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Long-Term Global Forecast? Fewer Continents
By WILLIAM J. BROAD, The New York Times, January 9, 2007
Kiss the Mediterranean goodbye. Ditto the Red Sea and its wonderland of coral reefs and exotic sea life. And prepare for the day when San Francisco has a gritty new suburb: Los Angeles. Indeed, much of Southern California, including the Baja Peninsula, will eventually migrate up the west coast to make Alaska even more gargantuan.
Geologists have long prided themselves on their ability to peer into the distant past and discern the slow movements of land and sea that have continuously revised the planet’s face over eons. Now, drawing on new insights, theories, measurements and technologies — and perhaps a bit of scientific bravado — they are forecasting the shape of terra firma in the distant future.
The maps and animations by these scientists are helping explain core principles of geology to increasingly wide audiences. Schools, textbooks, museums, Web sites and television shows now routinely feature images of what the forecasters say the planet will look like eons from now. And geologists are using the forecasts to deepen their own investigations of plate tectonics.
“It’s tremendous,” said Warren J. Nokleberg, a senior research geologist at the United States Geological Survey in Menlo Park, Calif. “It lets students and scientists better appreciate the mobile Earth, to see where it’s going. That’s very powerful.”
Practitioners acknowledge that their predictions, however intriguing, become more theoretical when pushed far into the future, as with advanced weather forecasts. Their most ambitious efforts peer 250 million years ahead. But their more short-term predictions, they note, draw on mountains of geophysical data and involve relatively small extrapolations of current trends, like the steady northward march of Southern California.
Despite uncertainties, the field of geopredictions is booming. One Web site has received almost 30 million hits since its debut in 1998, and the field’s admirers now include top scientists.
“It’s quite good pedagogically,” said Frank Press, a geologist and past president of the National Academy of Sciences. “It captures the attention.”
Dr. Press features one of the forecasts in his introductory college text, “Understanding Earth” (Freeman, 2006). He and three co-authors present a snapshot of how the planet’s surface might look 50 million years from now, calling it “a plausible scenario.”
Among other things, the snapshot shows that Africa has drifted to the north, plowing into Europe and fusing the two landmasses, eliminating the Mediterranean Sea and replacing it with the Mediterranean Mountains. The rugged range runs down the middle of a continent far bigger than current-day Eurasia, a giant new agglomeration that might be called Afrasia.
While peering 50 million years into the future may seem like a stretch, geologists consider such spans of time the blink of an eye. If one year represented Earth’s past, 50 million years would equal less than 4 days, or about the limit of accurate weather forecasts.
“Fifty million is fairly straightforward,” said Christopher R. Scotese, a geologist at the University of Texas, Arlington, who has pioneered the predictions in recent years. “It’s like you’re driving on the highway and you want to know where you’re going to be in 10 minutes. You check the speedometer, do a calculation, and project your present motion.
“But beyond 50 million years,” Dr. Scotese added, “like on the highway, unexpected things can happen.”
Forecasts of future continental motion developed slowly as offshoots of the theory of plate tectonics, which won acceptance in the 1960s and 1970s, shattering old dogmas of continental immobility. The theory of plate tectonics holds that the surface of Earth is composed of a dozen or so huge crustal slabs that float on a sea of partially molten rock. Over ages, hot convection currents in this sea, as well as gravitational forces, move the plates and their superimposed continents and ocean basins, tearing them apart and rearranging them like pieces of a giant jigsaw puzzle.
The theory, named for the Greek word “tekton,” or builder, is a study in slowness. Colliding plates grind past one another about as fast as fingernails grow.
Today, geologists measure such changes with great precision thanks to the advent of global positioning satellites and small base stations that dot remote areas of the planet and operate unattended. Arrays of such instruments track the overall movement of plates.
From the start of the theory’s acceptance, geologists worked hard to discover what plate tectonics revealed about Earth’s past and to render it in credible reconstructions. A famous result was Pangea — “all the land” in Greek — a supercontinent that some 200 million years ago held the outlines of today’s continents in embryonic form.
In 1970, Robert S. Dietz, who uncovered major clues to plate movement in the deep sea, wrote a Scientific American article on the breakup of Pangea. He also took a first step toward predicting the future, sketched out plausible continental shifts for the next 50 million years, and projected their local repercussions.
Dr. Dietz zeroed in on the San Andreas fault, the deep gash beneath California that spawned the devastating San Francisco earthquake of 1906 — one among many — and today also threatens the Los Angeles area. The fault marks the seam where the Pacific plate slides relentlessly northward past the North American plate.
