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It's Sensitive. Really
By WILLIAM J. BROAD, The New York Times, December 13, 2005
For centuries, the tusk of the narwhal has fascinated and baffled.
Narwhal tusks, up to nine feet long, were sold as unicorn horns in ages past, often for many times their weight in gold since they were said to possess magic powers. In the 16th century, Queen Elizabeth received a tusk valued at £10,000 - the cost of a castle. Austrian lore holds that Kaiser Karl the Fifth paid off a large national debt with two tusks. In Vienna, the Hapsburgs had one made into a scepter heavy with diamonds, rubies, sapphires and emeralds.
Scientists have long tried to explain why a stocky whale that lives in arctic waters, feeding on cod and other creatures that flourish amid the pack ice, should wield such a long tusk. The theories about how the narwhal uses the tusk have included breaking ice, spearing fish, piercing ships, transmitting sound, shedding excess body heat, poking the seabed for food, wooing females, defending baby narwhals and establishing dominance in social hierarchies.
But a team of scientists from Harvard and the National Institute of Standards and Technology has now made a startling discovery: the tusk, it turns out, forms a sensory organ of exceptional size and sensitivity, making the living appendage one of the planet's most remarkable, and one that in some ways outdoes its own mythology.
The find came when the team turned an electron microscope on the tusk's material and found new subtleties of dental anatomy. The close-ups showed that 10 million nerve endings tunnel from the tusk's core toward its outer surface, communicating with the outside world. The scientists say the nerves can detect subtle changes of temperature, pressure, particle gradients and probably much else, giving the animal unique insights.
"This whale is intent on understanding its environment," said Martin T. Nweeia, the team's leader and a clinical instructor at the Harvard School of Dental Medicine. Contrary to common views, he said, "The tusk is not about guys duking it out with sticks and swords."
Today in San Diego, Dr. Nweeia is presenting the team's findings at the 16th Biennial Conference on the Biology of Marine Mammals, sponsored by the Society for Marine Mammalogy.
James G. Mead, curator of marine mammals at the Smithsonian Institution in Washington, where Dr. Nweeia is a research associate, said the exposed nerve endings appear to be unparalleled in nature.
"As far as I can see, it's a unique thing," Dr. Mead said in an interview. "It's something new. It just goes to show just how little we know about whales and dolphins."
He noted that no theory about the tusk's function ever envisioned its use as a sensory organ.
In the Canadian wilds, the team recently conducted a field study on a captured narwhal, fitting electrodes on its head. Changes in salinity around the animal's tusk, Dr. Nweeia found, produced signs of altered brain waves, giving preliminary support to the sensor hypothesis. The unharmed whale was then released.
With the basics now in hand, the team is working to understand how the narwhal uses the information. One theory is that the tusk can detect salinity gradients that tell if ice is freezing, a hazard that has killed hundreds of narwhals. Tusk readings may also help the whales track environments that favor their preferred foods.
"It's the kind of discovery," said Dr. Mead of the Smithsonian, "that opens up a lot of other questions."
Little about the narwhal's appearance or behavior offers clues to the tusk's sensory importance. The whale has eyes, though small ones. It also has a thick layer of blubber and no dorsal fin so it can swim easily under the ice. Like any whale, it must surface periodically to breathe air. And as in dolphins, its mouth is set in a permanent smile.
The word narwhal (pronounced NAR-wall or NAR-way-l) is said to derive from old Norse for "corpse whale," apparently because the animal's mottled, splotchy coloring recalled the grayish, blotched color of drowned sailors.
Though shy of humans, the animals are quite social. They often travel in groups of 20 or 30 and form herds of up to 1,000 during migrations.
Males weigh up to 1.5 tons, grow about 15 feet long and are conspicuous by their tusks, which can grow from six to nine feet in length. A few females have tusks and, in rare cases, narwhals can wield two of the long teeth. Though often ramrod strait, the tusks always grow in tight spirals that, from the animal's point of view, turn counterclockwise.
The long ivory tusk "looks like a cross between a corkscrew and a jousting lance," Fred Bruemmer, an Arctic explorer, wrote in "The Narwhal" (Swan Hill Press, 1993).
Narwhals live mainly in the icy channels of northern Canada and northwestern Greenland, but they are found eastward as far as Siberia.
The whale's close cousin, the snowy white beluga, thrives in captivity. The shy narwhal tends to die.
Arctic explorers have often observed them at a distance because narwhals frequently raise their heads above the water, their tusks held high. Jens Rosing, in his book "The Unicorn of the Arctic Sea" (Penumbra Press, 1999), tells of seeing them during expeditions off Greenland. There the whales would frolic and apparently mate.
"Over a hundred can be seen at once," he wrote. "They often rise vertically out of the water, lifting themselves with strong movements of their tail fin so that half their body is above water."
Mr. Rosing added: "There is great confusion of movement - both females and males take part. Often one can see a male and female shoot up from the water, trembling, belly to belly."
When luxuriating on their backs in the water, narwhals often turn their heads so their tusks point straight up. Dr. Nweeia of Harvard said the Inuit, the indigenous peoples of the Arctic, who know the narwhal intimately, have a name for the whale that translates as "the one that is good at curving itself to the sky."
