Feb 242009

By Dr. S. Allen Counter, The Boston Globe, 8/25/08

Avataq is a 74-year-old Inuit hunter who has lived all of his life closer to the North Pole than almost anyone else. He is from a small village in northwest Greenland called Morriusaq, which is home to the Polar Eskimos, the smallest tribe of Inuit people – with about 750 members – and the planet’s northernmost permanent settlers.

Avataq is the grandson of legendary Arctic explorer Matthew Henson, an African-American who joined Admiral Robert E. Peary on eight expeditions to reach the North Pole (the final one, in 1909, was successful). Famous among the Polar Eskimos for his hunting skills, Avataq has been given the revered title Peeneeaktoe-Wha, which means “great hunter.”

But like most of the men in his village, Avataq is becoming deaf.

I visited the tribe several years ago to explore the region and study this problem. Tests showed that more than 70 percent of the Inuit hunters had untreatable, permanent hearing loss in both ears, with the right ear typically somewhat worse. Their inner ear receptors and the underlying neurons of the auditory nerve had been destroyed; once damaged in this way, the receptors and neurons never recover, and their loss results in varying degrees of hearing impairment, particularly in the high frequency range.

The Polar Eskimo men are still traditional hunters of seals and walruses and hearing is critical for their survival. They must hear the cracking of the ice for possible dangers. The hunters must hear the seals at the ice holes when the prey comes up to breathe; they must also hear the polar bears who hunt seals in the same area and will readily attack any human in their territory. And because the Polar Eskimos still travel by traditional dog sled, they must hear their dogs’ barking signals in response to their directional guidance calls.

After weeks of testing and retesting the hunters, it became clear that their epidemic of sensory-neural hearing loss was not caused by a virus or by otitis media, the middle ear bacterial infections known to be common among Inuit people all over the Arctic. I also ruled out their diet – which consists mostly of raw meat – as a cause. (Some years ago, I had discovered that toxins in the cassava plant, which is a main carbohydrate staple in the diet of many indigenous South American Indians, was triggering hearing loss.)

I got my first clue as to the cause of the Polar Eskimos’ hearing loss while traveling across the ice by dog sled on a hunt with two tribal members, Talilingqua and Ole Peary, the grandson and great grandson of Admiral Peary. Dressed in their polar bear pants, deerskin annaraaqs, and sealskin boots and gloves, the two would slide across the ice shielded from the view of their prey behind a white cloth screen through which the barrels of their rifles protruded. They fired from a distance at any seal or walrus basking on the ice, and also stood quietly and patiently for hours above an ice hole and fired at the first sign of an emerging seal.

Like all Polar Eskimo hunters, they used rifles ranging up from .22 caliber and hunted without any ear protectors.

Biomedical hearing tests before and after their hunts revealed that while most of the hunters had permanent high frequency hearing loss before the hunt, their hearing acuity was even worse after.

Most of the hunters were right-handed, and while aiming at their prey, tilted their head to the right side toward the butt of the rifle, thereby partially shielding the right ear and leaving the left ear more exposed to the sound of the rifle blast.

Some of the older women also had impaired hearing, and they accompanied their husbands on the hunts. They stood close by, on their husband’s left side, so their right ears received the repeated shock of the damaging impact noise. For them, the damage was worse on the right side.

The elders told me that before the introduction of rifles, the loudest sound they ever heard was that of an iceberg calving from a glacier. This natural phenomenon has a sound that is probably equivalent to the blast of a 1,000-pound conventional military bomb. But that explosive noise builds slowly – and the human ear has evolved to tolerate slowly building sounds, with small middle ear muscles that contract rapidly to keep the middle ear bones from slamming into the sensitive inner ear.

The sharply rising loud noise of the rifle blast enters the ear so rapidly that the middle ear muscles cannot contract rapidly enough. Thus, the tiny hair cells in the inner ear are repeatedly and progressively damaged, particularly those that serve the high frequencies.

Logically, I told them they needed earplugs. But the standard ones I provided them – the type that are common in noisy workplaces in the United States – were impractical. The earplugs prevented them from hearing the dangerous cracking of ice, the howling and the barking of their dogs, and the breathing seals at their ice holes. Plus, they could not fumble with the small earplugs while wearing their thick, sealskin gloves.

Back home, I contacted an American earplug manufacturer that supplied many of the standard earplugs to the military, and I learned that they had developed a novel, cone-shaped ear insert that is connected to a flexible headband, and is relatively easy to insert into the ear canal.

To my delight, the headband style ear inserts were a big hit on my return trip a few years ago, and were readily accepted by the hunters. The earplug manufacturer agreed to keep their supply replenished at no cost.

I was moved when the Inuit hunters and their wives thanked me for my efforts to conserve their hearing. But perhaps the most telling sign of appreciation came from the Great Hunter, Avataq, who said to me as I was leaving his village: “Kuyounah,” which means thank you.

“I may lose my ears soon,” he said. “But what you have done for us will help my son Massanguaq keep his ears while he fulfills my dream of seeing him become a Peeneeaktoe-Wah.”

Dr. S. Allen Counter is a professor of neurology at Harvard Medical School and director of the Harvard Foundation. He is a member of the Explorers Club and will travel to the North Pole on April 6, 2009, to commemorate the 100th anniversary of its discovery by Robert E. Peary and Matthew A. Henson.

Thanks to bhNEWS andNVRC, Fairfax