Ten million years from now, Dr. Dietz wrote, “Los Angeles will be abreast of San Francisco.” And in another 50 million years, he added, Los Angeles will have moved up the west coast into Alaskan waters.
Such visualizations caught the eye of Dr. Scotese in the late 1970s when he was a graduate student at the University of Chicago. He loved the challenge of the big picture, and of using his computer programs, new to such work, to speed the endless drawing and redrawing. With his graduate adviser, he made detailed maps showing the past evolution of the continents. And he toyed with their future shapes.
In 1982, Dr. Scotese got a call from Discover magazine asking if he would consider a bigger project: envisioning Earth not 50 million years from now but 200 million.
“I said, ‘Hold on, how could I possibly project that far?’ ” he recalled. “But being a rash graduate student in need of extra change, I decided to give it a try.”
The effort forced him to think beyond simple extrapolations and come up with rules that could govern the onset of major tectonic events, like the formation of subduction zones, deep ocean trenches that gobble up seafloor and tear continents apart.
Dr. Scotese drew a series of futuristic maps and, in the 1990s, found an ideal way to communicate his increasingly detailed visions of the terrestrial past and future: over the Internet. Today, Dr. Scotese’s Web site, www.scotese.com, which he started in 1998, showcases his work, called the Paleomap Project. Teachers use his animations, and his site has won scientific awards. (He aids the publishing world, too, providing Dr. Press and his co-authors with their map of the future world.)
Today, some of his most ambitious efforts center on envisioning how Earth might look 250 million years from now. The easy part, Dr. Scotese said, is the continents. Their masses might change shape but seldom disappear altogether because their bedrock weighs little compared with dense ocean crust. Continents literally float above the action. So do mountains. Once formed, they tend to persist, disappearing only after ages of erosion wear them down.
The difficult part, he said, is predicting the development of new subduction zones in the seabed, and in comprehending how aggressively they rearrange the land.
“It’s hard to understand all the forces down there,” he said. “There’s probably some input from the mantle,” the deep, hot, churning zone below the crust. “It probably has some say on which way the plates go.”
His long-term forecast, despite the uncertainties, portrays a distant time when the world’s continents come together again to form a new supercontinent, which he calls Pangea Ultima.
An animated depiction of Pangea Ultima demonstrates a bold exercise in futuristic thinking. First, the Mediterranean closes. Then — 25 million to 75 million years from now — Australia moves north, slamming into Indonesia and Malaysia before pirouetting counterclockwise to smash into the Philippines and then Asia, eventually merging with it.
Antarctica also moves north, shedding its icecap. Roughly 100 million years from now, it plows into the Indian Ocean, and 50 million years later wedges itself between Madagascar and Indonesia. The Indian Ocean becomes a virtual inland sea.
Meanwhile, Dr. Scotese said, the biggest tectonic change of all — driven by a giant subduction zone — has torn through the dark Atlantic and begun to eat up seabed, slowly closing the ocean. Some 200 million years from now, the closure forces Newfoundland to smash into Africa and, a bit later, Brazil to ram into South Africa.
The collisions gain force; 250 million years from now, the continents will have merged into a new supercontinent that encircles what remains of the Indian Ocean.
“It’s more like a big donut or bagel than Pangea,” Dr. Scotese noted. In looking for a name, “I tried Bagelea or Donutea but figured that would trivialize the whole experience. A friend suggested Pangea Ultima — classy, like a fancy car. It implies that it’s the last Pangea, which certainly isn’t true, but it’s the last one I’m going to come up with.”
Over billions of years, the continents have split and joined repeatedly in a slow dance. They do so, geologists say, in two very dissimilar ways. As Dr. Scotese envisioned, they can break apart and reverse course to merge again. Or they can move apart until their paths around the planet cause them to coalesce on the far side.
Some forecasters see the current expansion — with no course reversal — as dominating the remainder of this tectonic cycle. Instead of the Atlantic disappearing, they say, the Pacific might slowly vanish, sending North and South America careering into Asia.
Sergei A. Pisarevsky, a geologist at the Tectonics Special Research Center of the University of Western Australia, calls the resulting supercontinent “Amasia.” But he said his vision bore no special likelihood of coming true. “My guess,” he said, “is that the Pacific should disappear.”
J. Brendan Murphy, a specialist on tectonic cycles at St. Francis Xavier University in Nova Scotia, echoed that view. Geologists, he said, know too little about the causes of plate motion to predict the dance of continents into the far future.
But in the next few decades, he added, progress in geology is likely to lay bare Earth’s inner workings and enhance the art of plate forecasting.
