Why some humans have a better sense of direction

Scientists have known for years that some animals -- birds, fish, insects -- have tiny natural magnets embedded in their tissues, crystals of a mineral known as magnetite. The suspicion is that magnetite enables these creatures to sense the earth's magnetic field, letting them navigate from one place to another with what amounts to biological compasses.

Now a group of scientists at the California Institute of Technology has discovered that magnetite is found in human brains as well. That could eventually explain why some people have a better sense of direction -- perhaps they have more magnetite. The presence of magnetically sensitive crystals in the brain could conceivably explain the health problems some people claim are caused by electromagnetic fields. Until now, no one knew of anything in the body that could be affected by these fields. One caveat from a researcher: the magnetic fields from high-tension power lines, often cited as prime culprits, are not strong enough to affect the crystals his team found -- though those from some home appliances, like electric blankets, may be. Even then, the link is only more plausible than it once was, but still a long way from proved.