I always wondered about a connection with iron. Blacksmiths who forge iron tools and knives understand that orientating the piece being worked on to magnetic north and south helps align the molecules lengthwise along the work as it’s being drawn out to give it better linear strength. Why wouldn’t the high iron content of human blood cells also orient it’s self magnetic north and south? Could there be a sensor in the brain that reads this iron content orientation and process it into the four directions?
Agreed on our blood chemistry. Also for certain types of “dowsing” for metal pipes or even plastic pipes in some soils, although that is the earths electromagnetic field that folks respond to. The wands (metal) are just the indicator dial of what one’s body is picking up. It worked once for me - but usually it doesn’t. While some folks can do it easily all the time. Maybe I need to drink more Gaterade with the electrolytes!?
I’ve heard people say that sleeping with their head to the north helps with their sense of direction.