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The Science of a Happy Marriage
By TARA PARKER-POPE, The New York Times, May 10, 2010
Why do some men and women cheat on their partners while others resist the temptation?
To find the answer, a growing body of research is focusing on the science of commitment. Scientists are studying everything from the biological factors that seem to influence marital stability to a person’s psychological response after flirting with a stranger.
Their findings suggest that while some people may be naturally more resistant to temptation, men and women can also train themselves to protect their relationships and raise their feelings of commitment.
Recent studies have raised questions about whether genetic factors may influence commitment and marital stability. Hasse Walum, a biologist at the Karolinska Institute in Sweden, studied 552 sets of twins to learn more about a gene related to the body’s regulation of the brain chemical vasopressin, a bonding hormone.
Over all, men who carried a variation in the gene were less likely to be married, and those who had wed were more likely to have had serious marital problems and unhappy wives. Among men who carried two copies of the gene variant, about a third had experienced a serious relationship crisis in the past year, double the number seen in the men who did not carry the variant.
Although the trait is often called the “fidelity gene,” Mr. Walum called that a misnomer: his research focused on marital stability, not faithfulness. “It’s difficult to use this information to predict any future behavior in men,” he told me. Now he and his colleagues are working to replicate the findings and conducting similar research in women.
While there may be genetic differences that influence commitment, other studies suggest that the brain can be trained to resist temptation.
A series of unusual studies led by John Lydon, a psychologist at McGill University in Montreal, have looked at how people in a committed relationship react in the face of temptation. In one study, highly committed married men and women were asked to rate the attractiveness of people of the opposite sex in a series of photos. Not surprisingly, they gave the highest ratings to people who would typically be viewed as attractive.
Later, they were shown similar pictures and told that the person was interested in meeting them. In that situation, participants consistently gave those pictures lower scores than they had the first time around.
When they were attracted to someone who might threaten the relationship, they seemed to instinctively tell themselves, “He’s not so great.” “The more committed you are,” Dr. Lydon said, “the less attractive you find other people who threaten your relationship.”
But some of the McGill research has shown gender differences in how we respond to a cheating threat. In a study of 300 heterosexual men and women, half the participants were primed for cheating by imagining a flirtatious conversation with someone they found attractive. The other half just imagined a routine encounter.
Afterward, the study subjects were asked to complete fill-in-the-blank puzzles like LO_AL and THR__T.
Unbeknownst to the participants, the word fragments were a psychological test to reveal subconscious feelings about commitment. (Similar word puzzles are used to study subconscious feelings about prejudice and stereotyping.)
No pattern emerged among the study participants who imagined a routine encounter. But there were differences among men and women who had entertained the flirtatious fantasy. In that group, the men were more likely to complete the puzzles with the neutral words LOCAL and THROAT. But the women who had imagined flirting were far more likely to choose LOYAL and THREAT, suggesting that the exercise had touched off subconscious concerns about commitment.
Of course, this does not necessarily predict behavior in the real world. But the pronounced difference in responses led the researchers to think women might have developed a kind of early warning system to alert them to relationship threats.
Other McGill studies confirmed differences in how men and women react to such threats. In one, attractive actors or actresses were brought in to flirt with study participants in a waiting room. Later, the participants were asked questions about their relationships, particularly how they would respond to a partner’s bad behavior, like being late and forgetting to call.
Men who had just been flirting were less forgiving of the hypothetical bad behavior, suggesting that the attractive actress had momentarily chipped away at their commitment. But women who had been flirting were more likely to be forgiving and to make excuses for the man, suggesting that their earlier flirting had triggered a protective response when discussing their relationship.
“We think the men in these studies may have had commitment, but the women had the contingency plan — the attractive alternative sets off the alarm bell,” Dr. Lydon said. “Women implicitly code that as a threat. Men don’t.”
The question is whether a person can be trained to resist temptation. In another study, the team prompted male students who were in committed dating relationships to imagine running into an attractive woman on a weekend when their girlfriends were away. Some of the men were then asked to develop a contingency plan by filling in the sentence “When she approaches me, I will __________ to protect my relationship.”
