Cosmos

by Carl Sagan

We have five fingers because we have descended from a Devonian fish that had five phalanges or bones in its fins.

We hope that very soon in the perspective of cosmic time we will have unified our planet peacefully into an organization cherishing the life of every living creature on it and will be ready to take that next great step, to become part of a galactic society of communicating civilizations.

In our own solar system there are several bodies that may be suitable for life of some sort: the Earth certainly, and perhaps Mars, Titan and Jupiter.

What percentage of the lifetime of a planet is marked by a technical civilization? The Earth has harbored a technical civilization characterized by radio astronomy for only a few decades out of a lifetime of a few billion years.

If civilizations tend to destroy themselves soon after reaching a technological phase, there might be no one for us to talk with but ourselves. And that we do but poorly. Civilizations would take billions of years of tortuous evolution to arise, and then snuff themselves out in an instant of unforgivable neglect.