Can Humans Actually Sense the Earth’s Magnetic Field?

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Close your eyes and quietly repeat after me: “Om mani padme hum, om mani padme hum…” Feel anything unusual? You know, like a magnetic chill down your spine?

No? Don’t feel bad. I’m just teasing. That’s actually a popular Tibetan Buddhist mantra. And don’t be silly, you can’t really “feel” the Earth’s magnetic field, though according to a new study by the University of Massachusetts Medical School, you might be able to see it.

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How? With a light-sensitive protein that helps regulate our daily body rhythms known as cryptochrome, capable of detecting magnetic fields and actually acting like a compass when present in the eyes of Drosophila, the species commonly known as “fruit flies.”

It turns out we not only might at one point have been capable of “seeing” magnetic fields, as nonhuman migratory animals such as birds do, but that we may still retain some semblance of a visual ability to orient ourselves using the Earth’s magnetic field.

“May” being the operative word. The debate over whether humans can perceive direction, altitude or location based on the Earth’s magnetic field has been ongoing and somewhat contentious for decades. Research by Robin Baker at the University of Manchester during the 1970s and 1980s made claims that human-based magnetoception exists, but no one’s been able to reproduce his results, placing them somewhere in the scientific domain of “not science yet.”

Enter neurobiologist Steven Reppert and others at the University of Massachusetts Medical School, who’ve been fiddling with monarch butterflies and fruit flies, coming up with methods to determine cryptochrome’s efficacy at detecting magnetic fields. In a Nature study published last year, Reppert and colleagues showed how fruit flies without the innate ability to detect magnetic fields recovered it when induced to produce cryptochrome. And in a Nature study published just yesterday, Reppert and colleagues obtained similar results observing monarch butterflies with two inbuilt cryptochrome genes. The conclusion? Since a similar version of cryptochrome is actively found in the human eye, Reppert suspects humans may be able to “see” magnetic fields when the gene interacts with our retinas.

“I would be very surprised if we don’t have this sense,” Reppert told the BBC. “[It's] used in a variety of other animals. I think that the issue is to figure out how we use it.”

And the New York Times raises a tantalizing possibility: You know the stories about ancient Polynesian navigators making thousands of miles sea voyages without compasses and only intermittently starry skies? It’s a long shot, but yep, this could possibly explain that, too.

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