Originally posted by EdwardC:
An interesting point to ponder is that catastrophic bolide impacts may be the most important limiting factor preventing the evolution of intelligents species in other star systems. We have been pretty lucky that a major impact has not occurred in the last 2 million years as our hominid ancestors became fully human and migrated out of the African grasslands into other parts of the world.
Or you could look at it another way, which is once a species begins an obvious cultural decline and no longer has anything to offer to the universe, fate/god/the universal will/whatever exterminates the species and hopes for better luck next time.
