Ancient civilization trading secrets revealed

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Ancient civilization trading secrets revealed
Patience is key for measuring the trade system thoroughly
By: Karl Zynda

Issue date: 9/17/07 Section: News
PrintEmail DoubleClick Any Word Page 1 of 3 next > History and chemistry are intersecting on the lowlands of the coastal region of southern Mexico. From Cal State Fullerton, Tuan Vu is using the lab equipment in Dan Black Hall to put a magnifying glass on a long-lost culture. Archaeological and chemical studies are merging to decipher what tar samples can tell about an ancient civilization's trade habits.

Vu, 25, is a history major who is currently completing a minor at CSUF in chemistry. He is one of three students working on applying chemical analysis to bitumen samples. The testing is part of an archaeological project conducted by CSUF professors Carl Wendt and Scott Hewitt.

Vu originally decided to enroll in CSUF because of its good teaching credential program. He declared history as a major, hoping to become a history teacher. After earning his history degree, he changed his mind about teaching. He decided to earn a minor in chemistry, hoping instead to become a pharmacologist. Vu said he would like to apply to pharmacology programs at USC and Ohio State, which are his two top choices for school.

The project he worked on over the summer was about the trading of bitumen in ancient civilizations. Bitumen, or asphalt, was used by the Olmecs, a people who lived in the south Gulf region of what is Mexico today. They predated the later Aztec and Maya civilizations. The Olmec are best known for crafting sculptures of colossal heads. The tribe used bitumen for waterproofing boats, for building material, for trade and possibly as an adhesive. Wendt said that while beliefs about Olmec trade have been based upon conjecture and comparison, until now, this study can provide real data.

"The big picture is, we're trying to see how far the Olmec civilization reached, trade-wise," Vu said. "We look at tar samples, seep samples, and the bitumen, which are the rocks. We want to match up the rock samples to certain seeps so we can see how far it traveled going from civilization to civilization in the area."

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The research is being funded with a grant made in two payments by the National Science Foundation. Hard data has to be displayed by the end of the year for the second payment to be made. Hewitt said even with the GC/MS breakdown, there should be no problems meeting the deadline. Vu discovered that testing with the gas chronometer/mass spectrometer (GC/MS), a device that purifies and identifies exact compounds, can be painstakingly slow work. The GC/MS used for the research stopped working properly in June.

It was eventually shipped back to its manufacturer for adjustment. Vu and Hewitt said they hope it will be returned by the end of this month. It's absence has stopped further research for now. In order to maintain scientific consistency, the same GC/MS must be used to test all samples in an experiment. Hewitt said he understands Vu's difficulties. He said waiting for the GC/MS to be fixed and developing the testing methods must be tedious and frustrating.

"You have to be very careful because you want to get it right," Hewitt says of Vu's research. "I think what frustrates Tuan is that it's not always working and you have to solve the problems. In a class lab we set it up so it works and in the real world, it doesn't work that way."

On the counter top where the GC/MS was, only scattered wrenches and disconnected hoses and wires remain.

"It's kind of opened my eyes to how hard research is," Vu said. "Just how much work it is."

Testing a sample can take two to three hours, and sometimes tests fail due to mechanical malfunctions.

"The daily grind of it is, we work all day to make an inch of progress," Vu said.

In its absence, Vu ran samples on another GC/MS in order to perfect testing techniques. The methods of testing the bitumen samples with a GC/MS are being developed by Vu specifically for this experiment. This is much different from experimenting in a classroom setting, where the experiments are designed to result in predetermined outcomes.

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"It was in my field, history, and it was something I thought would be interesting," Vu says of why he chose to work on the project. Having some background in research could also help him to be accepted to a pharmacological program, he said.

Hewitt plans to let Vu present his results at a scientific conference sometime in the future. There they will get feedback from other scientists in the form of comments, questions and ideas.

"We'll probable have him present his results at a conference and then it will probably be much more satisfying," Hewitt said.

Hewitt finds Vu to be a satisfactory researcher.

"He's a good student," Hewitt said, "Especially given he's a history major, not a science major . . . On these research projects, we don't expect students to be experts when they start. Research is a learning experience for them. I think once he's started to get results, it will be much more satisfying."

That bitumen samples found at Olmec archaeological sites could be matched to tar seeps was in doubt when Wendt, an anthropology teacher, began to study them. A paper published in the Journal of Archaeological Review in January of 2006 confirmed that they could be. The GC/MS analysis is what made clear the chemical correlations that Dr. Wendt compares to fingerprints and DNA for their unique identifying capability.

Tar samples differ, Dr. Wendt explained, because each tar seep has its own unique chemistry. The tar is made of decomposed plankton, plants, and dinosaurs that was exposed to subsurface heat and bacterial decomposition. Isolated reservoirs of tar develop their own unique chemical compositions.

The chemical processes involved in the GC/MS identifications are complex. It can be described most simply, as explained by Hewitt, as a process of purification, followed by a process of chemical identification. The gas chromatography purifies the sample by forcing it through a column filled with silica gel, leaving only pure hydrocarbons. The mass spectrography then determines the amounts of particular compounds in the sample, thus reading its precise chemical identity.