![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
brdgt
Linking of Languages May Speak Volumes
By NICHOLAS WADE, The New York Times, September 27, 2005
Linguists have devised a new way of linking languages, which they say has allowed them to reconstruct a network of the languages spoken in islands near New Guinea.
The new method is designed for languages so old that little trace of their common vocabulary remains. It forges connections between languages through grammatical features, which change less quickly than words.
With the new tool, historians may be able to peer considerably further back in time than the 5,000 to 7,000 years or so that many linguists see as the limit beyond which no sure connections can be made between languages.
The authors of the new method say the relationships they can construct may be 10,000 years or older.
The researchers, who were led by Michael Dunn, of the Max Planck Institute for Psycholinguistics in Nijmegen, Holland, have published their work in the current issue of Science.
They say that on the basis of grammatical similarities they have constructed a network of the Papuan languages spoken in the island groups east of Papua New Guinea. Traveling eastward, these are the Bismarck Islands, Bougainville and the Solomon Islands.
The grammar-derived network correctly assigns all languages to their respective archipelagos, showing it has picked up the relatedness to be expected from geography. But the network gives a puzzling placement to the Solomon Island languages.
They fall in between those of the Bismarcks and Bougainville, stepping out of the sequence expected if the islands were first occupied by people migrating from west to east.
The explanation, Dr. Dunn and his colleagues say, is that 10,000 years ago, when sea levels were much lower because of the Pleistocene ice age, Bougainville and the Solomon Islands would have been joined in a single land mass, while the Bismarcks were always separate.
This might explain the Bougainville languages' closer relationship to those of the Solomons and distance from those of the Bismarcks. It would also indicate that the grammar-based linking is picking up a signal from 10,000 years ago.
The Solomons are well known as the arena in which American and Japanese forces clashed in World War II in the battle at Guadalcanal. They are of interest to linguists for a different reason.
They lie at the very end of a migration route that might have been taken by the first modern humans, who left Africa some 50,000 years ago, and that few others may have reached.
These early people reached Australia 5,000 years later and were established in the Bismarcks and Solomons by 35,000 years ago. A much later group of emigrants, people speaking Austronesian, is known to have reached the islands about 4,000 years ago from a home base in Taiwan.
The Austronesian languages are a distinctive family with many shared words. Many Papuan languages, by contrast, have lost any obvious relationship with each other, a sign of great antiquity.
William Foley, a linguist at the University of Sydney, has noted that the word structure of the Bougainville languages resembles those of Trans New Guinea, the languages spoken in a broad swath across the New Guinea highlands.
He has also found similarities between the Trans New Guinea languages and those of Australia, to which the island of Papua New Guinea was joined until 8,000 years ago in a super continent known as Sahul.
Could all these languages be echoes of the ancient tongue spoken by the first humans to arrive in Sahul? "That is part of the reason why we care about these languages and continue to look at them," Dr. Dunn said.
His work is part of a joint project by British, Dutch, German and Swedish researchers to study the languages, genetics and archaeology of people in the Bismarcks-Solomons archipelago and see if the history of Papuan speakers can be reconstructed.
Although all the non-Austronesian languages in the region are called Papuan, they do not have much in common with each other because time has erased most of their common vocabulary. Whether the remaining shared vocabulary is enough to establish relationships between the languages is a matter of dispute.
The late Joseph Greenberg, the great classifier of the world's languages, believed that all the Papuan languages, along with those of Tasmania and the Andaman Islands, belonged to a family he called Indo-Pacific.
Many linguists, including Dr. Dunn, reject Dr. Greenberg's grouping on the grounds that there are not enough remaining words of clearly common origin to define relationships between the Papuan languages. That was why Dr. Dunn's team sought to link the languages through grammatical features, borrowing a statistical approach used by biologists to connect related objects in the most plausible way.
Dr. Merritt Ruhlen, a colleague of Dr. Greenberg's, criticized Dr. Dunn's team for calling the languages of the region "a group of hitherto unrelatable isolates," since Dr. Greenberg had related them on the basis of their shared vocabulary and with much the same result as the grammar-based method.
But Russell Gray, a biologist at the University of Auckland in New Zealand who has pioneered applying biological tree-drawing methods to linguistics, writes in Science that the grammar-based approach will be "widely emulated" by researchers studying languages in other regions of the world. The new technique is "very promising," he said in an e-mail message.
The ancient Papuan languages of the islands east of Papua New Guinea have few words left in common, but can be linked by their grammar, right. The network shows the Bougainville languages are closest to those of the Solomons, suggesting these two archipelagos and the Bismarck Islands may have been colonized separately.
A Devil's Garden, Tended by Ants
By HENRY FOUNTAIN, The New York Times, September 27, 2005
In the song "High Hopes," a lowly ant moves a rubber tree. That's absurd, of course, because anyone knows an ant can't move a rubber tree plant.