Because the researchers could not bring in a real woman to act as a temptation, they created a virtual-reality game in which two out of four rooms included subliminal images of an attractive woman. The men who had practiced resisting temptation gravitated toward those rooms 25 percent of the time; for the others, the figure was 62 percent.
But it may not be feelings of love or loyalty that keep couples together. Instead, scientists speculate that your level of commitment may depend on how much a partner enhances your life and broadens your horizons — a concept that Arthur Aron, a psychologist and relationship researcher at Stony Brook University, calls “self-expansion.”
To measure this quality, couples are asked a series of questions: How much does your partner provide a source of exciting experiences? How much has knowing your partner made you a better person? How much do you see your partner as a way to expand your own capabilities?
The Stony Brook researchers conducted experiments using activities that stimulated self-expansion. Some couples were given mundane tasks, while others took part in a silly exercise in which they were tied together and asked to crawl on mats, pushing a foam cylinder with their heads. The study was rigged so the couples failed the time limit on the first two tries, but just barely made it on the third, resulting in much celebration.
Couples were given relationship tests before and after the experiment. Those who had taken part in the challenging activity posted greater increases in love and relationship satisfaction than those who had not experienced victory together.
Now the researchers are embarking on a series of studies to measure how self-expansion influences a relationship. They theorize that couples who explore new places and try new things will tap into feelings of self-expansion, lifting their level of commitment.
“We enter relationships because the other person becomes part of ourselves, and that expands us,” Dr. Aron said. “That’s why people who fall in love stay up all night talking and it feels really exciting. We think couples can get some of that back by doing challenging and exciting things together.”
Tara Parker-Pope’s new book is “For Better: The Science of a Good Marriage.”
Mapping Ancient Civilization, in a Matter of Days
By JOHN NOBLE WILFORD, The New York Times, May 10, 2010
For a quarter of a century, two archaeologists and their team slogged through wild tropical vegetation to investigate and map the remains of one of the largest Maya cities, in Central America. Slow, sweaty hacking with machetes seemed to be the only way to discover the breadth of an ancient urban landscape now hidden beneath a dense forest canopy.
Even the new remote-sensing technologies, so effective in recent decades at surveying other archaeological sites, were no help. Imaging radar and multispectral surveys by air and from space could not “see” through the trees.
Then, in the dry spring season a year ago, the husband-and-wife team of Arlen F. Chase and Diane Z. Chase tried a new approach using airborne laser signals that penetrate the jungle cover and are reflected from the ground below. They yielded 3-D images of the site of ancient Caracol, in Belize, one of the great cities of the Maya lowlands.
In only four days, a twin-engine aircraft equipped with an advanced version of lidar (light detection and ranging) flew back and forth over the jungle and collected data surpassing the results of two and a half decades of on-the-ground mapping, the archaeologists said. After three weeks of laboratory processing, the almost 10 hours of laser measurements showed topographic detail over an area of 80 square miles, notably settlement patterns of grand architecture and modest house mounds, roadways and agricultural terraces.
“We were blown away,” Dr. Diane Chase said recently, recalling their first examination of the images. “We believe that lidar will help transform Maya archaeology much in the same way that radiocarbon dating did in the 1950s and interpretations of Maya hieroglyphs did in the 1980s and ’90s.”
The Chases, who are professors of anthropology at the University of Central Florida in Orlando, had determined from earlier surveys that Caracol extended over a wide area in its heyday, between A.D. 550 and 900. From a ceremonial center of palaces and broad plazas, it stretched out to industrial zones and poor neighborhoods and beyond to suburbs of substantial houses, markets and terraced fields and reservoirs.
This picture of urban sprawl led the Chases to estimate the city’s population at its peak at more than 115,000. But some archaeologists doubted the evidence warranted such expansive interpretations.
“Now we have a totality of data and see the entire landscape,” Dr. Arlen Chase said of the laser findings. “We know the size of the site, its boundaries, and this confirms our population estimates, and we see all this terracing and begin to know how the people fed themselves.”
