One of the big news stories this week is the announcement (long suspected) that there was once free-flowing water on Mars. Of course, coupled to that announcement is the inevitable speculation that Mars could have once held life as we know it. I wrote the following bit in 1996, when the announcement of possible Martian bacteria had just been released. It was published in The UFO Invasion (Prometheus Press). My chapter, "Is intelligence inevitable?", concerned whether, once you had life, evolution would push invariably organisms to become ever more complex and eventually yield smart beings (aliens, in other words).
"There is a more depressing side to the announcement of possible past Martian life, however. Mars may be an entire biosphere that has gone extinct. We find living organisms living and often thriving in our planet's most hostile locations, so terrestrial life appears marvelously tenacious and resiliant. There is no evidence of life on Mars now, suggesting that if life originated on the red plant, it never managed to get a toehold: No macroscopic organisms, no increasing complexity, no smart Martians carved out by the forces of natural selection."
Replace "life" in the first sentence with "water," and it still sums up my attitude. It's also one of my favourite passages from anything I've written to date.