But in the Peruvian Amazon, there is an ant that is a remarkable landscaper. It clears out all except a single species of tree from patches of the rain forest.
That's the finding of Megan E. Frederickson, a doctoral student at Stanford, who studied what are known locally as devil's gardens, areas up to about a third of an acre that are dominated almost entirely by one type of tree, D. hirsuta.
Local legend has it that the patches are the work of a forest spirit. Scientists had two theories: D. hirsuta itself might be responsible, by producing a soil chemical that is toxic to other species. Or an ant that lives in tiny cavities in the trees, M. schumanni, might do the work.
Ms. Frederickson's field observations showed that the ants attacked saplings of other species, injecting the leaves with formic acid. "Not only did it seem like the ants are responsible, but they are doing it in a really fascinating manner," she said.
Many other ant species use this chemical to kill off parasites or attackers. But M. schumanni, Ms. Frederickson said, is the first known to use the acid as an herbicide.
"They actually attack plants in the same way that other ants in this family would attack another insect," she said. "They grab the tissue with their mandibles, make a hole in it, stick their abdomen in and release a couple of drops."
Her experiments, described in the journal Nature, show that the saplings lose most of their leaves within five days and die within several weeks. Ms. Frederickson said it appeared that the ants used chemical cues to determine which species to attack.
The behavior benefits both the D. hirsuta and M. schumanni. With no competing species, the trees get more light, nutrients and water. And as more of the trees grow and the devil's garden expands, the ants get more places to live.
M. schumanni colonies can be extremely large, with a million or more workers and as many as 15,000 queens. Colonies can exist for centuries, as Ms. Frederickson discovered when she analyzed the growth rates of the 26 plots in her study. The largest one, with 351 trees, had been tended by the same ant colony for more than 800 years.
In Heeding Health Warnings, Memory Can Be Tricky
By DEBORAH FRANKLIN, The New York Times, September 27, 2005
In briefing consumers on health risks, public health campaigns often rely on a catchy strategy: they list the myths about a behavior or product, then follow up those misconceptions with the truth.
Check any Internet search engine and you will find "myths and facts" on health topics like abortion, acne, vaccines and weight loss. But new research suggests that even the sharpest consumer can be tripped up by these warnings because of a flaw in the way we remember what we read or are told.
As time passes, the studies show, people remember the health information they were given. But they forget which part was myth, and which was the truth. Experts say consumers and doctors need to be aware of this problem so they can make sure that quirks of memory do not harm anyone's health.
"Here's what happens," said Ian Skurnik, a psychologist and assistant professor of marketing at the University of Toronto, who worked with colleagues from the University of Michigan to study the phenomenon.
"You notice that your grandmother has been taking useless medical treatments, and you're worried," he said. "You tell her, 'You know, Granny, shark cartilage doesn't help your arthritis.' You tell her three times to make sure she understands, and she seems to."
He continued, "But a few days later you talk to her again and find the warnings have had precisely the opposite effect of what you intended." This common problem arises, Dr. Skurnik said, because in laying down a memory trace, the human brain seems to encode the memory of the claim separately from its context - who said it, when and other particulars, including the important fact that the claim is not true.
The detailed memory of the experience of learning the information begins to fade almost immediately, and the contextual clues fade faster than the core claim.
"Long after you've forgotten the context, the claim will still seem vaguely familiar," Dr. Skurnik said. That is when a well-documented effect that Dr. Skurnik calls "the illusion of truth" kicks in.
Numerous studies over the last few decades have shown that unless people have some countervailing context or information to grab hold of, they tend to regard information that seems familiar as true.
To test the power of that effect related to health claims, Dr. Skurnik and colleagues gave 64 volunteers a few dozen bits of unrelated medical information that they were unlikely to have heard before, like "Corn chips contain twice as much fat as potato chips" and "Aspirin destroys tooth enamel."
The researchers arbitrarily labeled half the statements false and half as true. Each item was read aloud and simultaneously presented on a computer screen at least once, but half the items appeared three times within the list.
Half the volunteers were college students ages 18 to 25. The others were healthy adults, ages 71 to 86. Thirty minutes after the volunteers had seen the information, the researchers showed them another list of items that contained all the previous statements, with some new items mixed in.
They were asked to identify which statements were false, which were true and which were new. The same kind of quiz was repeated three days later.
The results, published in the March 2005 issue of The Journal of Consumer Research, showed that the older adults were much more likely than the younger ones to misremember the false statements as true, an effect that was exacerbated three days later.
What's more, having seen a statement three times in the initial list helped the younger people remember it correctly, but made things worse for the older volunteers.
"Even quite elderly people remain good detectors of information that's new, versus something they have seen before," Dr. Skurnik said. "But in this case, that ability worked against them." The repetition of a warning underscored its familiarity.
The implications of the findings are not limited to older people, Dr. Skurnik said.
In a follow-up study not yet published, he and his colleagues presented college-age volunteers with a health information pamphlet from the Web site of the Centers for Disease Control and Prevention, called "Is It a Flu Shot Fact or Myth?"