Even with today’s efforts, Dr. Murphy said, “all the coughing stops in class when I show a projection. It’s a very interesting way to look at the world.”
“The most important thing to realize,” he said, “is that modern geology is just a snapshot of a continuous-action movie. When you zoom out and look over a long enough time, you realize everything is mobile.”
Findings: All Is Not So Bad in the State of Denmark
By BENEDICT CAREY, The New York Times, January 9, 2007
Sweden has more blond beauties per capita, Italy and France have far better cuisine, and most of the free world can boast of better weather. But over the past 30 years, the citizens of Denmark have scored higher than any other Western country on measures of life satisfaction, and scientists think they know why.
In a paper appearing in the Dec. 23 issue of the medical journal BMJ, researchers review six likely and unlikely explanations, and conclude that the country’s secret is a culture of low expectations.
“It’s a David and Goliath thing,” said the lead author, Kaare Christensen, a professor of epidemiology at the University of Southern Denmark in Odense. “If you’re a big guy, you expect to be on the top all the time and you’re disappointed when things don’t go well. But when you’re down at the bottom like us, you hang on, you don’t expect much, and once in a while you win, and it’s that much better.”
The researchers arrived at their findings by a process of elimination and humor. Blonds may have more fun, they argue, but Sweden has a higher prevalence of them. As for climate, Danes “bask in a somewhat colder and cloudier version of the balmy English weather.” They also eat fatty foods and drink a lot, and genetically they are not significantly different from their gloomier Scandinavian neighbors. And in 1992 the Danes won the European Championship in soccer, creating “such a state of euphoria that the country has not been the same since.”
But on surveys, Danes continually report lower expectations for the year to come, compared with most other nations. And “year after year, they are pleasantly surprised to find that not everything is getting more rotten in the state of Denmark,” the paper concludes.
A Conversation With Nina G. Jablonski: Always Revealing, Human Skin Is an Anthropologist’s Map
By CLAUDIA DREIFUS, The New York Times, January 9, 2007
In an era of academic hyper-specialization, Dr. Nina G. Jablonski has an amazingly broad résumé. At 53, she heads the anthropology department at Pennsylvania State University. She’s also a primatologist, an evolutionary biologist and a paleontologist.
Last year, Dr. Jablonski led an expedition to China, where she dug for human fossils in an attempt to learn how early man coped with climate change. This month, she’s in Kenya, where she and Meave Leakey are putting together a study on prehistoric monkeys.
For more than a decade, Dr. Jablonski has been trying to get her arms around a ubiquitous and yet mysterious topic: the biology, evolution and social function of human skin. The results of her studies have been published by the University of California Press as “Skin: A Natural History.”
“Skin has been studied to absolute death by dermatologists,” Dr. Jablonski said jokingly during a recent visit to New York City. “They know it inside and out from the point of view of diseases that afflict it. What we wanted to learn was how human skin came to be as it is and what that meant for humanity.”
Q. What set you off on writing a natural history of human skin?
A. I had an insight in 1981, when I was teaching gross anatomy to medical students at the University of Hong Kong. The students had been presented with a cadaver to dissect, and they were tremendously frightened of it. However, their attitude changed the very moment they cut through the skin. With the skin gone, they began seeing it as a mere body devoid of a personal history, and they could get on with their work.
That moment showed me how much of what we consider our humanity is imbued in our skin. It stayed with me for a long time. Then about 15 years ago, I joined a project studying the natural history of skin color. The topic was so engrossing that I began looking into the larger question of what our skin does and is.
Q. And what have you found?
A. That skin is the most underappreciated of our organs. Unless we’re having the sort of problem that brings us to a dermatologist, we take our skin for granted. We never think of it as working very hard for our body or doing valuable things for us socially.
But when you really start thinking about it, it’s a factory that produces vitamin D, sweat, hormones, oils, wax, pigments — substances we need. Skin is a raincoat in that it protects us from water, bugs and noxious chemicals. It’s also a billboard which we adorn with powder, tattoos, piercing and scars to give off instant messages about our history, health, values and availability for mating.
On an evolutionary level, there are three remarkable facts about skin. It comes in colors, of course. Compared to other mammals, our skin is relatively hairless. And it’s sweaty. In the last few million years, humans became the sweatiest of mammals.
Q. Is that important?
A. Absolutely. It’s often said that our large brains are what made it possible for us to evolve from ape to human. But those big brains could never have developed if we didn’t have exceptionally sweaty skin.
