www.sciam.com March 17, 2003

Why the Mayan society, which prospered in the eighth and ninth centuries in Central America, collapsed remains a mystery. Numerous theories, from overpopulation and class warfare to climate change and environmental stresses, have been put forward over the years to explain the downfall. Now the most detailed sediment analysis yet, published in the current issue of the journal Science, further implicates climatic variation. It suggests that a prolonged dry spell, punctuated by three more severe droughts, could have been chiefly to blame for the civilization's demise.

Gerald H. Haug, now at Potsdam's Geoscience Center, and his colleagues studied a sediment core collected from the Cariaco Basin, located off the coast of northern Venezuela. By analyzing the levels of titanium, which is indicative of the amount of rainfall, the scientists determined that the area around the Yucatán peninsula (now part of Mexico) suffered three periods of very low rainfall around A.D. 810, 860 and 910. The droughts were relatively short-lived, lasting between three and nine years, the authors report. They note that these findings agree with archaeological evidence that suggests that Mayan society collapsed in three phases over the same time period.

The latest results will not be the last word on the Mayan collapse, however. Indeed, the authors note that "no one archaeological model is likely to capture completely a phenomenon as complex as the Mayan decline." No doubt scientists will be uncovering the secrets of this sophisticated society for years to come. --Sarah Graham

www.swissinfo.org Saturday 15.03.2003, CET 15:01 swissinfo   March 14, 2003 5:49 PM

The collapse of the Mayan civilization has been blamed on severe spells of drought, according to research carried out in Switzerland.

Scientists have long been baffled by the demise of the Maya, who flourished in present-day Mexico, Guatemala and Honduras until about 1,200 years ago.   But analysis of sediment extracted off the northern Venezuelan coast suggests they may have been devastated by severe droughts lasting between three and nine years. One of the study’s authors, Gerald Haug from the Swiss Federal Institute of Technology in Zurich, said between 750 and 950 AD the Maya experienced a “demographic disaster as profound as any other in human history”. At its height in 750 AD, the Mayan civilization is believed to have supported a population of between three and 13 million people. The Mayans began cultivating maize in Central America around 2000 BC, and eventually developed sophisticated irrigation techniques involving raised fields, canals, reservoirs and gravity-powered rainwater distribution systems.   High and dry   But their renowned mathematical and engineering brilliance appears not have been enough to save them. By the early 9th century most of the Mayan cities were abandoned. Haug told swissinfo that the droughts were what may have pushed Mayan society over the edge. He says the era during which the Mayan civilization went into decline coincided with one of the driest periods since the birth of Christ. “They were clearly running into problems,” said Haug. “One consequence of this was probably social upheaval and ideological decline… there is documentation of migration and war around this time.” The report – published in the journal Science on Friday – says the fate of the Maya remains difficult to determine.   Studying ocean floors   Using equipment at the institute in Zurich, researchers analysed the concentration of titanium in sediment cores drilled from ocean floor of what is known as the Cariaco Basin, north of Venezuela. Titanium is a key indicator of rainfall, because higher precipitation washes more of the metal from the land into ocean floor sediments. “We looked in detail at the period corresponding to the 9th and 10th centuries – taking 6,000 measurements per 30 centimetres of sediment – and found three extreme minima, as well as a low background level that lasted about 100 years,” said Haug.   Experts divided   Nonetheless the drought theory remains contentious. “Perhaps it was the straw that broke the camel’s back,” Jeremy Sabloff, from the University of Pennsylvania told New Scientist magazine. But Sabloff argues that the Maya had coped well through earlier droughts. “The Maya thrived for 1,500 years before these droughts, so it’s clearly not climate alone that brought down the southern cities of the Yucatàn peninsular,” he said. Another expert, Boston University’s Norman Hammond, also questioned the findings, pointing out that the northern Yucatàn city of Chichén Itzà was not abandoned until the 13th century. swissinfo, Jacob Greber and Isobel Johnson

