<p>Only two species of mammal have a post-reproductive life that lasts longer than their reproductive life: the killer whale, whose elders are able to sniff out food supplies over vast oceanic distances to keep their pods fed, and Homo sapiens. While the evolutionary purpose of the killer whale's extensive life seems clear, what is the point of ours?<br><br>This was a question that intrigued psychoanalyst Carl Jung, who observed that if a culture...