The title derives from one of the hypotheses
put forward in the book. As hominid
s were evolving in the Rift Valley region, one of their most destructive natural enemies might have been snake
. Primative language
might have first made its appearance as warnings indicating the presence of snakes - alerts sounded that would make the rest of the band pipe down and sit still. It is no coincidence that this is still a near universal throughout human socieites, when we want silence and calm we still imitate the snake and say 'shhhh!'
Thus, if the snake was indeed the impetus for language to begin developing, and developing language caused and resulted from enormous leaps in intelligence and social complexity, which would eventually lead to modern humans and civilization, Sagan says the biblical Eden myth is a particularly wonderful metaphor. Good stuff.