Sagan , 89 . This is the evolutionary phase in which our ancestors - to cite Socrates ' parable - got out of the metaphorical cave of ignorance . Instead of being controlled by the environment , they had become masters of the environment , no longer were they passive creatures following a rigid pattern of survival . Of course , some academians would argue that increased brain size doesn 't mean an increase in intelligence as well . But Carl Sagan had a different opinion . He believed that intelligence is...











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