In boldface type, the pamphlet contained eight statements about the flu vaccine - six labeled false, one true and one "maybe." Each statement was followed by a sentence or two of explanation in smaller type.
"Immediately after reading the flier, participants made few mistakes in recalling whether a particular statement from the flyer was described as a fact or myth, and there was no difference in the type of mistake," the researchers reported. "However," the researchers continued, "after a half an hour, participants were much more likely to misremember a fact as a myth."
"I think the message to physicians from this study and others is that even if you have lots to tell your patient in an office visit, you have to tell them several ways and over time to make sure they understand," said Dr. Joanne Schwartzberg, who oversees the health literacy program of the American Medical Association.
Dr. Schwartzberg advises patients never to worry about saying to a doctor: " 'Wait a minute, I need a little more time to see if I've got that right. When I go home, you want me to do this; is that right?' "
Putting complicated health instructions in your own words and repeating them aloud should help anchor the information accurately in your memory.
But Dr. Skurnik said, "Don't trust your memory."
Office visits are often time-pressured, anxiety-provoking, and packed with new and technical information - exactly the conditions most likely to jumble a memory of what was said. Whenever possible, get written information from the doctor, he said, and take a notebook to appointments to jot down instructions. It can also help to take along a friend or family member.
Patients under the intense stress of a new diagnosis may be those most likely to scan headlines and sift through Web pages in search of information. Print out what you read online, Dr. Skurnik suggested, so that you can go back later and identify the source of the information, as well as the particulars.
And doctors, he said, would do well to make sure that anything they hand out is written in simple, direct factual language.
"It's not enough to ensure that people get good information from credible sources," Dr. Skurnik said. "You also have to make sure that they'll be able to recall whether it's true or false later on."
The Very Cold Case of the Glacier
By GLENN COLLINS, The New York Times, September 14, 2005
Somewhere around 18,000 years ago, a glacier began to die.
It just so happens that this deglaciation - the more correct term for an expiring ice sheet - is an ancient climatological whodunit. And therefore, on a recent afternoon, like a homicide detective trying to clear a very old case, Joerg Schaefer was placing a small chunk of quartz from Central Park in his sample bag.
What, then, killed the glacier, and how long did it take to die? "We don't really know," said Dr. Schaefer, a researcher at the Lamont-Doherty Earth Observatory at Columbia University. Though his methodical quest could seem of interest only to geology buffs, it may shed new light on the accelerating and persistently controversial phenomenon of global warming, which has chased glaciers into retreat across the planet and could bring New Orleans-style flooding to coastal cities around the world.
The New York region was once covered by a vast crystalline shield of frozen water, known as the Laurentide ice sheet. It carved the terrain of the metropolitan area, and as it melted, dumped so much transported rock, gravel, sand and sediment that it created parts of Long Island, Connecticut and New Jersey - including the barrier islands at the coast. It also deposited such notable landforms as Battle Hill, in the Green-Wood Cemetery in Brooklyn.
"The rocks of New York City are a climate archive," Dr. Schaefer said. Most New Yorkers are unaware "that they are living in the middle of a glacial event park," he said, adding: "All they need do is open their eyes. By looking into the past, we can learn about the sensitivity of glaciers as climate indicators."
The disappearance of the ancient glacier "could relate directly to the current situation," he said, "and this could be of some concern."
And so, on Long Island, in Manhattan, and at locations up the Hudson River toward Albany, Dr. Schaefer, 36, and his three-scientist team are measuring the retreat velocity of the last glacier. What makes this possible for the first time is a new age-measuring technique that has one simple, but seemingly unreasonable, requirement: the testing of relatively clean surfaces that have been undisturbed for 18,000 years.
Enter, Central Park.
Not to mention Marcus Garvey Park in Harlem; Inwood and Morningside Parks on the West Side of Manhattan; a pristine glacial expanse in Harriman State Park; and even a truck-size glacial boulder in Port Jefferson, N.Y. (a parking lot was built around it, given its size). "It's spectacular that in such an urban setting, there are these completely ancient features," Dr. Schaefer said.
In Central Park, for example, much of the visible bedrock was shaped by ice, and unmodified glacial features abound. They include striations (abrasion grooves that show the flow direction from northwest to southeast), glacial polish (caused when rock was buffed by sediment), chatter marks (gouges in bedrock made by glacier-dragged stones), and erratics (boulders stranded on bedrock by the glacier).
One of the most impressive glacial remnants in Central Park is Umpire Rock (so called thanks to its proximity south of the Heckscher Ballfields), to the east of West 62nd Street, by the pétanque court.
The feature is a rarity in that its deep grooves reveal a carved channel and glacial fissures that suggest "possible evidence of subglacial streams," Dr. Schaefer said.
"As you see the deep grooves, you can almost imagine these big boulders gouging out the bedrock," said Neil Calvanese, vice president for operations of the Central Park Conservancy, which manages the park under a contract with the city.
