As kids, we all learned that people have five senses: sight, sound, smell, touch, and taste. But the truth is that we’ve got all kinds of perceptive abilities. We can feel pain, and the passing of time, and the location of our arms and legs relative to the rest of our bodies, to name a few. We may even be able to sense magnetic fields.

At one time, making such a suggestion would have gotten a researcher laughed out of the academy. But some modern scientists say it’s a real possibility. 

It would make sense for humans and other organisms to have magnetoreceptive abilities; after all, we did evolve on a planet that is essentially one enormous magnet. And in recent years, study after study has found evidence that magnetic fields can affect animal behavior, from a hunting fox’s pounce to the flight of a frightened deer. One study found magnetite molecules in the eyes of dogs, bears, wolves, foxes, badgers, orangutans, and macaques; in another, researchers spotted magnetically sensitive proteins in the bodies of birds, butterflies, whales, rats, and, yes, people. 

Does this mean that our bodies are affected by magnetic fields? Joe Kirschvink of the Caltech Paleomagnetics Laboratory says yes. Kirschvink, who has devoted his career to studying the intersection of geology and biology, wanted to build on the magnetite molecules concept. He designed an experiment to test the effects of magnets on humans—and made himself the first subject. 

The experimental set-up was more than a little mad scientist–looking. One at a time, Kirschvink and 24 volunteers sat in a Faraday cage—a little room fenced with conductive material to shield its inhabitant from external electromagnetic activity. On their heads, they wore caps studded with electroencephalogram (EEG) sensors, which monitored their brain activity. Each participant sat in the cage, in total darkness, wired up, for an hour, during which they were exposed to various strengths and configurations of magnetic activity. When the hour was up, the presumably bored study subjects left the cage, still wired, and were then bombarded with a pure magnetic field.

Kirschvink says the results clearly show how our brains respond to magnetic activity. They revealed that a counterclockwise-rotating magnetic field produced a drop in brain waves, which suggests to him that the participants' brains were reacting to the field. 

With just 24 non-Kirschvink participants, this was a small study, and the results have not yet been through peer review. Still, Kirschvink is confident that his findings are accurate and replicable. “It’s part of our evolutionary history,” he told Science [PDF]. “Magnetoreception may be the primal sense.” 

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