Actually, life as we know it isn’t a big caveat, not if we are talking about an organism with a larger capacity brain capable of intelligent thought. The larger brain to body mass requires diverse and abundant food sources driving the energy requirements to direct a higher percentage of fuel to the brain. That drives a whole raft of requirements on the host planet.
If you are talking about a single cell amoeba, then I’ll agree with you.
there may be other life out there, but the “bell curve” of live is limited.
“...not if we are talking about an organism with a larger capacity brain capable of intelligent thought.”
Isn’t that only if they think with brains and that they do so with the same size ratios and efficiency as the examples we know about so far? I mean, it seems to me that it is still the ‘example of one’ problem.
Freegards
That was not quite what I was talking about. I was referring to the fact that every living organism on this planet has a common biology. We all use DNA and RNA as carriers of genetic information, with the same nucleotides encoding protein sequences and genetic control elements. We all use proteins made up of the same 21 amino acids (or variants thereof). The fact that all life on this planet has this biochemical similarity does not mean that all life on other planets would be constrained to the same biochemistry. We simply do not know, since our sample size of planets supporting life is n=1, as is our sample size of biochemical parameters of living organisms.
Without really knowing the parameters within which life can exist--which we can only determine through finding and analyzing other life-bearing planets--we have no idea whether we are excluding potential life-bearing planets from consideration by constraining the search to "earth-like" planets. It is almost certainly a moot point, in any case--the time required to travel even to just the nearest star makes any real space exploration impossible.