You Are Here (12 page)

Loggerhead turtles lay their eggs in the sand on the eastern shore of Florida, and the young, following subtle contours of light and terrain, find their way to water. Assuming they avoid being eaten by shorebirds that lie in wait for the hatchling turtles to make their dash to the sea, loggerheads find deep water by sensing the directions of wave patterns and, once free of the beach, rely on magnetic fields to guide them across the ocean to the Atlantic’s eastern shore. Like many other ultra-long-distance navigators, loggerheads probably rely on simple combinations of cues, such as the direction of major ocean currents and of magnetic field lines to carry them to favored waters. Though not impossible, it is unlikely that these turtles use a gradient map for the initial transatlantic voyage because the scenery would be entirely new to them. But in addition
to these long-haul voyages, loggerheads are capable of surprising finesse in localizing their breeding grounds on the Florida beaches near Melbourne. Displacement experiments in which loggerheads are picked from the sea and returned to it far from their favored breeding grounds have shown that loggerheads show a well-developed ability to find their way back to traditional nesting sites that seems to rely on the magnetic sense. This sense probably includes an ability to read local microvariations in magnetic fields caused by the peculiarities of rock formations underlying the ocean floor.
⁷

Many years ago, I invited my parents to visit me at a house that I had just purchased. I gave what I thought was a foolproof set of directions from their home in St. Catharines, Ontario, to my house, about a two-hour drive. En route, my father telephoned to tell me they were lost. I had him explain to me where they were, and then I gave him a new set of directions. A few minutes later, the telephone rang again. They were lost again, so more directions were offered. I knew that they were now very close to my house, so I went outside, sat at the edge of the road with a cup of coffee in my hand, and did my best to behave as a highly visible and familiar navigational beacon for them. I was pleased to see their car appear at the end of the street, but my pleasure turned to dismay as I watched them drive right past me in spite of my standing at the very edge of the road, waving both arms madly. Both parents were oblivious to my presence and obviously in the middle of a heated discussion. Like so many married couples, it seems, there were strong differences of opinion about which way they were going, and who was to blame for their wayfinding struggles.

We’ve all been there. Unsure of our bearings, we pull the car up to an intersection and peer right and left. We make a choice
based on ephemeral feelings, gut instincts, and perhaps the quality (or volume) of arguments from our traveling companions. Some of us have a better sense of direction than others—my wife’s is better than mine—but we don’t know why.

Good friends of ours take advantage of their familiarity with their own senses of direction to find their way. Ian, an engineer, asks Brandy, an adventurous entrepreneur, which way they should go. She replies boldly. He applies what he calls the Leverette Transform (Leverette is her maiden name), which means that he always goes in the opposite direction to the one that she specifies. Though he has had to endure the occasional frosty silence on the drive, he says the strategy works much more than would be predicted by chance.

When we are lost and all navigational cues have abandoned us, we guess. Some of us guess well, and some others not, and little is understood about why this might be. Is it possible that, like pigeons, turtles, fish, and mole rats, we possess an intrinsic sense of direction based on sensitivity to magnetic fields?

In the 1980s, a British researcher named Robin Baker set out to answer this question in a long series of experiments that involved taking human observers on long bus rides into the countryside. The routes were chosen so as to be as baffling as possible, including lots of tortuous twists and turns and preventive measures to make it difficult for participants to use any of their conventional senses to keep track of their position. At the end of the ride, the participants were asked to point in the direction of home. Not only did Baker show that his participants could often do a good job of pointing homeward but he also showed that this ability could be disturbed by asking them to wear bar magnets on their heads or special helmets that produced magnetic fields.
⁸

In studies conducted in the laboratory, Baker had participants sit in rotating chairs while being deprived of both light and
sound. After spinning them extensively, Baker asked them to point toward north. His data showed some evidence that people could actually perform such a task, but that when they wore magnets on their heads, their responses fell to chance. Baker’s studies attracted a flurry of interest at the time, and several researchers attempted to replicate his findings, but with less success than reported by Baker. In spite of these failures, Baker continued to argue vehemently for the presence of a magnetic sense in human beings.

Today, there appear to be few supporters of Baker’s conjecture. Though one or two intriguing findings suggest that human beings may possess small deposits of iron in the bone lining the nasal cavity and that patterns of brain activity may be changed in subtle ways by exposure to magnetic fields, no new and unequivocal studies show a magnetic sense in human beings.
⁹

Although the scientific effort to identify a human magnetic sense lies fallow, the possibility of such ability is still raised occasionally as an explanation for anecdotal accounts of extraordinary single acts of navigation. Nainoa Thompson, one of the founding members of the Polynesian Voyaging Society, has devoted his life to the effort to preserve the traditional wayfinding methods of Polynesian seafarers. One of his most impressive adventures has been to repeat the 4,200-kilometer voyage from Hawaii to Tahiti in an outrigger canoe using only traditional methods along with some knowledge of modern astronomy. In an account of one of these voyages, he describes an episode in which, late at night, under heavy cloud cover in the notorious Doldrums with their constantly shifting wind patterns, he felt himself to be completely lost, yet moving at a quick clip of about 25 knots—the worst combination of circumstances for a navigator. In describing what happened next, Thompson says that he leaned back against a railing, relaxed, and was overcome by a feeling of warmth and a confidence that
he knew the direction of the moon. Acting on this confidence, Thompson found his way.