Dr. Schaefer's Central Park rock sampling has been conducted with the park's official blessing. As Mr. Calvanese said, "We don't encourage people whacking at our rocks." Through the years, the park has attracted research endeavors from astronomy to environmental science. In 2002, a new invertebrate, Nannarrup hoffmani, was discovered there.
Scientists have also compared the park's ginkgo trees to fossil ginkgos whose leaves were munched by the dinosaurs. The United States Geological Survey has monitored ground water in the park, and Lamont has also maintained a seismograph in the North Meadow.
But for the first time in the park, Dr. Schaefer is employing a new scientific tool called "cosmogenic dating," a name that describes not a New Age mate-matching service but rather a pioneering way of measuring the age of landforms.
The key is to identify beryllium-10, an unstable isotope, or radionuclide, which forms in locations that have been struck by cosmic rays, including rock surfaces.
As glacial ice retreated, "it opened up the rock to cosmic rays," Dr. Schaefer said. "An isotope is created at the moment the cosmic rays strike the rock, and when the surface is exposed, the clock begins ticking." The unstable isotope formed in the rock has a half-life of 1.5 million years, a rate of radioactive decay that can be measured.
Beryllium-10 accumulates in quartz, which has veined much of New York City's bedrock, including the Manhattan schist that underlies Central Park. Precision in identifying glacially exposed quartz "is crucial in taking the samples," Dr. Schaefer said, not only to get the right data, but also because, at $500 to $2,000 per test, the geological team cannot afford to choose too many wrong outcrops.
Therefore, an unconventional but decidedly low-tech research tool was a 1782 British Headquarters map from the occupation of New York in the Revolutionary War. The team referenced its depiction of Manhattan's streams, lakes and landforms while roaming Central Park to identify undisturbed glacial outcrops.
Dr. Schaefer and his team chisel out small pieces of quartz, number them with red marker, digitally photograph them and fix their latitude and longitude with a global positioning unit. In the lab, the rock is pulverized and, in a complex process, beryllium-10 is isolated from contaminants, then measured with a mass spectrometer to determine how long ago it was exposed to cosmic rays.
"We can date the retreat of the glacier to within 500 years with prime samples," said Dr. Schaefer, who is a geochemist. He hopes to reconcile his glacial-dating techniques with the ages of Hudson River marine sediments and marsh sediments. And his team hopes that study of the British Headquarters map may yield clues about subglacial water channels and patterns of ice-sheet melting, which tended to dump erratics in north-south alignments.
Central Park may evidence some "boulder trains," lineups of glacial erratic boulders that could mark debris fields deposited by subterranean water channels or at the meeting points of "glacial lobes," fingers of the ice sheet that stretched southward, then melted northward.
One such alignment may begin with a large erratic perched 70 paces to the east of the Sheep Meadow Cafe at the meadow's northeast margin; to the south, another giant erratic marks the meadow's southeastern margin, roughly parallel to West 67th Street. Two other large erratics to the south may be part of this train.
However, "there are boulders in the park that seem to be obviously placed," Mr. Calvanese said. "Luckily, Olmsted didn't move the rock outcroppings," he said of Frederick Law Olmsted, who designed the park with Calvert Vaux. The last glacial maximum - the greatest extent of the ice sheet - was 18,000 years ago, and the Lamont team has been comparing its Central Park age measurements with samples taken by Dr. Schaefer in Switzerland, New Zealand, the Tibetan Plateau and the Sierra Nevadas. His team is still identifying new sampling locations and analyzing data so that its key findings can be submitted for peer review.
So far, though, the worldwide evidence indicates that "wherever we look, the glacier seems to have decided to retreat at the same time - roughly 18,000 years ago," he said. "We have to figure out what global mechanism triggered this, if it is true."
Although it has been long believed that ice sheets took a long time to melt, glacial systems "may be much more quickly moving than we thought before, and they may react on pretty small climate changes in a very dramatic way," Dr. Schaefer said. "The indications are that the rate of collapse is faster than previously believed." Some scientists have theorized that the rapid melting of prehistoric glaciers could have triggered powerful climatic change. Eventually, as the last ice sheet melted, the planet entered the relatively warm, unusually stable interglacial era it currently enjoys.
If the last deglaciation happened rapidly, as Dr. Schaefer's research may indicate, it could mean that the current ice retreat - seen from Peru to Tibet to Greenland - could also switch from slow to abrupt. Some scientists are concerned that this could accelerate the ongoing rise in sea levels, and potentially add enough fresh water to the Atlantic to block the warm Gulf Stream, cooling Europe and perhaps the Northeast.
In other words, a modern counterpart of the 18,000-year-old global-warming event could trigger a new ice age. "Historically, interglacials are rare in the cold history of the planet," Dr. Schaefer said. "The system is perfect now for humans to be here, and it seems extremely fragile. If you push it out of stability, it could get dramatically worse."
