says Caroline Delbert March 18, 2020 on www.popularmechanics.com
- An experiment with 36 human subjects shows that some people may detect the Earth’s magnetic field.
- Human senses are specialized and highly developed, but no one has measured magneto-reception before.
- Subjects were examined inside a specially outfitted Faraday cage full of electrical coils.
Could some humans be able to sense the Earth’s magnetic field? Evidence suggests that in addition to quite a few animal species, humans could be — yes, this is the real term —magnetoreceptors. In a recent study, scientists conducted an experiment that measured how alpha waves interacted with a trace mineral that they believe registers magnetism.
Once upon a time, scientists thought animal magnetoreception was impossible, too. As they started to understand that birds and other animals used magnetoreception to navigate in the world, they still thought there was no way humans could do it.
But that assumption seems up for grabs too. In an experiment last year—hat tip to Gizmodo for unearthing it again—researchers built a specially equipped Faraday cage where subjects were fitted with EEG sensors. Inside the structure of the cage, they arranged coils that generate a magnetic field when active. The coils could be switched into a “sham mode” with no magnetic field, but that still looked and felt the same otherwise.
Inside, the test subjects relaxed in a dark, quiet room. “During experiments, participants sat with their eyes closed in total darkness. Participants were blind to active versus sham modes, trial sequences, and trial onset timings. The experimental chamber was dark, quiet and isolated from the control room during runs,” the researchers explain.
All subjects faced the same way so there was no directional bias from, well, the real magnetic field. Then they were swept with magnetic forces while the researchers recorded their brain waves.
“Our results indicate that human brains are indeed collecting and selectively processing directional input from magnetic field receptors,” they conclude. “Such neural activity is a necessary prerequisite for any subsequent behavioral expression of magnetoreception, and it represents a starting point for testing whether such an expression exists.”
In their full results, the scientists explain that the known magnetoreceptive animals experience this sense as a direct biological signal: the way birds use it to migrate, or sea turtles who use it to assess the safety of their waterways. That includes subliminal cues that a local field isn’t the magnetic field. Volcanoes can generate localized magnetic fields, and “an animal moving through magnetic features of this sort will receive a series of warning signals against using the magnetic field for long-range navigation.”
The researchers found this same pattern in their human subjects. “The selectivity of the response favored ecologically valid stimuli, distinguishing between rotations of otherwise equal speeds and magnitudes. This indicates that the effect is due to a biologically tuned mechanism rather than some generic physical influence,” they explain.
That means human subjects showed brain activity that responded to mimicry of the global magnetic field only, with the same rejection of local fluke magnetism. From this, the researchers speculate humans have developed their magnetoreception the same way animals have: by continued use and incentive over time. It’s something that serves us, not happenstance.
Could the magnetoreceptive humans be the last expression of an inherited trait from the hunter-gatherer days? We don’t know that yet, but the researchers are hopeful about future experiments: “The full extent of this inheritance remains to be discovered.”