Around A.D. 1000, the narwhal tusk debuted in history as a profitable lie. Historians say people in the far north learned of narwhals from Norsemen or perhaps from finding animal bodies occasionally washed up on northern shores. It is known that the Vikings hunted the narwhal and acquired tusks from Arctic natives.
Unscrupulous traders passed them off as one of the most prized objects of all time: unicorn horns.
The ancient Chinese, Greeks, Romans and other peoples had accepted the unicorn as real, and the arrival of the beautifully spiraled objects seemed to prove the animal's existence. The supposed horns sparked huge interest because they were said to have the power to cure ills and neutralize poisons.
Kings and emperors, eager to foil assassins, had cups and eating utensils made of the precious horns. A London doctor advertised a drink made from powdered tusks that could cure scurvy, ulcers, dropsy, gout, consumption, coughs, heart palpitations, fainting, rickets and melancholy.
The horns became an icon of power, both earthly and divine, in part because of their religious associations. In medieval times, the unicorn was seen as a symbol of great purity and of Christ, the motif common in religious art. The fantastic beast appeared in many thousands of images, Mr. Bruemmer wrote, and "All carry a horn that is unmistakably a narwhal tusk, the only long, spiraled horn in all creation."
Churches put small pieces of "unicorn horn" in holy water, giving ailing commoners hope of miracle cures. Meanwhile, the bishops of Vienna carried staffs made of the precious ivory, while St. Mark's Basilica in Venice displayed a horn wreathed in purple velvet.
By the 17th century, the deception began to falter amid the expansion of New World exploration and multiplying reports of bizarre whales that bore long tusks. Ole Wurm, a Danish zoologist, investigated the matter and in 1638 exposed the horn's true origins in a public lecture.
As the unicorn myth died a slow death, the reputation of the narwhal grew larger than life. Explorers claimed its tusk could punch holes in thick ice, and that males battled with their long tusks for supremacy. In 1870, Jules Verne told how a narwhal could pierce ships "clean through as easily as a drill pierces a barrel."
Dr. Nweeia, a general dentist in Sharon, Conn., with an interest in dental anthropology, developed a taste for exotic investigations while doing research on Indian tribes in the Amazon and children in Micronesia. He lectured on how animal and human teeth differ, and eight years ago he began to wonder about narwhals and their odd tusks.
"They defied most of the principles and properties of teeth," he recalled. Many narwhal reports proved contradictory, he found, and "my interest spiraled like the tooth."
In 2000, Dr. Nweeia decided to investigate the animal closely and first trekked to its icy habitat in 2002, going to Pond Inlet, a tiny settlement at the northern tip of Baffin Island. There he met David Angnatsiak, an Inuit guide who agreed to help. Under international agreement, the Inuits are allowed to hunt narwhals, which they eat and harvest for their tusks.
During expeditions in 2003 and 2004, aided by the Canadian Department of Fisheries and Oceans, Dr. Nweeia was able to gather head and tusk specimens, which he brought back for analysis. He and his colleagues tracked a clear nerve connection between the animal's brain and tusk, finding the long tooth heavily enervated. But why it should be so remained a mystery.
The investigators zeroed in on the riddle with sophisticated instruments at the Paffenbarger Research Center of the National Institute of Standards and Technology, a federal organization in Gaithersburg, Md. The American Dental Association finances the research center.
Rough deposits of calcified algae and plankton coated the outside of the tusks Dr. Nweeia brought back. The scientists decided to remove them in an acid bath to get down to the surface of the tooth before viewing it under an electron microscope. First, however, they decided to give the uncleaned tusk a cursory microscopic examination.
It was a shock. There, contrary to all known precepts of tooth anatomy, they found open tubules leading down through the mazelike coating to the tooth's inner nerves and pulp.
"That surprised us," recalled Frederick C. Eichmiller, director of the Paffenbarger Research Center. "Tubules in healthy teeth never go to the surface."
Extrapolating from a count of open tubules over one part of the tooth's surface, the team estimated that the average narwhal tusk had millions of openings that led down to inner nerves.
"No one knew that they were connecting to the outside environment," Dr. Nweeia said. "To find that was extraordinary."
His collaborators include Naomi Eidelman and Anthony A. Giuseppetti of the Paffenbarger Research Center, Yeon-Gil Jung of Changwon National University in South Korea and Yu Zhang of New York University.
Increasingly, the investigation centers on how the whales use their newly observed powers. One central unanswered question is how sensory abilities in males might relate to herd behavior and survival.
The scientists, noting that the males often hold their tusks high in the air, wonder if the long teeth might sometimes serve as sophisticated weather stations, letting the animals sense changes in temperature and barometric pressure that would tell of the arrival of cold fronts and the likelihood that open ice channels might soon freeze up.
Dr. Nweeia noted that the discovery does not eliminate some early theories of the whale's behavior. Tusks acting as sophisticated sensors, he said, may still play a role in mating rituals or determining male hierarchies.
He added that the nerve endings, in addition to other readings, undoubtedly produce tactile sensations when the tusk is rubbed or touched, and that these might be interpreted as pleasurable.
This tactile sense might explain why narwhals engage in what is known as "tusking," where two males gently rub tusks together, Dr. Nweeia said. He added that the Inuit seldom report aggressive contact, undermining ideas of ritualized battle.
