Magnetic ‘compass' discovered in the human brain
Humans have a hidden “magnetic sense” similar to that of many animals that may have helped their nomadic ancestors navigate without getting lost.
The natural “compass” built into the brain is still there, operating at a subconscious level, new evidence suggests.
Scientists discovered the ‘sixth sense’ after conducting a series of experiments in which more than 30 volunteers were exposed to moving Earth-strength magnetic fields.
Electrical brain recordings showed a subtle response that appeared to be tuned to the magnetic field of the northern hemisphere, where the experiment was conducted.
Artificial geomagnetic stimulation caused a drop in alpha-wave brain activity known to signal sensory processing.
The implication is that the Earth’s magnetic field can be sensed in humans just as it is in migrating birds and sea turtles.
However, none of the participants were able to tell when they were being subjected to changing magnetic fields.
The team led by Dr Joseph Kirschvink from the California Institute of Technology, US, wrote in the journal eNeuro: “Our results indicate that human brains are indeed collecting and selectively processing directional input from magnetic field receptors.
“These give rise to a brain response that is selective for field direction and rotation with a pattern of neural activity that is measurable at a group level and repeatable in strongly responding individuals.”
For the experiment, each volunteer sat on a non-conducting wooden chair within a “Faraday cage” that blocked out interfering electromagnetic fields.
Inside the chamber, electric current was run through wire coils to mimic the Earth’s magnetic field. The design allowed the direction of the field to be rotated.
Brain wave activity was measured by means of electroencephalogram (EEG) recordings using electrodes attached to the scalp.
How the magnetic sense works remains a mystery, but the scientists suspect it may involve tiny iron crystals in cells.
The researchers concluded: “Given the known presence of highly-evolved geomagnetic navigation systems across the animal kingdom, it is perhaps not surprising that we might retain at least some functioning components, especially given the nomadic hunter-gatherer lifestyle of our not-too-distant ancestors.
“The full extent of this inheritance remains to be discovered.”