of conscious.