By NICHOLAS WADE, The New York Times, September 27, 2005
Linguists have devised a new way of linking languages, which they say has allowed them to reconstruct a network of the languages spoken in islands near New Guinea.
The new method is designed for languages so old that little trace of their common vocabulary remains. It forges connections between languages through grammatical features, which change less quickly than words.
With the new tool, historians may be able to peer considerably further back in time than the 5,000 to 7,000 years or so that many linguists see as the limit beyond which no sure connections can be made between languages.
The authors of the new method say the relationships they can construct may be 10,000 years or older.
The researchers, who were led by Michael Dunn, of the Max Planck Institute for Psycholinguistics in Nijmegen, Holland, have published their work in the current issue of Science.
They say that on the basis of grammatical similarities they have constructed a network of the Papuan languages spoken in the island groups east of Papua New Guinea. Traveling eastward, these are the Bismarck Islands, Bougainville and the Solomon Islands.
The grammar-derived network correctly assigns all languages to their respective archipelagos, showing it has picked up the relatedness to be expected from geography. But the network gives a puzzling placement to the Solomon Island languages.
They fall in between those of the Bismarcks and Bougainville, stepping out of the sequence expected if the islands were first occupied by people migrating from west to east.
The explanation, Dr. Dunn and his colleagues say, is that 10,000 years ago, when sea levels were much lower because of the Pleistocene ice age, Bougainville and the Solomon Islands would have been joined in a single land mass, while the Bismarcks were always separate.
This might explain the Bougainville languages' closer relationship to those of the Solomons and distance from those of the Bismarcks. It would also indicate that the grammar-based linking is picking up a signal from 10,000 years ago.
The Solomons are well known as the arena in which American and Japanese forces clashed in World War II in the battle at Guadalcanal. They are of interest to linguists for a different reason.
They lie at the very end of a migration route that might have been taken by the first modern humans, who left Africa some 50,000 years ago, and that few others may have reached.
These early people reached Australia 5,000 years later and were established in the Bismarcks and Solomons by 35,000 years ago. A much later group of emigrants, people speaking Austronesian, is known to have reached the islands about 4,000 years ago from a home base in Taiwan.
The Austronesian languages are a distinctive family with many shared words. Many Papuan languages, by contrast, have lost any obvious relationship with each other, a sign of great antiquity.
William Foley, a linguist at the University of Sydney, has noted that the word structure of the Bougainville languages resembles those of Trans New Guinea, the languages spoken in a broad swath across the New Guinea highlands.
He has also found similarities between the Trans New Guinea languages and those of Australia, to which the island of Papua New Guinea was joined until 8,000 years ago in a super continent known as Sahul.
Could all these languages be echoes of the ancient tongue spoken by the first humans to arrive in Sahul? "That is part of the reason why we care about these languages and continue to look at them," Dr. Dunn said.
His work is part of a joint project by British, Dutch, German and Swedish researchers to study the languages, genetics and archaeology of people in the Bismarcks-Solomons archipelago and see if the history of Papuan speakers can be reconstructed.
Although all the non-Austronesian languages in the region are called Papuan, they do not have much in common with each other because time has erased most of their common vocabulary. Whether the remaining shared vocabulary is enough to establish relationships between the languages is a matter of dispute.
The late Joseph Greenberg, the great classifier of the world's languages, believed that all the Papuan languages, along with those of Tasmania and the Andaman Islands, belonged to a family he called Indo-Pacific.
Many linguists, including Dr. Dunn, reject Dr. Greenberg's grouping on the grounds that there are not enough remaining words of clearly common origin to define relationships between the Papuan languages. That was why Dr. Dunn's team sought to link the languages through grammatical features, borrowing a statistical approach used by biologists to connect related objects in the most plausible way.
Dr. Merritt Ruhlen, a colleague of Dr. Greenberg's, criticized Dr. Dunn's team for calling the languages of the region "a group of hitherto unrelatable isolates," since Dr. Greenberg had related them on the basis of their shared vocabulary and with much the same result as the grammar-based method.
But Russell Gray, a biologist at the University of Auckland in New Zealand who has pioneered applying biological tree-drawing methods to linguistics, writes in Science that the grammar-based approach will be "widely emulated" by researchers studying languages in other regions of the world. The new technique is "very promising," he said in an e-mail message.
The ancient Papuan languages of the islands east of Papua New Guinea have few words left in common, but can be linked by their grammar, right. The network shows the Bougainville languages are closest to those of the Solomons, suggesting these two archipelagos and the Bismarck Islands may have been colonized separately.
A Devil's Garden, Tended by Ants
By HENRY FOUNTAIN, The New York Times, September 27, 2005
In the song "High Hopes," a lowly ant moves a rubber tree. That's absurd, of course, because anyone knows an ant can't move a rubber tree plant.
But in the Peruvian Amazon, there is an ant that is a remarkable landscaper. It clears out all except a single species of tree from patches of the rain forest.
