Mayan 'collapse' disputed - Lengthy dry spell may have forced them to move

www.dallasnews.com 03/17/2003 Washington Post

Beginning in the eighth century and continuing for 150 years, the great Mayan civilization of the Petén rain forest in present-day Guatemala fell apart. Cities were abandoned, people fled and wars raged across the encroaching wilderness.

This prolonged event – known traditionally as the Maya "collapse" – is one of the enduring mysteries of pre-Columbian America and a subject of continued debate. How did it happen?

In research reported last week, a German-led team of earth scientists offered new evidence that a 200-year dry spell, punctuated by three periods of serious drought, may have played an important role.

"There's competition for food, there are wars, there's deforestation, and the climate is drier," says paleo-oceanographer Gerald Haug of Potsdam's Geoscience Center. "These were problems you could cope with to a certain degree – but then you had the extremes. It's a subtle catalyst."

By measuring the undisturbed sediments of Venezuela's Cariaco Basin on the Caribbean coast, Dr. Haug's team was able to identify a significant decline in regional rainfall beginning aroundA.D. 750, with drought spikes starting at 810, 860 and 910.

The sequence corresponds fairly closely to protracted Maya upheavals that began in the western Petén in the late seventh century, and in the central Petén lowlands in the ninth century. By 930, some archaeologists calculate that the Maya heartland had lost 95 percent of its population.

For more than a century, this diaspora bewildered archaeologists even as it cemented the popular vision of a "lost civilization" of spectacular pyramids and monuments overtaken by jungle in a trackless tropical wilderness.

Much more is known today, and archaeologists are much less likely to accept overarching theories for the "collapse," a term that is losing cachet as evidence accumulates that the Maya did not "disappear," but simply moved: north to Yucatan in Mexico, eastward to Belize and to highland settlements on the edges of the rain forest.

"It's not a question of whether there was a drought or an invasion. There wasn't some big, single anything that happened at some big, single time," says Vanderbilt University archaeologist Arthur Demarest, who is editing a book on the period. "This kind of theory doesn't have a place anymore, given the detail of cultural history we have."

More sympathetic was the University of Pennsylvania's Robert Sharer, author of a classic text on the Maya, who notes that "climate changes, including drought, have always been part of the mix," and "the argument has been strengthened" over the last 10 years. "But what everybody wants is a pat answer," Dr. Sharer says, "and we're still not at that point, and probably never will be."

The new research, reported in last week's issue of the journal Science , was sponsored by the Ocean Drilling Program, a multinational initiative led by the National Science Foundation. Dr. Haug's team studied the topmost layers of a 560-foot Cariaco Basin core sample.

The basin in Venezuela is about 1,800 miles east of the Petén, but both places lie on the "Intertropical Convergence Zone," also known as the doldrums, a band that encircles the Earth where the northern and southern trade winds meet to create a region of almost perpetual thunderstorms. When it rains in the basin, it is raining in the Petén.

"The Cariaco Basin is the best climatological archive in the tropics, and since the Maya region is clearly affected by the same climate, it was perfect for us," Dr. Haug says.

"No one archaeological model is likely to capture completely a phenomenon as complex as the Maya decline," the authors wrote in Science. "Nevertheless, the Cariaco Basin sediment record provides support for the hypothesis that regional drought played an important role."