Problem:

ask this question in relation to the origin of life. I realise it would probably be better suited to a geology stack exchange, but it does not yet exist.

The Miller-Urey experiment gives a lab based demonstration of how organic compounds may have been produced. It recreates that conditions that are thought to have existed in the early atmosphere (Hadean period).

Question: What this experiment relies on however is an assumption that the atmosphere lacked oxygen (reducing).

The Miller-Urey experiment does not produce proteins if it is conducted in a oxidizing environment. I've seen that there is some debate over the oxidation state of the atmosphere, and the main evidence for a reducing atmosphere is that life wouldn't have been able to begin without it.

Question: Is there evidence supporting an oxidized early atmosphere, and if so, how did life come about?

Any help would be greatly appreciated!