In the "X-Men" comics and movies, the character Magneto is a powerful mutant capable of sensing and manipulating magnetic fields. Though his powers seem obviously fantastical — fodder for the superhero genre — a growing amount of research now suggests that the character's abilities might actually have a distant basis in real human biology.
In fact, at least one scientist claims to have found evidence that humans are capable of sensing the magnetic fields around them. Call it a magnetic sixth sense, reports Science. This doesn't mean you should start trying to move metal objects around with your mind like Magneto, but you might be subconsciously using this extrasensory sense to orient yourself in some way.
The research isn't as far-fetched as it might sound. Many animals across the spectrum of life, from birds, bees and sea turtles to dogs and primates, have been shown to utilize the Earth's magnetic field for navigation. Exactly how the magnetic senses of these animals work isn't always clear, but these senses do exist.
Many other creatures have been shown to change their behavior when introduced to magnetic fields even when it's not obvious that they have any use for a magnetic sense when behaving normally.
"It’s part of our evolutionary history," said Joe Kirschvink, the geophysicist at the California Institute of Technology who has been testing humans for a magnetic sense. "Magnetoreception may be the primal sense."
Studies uncover answers
In Kirschvink's first experiment, rotating magnetic fields were passed through study participants while their brain waves were measured. Kirschvink found that when the magnetic field was rotated counterclockwise, certain neurons responded to this change, generating a spike in electrical activity.
Determining whether this neural activity was evidence of a magnetic sense or something else is the real question. For instance, even if the human brain responds to magnetic fields in some way, that doesn't mean this response is being processed as information by the brain.
There's also the mystery of what mechanisms are in place within the brain or body that receive the magnetic stimulus. If the human body has magnetoreceptors, where are they?
To get more answers, Kirschvink teamed up with Shinsuke Shimojo and Daw-An Wu, his colleagues at California Institute of Technology, with the aim of identifying that mechanism. They used Kirschvink's experimental chamber to apply a controlled magnetic field, then used electroencephalography (EEG) to test humans for brain responses to field changes, according to CalTech's introduction to their lab.
Writing for The Conversation, the scientists explained why this this setting provides an opportunity for learning:
In our experimental chamber, we can move the magnetic field silently relative to the brain, but without the brain having initiated any signal to move the head. This is comparable to situations when your head or trunk is passively rotated by somebody else, or when you’re a passenger in a vehicle which rotates. In those cases, though, your body will still register vestibular signals about its position in space, along with the magnetic field changes — in contrast, our experimental stimulation was only a magnetic field shift. When we shifted the magnetic field in the chamber, our participants did not experience any obvious feelings.
In contrast, the EEG showed that certain magnetic fields promoted a strong response, but only at one specific angle, suggesting a biological mechanism.
What it could mean
The researchers say there's still a lot of work to be done. Now that we know humans have working magnetic sensors sending signals to the brain, we need to determine what they're being used for. The most likely use would be that they afford us some sense of orientation or balance. After all, as primates, a three-dimensional sense of orientation has been evolutionarily important, at least for our tree-dwelling relatives.
Then again, it's also possible that our magnetoreceptors represent vestigial traits that have lost their evolutionary significance, mere remnants of an extrasensory past. But the story is likely more complicated than that. "The full extent of our magnetic inheritance remains to be discovered," they explain. And they are on the case.
Editor's note: This story has been updated with new information since it was originally published in June 2016.