Of course the complexities of human emotions obscure any simple explanation about our needs. If everything a human needed was food, water, air, shelter and human companionship, we would all conduct our lives very differently, and would probably not have evolved into the intelligent but befuddled creatures we are. Some philosophers have hypothesized the humans are motivated by a need for meaning; those who fail to find satisfactory meaning are driven to further extremes. There is a lot of room for religion in this theory. But it also includes the drive of the explorer, who in modern times has few places to go but within.
A couple of autobiographies I have been reading both draw interesting conclusions about the need for exploration in their prologues. As both men prepare to launch into their own amazing tales of misery and triumph, they make simple statements that in essence express a belief that they are not crazy, and they are not brave. They simply did what they had to do. It's not unlike the Buddhist monk who, when asked why he made a walking journey of 3,000 miles by dropping to his knees, hands and face with every step, simply looked away in silence, completely serene.
In "Minus 148," Art Davidson's enthralling account of the first winter ascent of Denali, Davidson writes: "During that summer expedition, Shiro and I caught only a few glimpses of what the McKinley winter would be like, but they were enough to infect us with what many explorers have described as a fever to go back to a region or landscape that has a grip on you. Not really understanding why they go, men have returned to the sea or to deserts, to jungles or to frozen wastes in the Arctic, knowing they will be miserable and frequently in danger."
Gary Paulsen closes his prologue in "Winterdance," his account of the Iditarod Sled Dog Race, by concluding, "I thought any sane man who was in his forties and had a good career going would quit now, would leave the dogs, end it now and go back to the world and sanity. I knew what scared me wasn't the canyon and wasn't the hook hanging by one prong, but the knowledge, the absolute fundamental knowledge that I could not stop, would not stop, would never be able to stop running dogs of my own free will."
It makes one wonder where the line between need and choice truly begins and ends.