It happened this way. There was a tremendous takeoff in human evolution about two million years ago when primates who could no longer be called apes appeared in the savannahs of East Africa. These early humans ran long distances in open areas. In order to survive in the equatorial sun, they needed to cool their brains. Early humans evolved an increased number of sweat glands for that purpose, which in turn permitted their brain size to expand. As soon as we developed larger brains, our planning capacity increased, and this allowed people to disperse out of Africa. There’s fossil evidence of humans appearing in Central Asia around this time.
Q. In a nutshell, what has your research shown about why humans have varying skin colors?
A. That it’s not about race — it’s about sun and about how close our ancestors lived to the Equator. Skin color is what regulates our body’s reaction to the sun and its rays. Dark skin evolved to protect the body from excessive sun rays. Light skin evolved when people migrated away from the Equator and needed to make vitamin D in their skin. To do that, they had to lose pigment. Repeatedly over history, many people moved dark to light and light to dark. That shows that color is not a permanent trait.
Q. Did early humans decorate their skin?
A. We don’t know. There’s no human skin in the fossil record. The oldest preserved skin we have is that of Ötzi, the Neolithic iceman whose mummified body was found in the Alps in 1991. Ötzi lived about 5,000 years ago. Interestingly, he has tattoos. But we can only guess what they mean.
Modern humans, we love to alter our skin. You’ll find very few people walking around today with unadorned skin. They might make permanent changes — piercing, scarring, tattooing — to memorialize events and announce their identity. Or they might use cosmetics for temporary alterations to announce their attractiveness, mood or sexual availability. The bottom line: humans are the self-decorating ape.
Q. I get the feeling that you think cosmetic use is some kind of ancient evolutionary behavior. Are we reading you correctly?
A. Evolution is all about attracting a mate and getting a chance to reproduce, so yes, makeup helps with that. When a woman uses eyeliner to make her eyes appear larger, she’s giving off a message: “I want you to see me as attractive.” Large eyes in a woman are almost universally seen as appealing. This is not just a girl thing. Male body paint in East Africa emphasizes forbidding facial expressions. They announce a man’s prowess as a warrior and as a mate.
Q. How do you feel about your own skin?
A. I like it. It is my unwritten biography. My skin reminds me that I’m a 53-year-old woman who has smiled and furrowed her brow and, on occasion, worked in the desert sun too long. I enjoy watching my skin change because it’s one of the few parts of my body that I can watch. We can’t view our livers or heart, but this we can. And yes, I use cosmetics. Like other humans, I have a penchant for changing my appearance easily and quickly. It also helps me feel more confident. That may seem silly, but I still do it.
Q. You made news in 2004 when you discovered the world’s oldest chimpanzee fossil. These were chimp teeth about a half-million years old. Where did you find them?
A. In a drawer at the National Museum of Kenya in Nairobi. I was rummaging through this bag labeled “fossil monkeys” and I saw it. “This doesn’t look like monkey,” I thought. It turned out they were from an early chimp. That find proved important because there had been no chimpanzee this old in the fossil record. By analyzing it, we’ve learned that chimpanzees in their current form have probably existed for longer than previously thought. (Laughs) Since my find, people have been rummaging through dusty museum drawers everywhere!
Vital Signs: Remedies: Small Study Raises a Question About Echinacea
By NICHOLAS BAKALAR, The New York Times, January 9, 2007
Some people take echinacea supplements in the hope that they will prevent or shorten colds, but a small study suggests that it may increase the number of intestinal bacteria associated with diarrhea, inflammatory bowel disease and an increased risk of colon cancer.
Researchers gave 15 volunteers 1,000 milligrams of Echinacea purpurea daily for 10 days. They collected stool samples before the supplementation, and at 10 days and 17 to 18 days after the volunteers had stopped taking the herb, then analyzed the samples for six types of bacteria. The study was published in December in The Journal of Clinical Pharmacy and Therapeutics.
After controlling for other diet variables, the scientists found significant increases in microbial counts for Bacteroides, Bacteroides fragilis, and total aerobic bacteria. There was no effect on enteric bacteria, enterococci, Lactobacillus, bifidobacteria, or total anaerobic bacteria.
“This changes the balance of the normal bacterial fauna,” said Jerald C. Foote, an assistant professor of human nutrition at the University of Arkansas. “But we don’t know yet what this means.”
Though the sample was small and the study was preliminary, the authors said it was the first to consider the effects of a botanical dietary supplement on gastrointestinal flora. Dr. Foote was not urging anyone to abandon echinacea. “I think we need a lot more research before we start taking echinacea off the shelves,” he said. “But this does raise some questions.”
