The
ability to sense the Earth’s magnetic field—a trait known as
magnetoreception—is well documented among many animals, but researchers
have struggled to show that humans are also capable of the feat. Until
now.
New experimental evidence published today in the science journal eNeuro suggests the human brain is capable of responding to the Earth’s magnetic field, though at an unconscious level. It’s not clear if our apparent ability to sense the magnetic field is in any way useful, as it’s likely a vestigial trait left over from our more primitive past. Giving the new finding, however, researchers should investigate further to determine if magnetoreception is somehow contributing to our behavior or abilities, such as spatial orientation.
Magnetoreception is found among both invertebrates and vertebrates, and it’s probably a capacity that’s been around for a very long time. Some bacteria and protozoans exhibit magnetoreception, as do some migratory birds and sea turtles, who use the added sense to assist with navigation. Dogs are also sensitive to the Earth’s magnetic field, orienting their bodies along the North-South axis when they poop.
Around 30 years ago, scientists tried to determine if humans have a similar capacity, but to no avail. These pioneering efforts produced results that were either inconclusive or unreproducible, so scientists largely gave up, figuring magnetoreception is something outside the human realm. In the years that followed, work on animals increasingly pointed to magnetoreception as the result of complex neurological processing—a possibility that motivated Caltech geophysicist Joseph Kirschvink and neuroscientist Shin Shimojo to revisit the issue.
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“Our approach was to focus on brainwave activity alone,” Kirschvink told Gizmodo. “If the brain is not responding to the magnetic field, then there is no way that the magnetic field can influence someone’s behavior. The brain must first perceive something in order to act on it—there is no such thing as ‘extra-sensory perception.’ What we have shown is this is a proper sensory system in humans, just like it is in many animals.”
To test whether the human brain is capable of magnetoreception, and to do so in a reliable, believable manner, Kirschvink and Shimojo set up a rather elaborate experiment involving a chamber specially designed to filter out any extraneous interference that might influence the results.
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The
isolated chamber, within which participants had their brainwaves
monitored by electroencephalogram (EEG), was housed inside a Faraday
Cage, which shielded all interior contents from external electromagnetic
fields. Three orthogonal sets of square coils, called Merritt coils,
allowed the researchers to control the ambient magnetic fields around a
participant’s head. Acoustic panels on the wall reduced external noise
from the building, while a wooden chair and isolated floor prevented any
unwanted interference with the magnetic coils. A battery-powered EEG
was placed next to the participant, which was connected to a computer in
another room with an optical fiber cable.
During carefully controlled experiments, participants sat upright in the chair with their heads positioned near the center of the magnetic field, while EEG data was collected from 64 electrodes. The hour-long tests, in which the direction of the magnetic fields were rotated repeatedly, were performed in total darkness. The experiment involved 34 adult volunteers, who collectively participated in hundreds of trials; all tests were done in a double blind manner, and control groups were also included.
After the experiments, none of the participants said they could tell when or if any change to the magnetic field had occurred. But for four of the 34 participants, the EEG data told a different story.
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As noted in the new study, the researchers recorded “a strong, specific human brain response” to simulated “rotations of Earth-strength magnetic fields.” Specifically, the magnetic stimulation caused a drop in the amplitude of EEG alpha waves between 8 and 13 Hertz—a response shown to be repeatable among those four participants, even months afterward. Two simple rotations of the magnetic field appeared to trigger the response—movements comparable to a person nodding their head up or down, or turning it from left to right.
The alpha rhythm is the dominant brain wave produced by neurons when individuals aren’t processing any specific sensory information or performing a specific task. When “stimulus is suddenly introduced and processed by the brain, the alpha rhythm generally decreases,” the authors wrote. The drop in alpha waves observed during these experiments suggested the brain interpreted the magnetic fields as some kind of stimulus—the neurological purpose or result of which is unclear. But as the new study pointed out, this observation now “provides a basis to start the behavioral exploration of human magnetoreception.”
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The researchers don’t know how the human brain is able to sense magnetic fields, but Kirschvink has a favorite theory. There may be “specialized sensory cells that contain tiny magnetite crystals,” he said, which is currently “the only theory that explains all of the results, and for which there is direct physiological data in animals.” Back in 1992, Kirschvink and his colleagues isolated crystals of biogenic magnetite from human brains, so he may be onto something; other researchers should now dive into this possibility to flesh this idea out.
“Magnetoreception is a normal sensory system in animals, just like vision, hearing, touch, taste, smell, gravity, temperature, and many others,” Kirschvink told Gizmodo. “All of these systems have specific cells that detect the photon, sound wave, or whatever, and send signals from them to the brain, as does a microphone or video camera connected to a computer. But without the software in the computer, the microphone or video camera will not work. We are saying that human neurophysiology evolved with a magnetometer—most likely based on magnetite—and the brain has extensive software to process the signals.”
