Maslow's hierarchy of needs - food, shelter, water.
http://en.wikipedia.org/wiki/Maslow's_hierarchy_of_needs
You can find a substitute for oil as it's not a basic need for survival ie its not inelastic to demand like food is.
IF oil goes up people to the point where it is the difference between whether people can afford shelter and food they will stay at home and travel from their homes alot less IMO.
