would we have today? Earth is estimated to be 4.5 billion years old. We assume that it has taken this long to developed advanced civilizations. By present measures, our advanced civilizations has existed for only a few thousand years. Before this we were part of the animal hierarchy. If an advanced civilization existed 1 billion years ago that was destroyed by a catastrophic event, what evidence would we expect to find today?
By advanced civilization, this is not restricted to humanoid mammals, but refers to intelligent life in general.
By advanced civilization, this is not restricted to humanoid mammals, but refers to intelligent life in general.