> given the diversity that we have now, there can be millions of forms of life all existing at the same place/time.
Sure, each niche favors a different specialist, but why do you think that whichever process led to the emergence of life will be any good at producing competing specialists? I'd think that evolution of existing organisms would be infinitely better at this task, as existing organisms have both a numerical advantage and the strategic advantage of DNA (a "playbook" of previous successful strategies to draw inspiration from).
Very few niches are available for the emergence of life, even though there are clearly many available for the evolution of existing life. The available niches require a level of sophistication that spontaneous process cannot achieve but that evolution can achieve (e.g. photosynthesis).
Actually, given that our star is a third-generation star, you could even ask the question : why wasn't there life in our very own solar system before earth even existed ? Before sol started burning or even coalesce ?
The first generation stars wouldn't have had anything but hydrogen clouds surrounding them, but second generation stars would have had similar amounts of other elements to what we have today floating around them.
Given that "our" biogenesis event happened only the second time it could happen (here and in billions of other solar systems in our galaxy), where the hell are the second generation societies ? Didn't they survive the supernovas ? (possible, I suppose, but not exactly hopeful for our own chances of spreading across the stars). Was there some kind of large scale disaster ? But the question is worse than that, because they should have been spacefaring ... if they had anything like our numbers of satellites, we should have been able to find something, somewhere, right ?
Sure, each niche favors a different specialist, but why do you think that whichever process led to the emergence of life will be any good at producing competing specialists? I'd think that evolution of existing organisms would be infinitely better at this task, as existing organisms have both a numerical advantage and the strategic advantage of DNA (a "playbook" of previous successful strategies to draw inspiration from).
Very few niches are available for the emergence of life, even though there are clearly many available for the evolution of existing life. The available niches require a level of sophistication that spontaneous process cannot achieve but that evolution can achieve (e.g. photosynthesis).