It's 5000 BC, and you've been given a map to find your way from the dry lands of Cairo to the fertile farms of Upper Egypt. The map shows the Nile River at the top, flowing down towards the Mediterranean Sea. You set off in its direction, soon realizing that “up” is actually South.

We've relied on maps to find our way for 14,000+ years. In that time, different cultures have imagined their "up" based on things that they value: the flow of the rivers, their most sacred city, the regions they visit, or the rising of the sun.

The most common maps in the US today place the northern hemisphere at the top, based on a map created by a Flemish cartographer in the 1500s. He may have made the decision randomly, or it may have reflected what he most valued. Either way, it sends a message. In a 2011 study, for example, when people were asked to look at a make-believe map, they usually wanted to live near the "top".

The things we create are shaped by the things we value. But when those creations become our "default", it's easy to forget that it was always just one way of looking at things.