The Caracol survey was the first application of the advanced laser technology on such a large archaeological site. Several journal articles describe the use of lidar in the vicinity of Stonehenge in England and elsewhere at an Iron Age fort and American plantation sites. Only last year, Sarah H. Parcak of the University of Alabama at Birmingham predicted, “Lidar imagery will have much to offer the archaeology of the rain forest regions.”
The Chases said they had been unaware of Dr. Parcak’s assessment, in her book “Satellite Remote Sensing for Archaeology” (Routledge, 2009), when they embarked on the Caracol survey. They acted on the recommendation of a Central Florida colleague, John F. Weishampel, a biologist who had for years used airborne laser sensors to study forests and other vegetation.
Dr. Weishampel arranged for the primary financing of the project from the little-known space archaeology program of the National Aeronautics and Space Administration. The flights were conducted by the National Science Foundation’s National Center for Airborne Laser Mapping, operated by the University of Florida and the University of California, Berkeley.
Other archaeologists, who were not involved in the research but were familiar with the results, said the technology should be a boon to explorations, especially ones in the tropics, with its heavily overgrown vegetation, including pre-Columbian sites throughout Mexico and Central America. But they emphasized that it would not obviate the need to follow up with traditional mapping to establish “ground truth.”
Jeremy A. Sabloff, a former director of the University of Pennsylvania Museum of Archaeology and Anthropology and now president of the Santa Fe Institute in New Mexico, said he wished he had had lidar when he was working in the Maya ruins at Sayil, in Mexico.
The new laser technology, Dr. Sabloff said, “would definitely have speeded up our mapping, given us more details and would have enabled us to refine our research questions and hypotheses much earlier in our field program than was possible in the 1980s.”
At first, Payson D. Sheets, a University of Colorado archaeologist, was not impressed with lidar. A NASA aircraft tested the laser system over his research area in Costa Rica, he said, “but when I saw it recorded the water in a lake sloping at 14 degrees, I did not use it again.”
Now, after examining the imagery from Caracol, Dr. Sheets said he planned to try lidar, with its improved technology, again. “I was stunned by the crisp precision and fine-grained resolution,” he said.
“Finally, we have a nondestructive and rapid means of documenting the present ground surface through heavy vegetation cover,” Dr. Sheets said, adding, “One can easily imagine, given the Caracol success, how important this would be in Southeast Asia, with the Khmer civilization at places like Angkor Wat.”
In recent reports at meetings of Mayanists and in interviews, the Chases noted that previous remote-sensing techniques focused more on the discovery of archaeological sites than on the detailed imaging of on-ground remains. The sensors could not see through much of the forest to resolve just how big the ancient cities had been. As a consequence, archaeologists may have underestimated the scope of Mayan accomplishments.
For the Caracol survey, the aircraft flew less than a half-mile above the terrain at the end of the dry season, when foliage is less dense. The Airborne Laser Terrain Mapper, as the specific advanced system is named, issued steady light pulses along 62 north-south flight lines and 60 east-west lines. This reached to what appeared to be the fringes of the city’s outer suburbs and most agricultural terraces, showing that the urban expanse encompassed at least 70 square miles.
Not all the laser pulses transmitted from the aircraft made it to the surface. Some were reflected by the tops of trees. But enough reached the ground and were reflected back to the airborne instruments. These signals, measured and triangulated by GPS receivers and processed by computers, produced images of the surface contours. This revealed distinct patterns of building ruins, causeways and other human modifications of the landscape.
The years the Chases spent on traditional explorations at Caracol laid the foundation for confirming the effectiveness of the laser technology. Details in the new images clearly matched their maps of known structures and cultural features, the archaeologists said. When the teams returned to the field, they used the laser images to find several causeways, terraced fields and many ruins they had overlooked.
The Chases said the new research demonstrates how a large, sustainable agricultural society could thrive in a tropical environment and thus account for the robust Maya civilization in its classic period from A.D. 250 to 900.