Dr. Nweeia said that gentle tusking might also be a way that males remove encrustations on their tusks so tubules stay open, allowing them to better function as sensors. "It may simply be their way of cleaning or brushing teeth," he said.
He called the basic discovery mind boggling, especially given the freezing temperatures of the Arctic.
"This is one of the last places you'd expect to find such a thing," Dr. Nweeia said of the large sensory organs. "Cold is one of the things that tubules are most sensitive to," as people sometimes discover when diseased gums of human teeth expose the tubules.
"Of all the places you'd think you'd want to do the most to insulate yourself from that outside environment," he said, "this guy has gone out of his way to open himself up to it."
The Consumer: Women Dress for Comfort in the Heat of the Night
By MARY DUENWALD, The New York Times, December 13, 2005
As fashion trends go, hot flash pajamas are not glamorous. But they stand a chance of holding on for more than one brief season. At least five brands have sprung up in the past five years and, perhaps as a result of the expanding ranks of women turning 50, sales are rising fast.
The various inventors of this new sleepwear all seem to have had essentially the same eureka moment - on a night when they started getting hot flashes of their own. They were all active and fit women, with years of experience with perspiration. And they realized that the temperature fluctuations of menopause called for the same wicking fabrics as running, hiking or exercising in the gym.
"When I first had hot flashes, I would change my T-shirts through the night," said Wendy McClung, a co-founder of HotCool Wear, in Toronto, which began making Hot Mama pajamas in 2000. "One night I grabbed one of my running shirts, and I thought, 'My goodness, this is what it is like to sleep.' "
Hot Mama sleepwear is made of CoolMax, a polyester fabric used in workout clothes, finely milled to make it light and soft, like cotton flannel. Wicking J. Sleepwear, from a company in Evergreen, Colo., uses a similar fabric called Intera. And Wildbleu, a Seattle brand, uses one called Dri-release. The polyester fibers are designed to lift sweat from the body and allow it to evaporate quickly, said Helen Rockey, the founder of Wildbleu.
Whether that leads to a better night's sleep is another question, one that's harder to answer because it's not clear that hot flashes disturb the sleep of menopausal women as much as they think. Recent laboratory research has found surprisingly little connection between hot flashes and sleep quality.
A 2004 study conducted at Wayne State University in Detroit looked at the sleep quality of 31 women ages 46 to 51, 12 of them experiencing an average of five hot flashes per night.
Sometimes the flashes woke them up, but more often it was the other way around.
"They awakened first and then they flashed," said Robert R. Freedman, a professor of psychiatry and obstetrics and gynecology, who conducted the study with Timothy A. Roehrs, a sleep researcher. "Perhaps their waking up is what triggered the flash."
When the researchers measured the subjects' daytime alertness - by testing their reaction time, for example, and clocking how long it took them to nod off when they were allowed to nap - they found that the women who had hot flashes were no sleepier than those who did not.
A study of 589 women at the University of Wisconsin in 2003 found that women who reported having hot flashes had no worse sleep quality than those who did not.
Perhaps, the researchers said, the bleary-eyed exhaustion that women reaching menopause often complain of may be caused by other things - like depression, pain or the various discomforts that sometimes come with age.
In a more recent study, not yet published, Dr. Freedman found that hot flashes woke his subjects only during the first half of the night, a period of slow-wave sleep. During the second half of the night, when the women were in REM (rapid eye movement) or dreaming sleep, they rested peacefully. If the subjects woke at all in the second half of the night, their awakenings preceded, rather than followed, hot flashes.
So Dr. Freedman now recommends that hot flash sufferers keep their bedrooms cool during the first half of the night. "Set the thermostat at 64 degrees Fahrenheit for the first four hours," he said. After that, he added, it will not hurt to let the air warm a bit (allowing anyone else in the room to quit shivering).
Estrogen supplements, now a subject of dispute, are an effective treatment for hot flashes. But herbal products like black cohosh, kava, red clover leaf, dong quai root and ginseng have not been shown to be effective, according to a report from a National Institutes of Health state-of-the-science conference this year.
Some doctors also use prescription drugs like antidepressants or blood pressure medications "off-label" to treat hot flashes, but the medications can have side effects. As for wicking pajamas, the Good Housekeeping Institute evaluated two brands, HotCool Wear and Wicking J., by asking seven menopausal women to wear them for a week and then rate them. Five of the testers said the fabrics kept them more comfortable during and after night sweats.
The pajamas come in various styles - gowns, nightshirts, kimonos, pants and T-shirts - and all of them tend to be blousy rather than skimpy. "The fabric can't work unless it's touching your skin," Ms. McClung explained.
The wicking fabrics are also odor-resistant.
Wildbleu nightwear comes in pastel solids and prints; Wicking J., in solids only. HotCool Wear offers some dark and bright colors. Wicking J. and HotCool Wear also sell pillowcases. All three of these brands are sold in small stores and online at Web sites like serenecomfort.com.
Scientists still do not know exactly why hot flashes occur, except that they seem to result from the body's diminishing sensitivity to estrogen in the years before and just after menopause.
"It's sort of a repositioning of the thermostat, if you will, where there's less variation in temperature between sweating and shivering," said Dr. Rogerio Lobo, a professor of obstetrics and gynecology at Columbia University.