That's the finding of Megan E. Frederickson, a doctoral student at Stanford, who studied what are known locally as devil's gardens, areas up to about a third of an acre that are dominated almost entirely by one type of tree, D. hirsuta.
Local legend has it that the patches are the work of a forest spirit. Scientists had two theories: D. hirsuta itself might be responsible, by producing a soil chemical that is toxic to other species. Or an ant that lives in tiny cavities in the trees, M. schumanni, might do the work.
Ms. Frederickson's field observations showed that the ants attacked saplings of other species, injecting the leaves with formic acid. "Not only did it seem like the ants are responsible, but they are doing it in a really fascinating manner," she said.
Many other ant species use this chemical to kill off parasites or attackers. But M. schumanni, Ms. Frederickson said, is the first known to use the acid as an herbicide.
"They actually attack plants in the same way that other ants in this family would attack another insect," she said. "They grab the tissue with their mandibles, make a hole in it, stick their abdomen in and release a couple of drops."
Her experiments, described in the journal Nature, show that the saplings lose most of their leaves within five days and die within several weeks. Ms. Frederickson said it appeared that the ants used chemical cues to determine which species to attack.
The behavior benefits both the D. hirsuta and M. schumanni. With no competing species, the trees get more light, nutrients and water. And as more of the trees grow and the devil's garden expands, the ants get more places to live.
M. schumanni colonies can be extremely large, with a million or more workers and as many as 15,000 queens. Colonies can exist for centuries, as Ms. Frederickson discovered when she analyzed the growth rates of the 26 plots in her study. The largest one, with 351 trees, had been tended by the same ant colony for more than 800 years.
In Heeding Health Warnings, Memory Can Be Tricky
By DEBORAH FRANKLIN, The New York Times, September 27, 2005
In briefing consumers on health risks, public health campaigns often rely on a catchy strategy: they list the myths about a behavior or product, then follow up those misconceptions with the truth.
Check any Internet search engine and you will find "myths and facts" on health topics like abortion, acne, vaccines and weight loss. But new research suggests that even the sharpest consumer can be tripped up by these warnings because of a flaw in the way we remember what we read or are told.
As time passes, the studies show, people remember the health information they were given. But they forget which part was myth, and which was the truth. Experts say consumers and doctors need to be aware of this problem so they can make sure that quirks of memory do not harm anyone's health.
"Here's what happens," said Ian Skurnik, a psychologist and assistant professor of marketing at the University of Toronto, who worked with colleagues from the University of Michigan to study the phenomenon.
"You notice that your grandmother has been taking useless medical treatments, and you're worried," he said. "You tell her, 'You know, Granny, shark cartilage doesn't help your arthritis.' You tell her three times to make sure she understands, and she seems to."
He continued, "But a few days later you talk to her again and find the warnings have had precisely the opposite effect of what you intended." This common problem arises, Dr. Skurnik said, because in laying down a memory trace, the human brain seems to encode the memory of the claim separately from its context - who said it, when and other particulars, including the important fact that the claim is not true.
The detailed memory of the experience of learning the information begins to fade almost immediately, and the contextual clues fade faster than the core claim.
"Long after you've forgotten the context, the claim will still seem vaguely familiar," Dr. Skurnik said. That is when a well-documented effect that Dr. Skurnik calls "the illusion of truth" kicks in.
Numerous studies over the last few decades have shown that unless people have some countervailing context or information to grab hold of, they tend to regard information that seems familiar as true.
To test the power of that effect related to health claims, Dr. Skurnik and colleagues gave 64 volunteers a few dozen bits of unrelated medical information that they were unlikely to have heard before, like "Corn chips contain twice as much fat as potato chips" and "Aspirin destroys tooth enamel."
The researchers arbitrarily labeled half the statements false and half as true. Each item was read aloud and simultaneously presented on a computer screen at least once, but half the items appeared three times within the list.
Half the volunteers were college students ages 18 to 25. The others were healthy adults, ages 71 to 86. Thirty minutes after the volunteers had seen the information, the researchers showed them another list of items that contained all the previous statements, with some new items mixed in.
They were asked to identify which statements were false, which were true and which were new. The same kind of quiz was repeated three days later.
The results, published in the March 2005 issue of The Journal of Consumer Research, showed that the older adults were much more likely than the younger ones to misremember the false statements as true, an effect that was exacerbated three days later.
What's more, having seen a statement three times in the initial list helped the younger people remember it correctly, but made things worse for the older volunteers.
"Even quite elderly people remain good detectors of information that's new, versus something they have seen before," Dr. Skurnik said. "But in this case, that ability worked against them." The repetition of a warning underscored its familiarity.
The implications of the findings are not limited to older people, Dr. Skurnik said.
In a follow-up study not yet published, he and his colleagues presented college-age volunteers with a health information pamphlet from the Web site of the Centers for Disease Control and Prevention, called "Is It a Flu Shot Fact or Myth?"