abc.net.au Friday, 14 March  2003

A long dry period punctuated by three intense droughts probably played a major role in the mysterious collapse of Mayan civilisation in Mexico, according to a new study. The severe droughts, each lasting between three and nine years, may have the been the final straws for a civilisation already on the verge of collapse, says a report published today in the journal Science. "Between about 750 and 950 AD, the Maya experienced a demographic disaster as profound as any other in human history," said the report, by an international research team led by Dr Gerald Haug of the Swiss Federal Institute of Technology in Zürich. The Mayan were so successful that at their so-called Classic Maya peak, around 750 AD, the civilisation supported a population of between three and 13 million people, the researchers said. But then it progressively collapsed and by the early 9th century, many of its cities and towns had been permanently abandoned. The study details new evidence that the three droughts occurred around 810, 860, and 910 AD - corresponding to the three phases of Mayan collapse suggested by archaeological evidence. The researchers also found that a more subtle but long-term drying trend was ongoing during the collapse. The droughts may have been what specifically "pushed Mayan society over the edge," they said. The findings are based on an analysis of long-term climate records as revealed in pristine undisturbed sediments from the Cariaco Basin, off northern Venezuela. The distinctly layered sediments, washed out from land by rivers, show up as pairs of light and dark bands that correspond to annual wet and dry seasons. Within them, the team identified yearly variations in titanium levels, which reflect the amount of rainfall each year. They correlate well with palaeoclimate data obtained elsewhere from sources such as ice cores and tree rings. Until now, however, climate records from the time had not been precise enough to test the relationship between drought and the Maya's downfall during the 9th and 10th centuries, the report said. The Mayans began cultivating maize in the region about 2000 BC, using dryland farming techniques that depended on fallowing to rest the soil and needed relatively little labour. Like other Native Americans, they went on to develop sophisticated ways of intensively cultivating fertile soils associated with seasonal and permanent wetlands, on which multiple crops could be grown year after year. Living in the Yucatan lowlands of Mexico and depending mainly on an inconsistent rainfall cycle, the Maya developed labour-intense networks of raised fields as well as canals, reservoirs and other systems for storing and gravity-powered distribution of rainwater. The Mayans had abandoned their major cities once before - between about 150 and 250 AD - an incident that may also be due to drought. But their population constantly recovered, cities were reoccupied and their culture blossomed. "The control of artificial water reservoirs by Maya rulers may also have played a role in both the florescence and the collapse of Maya civilisation," the researchers wrote. Other scientists have suggested that drought may have undermined the institution of Mayan ruling class when existing ceremonies and technologies failed to provide sufficient water. The Mayans were an ancient people whose high civilisation flourished in what is today Mexico, Honduras and Guatemala. They created monuments as impressive as those in ancient Egypt, were proficient in mathematics and astronomy and invented a unique written language.

Bob Beale - ABC Science Online

More Info? Sun cycle may have affected the Maya, News in Science 23 May 2001 El Nino cycles ancient and peaking, News in Science 20 Nov 2002

www.nj.com Friday, March 14, 2003 BY KITTA MacPHERSON Star-Ledger Staff

Scientists have decoded a grave lesson from the past that they say could shed light on whether global climate change really matters.

A long period of dry climate, punctuated by three intense droughts, probably played a major role in the collapse of Mayan civilization, researchers report today in the journal Science.

Studying ancient cores of mud drilled from the Cariaco Basin off the coast of Venezuela, researchers have found that the prolonged dry spell, with 10-year droughts in the years 810, 860 and 910, doomed a culture renowned for its wealth, might, art and inventiveness.

"Here they were, this prospering civilization with a relatively large population that was very active in agricultural pursuits, and they apparently suffered due to natural climate change," said Daniel Sigman, an assistant professor of geosciences at Princeton University and one of the authors of the study. "I'm not totally confident that we would do better than the Maya."

The Mayan civilization was at its peak from about 250 to 900. During that time, known as the Classic Period, it was centered in the tropical rain forest of the lowlands of what is now northern Guatemala. Many of the major Mayan cities, such as Piedras Negras, Tikal and Uaxactun, developed in this area.

Living in both desert and cleared jungle and depending on an inconsistent rainfall cycle, the Maya developed a variety of reservoirs, canals and other systems for catching and storing rainwater.

Until now, climate records from this time period have not been precise enough to test the relationship between the Maya's mysterious decline during the ninth and tenth centuries, Sigman said.

The scientific team, with members drawn from Switzerland, Florida, Massachusetts and New Jersey, was searching for clues about ancient climate in sea sediments, a field known as paleoceanography. To do this, the researchers scooped long cylinders of mud from the deep, undisturbed Cariaca Basin.