By WILLIAM J. BROAD, The New York Times, January 9, 2007
Kiss the Mediterranean goodbye. Ditto the Red Sea and its wonderland of coral reefs and exotic sea life. And prepare for the day when San Francisco has a gritty new suburb: Los Angeles. Indeed, much of Southern California, including the Baja Peninsula, will eventually migrate up the west coast to make Alaska even more gargantuan.
Geologists have long prided themselves on their ability to peer into the distant past and discern the slow movements of land and sea that have continuously revised the planet’s face over eons. Now, drawing on new insights, theories, measurements and technologies — and perhaps a bit of scientific bravado — they are forecasting the shape of terra firma in the distant future.
The maps and animations by these scientists are helping explain core principles of geology to increasingly wide audiences. Schools, textbooks, museums, Web sites and television shows now routinely feature images of what the forecasters say the planet will look like eons from now. And geologists are using the forecasts to deepen their own investigations of plate tectonics.
“It’s tremendous,” said Warren J. Nokleberg, a senior research geologist at the United States Geological Survey in Menlo Park, Calif. “It lets students and scientists better appreciate the mobile Earth, to see where it’s going. That’s very powerful.”
Practitioners acknowledge that their predictions, however intriguing, become more theoretical when pushed far into the future, as with advanced weather forecasts. Their most ambitious efforts peer 250 million years ahead. But their more short-term predictions, they note, draw on mountains of geophysical data and involve relatively small extrapolations of current trends, like the steady northward march of Southern California.
Despite uncertainties, the field of geopredictions is booming. One Web site has received almost 30 million hits since its debut in 1998, and the field’s admirers now include top scientists.
“It’s quite good pedagogically,” said Frank Press, a geologist and past president of the National Academy of Sciences. “It captures the attention.”
Dr. Press features one of the forecasts in his introductory college text, “Understanding Earth” (Freeman, 2006). He and three co-authors present a snapshot of how the planet’s surface might look 50 million years from now, calling it “a plausible scenario.”
Among other things, the snapshot shows that Africa has drifted to the north, plowing into Europe and fusing the two landmasses, eliminating the Mediterranean Sea and replacing it with the Mediterranean Mountains. The rugged range runs down the middle of a continent far bigger than current-day Eurasia, a giant new agglomeration that might be called Afrasia.
While peering 50 million years into the future may seem like a stretch, geologists consider such spans of time the blink of an eye. If one year represented Earth’s past, 50 million years would equal less than 4 days, or about the limit of accurate weather forecasts.
“Fifty million is fairly straightforward,” said Christopher R. Scotese, a geologist at the University of Texas, Arlington, who has pioneered the predictions in recent years. “It’s like you’re driving on the highway and you want to know where you’re going to be in 10 minutes. You check the speedometer, do a calculation, and project your present motion.
“But beyond 50 million years,” Dr. Scotese added, “like on the highway, unexpected things can happen.”
Forecasts of future continental motion developed slowly as offshoots of the theory of plate tectonics, which won acceptance in the 1960s and 1970s, shattering old dogmas of continental immobility. The theory of plate tectonics holds that the surface of Earth is composed of a dozen or so huge crustal slabs that float on a sea of partially molten rock. Over ages, hot convection currents in this sea, as well as gravitational forces, move the plates and their superimposed continents and ocean basins, tearing them apart and rearranging them like pieces of a giant jigsaw puzzle.
The theory, named for the Greek word “tekton,” or builder, is a study in slowness. Colliding plates grind past one another about as fast as fingernails grow.
Today, geologists measure such changes with great precision thanks to the advent of global positioning satellites and small base stations that dot remote areas of the planet and operate unattended. Arrays of such instruments track the overall movement of plates.
From the start of the theory’s acceptance, geologists worked hard to discover what plate tectonics revealed about Earth’s past and to render it in credible reconstructions. A famous result was Pangea — “all the land” in Greek — a supercontinent that some 200 million years ago held the outlines of today’s continents in embryonic form.
In 1970, Robert S. Dietz, who uncovered major clues to plate movement in the deep sea, wrote a Scientific American article on the breakup of Pangea. He also took a first step toward predicting the future, sketched out plausible continental shifts for the next 50 million years, and projected their local repercussions.
Dr. Dietz zeroed in on the San Andreas fault, the deep gash beneath California that spawned the devastating San Francisco earthquake of 1906 — one among many — and today also threatens the Los Angeles area. The fault marks the seam where the Pacific plate slides relentlessly northward past the North American plate.
