On the menu: Were ancient prehistoric mounds connected to food resources

The prehistoric earthworks at Poverty Point remain shrouded in mystery, but you can say one thing with relative confidence: The people who hauled basket upon basket of dirt to build it would have been hungry.

Sarah Gilleland is looking to discover what was on the menu and whether the use of the site coincided with the abundance of particular food resources. The graduate student recently received funding through the Harpur College Dean's Graduate Investment Initiative to examine animal bone fragments found at the site with high-tech tools in Binghamton University's Advanced Diagnostics Laboratory.

Located in northeastern Louisiana, Poverty Point is the single largest construction of its kind in North America before the advent of centralized political power; the UNESCO World Heritage Site bears the name of a former plantation that once operated there. It was created around 3,500 years ago by hunter-gatherer groups, who used innumerable baskets of dirt to build a 72-foot-tall mound, concentric half-circles and related earthworks.

"The largest mound contains 96 Olympic swimming pools' worth of dirt," said Gilleland, a South Carolina native who chose Binghamton's doctoral program in anthropology specifically to study with her advisor, Professor Carl Lipo.

Even with that analogy, it's difficult to compare the scale of the site and how it stands out in the landscape; even the half-dozen smaller mounds are composed of "huge mountains of earth," she said. Prior to the construction work, ancient peoples leveled 2 square kilometers of land.

The site took shape over a few hundred years at most for reasons that remain undetermined; for similarly unknown reasons, use of the fully developed site stopped after several hundred years. Artifacts, such as spearpoints made of stone found in Nebraska or Kentucky, show that individuals associated with the site came from throughout the southeastern United States.

"It's an enormous work of group cooperation at a time when people are presumed to have been fairly disconnected from each other, living in the landscape in small, mobile groups," she said.

Little is known about what the people who built and used the site ate. Archaeologists often rely on midden piles -ancient trash heaps - for this information, but Louisiana's hot, wet climate and acidic soils break down such remnants quickly. These include human remains, none of which have been found at the site.

Bones from suspected midden heaps do exist, but they're virtually crumbs - highly degraded, even their species undetectable to the naked eye.

Initially, Gilleland tried analyzing soil samples for ancient DNA without much success due to the degradation issue; she did, however, discover that samples seem to derive primarily from birds and fish, occasionally large mammals such as deer.

Currently, she is working with Louisiana state archaeologists and local tribes to conduct zooarchaeology by mass spectrometry, which involves extracting collagen from bone samples and analyzing it with a mass spectrometer.

"The length and weight of the different collagen molecules will tell you what species you're dealing with," she explained.

Were the birds a migratory species, abundant at certain times? Was fish consumption connected with spawning patterns? Did hunter-gatherer groups visit the mounds at predictable seasons to take advantage of these resources?

High-tech equipment such as mass spectrometers may point researchers to an answer. Tools from the hard sciences are becoming more common in archaeology, Gilleland acknowledged; the use of light detection and ranging (LIDAR), which comes from geophysics, is already widespread.

"The field is growing and changing in really interesting ways," she said.

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