They identified annual variations in titanium levels, which reflect the amount of rainfall each year. The pristine sediment layers in the basin form distinct bands, corresponding to yearly dry and wet seasons.

The three drought periods identified through the samples correspond to the three phases of Mayan collapse suggested by archeological evidence. The three droughts may have been what "pushed Mayan society over the edge," the authors wrote.

By about 900, most of the Maya abandoned the Guatemalan lowlands and moved to areas to the north and south, including Yucatan and the highlands of southern Guatemala. In those areas, they continued to survive until Spain conquered almost all of the Maya in the mid-1500s.

Today, descendants of the Maya live in Mexico and Central America. They speak Mayan languages and carry on some religious customs of their ancestors.

The results also suggest that a more subtle but long-term drying trend was occurring during the collapse.

"This fits, it makes sense," said Gillett Griffin, the faculty curator of ancient American art at the Princeton University Art Museum. "It corroborates what I thought must have happened."

The Mayan civilization reached its period of greatest development in the year 250. They produced remarkable architecture, painting, pottery and sculpture. They made great advances in astronomy and mathematics and developed an accurate yearly calendar. They were one of the first peoples in the Western Hemisphere to develop an advanced form of writing.

abc.net.au Friday, 14 March  2003

A long dry period punctuated by three intense droughts probably played a major role in the mysterious collapse of Mayan civilisation in Mexico, according to a new study. The severe droughts, each lasting between three and nine years, may have the been the final straws for a civilisation already on the verge of collapse, says a report published today in the journal Science. "Between about 750 and 950 AD, the Maya experienced a demographic disaster as profound as any other in human history," said the report, by an international research team led by Dr Gerald Haug of the Swiss Federal Institute of Technology in Zürich. The Mayan were so successful that at their so-called Classic Maya peak, around 750 AD, the civilisation supported a population of between three and 13 million people, the researchers said. But then it progressively collapsed and by the early 9th century, many of its cities and towns had been permanently abandoned. The study details new evidence that the three droughts occurred around 810, 860, and 910 AD - corresponding to the three phases of Mayan collapse suggested by archaeological evidence. The researchers also found that a more subtle but long-term drying trend was ongoing during the collapse. The droughts may have been what specifically "pushed Mayan society over the edge," they said. The findings are based on an analysis of long-term climate records as revealed in pristine undisturbed sediments from the Cariaco Basin, off northern Venezuela. The distinctly layered sediments, washed out from land by rivers, show up as pairs of light and dark bands that correspond to annual wet and dry seasons. Within them, the team identified yearly variations in titanium levels, which reflect the amount of rainfall each year. They correlate well with palaeoclimate data obtained elsewhere from sources such as ice cores and tree rings. Until now, however, climate records from the time had not been precise enough to test the relationship between drought and the Maya's downfall during the 9th and 10th centuries, the report said. The Mayans began cultivating maize in the region about 2000 BC, using dryland farming techniques that depended on fallowing to rest the soil and needed relatively little labour. Like other Native Americans, they went on to develop sophisticated ways of intensively cultivating fertile soils associated with seasonal and permanent wetlands, on which multiple crops could be grown year after year. Living in the Yucatan lowlands of Mexico and depending mainly on an inconsistent rainfall cycle, the Maya developed labour-intense networks of raised fields as well as canals, reservoirs and other systems for storing and gravity-powered distribution of rainwater. The Mayans had abandoned their major cities once before - between about 150 and 250 AD - an incident that may also be due to drought. But their population constantly recovered, cities were reoccupied and their culture blossomed. "The control of artificial water reservoirs by Maya rulers may also have played a role in both the florescence and the collapse of Maya civilisation," the researchers wrote. Other scientists have suggested that drought may have undermined the institution of Mayan ruling class when existing ceremonies and technologies failed to provide sufficient water. The Mayans were an ancient people whose high civilisation flourished in what is today Mexico, Honduras and Guatemala. They created monuments as impressive as those in ancient Egypt, were proficient in mathematics and astronomy and invented a unique written language.

Bob Beale - ABC Science Online

More Info? Sun cycle may have affected the Maya, News in Science 23 May 2001 El Nino cycles ancient and peaking, News in Science 20 Nov 2002