“This will revolutionize the way we do settlement studies of the Maya,” Dr. Arlen Chase said on returning from this spring’s research at Caracol.
Lidar is not expected to have universal application. Dr. Sheets said that, for example, it would not be useful at his pre-Columbian site at Cerén, in El Salvador. The ancient village and what were its surrounding manioc fields are buried under many feet of volcanic ash, beyond laser detection.
Other modern technologies, including radar and satellite imaging, are already proving effective in the land beyond the temples at Angkor, in Cambodia, and in surveys of the Nile delta and ancient irrigation systems in Iraq.
Laser signals breaking through jungle cover are only the newest form of remote sensing in the pursuit of knowledge of past cultures, which began in earnest about a century ago with the advent of aerial photography. Charles Lindbergh drew attention to its application in archaeology with picture-taking flights over unexplored Pueblo cliff dwellings in the American Southwest.
NASA recently stepped up its promotion of technologies developed for broad surveys of Earth and other planets to be used in archaeological research. Starting with a few preliminary tests over the years, the agency has now established a formal program for financing archaeological remote-sensing projects by air and space.
“We’re not looking for monoliths on the Moon,” joked Craig Dobson, manager of the NASA space archaeology program.
Every two years, Dr. Dobson said, NASA issues several three-year grants for the use of remote sensing at ancient sites. In addition to the Caracol tests, the program is supporting two other Maya research efforts, surveys of settlement patterns in North Africa and Mexico and reconnaissance of ancient ruins in the Mekong River Valley and around Angkor Wat.
Nothing like a latter-day Apollo project, of course, but the archaeology program is growing, Dr. Dobson said, and will soon double in size, to an annual budget of $1 million.
A Bottom Feeder Leaves Traces Below
By SINDYA N. BHANOO, The New York Times, May 10, 2010
The series of squiggles and little ovals were perplexing, at first.
But it was only a matter of time before Anthony Martin, a fossil trace expert, deciphered the fossil’s code, and used it to tell the story of a fish that lived 50 million years ago in Wyoming’s Fossil Lake and swam at depths previously thought to be too deep for a fish to breathe in.
The squiggles were impressions of the fish’s fins, sweeping across the lake’s bottom, said Dr. Martin, a professor in the department of environmental studies at Emory University.
And the ovals, exactly the size of the fish’s mouth, indicate that the fish was gliding along the deepest part of the lake’s bottom in search of food. Using the distance between the fin marks, Dr. Martin and his colleagues determined that the fish was about 18 inches long. They concluded that the marks were from an extinct bottom-feeding fish known as Notogoneus osculus.
The findings contradict a previously held theory that the oxygen content at the deepest part of the lake, thought to be about 35 to 50 feet down, was too low for a fish to breathe in, Dr. Martin said.
“Not only were there fish swimming there, there were fish feeding there,” he said.
The results were published in the May 5 edition of PLoS One.
Fruit Fly Gender Varies at the Cellular Level
By SINDYA N. BHANOO, The New York Times, May 10, 2010
Thirty years ago, the biologist Bruce S. Baker discovered that the gender of a fruit fly is determined not by a hormone, but by the expression of a gene called doublesex in individual cells. Female fruit flies express one form of the gene in their cells, while males express another.
Now, with the help of DNA technology, Dr. Baker and his colleagues have made a surprising discovery: not every cell in the fly is marked as male or female.
In a sense, some cells know their sex while others do not. Until now it was believed that every cell in a fruit fly had the appropriate male or female version of doublesex switched on.
The research “generates real thinking of what sexuality means,” said Dr. Baker, a scientist at Janelia Farm, a division of the Howard Hughes Medical Institute. “Both males and females were a mixture of some cells that knew their sex and some that did not.”
It is possible that this paradigm, that gender varies at the cellular level, may be applicable to other organisms, even humans. This is only a hypothesis and would require intensive research, Dr. Baker said.
But “flies and people show an amazing similarity,” he said. “With the basic commonalities in the animal kingdom, it’s possible.”
The study’s results were published in the May 4 issue of PLoS Biology.