Ben Finney, a professor emeritus of anthropology at the University of Hawaii, also a seasoned navigator and founder of the Polynesian Voyaging Society, has suggested Thompson’s case and a few other similar ones might be explained by a deep, latent magnetic sense that can be tapped by those with vast amounts of navigational experience.
¹⁰
Though such arguments by themselves are not enough to turn the tide of scientific opinion, they suggest that a few human beings with the right combination of intuition, experience, and perhaps desperation can tap into resources that are not available to everyday navigators such as quarreling couples driving through unfamiliar towns looking for antique stores and teahouses.

Yet this mysterious capacity to tap into resources that seem completely foreign to the rest of us to produce gradient maps may have less to do with exotic sense organs and more to do with exquisite sensitivities among the more commonly understood sensory systems of sight, sound, and feeling.

On my way to a temporary posting in Australia some years ago, I took advantage of a generous travel allowance to make a brief stop in Tahiti. To experience a little bit of Polynesian life off the beaten track, I booked a ticket on a small and ancient ferry that transported people across 18 kilometers of open sea to Moorea, a gorgeous island reminiscent of the mythical Bali Hai that James Michener described in
Tales of the South Pacific
. As I looked down at the dock from my perch on the old rust bucket, I noticed a group of men looking up at me and the other passengers and gleefully throwing small packets of money down to the ground. After our short voyage began, and the boat started to toss about in the rough
seas, it occurred to me that the men may have been placing bets on whether any of us would be seen again. I’m not known for my sea legs, but when the man who was seated beside me, an experienced airline pilot, made his third lurching visit to the rail, I realized that I was in the grip of something exceptional. Much to the chagrin of my traveling companion, who seemed to have a constitution of steel and who had hoped for a romantic tête-à-tête en route, my stomach contents and I survived the trip intact only because I found a small spot of dirt on the floor to fixate upon and refused to move my head or eyes for the entire duration of the journey.

It doesn’t take much time aboard a small vessel at sea to learn that one will be tossed about by ocean currents, swells, and waves in all but the most unusually calm situations. Though a casual observer will only feel buffeted by random and chaotic movements of water, a keen navigator can use these movements to establish both direction and position.

On the open sea, swell patterns are set up by interactions between directions of prevailing winds and ocean currents. Expert navigators, relying on a detailed knowledge of both of these forces, can read the swell pattern to determine direction. When several swell types intersect, navigators can also use interference patterns to obtain some positional information: the presence of intersecting waves moving in two different directions sets up the minimal conditions required for a gradient map. Under the tutelage of traditional navigators from the island of Puluwat in the South Pacific, anthropologist David Lewis was able to learn to read some of these patterns himself. Suggesting to his teachers in a tongue-in-cheek manner that navigating by swell pattern was real “seat of the pants” work, he was told that navigators learn that the pattern of swells is easiest to detect by paying attention to the pattern of stimulation of the testicles, as, while seated, this was the part of the body that was
most sensitive to the smallest movements of the boat.
¹¹
If true, this argument presents incontrovertible evidence for one kind of sex difference in navigational skills!

In open water, swell pattern can indicate direction and, in some cases, position. Near landmasses, complicated patterns of refraction or reflection are established. Evidently, Puluwatese navigators are able to interpret these patterns. The virtuoso navigational performance of the renowned Tevake, described by Lewis in chapter 2, was conducted under overcast skies, so there was no opportunity to use any kind of astronomical information. Under these conditions, the most likely explanation for Tevake’s success would be that he was able to analyze swell patterns to compute his position in a manner very similar to that of sea turtles that may use microvariations in the patterns of magnetic fields on the sea floor.

In the Arctic, reliable landmarks or inukshuks that can be used to guide trekkers on the tundra are not always around. In the huge central Arctic Barrens, a traveler is more likely to be confronted with nothing more than flat fields of white ground that extend as far as the eye can see in all directions. In this sense, Barrens navigators are in a situation not very different from that of Polynesian seafarers. Though Inuit navigators can use some simple celestial information such as the position of the sun or moon for navigation, they rely less commonly on sophisticated star maps than their more southerly counterparts. One reason for this is that much travel takes place in the summer months, when the periods of darkness can be very short or even nonexistent.

Fortunately, the Inuit have some other resources to help them find their way. Inuit navigators have an understanding of wind patterns that equals the understanding of ocean swell patterns in
marine navigators. Even when the winds are not active, their history is etched into patterns in the snow known as sastrugi. Though it would be unusual for patterns of sastrugi or wind to set up the right conditions for a gradient map (because this would require at least two directions of prevailing winds), sastrugi can be used effectively as a kind of compass.

Compass headings given by wind or snow are accurate only to within about 10 degrees, so other tools are required to zero in precisely on targets. Barrens Inuit make use of tracking for these purposes. Long before you reach a target in the Arctic, you are likely to encounter the trails of other parties of dogsleds. Skilled navigators can read these trails in order to determine the identities of the sleds that have passed (based on the width of the runners and even the footprints of individual sled dogs). This information can be used to help achieve more precise navigation. In traditional Inuit societies, social networks are inextricably tied to places, so the facts of one may be used to predict the facts of the other.