About 80 percent of women have hot flashes at the onset of menopause, according to a large survey of women conducted in the Netherlands in 1993. During this peak time, women may have a half-dozen hot flashes a day and the same number at night, doctors say, though the frequency varies widely.
The record holder among Dr. Freedman's subjects had 39 in 24 hours.
Hot flashes usually decline in intensity and in number during the two or three years after menopause, but about half of women still have some mild flashes as long as 10 years after menopause, according to the Dutch survey.
By measuring temperature and perspiration in women experiencing flashes, Dr. Freedman has observed that the body's core temperature begins to rise as much as 17 minutes before the woman feels a flash. Her metabolic rate increases two or three minutes beforehand, and skin temperature rises 30 to 45 seconds ahead of the feeling.
A typical flash lasts two to five minutes, though in some women they can continue for as long as 10 minutes. Flashes cool the body, so after a woman has one, she may feel chilly.
Given that by 2030, according to the World Health Organization, as many as 1.2 billion women worldwide will have reached the age of 50, when hot flashes often occur, the scientific explanations are coming none too soon.
"If we can delineate the basic mechanism of hot flashes," Dr. Freedman said, "it should mean we can develop better treatments."
Beating Malaria Means Understanding Mosquitoes
By NICHOLAS BAKALAR, The New York Times, December 13, 2005
In Africa, 20 percent of the children get 80 percent of the bites from malarial mosquitoes, and an understanding of this could be central to controlling the deadly disease.
Researchers have developed a mathematical model that describes the complex relationship between the proportion of people who are infected with Plasmodium falciparum, the parasite that causes malaria, and the rate at which people are bitten by the mosquitoes that carry it.
Some people are bitten more than others because they live where mosquitoes are more common or because the mosquitoes, for various reasons, find them more attractive.
Those who are bitten most often play a role in malarial transmission similar to that played by the most sexually active in the transmission of sexually transmitted diseases: they are the ones who spread the disease. The people who are bitten most become infected and stay infected.
Then the heavy biting continues, so large numbers of mosquitoes acquire the parasite from their blood and can transmit it to others. So, the total burden of disease is influenced by a small minority of people.
A paper on the work appeared in the Nov. 24 issue of Nature.
Identifying the 20 percent of the population that is most often bitten is hard, said David Smith, an epidemiologist at the Centers for Disease Control and Prevention and the lead author. "No one knows how to do this," Dr. Smith said, "so right now the goal is to protect everyone. However, the gains from targeting may be so large that it is worthwhile. I think this should become a very active area of research."
Accounting for these factors requires a mathematical model that describes the way transmission occurs and who is likely to be infected. Using such a model, health officials can direct prevention efforts more accurately by concentrating on those most likely to carry the parasite.
"What I liked about this paper is that it is an elegant analytical extension of the 20-80 rule," said Thomas W. Scott, a professor of entomology at the University of California, Davis, who was not part of the study.
"It may be difficult to identify who the 20 percent are that are contributing most to transmission," Dr. Scott said, "but if they could be identified, there would be a huge payoff in improved public health."
Two factors are central to the model: the proportion of people who are infected and the rate at which people are bitten by infectious mosquitoes.
In applying the model, the researchers found that selective biting and susceptibility to infection play an important role in determining the proportion of people infected. But immunity to infection in early childhood does not. This may be because people who are immune can nevertheless still infect others.
The model also shows that it is difficult to reduce the proportion of people who are infected just by reducing the number bitten. Cutting the rate of biting in half would reduce the number of people infected by only 4 percent, the researchers concluded. Halving it again would reduce the number by 5 percent more.
Because so few people get so many of the mosquito bites, applying control measures uniformly across the population will almost certainly be unsuccessful.
But focusing on the small number of people who are bitten most often should have much wider community benefits by reducing the number of asymptomatic carriers, lowering the rate of parasites among mosquitoes, and finally decreasing overall transmission among the population, the researchers said.
Vital Signs: Having a Baby: Risk and Reality in V-Births and C-Sections
By NICHOLAS BAKALAR, The New York Times, December 13, 2005
Elective Caesarean sections have become more common in recent years, in part because many women and doctors believe that vaginal birth is a major risk factor for urinary incontinence.
But a new study published in the December issue of Obstetrics and Gynecology has found no support for this belief.
Researchers sampled 143 pairs of postmenopausal biological sisters. In each pair, one had had a vaginal delivery and one had never had a baby. They completed questionnaires concerning symptoms of pelvic floor disorders, and 101 of the pairs were given clinical evaluations for urinary incontinence.
The results ran counter to the conventional wisdom: 49.7 percent of the women who had given birth suffered some urinary incontinence, but so did 47.6 percent of their sisters, reflecting a difference that was statistically insignificant.
The researchers concluded that in postmenopausal women family factors were more associated with urinary incontinence than with having had a vaginal delivery.
Dr. Gunhilde M. Buchsbaum, the study's lead author and an associate professor of obstetrics at the University of Rochester, said she doubted that these results would affect clinical practice. "People have strong feelings and opinions about elective C-section one way or the other," she said. "For that reason, I doubt that the findings of our study will change any minds."
The authors acknowledged that they did not determine the age at which incontinence began, and that incontinence might occur earlier in women who delivered vaginally. The authors also pointed out that their finding pertained to white women only.
