New Technique Sheds Light On Maya History

Newswise — There are elaborate hieroglyphs, burial objects and other clues.

But the recent application of a geological technique to an archaeological problem may offer a unique tool for gleaning seemingly unknowable facts about the ancient Maya " based only on excavated bones and teeth.

University of Florida geology Professor David Hodell and Associate Professor Mark Brenner did an elaborate review of the technique, which combines elements of geology, anthropology and forensic science, in the Central American region that was home to the classic Maya civilization. Their conclusion: The method can help determine where long-dead leaders and ordinary residents of such grand settlements as Tikal were born and raised, building on " and sometimes contradicting " history that until recently had been gleaned only from hieroglyphics and other archaeological evidence.

"We were able to demonstrate that you can distinguish between the different parts of the Maya area," Hodell said of the research, described in a May article in the Journal of Archaeological Science. "You can tell whether an individual was raised in Tikal or whether they came from somewhere else."

At their peak, from about A.D. 650 to 800, the Maya occupied large city-states spread out across parts of present-day Mexico, Guatemala, western Honduras and Belize. They practiced astronomy, organized their activities around a solar calendar and built enormous stone temples, the ruins of which remain in large abandoned cities and scattered throughout the jungle. Although the Maya empire fell apart from 800 to 1000, isolated settlements persisted through colonization, and many Central Americans speak Mayan languages and practice Maya religions to this day, he said.

For archaeologists, understanding mobility in Maya society " how much and how far people moved " is essential to grasping the rise and fall of their empire.

For example, one important question about Tikal is whether its large population of about 60,000 was the result of local population growth or migration to the area, said Lori Wright, an associate professor of anthropology and bioarcheologist at Texas A&M University in College Station who specializes in the study of skeletal remains.

Until recently, scientists' main tools included deciphering the stone hieroglyphs that Maya scribes left behind. But while these hieroglyphs, not yet completely translatable, describe movement among Maya elites, they provide few clues about the majority of ordinary residents, Wright said. And as with any society's official records, some hieroglyphs also may be misleading, she said.

"Hieroglyphs are political documents, and it may be that history is rewritten to suit political themes," she said, explaining that Maya historians may have wanted to play up a leader's origins or connections to other cities or regions, even when those connections were tenuous or nonexistent.

Hoping to address the migration issue more definitively, scientists recently began applying a standard geological technique " comparing the ratio of the strontium element isotopes 86 and 87 " to excavated bones and teeth from Maya burial sites.

Because rocks form through a variety of processes and at different times during Earth's history, strontium 86 and 87 ratios naturally vary from place to place. People readily uptake the isotopes and deposit them in bones and teeth, so those raised in a region underlain by volcanic basalts will have different ratios than those from one underlain by limestone " provided they eat mostly local food, a likely scenario before refrigeration and mechanized transportation.

Strontium isotope ratios are especially revealing for tooth enamel, which is extremely hard and forms during a person's youth, Hodell said. Bone, on the other hand, can be more telling of a person's recent whereabouts because it continues to grow slowly throughout life, he said.

Although initial results using the technique on Maya remains over the past few years have been promising, questions persisted about its usefulness and accuracy. Hodell and Brenner's research represents the first comprehensive assessment of the technique's capabilities in the Maya region. Along with graduate students Rhonda Quinn and George Kamenov, the researchers surveyed 216 sites throughout Mexico's Yucatan Peninsula and Guatemala, collecting water, bedrock, soils and plants from a wide area, analyzed the strontium ratios in each, then plotted the results on a map. The project was funded by a $13,000 grant from the UF College of Liberal Arts and Sciences.

The study demonstrated there are five distinct geological regions that can be "readily distinguished" from one another based on strontium isotope ratios " providing a "powerful tool" for archaeologists to determine the origins of skeletal remains in these subregions, the paper says.

Brenner said one reason the method works so well in the Maya lowlands is that the underlying limestone varies so consistently. "In the Maya highlands, the rocks are formed by volcanic and metamorphic processes which have different strontium isotope ratios from the lowlands," he said.

That said, he cautioned there also can be some overlap between regions, which could confound results and is one limitation they discovered.

Wright said the technique has revealed that several of the skeletons she is examining from Tikal are not those of longtime residents of the city. "Some of the data is contradicting what the hieroglyphs suggest about the identity of some skeletons," Wright said.