Origin of life: chicken and egg paradox
In his book Life Ascending, Nick Lane presents a strong case for life evolving from hydro-thermal vents in the the earth's early oceans. And we are told that the earth's early atmosphere was very different than it is today.
Yet in the same book he goes on to talk about photosynthesis, saying that without oxygen-based photosynthesis, the lack of an ozone layer would have meant that the oceans would have bled away into space, resulting in a dead planet.
I am new to evolutionary biology and may be missing something, but this seems like a chicken and egg scenario/paradox.
How is it possible for the oceans to exist on the planet without oxygen and how is it possible for the oxygen to exist without oxygen-based photosynthesis, which in turn requires plants?
Obviously plants themselves must stem from the origin of life which is that of the oceans and the aforementioned hydro-thermal vents.
Can anyone help me here?
I simply wish to gain a better understanding of the issues at hand.