By WILLIAM J. BROAD, The New York Times, December 13, 2005
For centuries, the tusk of the narwhal has fascinated and baffled.
Narwhal tusks, up to nine feet long, were sold as unicorn horns in ages past, often for many times their weight in gold since they were said to possess magic powers. In the 16th century, Queen Elizabeth received a tusk valued at £10,000 - the cost of a castle. Austrian lore holds that Kaiser Karl the Fifth paid off a large national debt with two tusks. In Vienna, the Hapsburgs had one made into a scepter heavy with diamonds, rubies, sapphires and emeralds.
Scientists have long tried to explain why a stocky whale that lives in arctic waters, feeding on cod and other creatures that flourish amid the pack ice, should wield such a long tusk. The theories about how the narwhal uses the tusk have included breaking ice, spearing fish, piercing ships, transmitting sound, shedding excess body heat, poking the seabed for food, wooing females, defending baby narwhals and establishing dominance in social hierarchies.
But a team of scientists from Harvard and the National Institute of Standards and Technology has now made a startling discovery: the tusk, it turns out, forms a sensory organ of exceptional size and sensitivity, making the living appendage one of the planet's most remarkable, and one that in some ways outdoes its own mythology.
The find came when the team turned an electron microscope on the tusk's material and found new subtleties of dental anatomy. The close-ups showed that 10 million nerve endings tunnel from the tusk's core toward its outer surface, communicating with the outside world. The scientists say the nerves can detect subtle changes of temperature, pressure, particle gradients and probably much else, giving the animal unique insights.
"This whale is intent on understanding its environment," said Martin T. Nweeia, the team's leader and a clinical instructor at the Harvard School of Dental Medicine. Contrary to common views, he said, "The tusk is not about guys duking it out with sticks and swords."
Today in San Diego, Dr. Nweeia is presenting the team's findings at the 16th Biennial Conference on the Biology of Marine Mammals, sponsored by the Society for Marine Mammalogy.
James G. Mead, curator of marine mammals at the Smithsonian Institution in Washington, where Dr. Nweeia is a research associate, said the exposed nerve endings appear to be unparalleled in nature.
"As far as I can see, it's a unique thing," Dr. Mead said in an interview. "It's something new. It just goes to show just how little we know about whales and dolphins."
He noted that no theory about the tusk's function ever envisioned its use as a sensory organ.
In the Canadian wilds, the team recently conducted a field study on a captured narwhal, fitting electrodes on its head. Changes in salinity around the animal's tusk, Dr. Nweeia found, produced signs of altered brain waves, giving preliminary support to the sensor hypothesis. The unharmed whale was then released.
With the basics now in hand, the team is working to understand how the narwhal uses the information. One theory is that the tusk can detect salinity gradients that tell if ice is freezing, a hazard that has killed hundreds of narwhals. Tusk readings may also help the whales track environments that favor their preferred foods.
"It's the kind of discovery," said Dr. Mead of the Smithsonian, "that opens up a lot of other questions."
Little about the narwhal's appearance or behavior offers clues to the tusk's sensory importance. The whale has eyes, though small ones. It also has a thick layer of blubber and no dorsal fin so it can swim easily under the ice. Like any whale, it must surface periodically to breathe air. And as in dolphins, its mouth is set in a permanent smile.
The word narwhal (pronounced NAR-wall or NAR-way-l) is said to derive from old Norse for "corpse whale," apparently because the animal's mottled, splotchy coloring recalled the grayish, blotched color of drowned sailors.
Though shy of humans, the animals are quite social. They often travel in groups of 20 or 30 and form herds of up to 1,000 during migrations.
Males weigh up to 1.5 tons, grow about 15 feet long and are conspicuous by their tusks, which can grow from six to nine feet in length. A few females have tusks and, in rare cases, narwhals can wield two of the long teeth. Though often ramrod strait, the tusks always grow in tight spirals that, from the animal's point of view, turn counterclockwise.
The long ivory tusk "looks like a cross between a corkscrew and a jousting lance," Fred Bruemmer, an Arctic explorer, wrote in "The Narwhal" (Swan Hill Press, 1993).
Narwhals live mainly in the icy channels of northern Canada and northwestern Greenland, but they are found eastward as far as Siberia.
The whale's close cousin, the snowy white beluga, thrives in captivity. The shy narwhal tends to die.
Arctic explorers have often observed them at a distance because narwhals frequently raise their heads above the water, their tusks held high. Jens Rosing, in his book "The Unicorn of the Arctic Sea" (Penumbra Press, 1999), tells of seeing them during expeditions off Greenland. There the whales would frolic and apparently mate.
"Over a hundred can be seen at once," he wrote. "They often rise vertically out of the water, lifting themselves with strong movements of their tail fin so that half their body is above water."
Mr. Rosing added: "There is great confusion of movement - both females and males take part. Often one can see a male and female shoot up from the water, trembling, belly to belly."
When luxuriating on their backs in the water, narwhals often turn their heads so their tusks point straight up. Dr. Nweeia of Harvard said the Inuit, the indigenous peoples of the Arctic, who know the narwhal intimately, have a name for the whale that translates as "the one that is good at curving itself to the sky."
