The link below is to an article from the Boston Globe, a paper that's in an incestuous relationship with the NYTimes. I don't know which one of them wears the pants in the family (in other words, "who pimps whom"), but since it's completely off the point, it doesn't matter.
The article (above) concerns the ramifications of finding evidence that life on Mars delevoped at some point in the planet's history. The writer posits that if we DO find this evidence, it implies bad news for us. His point (I think) is that if we find that life has independently arisen twice in our small solar system, it stands to reason that other greater lifeforms and civilizations must be out there, larking around through deep space, in amazingly large numbers, given the vastness of space and the number of solar systems that inhabit each of it's billions of galaxies. And yet we have no evidence that such is the case. Where are all the E.T.s, the visitations, radio communications, alien soap-operas, nebular road signs saying "Bellatrix - 48 light years ahead. Use exits 4a, 4b, 5 (Spaceliners use Exit 5n to access beltway)? That there is nothing but silence means to him that there is some defining event or moment when life is extinguished, or at least prevented from developing much beyond a unicellular level.
What he doesn't mention is that for most of the history of life on Earth, evidence of extrasolar intelligence readily detectable to radio telescopes could have been blinking and beeping on and off like smoke alarms in a darkened house. Because even though we've been living in the house, we've been the slime mold that clings to the bottom of the step leading out into the garden. We wouldn't have known a smoke alarm (or a radio signal) if we'd oozed over one. In the last couple of hundred years we have indeed developed the technology to detect waves from the entire electromagnetic spectrum, to pin-point them in some cases (as in the gamma ray burst that indicated a particular supernova, or not, like the background microwave radiation that comes from everywhere at once; a remnant of the 'Big Bang'. (Now there's something for which to thank Bell Labs!)
But a couple of hundred years is nothing! The Universe is 15 billion years old. 200 years is a blip, a blink, a nanosecond. We've been looking and listening for virtually no time at all. Will we, as a species, ever traverse the galaxy? Probably not. It's almost certainly beyond our present potential. If we have time before our sun dies, we may evolve into beings who would make such a journey or at least be patient enough to listen for a phone call. Would they be humans? No more than the slime mold is. But they would possess that quality that all life on Earth seems to possess, the will to persist. And maybe they would be ready, listening in the right place and at the right time, to catch an invitation to the dance.
The picture at the top of this post is not of Mars. It's a rock, covered with colonies of lichens, two organisms that live in symbiosis in order that both may survive. These little plant/fungus colonies (And, no. A fungus is not a plant.) may increase their diameter by less than a millimeter a year. If they were sentient, would they take any notice of the large, mobile, juicy creatures that whizz by them in an instant, while they stay, dryly sitting on their grave markers and old stone walls? Most people (city boys) just think that lichens are crud on a rock. They don't recognize them as life. Complex, busy life, that people walk by everyday, seeing them not. What else is waiting to be found right under our noses, or right over our heads?- Hermana