Our solar system is almost 5 billion years old (4.6, really) and we haven't yet had any indication that there are other forms of life in the cosmos, especially intelligent ones.
That's the perspective of a new book by science journalist Lee Billings titled Five Billion Years of Solitude, a nod to the Gabriel García Márquez masterpiece One Hundred Years of Solitude. Billings constructs a moving tale of our collective yearning to find companionship in the vastness of space, using interviews with a few of the key players in the search for intelligent life (such as SETI's Frank Drake) and exoplanet hunting (such as MIT's Sara Seager, who just received a MacArthur award) as a means to humanize the story.
If we are alone, or if life is rare, we must be the protectors of life and take charge to preserve it at all costs, possibly spreading it to other planetary platforms. If nothing else, we know our sun will end its existence in under 5 billion years and that it will take Earth and life here with it. Assuming we, or our distant descendants, will still be here then, perhaps more machine than flesh, the only way to preserve our legacy is to go elsewhere. There is thus a firm deadline for leaving, even if it sits on the far horizon.
As I wrote in A Tear at the Edge of Creation, the study of life on Earth implies that we are unique. There are no other humans out there, even if there may be life. The history of life on a planet mirrors the history of the planet. This means that the particulars, the specific cataclysmic events that happened over the eons, the shuffling of the atmospheric composition, the shifting of the magnetic field, the nature of the planet's moons (or moon), all these are key factors on how life would evolve. Life here had to jump over many hoops to get to where it is today, hoops that are far from being trivial either biochemically or biologically.
This means that in spite of our efforts to find life elsewhere (and we will find it only if we look), life here becomes something of a rare gem that must be worshipped and preserved at all costs. Whatever lies out there, we must focus our efforts in preserving what we have here. We live on a magic planet. Even if there may be other magic planets in the vastness of space, for us everything starts with this one. Let us not forget this simple lesson as we look up in search of companionship.