How likely are alien civilizations? That’s the question at the heart of the Drake equation. And while I agree with most of the assumptions that Astrobiologists and others make, there’s one—evolutionary question—which I think they haven’t thought through completely.
I agree that life as such is probably ubiquitous in the universe—there’s probably microbial life almost everywhere. I also agree with most that liquid-water planets are probably common enough; and that complex and motile life probably appears on most of them.
And I can even imagine that life with self-awareness—which I would define as the ability to identify ones’ own reflection—is rare, but not extremely rare. Metaphorically, “silver-rare,” and not “platinum-rare.” Even on Earth, with currently extant species, we have at least eight species that can (seven excluding humans): Chimpanzees, orangutans, gorillas, dolphins, elephants, pigs, and octopae. (I’d note here that two of these are aquatic, and as such, could not develop fire as a tool.) So even, just on Earth, self-aware organisms aren’t that rare; although as a proportion of the Earth’s biomass, a really, really tiny slice. But; that aside…
To develop an organism that has to live by its tools—an organism that needs technology to survive… You need an organism that, not only has grasping appendages, probably a form of stereoscopic vision, and a degree of native intelligence (motifs that have arisen several times on Earth, not just in humans), you need something else. You need an organism that has these things, and no other natural advantages. Because if an organism has other natural advantages, it will likely use those rather than developing a culture. And, more often than not, organisms that don’t have any other natural advantages probably won’t survive long enough to develop enough technology—most likely necessarily including fire—quickly enough to avoid being predated to extinction. Or evolving into something else that does have natural advantages.
It’s an extremely delicate line. And looking just at biohistory on Earth, many of the same factors have come together in other organisms in the past (Raptor-based dinosaurs come to mind) but all of those had built-in natural advantages (raptor-based dinosaurs come to mind).
So the question about alien civilizations (as opposed to alien life and alien intelligence) is this: Exactly how delicate is that line between being delicate enough to need technology to survive and not surviving it? How rare or common is it that such an organism would evolve in the first place; in great enough numbers to have a genetic and intellectual pool? And avoid extinction long enough? I don’t know the answer to that, but it seems to me relatively unlikely.