Ten million years from now, Dr. Dietz wrote, “Los Angeles will be abreast of San Francisco.” And in another 50 million years, he added, Los Angeles will have moved up the west coast into Alaskan waters.
Such visualizations caught the eye of Dr. Scotese in the late 1970s when he was a graduate student at the University of Chicago. He loved the challenge of the big picture, and of using his computer programs, new to such work, to speed the endless drawing and redrawing. With his graduate adviser, he made detailed maps showing the past evolution of the continents. And he toyed with their future shapes.
In 1982, Dr. Scotese got a call from Discover magazine asking if he would consider a bigger project: envisioning Earth not 50 million years from now but 200 million.
“I said, ‘Hold on, how could I possibly project that far?’ ” he recalled. “But being a rash graduate student in need of extra change, I decided to give it a try.”
The effort forced him to think beyond simple extrapolations and come up with rules that could govern the onset of major tectonic events, like the formation of subduction zones, deep ocean trenches that gobble up seafloor and tear continents apart.
Dr. Scotese drew a series of futuristic maps and, in the 1990s, found an ideal way to communicate his increasingly detailed visions of the terrestrial past and future: over the Internet. Today, Dr. Scotese’s Web site, www.scotese.com, which he started in 1998, showcases his work, called the Paleomap Project. Teachers use his animations, and his site has won scientific awards. (He aids the publishing world, too, providing Dr. Press and his co-authors with their map of the future world.)
Today, some of his most ambitious efforts center on envisioning how Earth might look 250 million years from now. The easy part, Dr. Scotese said, is the continents. Their masses might change shape but seldom disappear altogether because their bedrock weighs little compared with dense ocean crust. Continents literally float above the action. So do mountains. Once formed, they tend to persist, disappearing only after ages of erosion wear them down.
The difficult part, he said, is predicting the development of new subduction zones in the seabed, and in comprehending how aggressively they rearrange the land.
“It’s hard to understand all the forces down there,” he said. “There’s probably some input from the mantle,” the deep, hot, churning zone below the crust. “It probably has some say on which way the plates go.”
His long-term forecast, despite the uncertainties, portrays a distant time when the world’s continents come together again to form a new supercontinent, which he calls Pangea Ultima.
An animated depiction of Pangea Ultima demonstrates a bold exercise in futuristic thinking. First, the Mediterranean closes. Then — 25 million to 75 million years from now — Australia moves north, slamming into Indonesia and Malaysia before pirouetting counterclockwise to smash into the Philippines and then Asia, eventually merging with it.
Antarctica also moves north, shedding its icecap. Roughly 100 million years from now, it plows into the Indian Ocean, and 50 million years later wedges itself between Madagascar and Indonesia. The Indian Ocean becomes a virtual inland sea.
Meanwhile, Dr. Scotese said, the biggest tectonic change of all — driven by a giant subduction zone — has torn through the dark Atlantic and begun to eat up seabed, slowly closing the ocean. Some 200 million years from now, the closure forces Newfoundland to smash into Africa and, a bit later, Brazil to ram into South Africa.
The collisions gain force; 250 million years from now, the continents will have merged into a new supercontinent that encircles what remains of the Indian Ocean.
“It’s more like a big donut or bagel than Pangea,” Dr. Scotese noted. In looking for a name, “I tried Bagelea or Donutea but figured that would trivialize the whole experience. A friend suggested Pangea Ultima — classy, like a fancy car. It implies that it’s the last Pangea, which certainly isn’t true, but it’s the last one I’m going to come up with.”
Over billions of years, the continents have split and joined repeatedly in a slow dance. They do so, geologists say, in two very dissimilar ways. As Dr. Scotese envisioned, they can break apart and reverse course to merge again. Or they can move apart until their paths around the planet cause them to coalesce on the far side.
Some forecasters see the current expansion — with no course reversal — as dominating the remainder of this tectonic cycle. Instead of the Atlantic disappearing, they say, the Pacific might slowly vanish, sending North and South America careering into Asia.
Sergei A. Pisarevsky, a geologist at the Tectonics Special Research Center of the University of Western Australia, calls the resulting supercontinent “Amasia.” But he said his vision bore no special likelihood of coming true. “My guess,” he said, “is that the Pacific should disappear.”
J. Brendan Murphy, a specialist on tectonic cycles at St. Francis Xavier University in Nova Scotia, echoed that view. Geologists, he said, know too little about the causes of plate motion to predict the dance of continents into the far future.
But in the next few decades, he added, progress in geology is likely to lay bare Earth’s inner workings and enhance the art of plate forecasting.