By TARA PARKER-POPE, The New York Times, May 10, 2010
Why do some men and women cheat on their partners while others resist the temptation?
To find the answer, a growing body of research is focusing on the science of commitment. Scientists are studying everything from the biological factors that seem to influence marital stability to a person’s psychological response after flirting with a stranger.
Their findings suggest that while some people may be naturally more resistant to temptation, men and women can also train themselves to protect their relationships and raise their feelings of commitment.
Recent studies have raised questions about whether genetic factors may influence commitment and marital stability. Hasse Walum, a biologist at the Karolinska Institute in Sweden, studied 552 sets of twins to learn more about a gene related to the body’s regulation of the brain chemical vasopressin, a bonding hormone.
Over all, men who carried a variation in the gene were less likely to be married, and those who had wed were more likely to have had serious marital problems and unhappy wives. Among men who carried two copies of the gene variant, about a third had experienced a serious relationship crisis in the past year, double the number seen in the men who did not carry the variant.
Although the trait is often called the “fidelity gene,” Mr. Walum called that a misnomer: his research focused on marital stability, not faithfulness. “It’s difficult to use this information to predict any future behavior in men,” he told me. Now he and his colleagues are working to replicate the findings and conducting similar research in women.
While there may be genetic differences that influence commitment, other studies suggest that the brain can be trained to resist temptation.
A series of unusual studies led by John Lydon, a psychologist at McGill University in Montreal, have looked at how people in a committed relationship react in the face of temptation. In one study, highly committed married men and women were asked to rate the attractiveness of people of the opposite sex in a series of photos. Not surprisingly, they gave the highest ratings to people who would typically be viewed as attractive.
Later, they were shown similar pictures and told that the person was interested in meeting them. In that situation, participants consistently gave those pictures lower scores than they had the first time around.
When they were attracted to someone who might threaten the relationship, they seemed to instinctively tell themselves, “He’s not so great.” “The more committed you are,” Dr. Lydon said, “the less attractive you find other people who threaten your relationship.”
But some of the McGill research has shown gender differences in how we respond to a cheating threat. In a study of 300 heterosexual men and women, half the participants were primed for cheating by imagining a flirtatious conversation with someone they found attractive. The other half just imagined a routine encounter.
Afterward, the study subjects were asked to complete fill-in-the-blank puzzles like LO_AL and THR__T.
Unbeknownst to the participants, the word fragments were a psychological test to reveal subconscious feelings about commitment. (Similar word puzzles are used to study subconscious feelings about prejudice and stereotyping.)
No pattern emerged among the study participants who imagined a routine encounter. But there were differences among men and women who had entertained the flirtatious fantasy. In that group, the men were more likely to complete the puzzles with the neutral words LOCAL and THROAT. But the women who had imagined flirting were far more likely to choose LOYAL and THREAT, suggesting that the exercise had touched off subconscious concerns about commitment.
Of course, this does not necessarily predict behavior in the real world. But the pronounced difference in responses led the researchers to think women might have developed a kind of early warning system to alert them to relationship threats.
Other McGill studies confirmed differences in how men and women react to such threats. In one, attractive actors or actresses were brought in to flirt with study participants in a waiting room. Later, the participants were asked questions about their relationships, particularly how they would respond to a partner’s bad behavior, like being late and forgetting to call.
Men who had just been flirting were less forgiving of the hypothetical bad behavior, suggesting that the attractive actress had momentarily chipped away at their commitment. But women who had been flirting were more likely to be forgiving and to make excuses for the man, suggesting that their earlier flirting had triggered a protective response when discussing their relationship.
“We think the men in these studies may have had commitment, but the women had the contingency plan — the attractive alternative sets off the alarm bell,” Dr. Lydon said. “Women implicitly code that as a threat. Men don’t.”
The question is whether a person can be trained to resist temptation. In another study, the team prompted male students who were in committed dating relationships to imagine running into an attractive woman on a weekend when their girlfriends were away. Some of the men were then asked to develop a contingency plan by filling in the sentence “When she approaches me, I will __________ to protect my relationship.”
