People may have a crappy built-in magnetometer, but it seems you don't need one - just a lot of practice. There are cultures that put such weight on the cardinal directions that they always maintain a sense of where they are facing.
Very interesting. I always had a very accurate sense of direction, to the point of not needing a compass when bushwalking to a map. Yet, when I moved to the other side of the continent, I was completely thrown.
I wondered to myself whether it was something to do with the very different magnetic declination. No evidence, of course.
I moved back and have regained it again. Mysterious.
en.wikipedia.org/wiki/Magnetoception#In_humans http://www.isegoria.net/2010/08/does-your-language-shape-how...