Human Magnetism

July 19, 2019

For centuries, people have navigated the globe using instruments. But what if the Earth itself can help us feel our way?

Navigating to unfamiliar destinations is often a matter of consulting a digital map of the planetary surface. Once accessed, it literally tells us every turn we need to take to get to our destination.

However, without any map – digital or paper – navigation is often an unsettling, time-consuming challenge. Sometimes, it’s even a nightmare, and innumerable lives have been lost when navigation failed. The British explorer John Franklin set out with 129 men in 1845 to find and map the fabled Northwest passage – a seaway to Asia originally sought by Columbus in 1492 – but the expedition never returned. Instead, they spent three years stuck on Arctic ice before resorting to cannibalism and perishing.

Yet some navigators seem to have a special sense. Wayfinders such as Nainoa Thompson in Hawai’i, who has dedicated his life to the study of the ancient Polynesian art of seafaring, say that they can navigate long distances unaided. How is that done? Thompson recalls a life-or-death situation on a voyage by canoe from Hawai’i to Tahiti in 1980 – a journey of more than 2,600 miles that he and his team undertook without the aid of any navigational instruments.

Around the halfway point, sleep-deprived and lost in a remote, desolate area known as the ‘doldrums’, a region near the equator known for being featureless, Thompson says he could somehow ‘feel’ the direction of the Moon, his only point of reference: ‘There was something, a mechanism, that allowed me to understand where the direction was, without seeing it,’ he told an interviewer.

‘[W]hen I just gave up fighting to try to find something with my eyes … I felt this warmth come over me, and all of a sudden, I knew where the Moon was.’ Eventually, there was a break in the clouds, and the Moon was exactly where he felt it to be. Nonetheless, the ‘deep connection’ he experienced remains a mystery. Could he unconsciously sense where the Moon is? Was he guided by some mysterious force?

For the bulk of our evolution, before we could be considered ‘human’, our navigational abilities relied on using our sense organs. We take it for granted that we can see our way with our eyes. But we also have other senses that we can use to orient ourselves – more than ‘six’ if we include the vestibular system, which underlies our ability to balance, and proprioception, our sense of bodily articulation and movement.

Yet, we seem so unlike nonhuman animals, who tap a host of alternative senses to find their way: bees see ultraviolet light, sharks sense electrical patterns, and bats echolocate.

When no other sensory aid is available, some nonhuman animals can also guide themselves using Earth’s magnetic field. Our planet is an enormous magnet, an object whose internal electrical charge causes it to be positive at one end and negative at the other. This means that Earth – like other, smaller magnets – can physically align a compass needle towards its North and South poles, a property known as polarity.

The pull of a magnet is represented, in textbooks, by lines of force that predict where, precisely, the needle will point. But it’s nuanced: the force lines shift with what scientists call ‘inclination’ and ‘declination’, pointing towards Earth with increasing or decreasing angles to the horizontal plane, depending on how far or near the observer is to each pole.

Arguably, these properties offer far superior navigational cues relative to your smartphone, which can break, malfunction or, ironically, become lost.

Perhaps our distant evolutionary ancestors, millions of years in the past, also had an innate navigational ability that exploited magnetic field lines. This would be extremely useful, offering advantages not only in barren environments, but when exploring new territories to find resources for survival.

Even Charles Darwin added his two cents on these topics, claiming that ‘some part of the brain is specialised for the function of direction’. If such a mechanism did exist in our ancestors, could it have been muted – phased out with the advancement of consciousness and communication, the onset of civilisation, the invention of artificial means such as the compass and, ultimately, technologies such as GPS?

Among other species, there are incredible navigational feats that seem to defy reality unless we invoke the existence of a magnetic sense. For instance, the Arctic terns I see outside my window during summer in the high Arctic of Norway have just returned from feeding grounds on the other side of the planet, in Antarctica. Bar-tailed godwits, their avian neighbours at a nearby lake, can fly 6,000 miles to New Zealand – a minuscule target in the context of such great distances.

But perhaps the most well-known example is the homing pigeon: with their uncanny ability to fly home, pigeons have dutifully delivered post, medication, contraband and intelligence across distances that span hundreds of miles, from locations they’ve never visited before.

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