A lab test has revealed for the first time that humans may have an internal compass that can tell which way the Earth’s magnetic field is pointing.

Scientists who found the signals suggest that it might have been used by our hunter-gatherer ancestors to help them navigate and get back home safely.

While we aren’t consciously aware of what this sense is telling us, it’s possible that could change in future if we find a way to harness it.

Many animals already use the field that pulls compasses north to navigate, but it has never been observed in humans before.

The test had 30 human guinea pigs sit in a wooden chair in a chamber shielded from outside fields and be subjected to artificial magnetic fields.

The researchers then measured their brain waves as they moved that field around while the subjects sat motionless.

To their surprise, they saw marked changes as the field shifted, but only as long as it behaved in the same way as it does in the Northern Hemisphere.

Shifts in directions of the field around them “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,” according to Dr. Joseph Kirschvink of the California Institute of Technology.

As the tests were carried out in California, which is on the top half of the globe, and all the subjects lived above the equator, this actually backs up the findings.

Animals that use magnetic fields naturally filter out information from those senses that doesn’t make sense — such as those caused by lightning strikes or serious man-made interference — so the fact that our brains appear to do the same thing suggests we may be able to tap into the sense in the same way.

Writing in the journal eNeuro, the researchers said: “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.”

It was recently revealed that the Earth’s magnetic field may actually be shifting, with the true North Pole moving by as much as 34 miles a year — but that doesn’t stop the field protecting us from the excesses of the sun’s magnetic storms and the problems that would otherwise be caused by solar flares.