In boldface type, the pamphlet contained eight statements about the flu vaccine - six labeled false, one true and one "maybe." Each statement was followed by a sentence or two of explanation in smaller type.
"Immediately after reading the flier, participants made few mistakes in recalling whether a particular statement from the flyer was described as a fact or myth, and there was no difference in the type of mistake," the researchers reported. "However," the researchers continued, "after a half an hour, participants were much more likely to misremember a fact as a myth."
"I think the message to physicians from this study and others is that even if you have lots to tell your patient in an office visit, you have to tell them several ways and over time to make sure they understand," said Dr. Joanne Schwartzberg, who oversees the health literacy program of the American Medical Association.
Dr. Schwartzberg advises patients never to worry about saying to a doctor: " 'Wait a minute, I need a little more time to see if I've got that right. When I go home, you want me to do this; is that right?' "
Putting complicated health instructions in your own words and repeating them aloud should help anchor the information accurately in your memory.
But Dr. Skurnik said, "Don't trust your memory."
Office visits are often time-pressured, anxiety-provoking, and packed with new and technical information - exactly the conditions most likely to jumble a memory of what was said. Whenever possible, get written information from the doctor, he said, and take a notebook to appointments to jot down instructions. It can also help to take along a friend or family member.
Patients under the intense stress of a new diagnosis may be those most likely to scan headlines and sift through Web pages in search of information. Print out what you read online, Dr. Skurnik suggested, so that you can go back later and identify the source of the information, as well as the particulars.
And doctors, he said, would do well to make sure that anything they hand out is written in simple, direct factual language.
"It's not enough to ensure that people get good information from credible sources," Dr. Skurnik said. "You also have to make sure that they'll be able to recall whether it's true or false later on."
The Very Cold Case of the Glacier
By GLENN COLLINS, The New York Times, September 14, 2005
Somewhere around 18,000 years ago, a glacier began to die.
It just so happens that this deglaciation - the more correct term for an expiring ice sheet - is an ancient climatological whodunit. And therefore, on a recent afternoon, like a homicide detective trying to clear a very old case, Joerg Schaefer was placing a small chunk of quartz from Central Park in his sample bag.
What, then, killed the glacier, and how long did it take to die? "We don't really know," said Dr. Schaefer, a researcher at the Lamont-Doherty Earth Observatory at Columbia University. Though his methodical quest could seem of interest only to geology buffs, it may shed new light on the accelerating and persistently controversial phenomenon of global warming, which has chased glaciers into retreat across the planet and could bring New Orleans-style flooding to coastal cities around the world.
The New York region was once covered by a vast crystalline shield of frozen water, known as the Laurentide ice sheet. It carved the terrain of the metropolitan area, and as it melted, dumped so much transported rock, gravel, sand and sediment that it created parts of Long Island, Connecticut and New Jersey - including the barrier islands at the coast. It also deposited such notable landforms as Battle Hill, in the Green-Wood Cemetery in Brooklyn.
"The rocks of New York City are a climate archive," Dr. Schaefer said. Most New Yorkers are unaware "that they are living in the middle of a glacial event park," he said, adding: "All they need do is open their eyes. By looking into the past, we can learn about the sensitivity of glaciers as climate indicators."
The disappearance of the ancient glacier "could relate directly to the current situation," he said, "and this could be of some concern."
And so, on Long Island, in Manhattan, and at locations up the Hudson River toward Albany, Dr. Schaefer, 36, and his three-scientist team are measuring the retreat velocity of the last glacier. What makes this possible for the first time is a new age-measuring technique that has one simple, but seemingly unreasonable, requirement: the testing of relatively clean surfaces that have been undisturbed for 18,000 years.
Enter, Central Park.
Not to mention Marcus Garvey Park in Harlem; Inwood and Morningside Parks on the West Side of Manhattan; a pristine glacial expanse in Harriman State Park; and even a truck-size glacial boulder in Port Jefferson, N.Y. (a parking lot was built around it, given its size). "It's spectacular that in such an urban setting, there are these completely ancient features," Dr. Schaefer said.
In Central Park, for example, much of the visible bedrock was shaped by ice, and unmodified glacial features abound. They include striations (abrasion grooves that show the flow direction from northwest to southeast), glacial polish (caused when rock was buffed by sediment), chatter marks (gouges in bedrock made by glacier-dragged stones), and erratics (boulders stranded on bedrock by the glacier).
One of the most impressive glacial remnants in Central Park is Umpire Rock (so called thanks to its proximity south of the Heckscher Ballfields), to the east of West 62nd Street, by the pétanque court.
The feature is a rarity in that its deep grooves reveal a carved channel and glacial fissures that suggest "possible evidence of subglacial streams," Dr. Schaefer said.
"As you see the deep grooves, you can almost imagine these big boulders gouging out the bedrock," said Neil Calvanese, vice president for operations of the Central Park Conservancy, which manages the park under a contract with the city.
