The Rise and Fall of the Mayan Empire

Scientists are using space satellites to unravel one of the great mysteries of the ancient Mayan Empire.

Where the rain forests of Guatemala now stand, a great civilization once flourished. The people of Mayan society built vast cities, ornate temples, and towering pyramids. At its peak around 900 A.D., the population numbered 500 people per square mile in rural areas, and more than 2,000 people per square mile in the cities - comparable to modern Los Angeles County.

This vibrant "Classic Period" of Mayan civilization thrived for six centuries. Then, for some reason, it collapsed.

The fall of the Maya has long been one of the great mysteries of the ancient world. But it's more than a historical curiosity. Within sight of the Mayan ruins, in the Petén region of Guatemala near the border with Mexico, the population is growing again, and rain forest is being cut to make farmland.

"By learning what the Maya did right and what they did wrong, maybe we can help local people find sustainable ways to farm the land while stopping short of the excesses that doomed the Maya," says Tom Sever at the Marshall Space Flight Center (MSFC).

Photo copyright Tom Sever. Mayan ruins in Guatemala

Sever, NASA's only archeologist, has been using satellites to examine Mayan ruins. Combining those data with conventional down-in-the-dirt archeological findings, Sever and others have managed to piece together much of what happened:

From pollen trapped in ancient layers of lake sediment, scientists have learned that around 1,200 years ago, just before the civilization's collapse, tree pollen disappeared almost completely and was replaced by the pollen of weeds. In other words, the region became almost completely deforested.

Without trees, erosion would have worsened, carrying away fertile topsoil. The changing groundcover would have boosted the temperature of the region by as much as 6 degrees, according to computer simulations by NASA climate scientist Bob Oglesby, a colleague of Sever at the MSFC. Those warmer temperatures would have dried out the land, making it even less suitable for raising crops.