Even with today’s efforts, Dr. Murphy said, “all the coughing stops in class when I show a projection. It’s a very interesting way to look at the world.”
“The most important thing to realize,” he said, “is that modern geology is just a snapshot of a continuous-action movie. When you zoom out and look over a long enough time, you realize everything is mobile.”
Findings: All Is Not So Bad in the State of Denmark
By BENEDICT CAREY, The New York Times, January 9, 2007
Sweden has more blond beauties per capita, Italy and France have far better cuisine, and most of the free world can boast of better weather. But over the past 30 years, the citizens of Denmark have scored higher than any other Western country on measures of life satisfaction, and scientists think they know why.
In a paper appearing in the Dec. 23 issue of the medical journal BMJ, researchers review six likely and unlikely explanations, and conclude that the country’s secret is a culture of low expectations.
“It’s a David and Goliath thing,” said the lead author, Kaare Christensen, a professor of epidemiology at the University of Southern Denmark in Odense. “If you’re a big guy, you expect to be on the top all the time and you’re disappointed when things don’t go well. But when you’re down at the bottom like us, you hang on, you don’t expect much, and once in a while you win, and it’s that much better.”
The researchers arrived at their findings by a process of elimination and humor. Blonds may have more fun, they argue, but Sweden has a higher prevalence of them. As for climate, Danes “bask in a somewhat colder and cloudier version of the balmy English weather.” They also eat fatty foods and drink a lot, and genetically they are not significantly different from their gloomier Scandinavian neighbors. And in 1992 the Danes won the European Championship in soccer, creating “such a state of euphoria that the country has not been the same since.”
But on surveys, Danes continually report lower expectations for the year to come, compared with most other nations. And “year after year, they are pleasantly surprised to find that not everything is getting more rotten in the state of Denmark,” the paper concludes.
A Conversation With Nina G. Jablonski: Always Revealing, Human Skin Is an Anthropologist’s Map
By CLAUDIA DREIFUS, The New York Times, January 9, 2007
In an era of academic hyper-specialization, Dr. Nina G. Jablonski has an amazingly broad résumé. At 53, she heads the anthropology department at Pennsylvania State University. She’s also a primatologist, an evolutionary biologist and a paleontologist.
Last year, Dr. Jablonski led an expedition to China, where she dug for human fossils in an attempt to learn how early man coped with climate change. This month, she’s in Kenya, where she and Meave Leakey are putting together a study on prehistoric monkeys.
For more than a decade, Dr. Jablonski has been trying to get her arms around a ubiquitous and yet mysterious topic: the biology, evolution and social function of human skin. The results of her studies have been published by the University of California Press as “Skin: A Natural History.”
“Skin has been studied to absolute death by dermatologists,” Dr. Jablonski said jokingly during a recent visit to New York City. “They know it inside and out from the point of view of diseases that afflict it. What we wanted to learn was how human skin came to be as it is and what that meant for humanity.”
Q. What set you off on writing a natural history of human skin?
A. I had an insight in 1981, when I was teaching gross anatomy to medical students at the University of Hong Kong. The students had been presented with a cadaver to dissect, and they were tremendously frightened of it. However, their attitude changed the very moment they cut through the skin. With the skin gone, they began seeing it as a mere body devoid of a personal history, and they could get on with their work.
That moment showed me how much of what we consider our humanity is imbued in our skin. It stayed with me for a long time. Then about 15 years ago, I joined a project studying the natural history of skin color. The topic was so engrossing that I began looking into the larger question of what our skin does and is.
Q. And what have you found?
A. That skin is the most underappreciated of our organs. Unless we’re having the sort of problem that brings us to a dermatologist, we take our skin for granted. We never think of it as working very hard for our body or doing valuable things for us socially.
But when you really start thinking about it, it’s a factory that produces vitamin D, sweat, hormones, oils, wax, pigments — substances we need. Skin is a raincoat in that it protects us from water, bugs and noxious chemicals. It’s also a billboard which we adorn with powder, tattoos, piercing and scars to give off instant messages about our history, health, values and availability for mating.
On an evolutionary level, there are three remarkable facts about skin. It comes in colors, of course. Compared to other mammals, our skin is relatively hairless. And it’s sweaty. In the last few million years, humans became the sweatiest of mammals.
Q. Is that important?
A. Absolutely. It’s often said that our large brains are what made it possible for us to evolve from ape to human. But those big brains could never have developed if we didn’t have exceptionally sweaty skin.
