Q&A: Discarded ancient 'trash' now protecting Georgia barrier islands

UNIVERSITY PARK, Pa. — Penn State Assistant Professor of Anthropology Jacob Holland-Lulewicz is among a group of archaeologists who have spent years conducting research on the barrier islands off the coast of Georgia. The islands have changed shape and even numbers over the centuries, with Hurricane Irma splitting one into two distinct masses in 2018 and potential changes on the horizon now that the current hurricane season is underway.

The largest and most lasting influence, however, may be people. 

The islands have been hugely impacted by human activity going back nearly 5,000 years or so, when the Indigenous ancestors of the Muskogee Creek Nation began inhabiting them. Over millennia, the discarded oyster shells that constituted a large part of their diet multiplied into the billions, changing the landscape in ways that have preserved the islands’ ecosystems and protected the coastlines from the effects of changing climate.

Using data from the U.S. Geological Survey and the National Oceanic and Atmospheric Administration, Holland-Lulewicz and five other researchers — Penn State Assistant Professor of Anthropology and Ecology Isabelle Holland-Lulewicz, Brandon T. Ritchison of the University of Illinois Urbana-Champaign, Matthew D. Howland of Wichita State University, and Amanda Roberts Thompson and Victor D. Thompson of the University of Georgia — determined that the added elevation from the shell deposits has protected significant portions of the coastline from being submerged by high tides and the effects of hurricanes and tropical storms.

The researchers published their findings in the journal Communications Earth and Environment, and their work was spotlighted in a National Geographic article. Funding for the research came from a number of sources, including the U.S. National Science Foundation, Penn State, the Ossabaw Island Foundation, the University of Georgia Marine Institute and the Georgia Department of Natural Resources.

In the Q&A below, Jacob Holland-Lulewicz discussed the team’s findings.

Q: How did you and your fellow researchers come to write about this subject?

Holland-Lulewicz: The paper we put together was a synthesis of our datasets and research collected over the last 15 to 20 years, although none of our projects were addressing this topic in particular. Most of our work was addressing things specific to understanding Indigenous history on the coast — how people engaged with the environment and these ecosystems and created institutions over the past 5,000 years.

That said, we’re all dirt field archaeologists, meaning we tromp all over these islands and interact with these landscapes very intensely. We excavate, we put holes in the ground. Where people might look at these places like natural, untouched, pristine wilderness, we archaeologists see the signatures of human activity everywhere in the landscape. The reason these places are so well-preserved and outstanding examples of what a landscape could look like when humans don’t ruin it is actually the result of thousands of years of Indigenous people actively managing these places. It’s important for people to understand that, especially when it comes to Indigenous people who have been removed from these landscapes and have been mostly invisible to the public.

Q: Can you talk a bit about Ossabaw and Sapelo Islands, where you conducted your specific research?

Holland-Lulewicz: One of the article’s co-authors, Brandon Ritchison, has dug over 1,000 holes across a site on Sapelo Island that was once a large Indigenous town. His calculations, combined with our recent work at another large Indigenous town on Ossabaw Island, were just bananas. At his site on Sapelo alone, 11% of that landform is made from oyster shells. It’s something like 1.6 billion oysters deposited; the scale is just huge. And there would have been a deep ecological knowledge among Indigenous people about the relationship between the land and between their actions depositing shell, which I think is important to think about because they didn’t do it by accident — they knew that what they were doing was contributing to a landscape they were familiar with.

The Indigenous people stopped living on Ossabaw Island in the mid-1500s, and then there were plantations there in the 1700s into the 1800s, with the enslaved communities and the free Black Gullah Geechee communities also living there. Those people continued to interact with oysters and deposited them on the landscape. We have one Gullah Geechee woman’s account of moving from one town to another on Sapelo Island and how the new town wasn’t as good because it didn’t have oyster in the soil. The oyster deposition is clearly a beneficial part of the landscape, and they have created these really critical ecological legacies.

Q: How have the oyster shell deposits made the islands ecologically unique?

Holland-Lulewicz: There are certain grasses or plants or shrubs or berries that grow at archaeological sites on these islands that don’t grow anywhere else on the coast, which is kind of cool when you’re thinking about biodiversity. If it weren’t for the buildup of shells, there would be a large percentage of this land that would be gone and unable to support life and those ecosystems.

People have been living on the coast for about 13,000 years or so or earlier. And a lot of those islands we’ve been working on have been occupied for 5,000 years — a lot of them popped up only 5,000 years ago, and almost immediately when some of these islands became land people began living on them. Which is amazing to think about, because a lot of them today are undeveloped and no one lives on them, which means this is the first time in 5,000 years that people haven’t been part of those ecosystems. Those islands don’t know what it’s like to be a natural ecosystem without humans.

Q: Why was it important for you and your colleagues to share your results with an audience beyond the archaeological community?  

Holland-Lulewicz: We sent the article to an interdisciplinary earth science journal to get it out there beyond colleagues in our field. The thought was, "How do we express this to our colleagues in ecology who are working on conservation and climate change?" Because our models of the impacts of climate change, and what potential solutions are to mediating rising sea levels and erosion, are often based on assumptions about natural places. What kind of baseline does an ecologist use to measure change or how far we’ve come or the impacts of conservation when those baselines haven’t incorporated the role of people? If we don’t understand that people over the last 5,000 years have had a heavy hand in shaping that baseline, we’re probably not set up for creating effective solutions for the future if we’re treating these as natural places.

Our main goal was to show that it takes a highly interdisciplinary perspective to approach the challenges of ecological disaster and planning and conservation and sustainability. It’s hard to translate our findings into actionable, applied practice, which is one reason we’re trying to talk to broader communities — maybe if we use their language to describe our results then this will be more useful and usable by these other parties. How can we give this information to people who can use it really well, like fishery scientists and conservationists and Indigenous tribes that are trying to revitalize fishing practices and other things? That takes intentional effort.