Because the researchers could not bring in a real woman to act as a temptation, they created a virtual-reality game in which two out of four rooms included subliminal images of an attractive woman. The men who had practiced resisting temptation gravitated toward those rooms 25 percent of the time; for the others, the figure was 62 percent.
But it may not be feelings of love or loyalty that keep couples together. Instead, scientists speculate that your level of commitment may depend on how much a partner enhances your life and broadens your horizons — a concept that Arthur Aron, a psychologist and relationship researcher at Stony Brook University, calls “self-expansion.”
To measure this quality, couples are asked a series of questions: How much does your partner provide a source of exciting experiences? How much has knowing your partner made you a better person? How much do you see your partner as a way to expand your own capabilities?
The Stony Brook researchers conducted experiments using activities that stimulated self-expansion. Some couples were given mundane tasks, while others took part in a silly exercise in which they were tied together and asked to crawl on mats, pushing a foam cylinder with their heads. The study was rigged so the couples failed the time limit on the first two tries, but just barely made it on the third, resulting in much celebration.
Couples were given relationship tests before and after the experiment. Those who had taken part in the challenging activity posted greater increases in love and relationship satisfaction than those who had not experienced victory together.
Now the researchers are embarking on a series of studies to measure how self-expansion influences a relationship. They theorize that couples who explore new places and try new things will tap into feelings of self-expansion, lifting their level of commitment.
“We enter relationships because the other person becomes part of ourselves, and that expands us,” Dr. Aron said. “That’s why people who fall in love stay up all night talking and it feels really exciting. We think couples can get some of that back by doing challenging and exciting things together.”
Tara Parker-Pope’s new book is “For Better: The Science of a Good Marriage.”
Mapping Ancient Civilization, in a Matter of Days
By JOHN NOBLE WILFORD, The New York Times, May 10, 2010
For a quarter of a century, two archaeologists and their team slogged through wild tropical vegetation to investigate and map the remains of one of the largest Maya cities, in Central America. Slow, sweaty hacking with machetes seemed to be the only way to discover the breadth of an ancient urban landscape now hidden beneath a dense forest canopy.
Even the new remote-sensing technologies, so effective in recent decades at surveying other archaeological sites, were no help. Imaging radar and multispectral surveys by air and from space could not “see” through the trees.
Then, in the dry spring season a year ago, the husband-and-wife team of Arlen F. Chase and Diane Z. Chase tried a new approach using airborne laser signals that penetrate the jungle cover and are reflected from the ground below. They yielded 3-D images of the site of ancient Caracol, in Belize, one of the great cities of the Maya lowlands.
In only four days, a twin-engine aircraft equipped with an advanced version of lidar (light detection and ranging) flew back and forth over the jungle and collected data surpassing the results of two and a half decades of on-the-ground mapping, the archaeologists said. After three weeks of laboratory processing, the almost 10 hours of laser measurements showed topographic detail over an area of 80 square miles, notably settlement patterns of grand architecture and modest house mounds, roadways and agricultural terraces.
“We were blown away,” Dr. Diane Chase said recently, recalling their first examination of the images. “We believe that lidar will help transform Maya archaeology much in the same way that radiocarbon dating did in the 1950s and interpretations of Maya hieroglyphs did in the 1980s and ’90s.”
The Chases, who are professors of anthropology at the University of Central Florida in Orlando, had determined from earlier surveys that Caracol extended over a wide area in its heyday, between A.D. 550 and 900. From a ceremonial center of palaces and broad plazas, it stretched out to industrial zones and poor neighborhoods and beyond to suburbs of substantial houses, markets and terraced fields and reservoirs.
This picture of urban sprawl led the Chases to estimate the city’s population at its peak at more than 115,000. But some archaeologists doubted the evidence warranted such expansive interpretations.
“Now we have a totality of data and see the entire landscape,” Dr. Arlen Chase said of the laser findings. “We know the size of the site, its boundaries, and this confirms our population estimates, and we see all this terracing and begin to know how the people fed themselves.”
