Years ago I read a book called Rare Earth: Why Complex Life is Uncommon in the Universe.
The authors, Peter Ward and Donald Brownlee, put forth the idea that intelligent life–indeed, all life above the level of a single cell–may be vanishingly rare in our universe. Ward and Brownlee argue that the combinations of physical situations and significant astronomical events necessary for complex life to develop are very likely to be vanishingly rare (much in contradiction to the popular Drake/Sagan formula).
The book not only puts forth this most interesting notion; it also contains pithy, concise descriptions of earth-centric geology, astronomy, biochemistry, and other branches of science, and binds them in prose that reminded me pleasantly of that wonderful BBC series Connections by science historian James Burke. It would make a great textbook for teachers/homeschooling parents looking for a connection-based flavor of teaching science.
Why do I mention this book? The idea that intelligent life is rare, or perhaps unique to humanity, resonates strongly within me. The notion that our race may have the unique gift of tool-bearing sentience in all of existence gives me frissons of fear and exaltation at the same time. And it gives new, rather ominous important to the preservation of our race and to expansion off this planet. (Think: we have all of our eggs in one basket right now.)