Looking ahead, Kirschvink would like to better understand the biophysics of this capacity, including measuring threshold sensitives. Shimojo believes it might be possible to bring magnetoreception into conscious awareness, a possibility that could spawn entirely new directions of research. Imagine, for example, if future humans had a built-in compass, allowing them to sense magnetic north.
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Michael Winklhofer from the Institute of Biology and Environmental Sciences at Carl von Ossietzky University of Oldenburg, liked the new study, saying the authors “did everything to rule out artifacts [noise] which could easily occur during recording electrical brain activity in a changing magnetic field.” Also, the description of the setup and methods was so detailed that the study can be easily replicated, he said.
“For the first time in humans, clear responses to magnetic field changes were observed. Even though the magnetic field was not consciously perceived in the test persons that showed brain responses to the field, the study invites [other scientists] to follow up research to understand the mechanism by which the magnetic field elicits neuronal activity,” Winklhofer told Gizmodo.
Biologist Kenneth J. Lohmann from the University of North Carolina at Chapel Hill said it was a “fascinating and provocative study.” Given that “a number of other animals can sense Earth’s magnetic field, it is certainly within the realm of possibility that humans can as well,” he told Gizmodo. That said, he believed the results should be interpreted with “great caution.”
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“It is one thing to find a subtle change in brain activity in response to a weak magnetic field, and another thing to show that people really detect and use magnetic field information in a meaningful way,” said Lohmann.
Indeed, for now we’ll have to be content with the observation that human brains can detect magnetic waves, and leave it at that. Researchers will now have to figure out why human magnetoreception exists, and if this capacity somehow extends to our behavior. Regardless, we can look forward to some exciting new science in the future.
[eNeuro]
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Interesting. I’ve always been a person who has had an great sense of direction. It is nearly impossible for me to get lost. I wonder if this has somthing to do with it.
Though perhaps not, I don’t get lost when playing video games. Which probably means that my brain is just really good at assembling a 3 dimensional map based off landmarks, rather than anything to do with ambient magnetic fields.
I’m like this when not surrounded by a lot of tall buildings; for example, I easily get lost in downtown Los Angeles, but do pretty good outside that concentration of concrete and steel. My husband thinks I just overwhelmed by the closed-in feeling and noise, which is possible.
Never mind.
Do you get really annoyed when people say something like “Let’s go to Bob’s house” and they point and it’s a completely wrong direction? Drives me insane. Can’t they just feel that it’s wrong?
Nope! We absolutely cannot. However, I can wander out of the kitchen, go do something for a bit, and then wander back in around four seconds before the microwave finishes. It’s a useful skill. Not actually as useful as knowing where the heck I am, but useful.
It is my considered opinion that humans are full of these little quirks and abilities, but that we forget about them and never develop them. When I was a little girl, I could always tell my Mom who was calling on the phone. This worked even after we moved to a bigger city and upgraded to a two-line electronic phone. It was insanely handy for her. The skill vanished when I was about nine or ten.
This is the same phenomena as when a parent senses their child is painting the bathroom in toothpaste from downstairs.
Toothpaste? You got off easy.
I was trying to keep it family friendly. There have been other foreign substances used to Van Gogh the bathroom.
you’re the first person in the comments to make a tiny bit of sense even if it’s just noticing a lack of sound and registering it means trouble.
Yep. Suddenly, everything goes nice and quiet. Too quiet.
Does this mean that the hitherto unexplained phenomenon of “dowsing” is no longer deserving of ridicule by default?
I don’t think so. Even if it’s for real, that stick is still kinda funny.
Dowsing would be more general vibrations I would think. Ground with water running under it would have a slightly different vibration when stepped on opposed to solid ground. That why you would usually use a stick. I suspect dowsing is like herbal medicine there were people who were good at it and knew what they were doing but a bunch of shills also used it to exploit people. So it developed a suspect reputation even though its a real thing if the person you hire knows what they are doing.
As a child my father would let me dowse for him and local construction crews when looking for the septic tank in rural homes. I had a pretty good success rate. (using the two metal rod method)
I assumed it was due some change in the local magnetic field due to the piping. still it was a good way for a 7 year old to make a few bucks.
I don’t think there have been any peer-reviewed studies showing dowsing was more effective then just guessing/chance.
Ok, so sitting in a little dark, silent room on a wooden chair for over a hour. What’s that pay? How’d they keep the test subjects awake??
Probably not very much. I’d assume they were adults who were asked not to sleep. Most people can stay awake for an hour in a dark room.
It’s pretty easy to tell on an EEG if someone is asleep or not. (I read EEG’s in part for a living).
Same way you keep MRI patients awake when they have to sit perfectly still in a dim little space: hope and polite insistence.
Don’t know about this one, but when I was getting my experimental psych degree unpaid student volunteers were used.
Would this help explain why some people are attracted to others?
yeah they put two people with opposite personalities in the room and their heads kept clunking together
That explains much of my life since my 20s.