WASHINGTON (Reuters) - The ancient Maya people were obsessed with the sun, moon and planets -- and perhaps for good reason.
The Yucatan peninsula, home to the Maya civilization during the first millennium A.D., was victimized by recurrent droughts linked to cyclical variations in the Sun's energy output, researchers on Thursday said. The worst of the droughts appears to have been instrumental in the collapse of the civilization at around A.D. 900, the researchers added.
Archeologists long have debated what snuffed out such a vibrant and durable civilization.
The Maya were among the great ancient civilizations of Mesoamerica, building cities with elaborate ceremonial centers and soaring stone pyramids such as Tikal in Guatemala, Palenque in Mexico and Copan in Honduras. The classic period in Maya civilization (starting around A.D. 300) pre-dated by hundreds of years the rise of the Aztecs in Mexico and the Incas in Peru.
A team led by University of Florida geologist David Hodell analyzed sediment from beneath Lake Chichancanab in Mexico to establish a record of changes in climate in a region already predisposed to be hit hard by drought, much like sub-Saharan Africa. The team dug a 6-1/4-foot core sample of lake sediment by driving a hollow tube into the lake bottom.
The researchers found layers of gypsum (calcium sulfate) concentrated at certain levels in the cores. When rainfall decreased, evaporation from the lake concentrated salts in the lake water and left behind bands of gypsum on the bottom, providing an enduring testimony to the periods of drought.
The recurrence of drought was remarkably cyclical, the researchers noted, occurring every 208 years. That interval was nearly identical to the previously known oscillation in which the sun is at its most intense every 206 years.
An ironic end
The Maya were skilled astronomers, religiously tracking the movement of heavenly bodies.
"I do think it was ironic that considering this culture really placed so much emphasis on tracking the movements of the sun and the moon and some of the planets, particularly Venus, that they may have met their ultimate demise due to a 208-year solar cycle,'' Hodell said in an interview.
"There's no evidence that I know of that the Maya were cognizant of this long-term cycle.''
The timing of the droughts matched periodic downturns in the Maya culture, as demonstrated by abandonment of cities or diminished stone carving and building activity, he said.
Hodell found that the worst drought in the region in 7,000 years took place from about A.D. 750 to A.D. 850, coinciding with the civilization's slip toward oblivion.
He said it is hard to believe this was mere coincidence, adding the drought may have triggered a cascade of events.
The population centers had become densely packed with people, almost to the breaking point, making agricultural production crucial in order to keep everyone fed, he said.
'A chain reaction'
"When drought hit, then it may have started a chain reaction -- you have crop failure, which leads to malnutrition, increased disease, increased competition for resources, which would have caused increased warfare between city states, and sociopolitical upheaval," Hodell said.
The study, appearing in the journal Science, built on work by Hodell in 1995 that found evidence of the big drought, but offered no mechanism to explain it.
Some archeologists seem willing to accept that climate played a role in the collapse, but are divided over the size of the role. Others note that the civilization's demise actually began in the wetter southern highlands of Guatemala before reaching the more arid northern Yucatan lowlands.
"The biggest problem is why, in a drought, does the dry area last longer than the wet area,'' archeologist Matt O'Mansky of Vanderbilt University said in an article accompanying the study in Science.
advertisement