Around A.D. 1000, the narwhal tusk debuted in history as a profitable lie. Historians say people in the far north learned of narwhals from Norsemen or perhaps from finding animal bodies occasionally washed up on northern shores. It is known that the Vikings hunted the narwhal and acquired tusks from Arctic natives.
Unscrupulous traders passed them off as one of the most prized objects of all time: unicorn horns.
The ancient Chinese, Greeks, Romans and other peoples had accepted the unicorn as real, and the arrival of the beautifully spiraled objects seemed to prove the animal's existence. The supposed horns sparked huge interest because they were said to have the power to cure ills and neutralize poisons.
Kings and emperors, eager to foil assassins, had cups and eating utensils made of the precious horns. A London doctor advertised a drink made from powdered tusks that could cure scurvy, ulcers, dropsy, gout, consumption, coughs, heart palpitations, fainting, rickets and melancholy.
The horns became an icon of power, both earthly and divine, in part because of their religious associations. In medieval times, the unicorn was seen as a symbol of great purity and of Christ, the motif common in religious art. The fantastic beast appeared in many thousands of images, Mr. Bruemmer wrote, and "All carry a horn that is unmistakably a narwhal tusk, the only long, spiraled horn in all creation."
Churches put small pieces of "unicorn horn" in holy water, giving ailing commoners hope of miracle cures. Meanwhile, the bishops of Vienna carried staffs made of the precious ivory, while St. Mark's Basilica in Venice displayed a horn wreathed in purple velvet.
By the 17th century, the deception began to falter amid the expansion of New World exploration and multiplying reports of bizarre whales that bore long tusks. Ole Wurm, a Danish zoologist, investigated the matter and in 1638 exposed the horn's true origins in a public lecture.
As the unicorn myth died a slow death, the reputation of the narwhal grew larger than life. Explorers claimed its tusk could punch holes in thick ice, and that males battled with their long tusks for supremacy. In 1870, Jules Verne told how a narwhal could pierce ships "clean through as easily as a drill pierces a barrel."
Dr. Nweeia, a general dentist in Sharon, Conn., with an interest in dental anthropology, developed a taste for exotic investigations while doing research on Indian tribes in the Amazon and children in Micronesia. He lectured on how animal and human teeth differ, and eight years ago he began to wonder about narwhals and their odd tusks.
"They defied most of the principles and properties of teeth," he recalled. Many narwhal reports proved contradictory, he found, and "my interest spiraled like the tooth."
In 2000, Dr. Nweeia decided to investigate the animal closely and first trekked to its icy habitat in 2002, going to Pond Inlet, a tiny settlement at the northern tip of Baffin Island. There he met David Angnatsiak, an Inuit guide who agreed to help. Under international agreement, the Inuits are allowed to hunt narwhals, which they eat and harvest for their tusks.
During expeditions in 2003 and 2004, aided by the Canadian Department of Fisheries and Oceans, Dr. Nweeia was able to gather head and tusk specimens, which he brought back for analysis. He and his colleagues tracked a clear nerve connection between the animal's brain and tusk, finding the long tooth heavily enervated. But why it should be so remained a mystery.
The investigators zeroed in on the riddle with sophisticated instruments at the Paffenbarger Research Center of the National Institute of Standards and Technology, a federal organization in Gaithersburg, Md. The American Dental Association finances the research center.
Rough deposits of calcified algae and plankton coated the outside of the tusks Dr. Nweeia brought back. The scientists decided to remove them in an acid bath to get down to the surface of the tooth before viewing it under an electron microscope. First, however, they decided to give the uncleaned tusk a cursory microscopic examination.
It was a shock. There, contrary to all known precepts of tooth anatomy, they found open tubules leading down through the mazelike coating to the tooth's inner nerves and pulp.
"That surprised us," recalled Frederick C. Eichmiller, director of the Paffenbarger Research Center. "Tubules in healthy teeth never go to the surface."
Extrapolating from a count of open tubules over one part of the tooth's surface, the team estimated that the average narwhal tusk had millions of openings that led down to inner nerves.
"No one knew that they were connecting to the outside environment," Dr. Nweeia said. "To find that was extraordinary."
His collaborators include Naomi Eidelman and Anthony A. Giuseppetti of the Paffenbarger Research Center, Yeon-Gil Jung of Changwon National University in South Korea and Yu Zhang of New York University.
Increasingly, the investigation centers on how the whales use their newly observed powers. One central unanswered question is how sensory abilities in males might relate to herd behavior and survival.
The scientists, noting that the males often hold their tusks high in the air, wonder if the long teeth might sometimes serve as sophisticated weather stations, letting the animals sense changes in temperature and barometric pressure that would tell of the arrival of cold fronts and the likelihood that open ice channels might soon freeze up.
Dr. Nweeia noted that the discovery does not eliminate some early theories of the whale's behavior. Tusks acting as sophisticated sensors, he said, may still play a role in mating rituals or determining male hierarchies.
He added that the nerve endings, in addition to other readings, undoubtedly produce tactile sensations when the tusk is rubbed or touched, and that these might be interpreted as pleasurable.
This tactile sense might explain why narwhals engage in what is known as "tusking," where two males gently rub tusks together, Dr. Nweeia said. He added that the Inuit seldom report aggressive contact, undermining ideas of ritualized battle.
