Facts On File Science Library 2007, Joseph A. Angelo, Jr.: "Life in the Universe".
Quite an interesting read about the search for life in the universe.
Also somewhat frustrating for anybody who hopes we find life out there - we have 300 pages to tell us we haven't yet found any even halfway conclusive evidence for any form of extraterrestrial life in the solar system or sentient life elsewhere.
It doesn't surprise me. I could well imagine that we are the first sentient life at least in our galaxy if not in the universe. The universe is 13.7 billion years old; the first three or 4 bgillion years first had to pass, the first generations of stars to live and die to create the heavier elements we need for life as we know it.
Even then, it took 4.5 billion years from the formation of the earth to sentient life to arise - about HALF the time the option for such life has existed.
We observe a place suitable for life as we know it because if it weren't, we wouldn't be here.
Small bipedal dinosaurs with free forelimbs and a large brain had been around for many million years without ever evolving into sentience like we did.
Alas, maybe we ARE a "freak accident" - life, on the other hand, IMO should be abundant in the universe on every planet with the right conditions.