The Caracol survey was the first application of the advanced laser technology on such a large archaeological site. Several journal articles describe the use of lidar in the vicinity of Stonehenge in England and elsewhere at an Iron Age fort and American plantation sites. Only last year, Sarah H. Parcak of the University of Alabama at Birmingham predicted, “Lidar imagery will have much to offer the archaeology of the rain forest regions.”
The Chases said they had been unaware of Dr. Parcak’s assessment, in her book “Satellite Remote Sensing for Archaeology” (Routledge, 2009), when they embarked on the Caracol survey. They acted on the recommendation of a Central Florida colleague, John F. Weishampel, a biologist who had for years used airborne laser sensors to study forests and other vegetation.
Dr. Weishampel arranged for the primary financing of the project from the little-known space archaeology program of the National Aeronautics and Space Administration. The flights were conducted by the National Science Foundation’s National Center for Airborne Laser Mapping, operated by the University of Florida and the University of California, Berkeley.
Other archaeologists, who were not involved in the research but were familiar with the results, said the technology should be a boon to explorations, especially ones in the tropics, with its heavily overgrown vegetation, including pre-Columbian sites throughout Mexico and Central America. But they emphasized that it would not obviate the need to follow up with traditional mapping to establish “ground truth.”
Jeremy A. Sabloff, a former director of the University of Pennsylvania Museum of Archaeology and Anthropology and now president of the Santa Fe Institute in New Mexico, said he wished he had had lidar when he was working in the Maya ruins at Sayil, in Mexico.
The new laser technology, Dr. Sabloff said, “would definitely have speeded up our mapping, given us more details and would have enabled us to refine our research questions and hypotheses much earlier in our field program than was possible in the 1980s.”
At first, Payson D. Sheets, a University of Colorado archaeologist, was not impressed with lidar. A NASA aircraft tested the laser system over his research area in Costa Rica, he said, “but when I saw it recorded the water in a lake sloping at 14 degrees, I did not use it again.”
Now, after examining the imagery from Caracol, Dr. Sheets said he planned to try lidar, with its improved technology, again. “I was stunned by the crisp precision and fine-grained resolution,” he said.
“Finally, we have a nondestructive and rapid means of documenting the present ground surface through heavy vegetation cover,” Dr. Sheets said, adding, “One can easily imagine, given the Caracol success, how important this would be in Southeast Asia, with the Khmer civilization at places like Angkor Wat.”
In recent reports at meetings of Mayanists and in interviews, the Chases noted that previous remote-sensing techniques focused more on the discovery of archaeological sites than on the detailed imaging of on-ground remains. The sensors could not see through much of the forest to resolve just how big the ancient cities had been. As a consequence, archaeologists may have underestimated the scope of Mayan accomplishments.
For the Caracol survey, the aircraft flew less than a half-mile above the terrain at the end of the dry season, when foliage is less dense. The Airborne Laser Terrain Mapper, as the specific advanced system is named, issued steady light pulses along 62 north-south flight lines and 60 east-west lines. This reached to what appeared to be the fringes of the city’s outer suburbs and most agricultural terraces, showing that the urban expanse encompassed at least 70 square miles.
Not all the laser pulses transmitted from the aircraft made it to the surface. Some were reflected by the tops of trees. But enough reached the ground and were reflected back to the airborne instruments. These signals, measured and triangulated by GPS receivers and processed by computers, produced images of the surface contours. This revealed distinct patterns of building ruins, causeways and other human modifications of the landscape.
The years the Chases spent on traditional explorations at Caracol laid the foundation for confirming the effectiveness of the laser technology. Details in the new images clearly matched their maps of known structures and cultural features, the archaeologists said. When the teams returned to the field, they used the laser images to find several causeways, terraced fields and many ruins they had overlooked.
The Chases said the new research demonstrates how a large, sustainable agricultural society could thrive in a tropical environment and thus account for the robust Maya civilization in its classic period from A.D. 250 to 900.