It happened this way. There was a tremendous takeoff in human evolution about two million years ago when primates who could no longer be called apes appeared in the savannahs of East Africa. These early humans ran long distances in open areas. In order to survive in the equatorial sun, they needed to cool their brains. Early humans evolved an increased number of sweat glands for that purpose, which in turn permitted their brain size to expand. As soon as we developed larger brains, our planning capacity increased, and this allowed people to disperse out of Africa. There’s fossil evidence of humans appearing in Central Asia around this time.
Q. In a nutshell, what has your research shown about why humans have varying skin colors?
A. That it’s not about race — it’s about sun and about how close our ancestors lived to the Equator. Skin color is what regulates our body’s reaction to the sun and its rays. Dark skin evolved to protect the body from excessive sun rays. Light skin evolved when people migrated away from the Equator and needed to make vitamin D in their skin. To do that, they had to lose pigment. Repeatedly over history, many people moved dark to light and light to dark. That shows that color is not a permanent trait.
Q. Did early humans decorate their skin?
A. We don’t know. There’s no human skin in the fossil record. The oldest preserved skin we have is that of Ötzi, the Neolithic iceman whose mummified body was found in the Alps in 1991. Ötzi lived about 5,000 years ago. Interestingly, he has tattoos. But we can only guess what they mean.
Modern humans, we love to alter our skin. You’ll find very few people walking around today with unadorned skin. They might make permanent changes — piercing, scarring, tattooing — to memorialize events and announce their identity. Or they might use cosmetics for temporary alterations to announce their attractiveness, mood or sexual availability. The bottom line: humans are the self-decorating ape.
Q. I get the feeling that you think cosmetic use is some kind of ancient evolutionary behavior. Are we reading you correctly?
A. Evolution is all about attracting a mate and getting a chance to reproduce, so yes, makeup helps with that. When a woman uses eyeliner to make her eyes appear larger, she’s giving off a message: “I want you to see me as attractive.” Large eyes in a woman are almost universally seen as appealing. This is not just a girl thing. Male body paint in East Africa emphasizes forbidding facial expressions. They announce a man’s prowess as a warrior and as a mate.
Q. How do you feel about your own skin?
A. I like it. It is my unwritten biography. My skin reminds me that I’m a 53-year-old woman who has smiled and furrowed her brow and, on occasion, worked in the desert sun too long. I enjoy watching my skin change because it’s one of the few parts of my body that I can watch. We can’t view our livers or heart, but this we can. And yes, I use cosmetics. Like other humans, I have a penchant for changing my appearance easily and quickly. It also helps me feel more confident. That may seem silly, but I still do it.
Q. You made news in 2004 when you discovered the world’s oldest chimpanzee fossil. These were chimp teeth about a half-million years old. Where did you find them?
A. In a drawer at the National Museum of Kenya in Nairobi. I was rummaging through this bag labeled “fossil monkeys” and I saw it. “This doesn’t look like monkey,” I thought. It turned out they were from an early chimp. That find proved important because there had been no chimpanzee this old in the fossil record. By analyzing it, we’ve learned that chimpanzees in their current form have probably existed for longer than previously thought. (Laughs) Since my find, people have been rummaging through dusty museum drawers everywhere!
Vital Signs: Remedies: Small Study Raises a Question About Echinacea
By NICHOLAS BAKALAR, The New York Times, January 9, 2007
Some people take echinacea supplements in the hope that they will prevent or shorten colds, but a small study suggests that it may increase the number of intestinal bacteria associated with diarrhea, inflammatory bowel disease and an increased risk of colon cancer.
Researchers gave 15 volunteers 1,000 milligrams of Echinacea purpurea daily for 10 days. They collected stool samples before the supplementation, and at 10 days and 17 to 18 days after the volunteers had stopped taking the herb, then analyzed the samples for six types of bacteria. The study was published in December in The Journal of Clinical Pharmacy and Therapeutics.
After controlling for other diet variables, the scientists found significant increases in microbial counts for Bacteroides, Bacteroides fragilis, and total aerobic bacteria. There was no effect on enteric bacteria, enterococci, Lactobacillus, bifidobacteria, or total anaerobic bacteria.
“This changes the balance of the normal bacterial fauna,” said Jerald C. Foote, an assistant professor of human nutrition at the University of Arkansas. “But we don’t know yet what this means.”
Though the sample was small and the study was preliminary, the authors said it was the first to consider the effects of a botanical dietary supplement on gastrointestinal flora. Dr. Foote was not urging anyone to abandon echinacea. “I think we need a lot more research before we start taking echinacea off the shelves,” he said. “But this does raise some questions.”
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Date: 2007-01-09 07:58 pm (UTC)