Dr. Schaefer's Central Park rock sampling has been conducted with the park's official blessing. As Mr. Calvanese said, "We don't encourage people whacking at our rocks." Through the years, the park has attracted research endeavors from astronomy to environmental science. In 2002, a new invertebrate, Nannarrup hoffmani, was discovered there.
Scientists have also compared the park's ginkgo trees to fossil ginkgos whose leaves were munched by the dinosaurs. The United States Geological Survey has monitored ground water in the park, and Lamont has also maintained a seismograph in the North Meadow.
But for the first time in the park, Dr. Schaefer is employing a new scientific tool called "cosmogenic dating," a name that describes not a New Age mate-matching service but rather a pioneering way of measuring the age of landforms.
The key is to identify beryllium-10, an unstable isotope, or radionuclide, which forms in locations that have been struck by cosmic rays, including rock surfaces.
As glacial ice retreated, "it opened up the rock to cosmic rays," Dr. Schaefer said. "An isotope is created at the moment the cosmic rays strike the rock, and when the surface is exposed, the clock begins ticking." The unstable isotope formed in the rock has a half-life of 1.5 million years, a rate of radioactive decay that can be measured.
Beryllium-10 accumulates in quartz, which has veined much of New York City's bedrock, including the Manhattan schist that underlies Central Park. Precision in identifying glacially exposed quartz "is crucial in taking the samples," Dr. Schaefer said, not only to get the right data, but also because, at $500 to $2,000 per test, the geological team cannot afford to choose too many wrong outcrops.
Therefore, an unconventional but decidedly low-tech research tool was a 1782 British Headquarters map from the occupation of New York in the Revolutionary War. The team referenced its depiction of Manhattan's streams, lakes and landforms while roaming Central Park to identify undisturbed glacial outcrops.
Dr. Schaefer and his team chisel out small pieces of quartz, number them with red marker, digitally photograph them and fix their latitude and longitude with a global positioning unit. In the lab, the rock is pulverized and, in a complex process, beryllium-10 is isolated from contaminants, then measured with a mass spectrometer to determine how long ago it was exposed to cosmic rays.
"We can date the retreat of the glacier to within 500 years with prime samples," said Dr. Schaefer, who is a geochemist. He hopes to reconcile his glacial-dating techniques with the ages of Hudson River marine sediments and marsh sediments. And his team hopes that study of the British Headquarters map may yield clues about subglacial water channels and patterns of ice-sheet melting, which tended to dump erratics in north-south alignments.
Central Park may evidence some "boulder trains," lineups of glacial erratic boulders that could mark debris fields deposited by subterranean water channels or at the meeting points of "glacial lobes," fingers of the ice sheet that stretched southward, then melted northward.
One such alignment may begin with a large erratic perched 70 paces to the east of the Sheep Meadow Cafe at the meadow's northeast margin; to the south, another giant erratic marks the meadow's southeastern margin, roughly parallel to West 67th Street. Two other large erratics to the south may be part of this train.
However, "there are boulders in the park that seem to be obviously placed," Mr. Calvanese said. "Luckily, Olmsted didn't move the rock outcroppings," he said of Frederick Law Olmsted, who designed the park with Calvert Vaux. The last glacial maximum - the greatest extent of the ice sheet - was 18,000 years ago, and the Lamont team has been comparing its Central Park age measurements with samples taken by Dr. Schaefer in Switzerland, New Zealand, the Tibetan Plateau and the Sierra Nevadas. His team is still identifying new sampling locations and analyzing data so that its key findings can be submitted for peer review.
So far, though, the worldwide evidence indicates that "wherever we look, the glacier seems to have decided to retreat at the same time - roughly 18,000 years ago," he said. "We have to figure out what global mechanism triggered this, if it is true."
Although it has been long believed that ice sheets took a long time to melt, glacial systems "may be much more quickly moving than we thought before, and they may react on pretty small climate changes in a very dramatic way," Dr. Schaefer said. "The indications are that the rate of collapse is faster than previously believed." Some scientists have theorized that the rapid melting of prehistoric glaciers could have triggered powerful climatic change. Eventually, as the last ice sheet melted, the planet entered the relatively warm, unusually stable interglacial era it currently enjoys.
If the last deglaciation happened rapidly, as Dr. Schaefer's research may indicate, it could mean that the current ice retreat - seen from Peru to Tibet to Greenland - could also switch from slow to abrupt. Some scientists are concerned that this could accelerate the ongoing rise in sea levels, and potentially add enough fresh water to the Atlantic to block the warm Gulf Stream, cooling Europe and perhaps the Northeast.
In other words, a modern counterpart of the 18,000-year-old global-warming event could trigger a new ice age. "Historically, interglacials are rare in the cold history of the planet," Dr. Schaefer said. "The system is perfect now for humans to be here, and it seems extremely fragile. If you push it out of stability, it could get dramatically worse."
