During the early days of the atom era, several Sci-Fi authors wrote stories under the assumption that the Galactic Federation defines a civilized planet as a planet, whose lifeforms have been successful in using atomic energy.
A day ago I browsed a book about Life in a bookshop (sorry but its name escaped my memory). According to the book, it seems that life on a planet starts surprisingly short time after the conditions on it have been stabilized. However, if a planet is being continuously bombarded by asteroids and comets, all life is destroyed and needs to restart evolution from the beginning.
Apparently, this was the condition on Earth until 3.8 billion years ago. Only then, the time between consecutive catastrophic asteroid collisions began to be low enough for life to make significant progress in evolution.
This leads to the observation that a truly civilized lifeform on a planet is a lifeform, which can actively defend itself against asteroids and comets on collision course with its home planet.
- Humans were created by bacteria (the really dominant lifeform on the planet, according to the book), with the goal of developing technology to defend the bacteria against asteroids and comets.
- Once humans demonstrate the ability to defend Earth from killer asteroids, they become eligible for membership in the Galactic Federation. Not once they explode the first atom bomb
- Planets with rings may be harboring sentient life. The rings may have been result of destruction of killer asteroids. In the solar system, there are rings around Saturn and Neptune. Is there sentient life on Titan?
- The rate of knowledge accumulation is higher in mammals than in other animals such as dinosaurs. This is because when a child is not attached to its parent for long time, the child learns slowly from the environment and does not pass its knowledge on to the next generations. So the evolution depends only upon DNA. Once mammals came into existence, parents started imparting knowledge to their offspring together with the milk. So the rate of knowledge accumulation became independent of DNA mutation rate. Humans made the transition to the next stage by developing the technologies of writing and computers. This stage apparently is what is required to develop effective defenses against killer asteroids.