Dr. Nweeia said that gentle tusking might also be a way that males remove encrustations on their tusks so tubules stay open, allowing them to better function as sensors. "It may simply be their way of cleaning or brushing teeth," he said.
He called the basic discovery mind boggling, especially given the freezing temperatures of the Arctic.
"This is one of the last places you'd expect to find such a thing," Dr. Nweeia said of the large sensory organs. "Cold is one of the things that tubules are most sensitive to," as people sometimes discover when diseased gums of human teeth expose the tubules.
"Of all the places you'd think you'd want to do the most to insulate yourself from that outside environment," he said, "this guy has gone out of his way to open himself up to it."
The Consumer: Women Dress for Comfort in the Heat of the Night
By MARY DUENWALD, The New York Times, December 13, 2005
As fashion trends go, hot flash pajamas are not glamorous. But they stand a chance of holding on for more than one brief season. At least five brands have sprung up in the past five years and, perhaps as a result of the expanding ranks of women turning 50, sales are rising fast.
The various inventors of this new sleepwear all seem to have had essentially the same eureka moment - on a night when they started getting hot flashes of their own. They were all active and fit women, with years of experience with perspiration. And they realized that the temperature fluctuations of menopause called for the same wicking fabrics as running, hiking or exercising in the gym.
"When I first had hot flashes, I would change my T-shirts through the night," said Wendy McClung, a co-founder of HotCool Wear, in Toronto, which began making Hot Mama pajamas in 2000. "One night I grabbed one of my running shirts, and I thought, 'My goodness, this is what it is like to sleep.' "
Hot Mama sleepwear is made of CoolMax, a polyester fabric used in workout clothes, finely milled to make it light and soft, like cotton flannel. Wicking J. Sleepwear, from a company in Evergreen, Colo., uses a similar fabric called Intera. And Wildbleu, a Seattle brand, uses one called Dri-release. The polyester fibers are designed to lift sweat from the body and allow it to evaporate quickly, said Helen Rockey, the founder of Wildbleu.
Whether that leads to a better night's sleep is another question, one that's harder to answer because it's not clear that hot flashes disturb the sleep of menopausal women as much as they think. Recent laboratory research has found surprisingly little connection between hot flashes and sleep quality.
A 2004 study conducted at Wayne State University in Detroit looked at the sleep quality of 31 women ages 46 to 51, 12 of them experiencing an average of five hot flashes per night.
Sometimes the flashes woke them up, but more often it was the other way around.
"They awakened first and then they flashed," said Robert R. Freedman, a professor of psychiatry and obstetrics and gynecology, who conducted the study with Timothy A. Roehrs, a sleep researcher. "Perhaps their waking up is what triggered the flash."
When the researchers measured the subjects' daytime alertness - by testing their reaction time, for example, and clocking how long it took them to nod off when they were allowed to nap - they found that the women who had hot flashes were no sleepier than those who did not.
A study of 589 women at the University of Wisconsin in 2003 found that women who reported having hot flashes had no worse sleep quality than those who did not.
Perhaps, the researchers said, the bleary-eyed exhaustion that women reaching menopause often complain of may be caused by other things - like depression, pain or the various discomforts that sometimes come with age.
In a more recent study, not yet published, Dr. Freedman found that hot flashes woke his subjects only during the first half of the night, a period of slow-wave sleep. During the second half of the night, when the women were in REM (rapid eye movement) or dreaming sleep, they rested peacefully. If the subjects woke at all in the second half of the night, their awakenings preceded, rather than followed, hot flashes.
So Dr. Freedman now recommends that hot flash sufferers keep their bedrooms cool during the first half of the night. "Set the thermostat at 64 degrees Fahrenheit for the first four hours," he said. After that, he added, it will not hurt to let the air warm a bit (allowing anyone else in the room to quit shivering).
Estrogen supplements, now a subject of dispute, are an effective treatment for hot flashes. But herbal products like black cohosh, kava, red clover leaf, dong quai root and ginseng have not been shown to be effective, according to a report from a National Institutes of Health state-of-the-science conference this year.
Some doctors also use prescription drugs like antidepressants or blood pressure medications "off-label" to treat hot flashes, but the medications can have side effects. As for wicking pajamas, the Good Housekeeping Institute evaluated two brands, HotCool Wear and Wicking J., by asking seven menopausal women to wear them for a week and then rate them. Five of the testers said the fabrics kept them more comfortable during and after night sweats.
The pajamas come in various styles - gowns, nightshirts, kimonos, pants and T-shirts - and all of them tend to be blousy rather than skimpy. "The fabric can't work unless it's touching your skin," Ms. McClung explained.
The wicking fabrics are also odor-resistant.
Wildbleu nightwear comes in pastel solids and prints; Wicking J., in solids only. HotCool Wear offers some dark and bright colors. Wicking J. and HotCool Wear also sell pillowcases. All three of these brands are sold in small stores and online at Web sites like serenecomfort.com.
Scientists still do not know exactly why hot flashes occur, except that they seem to result from the body's diminishing sensitivity to estrogen in the years before and just after menopause.
"It's sort of a repositioning of the thermostat, if you will, where there's less variation in temperature between sweating and shivering," said Dr. Rogerio Lobo, a professor of obstetrics and gynecology at Columbia University.