“This will revolutionize the way we do settlement studies of the Maya,” Dr. Arlen Chase said on returning from this spring’s research at Caracol.
Lidar is not expected to have universal application. Dr. Sheets said that, for example, it would not be useful at his pre-Columbian site at Cerén, in El Salvador. The ancient village and what were its surrounding manioc fields are buried under many feet of volcanic ash, beyond laser detection.
Other modern technologies, including radar and satellite imaging, are already proving effective in the land beyond the temples at Angkor, in Cambodia, and in surveys of the Nile delta and ancient irrigation systems in Iraq.
Laser signals breaking through jungle cover are only the newest form of remote sensing in the pursuit of knowledge of past cultures, which began in earnest about a century ago with the advent of aerial photography. Charles Lindbergh drew attention to its application in archaeology with picture-taking flights over unexplored Pueblo cliff dwellings in the American Southwest.
NASA recently stepped up its promotion of technologies developed for broad surveys of Earth and other planets to be used in archaeological research. Starting with a few preliminary tests over the years, the agency has now established a formal program for financing archaeological remote-sensing projects by air and space.
“We’re not looking for monoliths on the Moon,” joked Craig Dobson, manager of the NASA space archaeology program.
Every two years, Dr. Dobson said, NASA issues several three-year grants for the use of remote sensing at ancient sites. In addition to the Caracol tests, the program is supporting two other Maya research efforts, surveys of settlement patterns in North Africa and Mexico and reconnaissance of ancient ruins in the Mekong River Valley and around Angkor Wat.
Nothing like a latter-day Apollo project, of course, but the archaeology program is growing, Dr. Dobson said, and will soon double in size, to an annual budget of $1 million.
A Bottom Feeder Leaves Traces Below
By SINDYA N. BHANOO, The New York Times, May 10, 2010
The series of squiggles and little ovals were perplexing, at first.
But it was only a matter of time before Anthony Martin, a fossil trace expert, deciphered the fossil’s code, and used it to tell the story of a fish that lived 50 million years ago in Wyoming’s Fossil Lake and swam at depths previously thought to be too deep for a fish to breathe in.
The squiggles were impressions of the fish’s fins, sweeping across the lake’s bottom, said Dr. Martin, a professor in the department of environmental studies at Emory University.
And the ovals, exactly the size of the fish’s mouth, indicate that the fish was gliding along the deepest part of the lake’s bottom in search of food. Using the distance between the fin marks, Dr. Martin and his colleagues determined that the fish was about 18 inches long. They concluded that the marks were from an extinct bottom-feeding fish known as Notogoneus osculus.
The findings contradict a previously held theory that the oxygen content at the deepest part of the lake, thought to be about 35 to 50 feet down, was too low for a fish to breathe in, Dr. Martin said.
“Not only were there fish swimming there, there were fish feeding there,” he said.
The results were published in the May 5 edition of PLoS One.
Fruit Fly Gender Varies at the Cellular Level
By SINDYA N. BHANOO, The New York Times, May 10, 2010
Thirty years ago, the biologist Bruce S. Baker discovered that the gender of a fruit fly is determined not by a hormone, but by the expression of a gene called doublesex in individual cells. Female fruit flies express one form of the gene in their cells, while males express another.
Now, with the help of DNA technology, Dr. Baker and his colleagues have made a surprising discovery: not every cell in the fly is marked as male or female.
In a sense, some cells know their sex while others do not. Until now it was believed that every cell in a fruit fly had the appropriate male or female version of doublesex switched on.
The research “generates real thinking of what sexuality means,” said Dr. Baker, a scientist at Janelia Farm, a division of the Howard Hughes Medical Institute. “Both males and females were a mixture of some cells that knew their sex and some that did not.”
It is possible that this paradigm, that gender varies at the cellular level, may be applicable to other organisms, even humans. This is only a hypothesis and would require intensive research, Dr. Baker said.
But “flies and people show an amazing similarity,” he said. “With the basic commonalities in the animal kingdom, it’s possible.”
The study’s results were published in the May 4 issue of PLoS Biology.
