Just a short comment. Yesterday, the Astrobiology Magazine discussed a paper that will be heavily promoted in the coming issue of Chemical Science,
Synthesis of functionalized nitrogen-containing polycyclic aromatic hydrocarbons and other prebiotic compounds in impacting glycine solutionsby Rebecca Lindsey and 2 men from LLNL. (I chose the middle author because the name is both female and easy to pronounce. That's how it works today, sorry, Gentlemen.) They used some nice quantum quantum chemistry approaches to argue that comets could have been helpful for the birth of life on Earth.
Comets contained some amino acids, it's being assumed.
Some of them landed on the Earth which had some sweet juice where the amino acids could be placed for a nice beverage. The impact has brought some huge pressure which may be hurtful but in that situation, it was actually helpful to produce something like "polymers with nitrogen" or "poly-peptides" which could be crucial for the early life.
Note that my description is a vulgarization of a vulgarization but I still try to keep it about 3 academic degrees above the level that would be expected in the mainstream media.
You might object that they just "made up" a possibility and there's no guarantee that such processes were important for the early evolution of life on Earth – because I think it's likely that they were happening, to one extent or another.
But this research is a particular example of the possibilities that should shape our perception about the conditions needed for life to arise. I would classify the research as a part of the broader "panspermia" paradigm that assumes the outsourcing of some important jobs to employees who work outside the Earth.
People have imagined that the life was created here and everywhere – in any point of the ocean on Earth or all points – and there's nothing much to discuss. Suddenly, some simple organisms arose and started their evolution journey. Everywhere. Equally. All the time.
I think that such an imagination is extremely naive because even the simplest life forms are extremely complex and their evolution required many processes whose combination forms a rather complicated structure. I do believe that many such processes took place outside the Earth, perhaps in some interplanetary dust, perhaps on comets, and perhaps all these objects in the outer space and many more were needed.
Also, they make the high pressure from the impact look "helpful". This is also a good point. We tend to look at physical conditions from some anthropocentric 2019 point of view. The pressure of "many and many atmospheres" is deadly etc. However, what is deadly for us and now wasn't necessarily deadly for all stages of terrestrial life that has existed. (The air without oxygen would be deadly for us today but it was required by earlier life forms.) On the contrary, such conditions that are unpleasant for us could have been absolutely crucial in the earlier stages of the development. And we wouldn't be here without the conditions that look deadly to us today.
It reminds me of the discussions with the world's top creationists in 2010. They were presenting arguments with the ambition to show that there wasn't enough time for certain evolution of species so the evolution theory is dead. However, these "disproofs" were assuming the worst case scenario when it came to certain quantities. The point is that the evolution – the rate of mutations in particular – could have been variable and much faster at some moments – moments when the accelerated evolution looked like a good idea.
The point is that life tries many tricks to reproduce and adapt to the environment and seemingly "constant" quantities such as the rate of mutations – but also the pressure at which some processes are taking place – are also "dynamical" and the system tries to find the "optimal" values at every moment. Sometimes, it's better for the whole species to allow faster mutations, sometimes it has slower mutations. Similarly, some production of polymers may prefer conditions with a huge pressure such as the collision of comets with the Earth.
There has simply been a lot of structures, stages of some evolution etc. that we are still largely ignorant about. And one possible euphemism for this ignorance is "egalitarianism". Some people may be uninterested in the structure – in insights such as "some important processes took place exactly in some special environments such as the comets colliding with our planet" – because these insights "break the equality" between the places on Earth.
But the "equality" has been broken since the beginning of time and this "violation of equality" or "symmetry breaking" has been totally essential for basically everything. Almost every "historical" insight about natural science and social science – why things could evolve so that they work – requires some key processes that "break the equality". The egalitarian thinking is really a big enemy of the progress in science.