About 80 percent of women have hot flashes at the onset of menopause, according to a large survey of women conducted in the Netherlands in 1993. During this peak time, women may have a half-dozen hot flashes a day and the same number at night, doctors say, though the frequency varies widely.
The record holder among Dr. Freedman's subjects had 39 in 24 hours.
Hot flashes usually decline in intensity and in number during the two or three years after menopause, but about half of women still have some mild flashes as long as 10 years after menopause, according to the Dutch survey.
By measuring temperature and perspiration in women experiencing flashes, Dr. Freedman has observed that the body's core temperature begins to rise as much as 17 minutes before the woman feels a flash. Her metabolic rate increases two or three minutes beforehand, and skin temperature rises 30 to 45 seconds ahead of the feeling.
A typical flash lasts two to five minutes, though in some women they can continue for as long as 10 minutes. Flashes cool the body, so after a woman has one, she may feel chilly.
Given that by 2030, according to the World Health Organization, as many as 1.2 billion women worldwide will have reached the age of 50, when hot flashes often occur, the scientific explanations are coming none too soon.
"If we can delineate the basic mechanism of hot flashes," Dr. Freedman said, "it should mean we can develop better treatments."
Beating Malaria Means Understanding Mosquitoes
By NICHOLAS BAKALAR, The New York Times, December 13, 2005
In Africa, 20 percent of the children get 80 percent of the bites from malarial mosquitoes, and an understanding of this could be central to controlling the deadly disease.
Researchers have developed a mathematical model that describes the complex relationship between the proportion of people who are infected with Plasmodium falciparum, the parasite that causes malaria, and the rate at which people are bitten by the mosquitoes that carry it.
Some people are bitten more than others because they live where mosquitoes are more common or because the mosquitoes, for various reasons, find them more attractive.
Those who are bitten most often play a role in malarial transmission similar to that played by the most sexually active in the transmission of sexually transmitted diseases: they are the ones who spread the disease. The people who are bitten most become infected and stay infected.
Then the heavy biting continues, so large numbers of mosquitoes acquire the parasite from their blood and can transmit it to others. So, the total burden of disease is influenced by a small minority of people.
A paper on the work appeared in the Nov. 24 issue of Nature.
Identifying the 20 percent of the population that is most often bitten is hard, said David Smith, an epidemiologist at the Centers for Disease Control and Prevention and the lead author. "No one knows how to do this," Dr. Smith said, "so right now the goal is to protect everyone. However, the gains from targeting may be so large that it is worthwhile. I think this should become a very active area of research."
Accounting for these factors requires a mathematical model that describes the way transmission occurs and who is likely to be infected. Using such a model, health officials can direct prevention efforts more accurately by concentrating on those most likely to carry the parasite.
"What I liked about this paper is that it is an elegant analytical extension of the 20-80 rule," said Thomas W. Scott, a professor of entomology at the University of California, Davis, who was not part of the study.
"It may be difficult to identify who the 20 percent are that are contributing most to transmission," Dr. Scott said, "but if they could be identified, there would be a huge payoff in improved public health."
Two factors are central to the model: the proportion of people who are infected and the rate at which people are bitten by infectious mosquitoes.
In applying the model, the researchers found that selective biting and susceptibility to infection play an important role in determining the proportion of people infected. But immunity to infection in early childhood does not. This may be because people who are immune can nevertheless still infect others.
The model also shows that it is difficult to reduce the proportion of people who are infected just by reducing the number bitten. Cutting the rate of biting in half would reduce the number of people infected by only 4 percent, the researchers concluded. Halving it again would reduce the number by 5 percent more.
Because so few people get so many of the mosquito bites, applying control measures uniformly across the population will almost certainly be unsuccessful.
But focusing on the small number of people who are bitten most often should have much wider community benefits by reducing the number of asymptomatic carriers, lowering the rate of parasites among mosquitoes, and finally decreasing overall transmission among the population, the researchers said.
Vital Signs: Having a Baby: Risk and Reality in V-Births and C-Sections
By NICHOLAS BAKALAR, The New York Times, December 13, 2005
Elective Caesarean sections have become more common in recent years, in part because many women and doctors believe that vaginal birth is a major risk factor for urinary incontinence.
But a new study published in the December issue of Obstetrics and Gynecology has found no support for this belief.
Researchers sampled 143 pairs of postmenopausal biological sisters. In each pair, one had had a vaginal delivery and one had never had a baby. They completed questionnaires concerning symptoms of pelvic floor disorders, and 101 of the pairs were given clinical evaluations for urinary incontinence.
The results ran counter to the conventional wisdom: 49.7 percent of the women who had given birth suffered some urinary incontinence, but so did 47.6 percent of their sisters, reflecting a difference that was statistically insignificant.
The researchers concluded that in postmenopausal women family factors were more associated with urinary incontinence than with having had a vaginal delivery.
Dr. Gunhilde M. Buchsbaum, the study's lead author and an associate professor of obstetrics at the University of Rochester, said she doubted that these results would affect clinical practice. "People have strong feelings and opinions about elective C-section one way or the other," she said. "For that reason, I doubt that the findings of our study will change any minds."
The authors acknowledged that they did not determine the age at which incontinence began, and that incontinence might occur earlier in women who delivered vaginally. The authors also pointed out that their finding pertained to white women only.
