What can a bunch of old oyster shells tell you about the Chesapeake Bay’s past, and maybe its future? More than you’d think, according to Alex Jansen, a researcher with the Smithsonian National Museum of Natural History.

For several years, Jansen has been working with other researchers poking around on both shores of the Bay, digging up “shell middens,” primitive landfills holding ancient debris and other castoff artifacts. Around the Chesapeake, they mostly contain heaps of oyster shells, an indication of the dietary importance of the Bay’s bivalves to indigenous people long before European settlers arrived. 

As described in a paper published in January’s North American Archeologist, Jansen recently excavated six middens along the Rhode River, on the grounds of the Smithsonian Environmental Research Center in Edgewater, MD. Screens were used to sift out shells and shell fragments, bones and other items. Carbon dating was used to determine their age.

The earliest shell midden found at the Smithsonian center dates to the Early Woodland period, which goes back as far as 1200 B.C., Jansen said.

“There have been no shell middens located that date prior to this time period on the Rhode River,” he added in an email. “This indicates that people fed extensively on oysters from the Early Woodland period up to the time of European settlement.” 

But the middens also yielded evidence that early Bay residents didn’t rely exclusively on oysters. Found amid the shells were projectile points, clay pot sherds, and fragments of stone and bone tools. To Jansen, that suggests the early Bay residents supplemented their diets with some hunting. 

The findings of his and others’ midden analyses helps to flesh out the understanding of Native American life before European settlement. But it also offers some tips for modern-day management of oysters, Jansen said.

He said his findings tend to back up the conclusions of his mentor, Torben Rick, chair of anthropology at the Museum of Natural History, that Native Americans were able to rely on the oyster fishery as a sustainable resource.

Evidence has been found that prehistoric harvest pressures may have been intense in places, he noted, as shell sizes shrank over time. But it would appear that Native Americans collected the bivalves by hand from near-shore waters, as there were no artifacts found that indicated tools were used to harvest them. So, though it may not have been a conscious act of conservation, those early watermen and waterwomen apparently did not harvest oysters from reefs in deeper water, so those could reproduce and restock the population with fresh crops of bivalves.  

“You need to balance management with fishery needs,” he said.

Jansen said his research demonstrates the value of using radiocarbon dating along with artifact analysis to identify and evaluate archeological sites. Those methods of cataloguing a site are vital in coastal areas, he noted, as they’re increasingly being washed away or inundated by erosion and sea level rise. 

“Carbon dating can provide you quick information before they’re lost,” he said. Most of the shell midden sites like the ones he studied, he said “are going to be underwater in the next 10 to 20 years…Once they’re under water, they’re lost.”