What the (Prehistoric) Shell?

Archaeology involves the interpretation of material culture from peoples in the past. But we rely on contemporary theoretical concepts and analytical tools to study the objects that we find.

Porc-Epic, located in northeast Ethiopia, is a Middle Stone Age (MSA) cave site. The assemblage at the site dates to around 70,000 years ago (ka) and contains MSA stone tools and fauna. At this site, archaeologists have also discovered over 400 perforated land snail opercula from the species Revoilia guillainopsis.

Opercula are the round, hard covers that close the opening of shells in many land and marine snail species. The opercula, unbroken except for a central perforation, resemble disc beads made from material such as ostrich eggshell and terrestrial snail whorl shell. Researchers at the site refer to these perforated opercula as beads and use this as evidence of symbolic behavior. The perforated opercula at Porc-Epic are a particularly fascinating case study in shell bead materiality for two reasons: first, opercula are an uncommon material for bead making, and second, it is not entirely clear that the perforated opercula were used as beads in the first place. This ambiguity allows us to explore how we can understand the past through the materiality of the archaeological assemblage.

Photograph illustrating terrestrial snails with spiral shells in a light to dark brown color and small cream opercula samples.
Image description: Six spiral shells in varying shades of brown are laid out in two rows of three shells each. Below the sixth shell is a legend indicating what represents a length of two centimeters. The spiral shells vary from four to six centimeters. Below those shells are six cream-colored opercula in one row.
Caption: Examples of contemporary terrestrial snail shell and opercula samples.
Cindy H. Huang and John K. Murray

Without written text to ground interpretations, prehistoric archaeologists face a number of challenges. We must rely on artifacts to understand archaeological assemblages and their implications for human behavior. We cannot look into the minds of prehistoric populations; thus, we can only interpret the material through the lens of our modern cognition. Therefore, researchers have turned to concepts of symbolic behavior as a way to get at an understanding of cognitive processes of prehistoric humans; while others are interested in symbolic behavior because being able to abstract thought into symbols allows us to learn, teach, and otherwise communicate our thoughts and ideas ecosomatically.

Personal ornaments are frequently cited as some of the earliest evidence of symbolic behavior, as they are thought to be an early form of self-expression. These ornaments have been found in the form of beads made from material such as marine shells, terrestrial shells, and ostrich eggshells. However, since the populations that made some of the beads in the archaeological record lived as far back as 70 ka, imposing our cognitive processes onto those humans is problematic. Turning our attention to the materiality of the beads—the intersection of the material and the social—allows us to interrogate both the archaeological meaning of the material record and the researcher’s preconceived assumptions about it.

Weaving a meshwork of relations

To limit the imposition of our contemporary cognitive biases, we employ two linked concepts of material culture studies: Tim Ingold’s “meshwork of relations” and Carl Knappett’s “processes of commodification.” The perforated opercula can be studied as a process. The object exists within a meshwork of relations, flowing, mixing, and mutating along the lines. Studying this meshwork allows us to engage with multiple aspects of an object, instead of only the immaterial “social” relationship. Recently, Ingold likens human engagement with the world to the act of weaving, where social transformations emerge from the material conditions to create meaning and culture; the mind and the material are thus intertwined as we weave the world of our experience. Knappett, using ideas informed by practice theory, proposes the process of commodification. In this view, things, which are undefined clusters of material, become objects—transparent and meaningful— through practice, standardization, and routine. This alternative lens challenges our preconceived notions of MSA people.

Assigning significance to the perforated opercula by simply labeling it as a “bead” is a problematic process

Situating the processes of opercula production within the landscape of where Middle Stone Age people lived allows us to interpret, through the opercula, the ways that MSA people understood their environments. Each operculum exists within the meshwork of knowledge and material and are a part of how MSA people wove their world of experiences. The explicitly material component of the perforated opercula reveals a surprising amount of information about what MSA people knew about their environments and the choices that they made.

In order to collect four hundred opercula, MSA people must have understood the differences between various species of snails. They needed to know which snails have opercula, since some shell openings are sealed by a mucus covering, and specifically, which opercula were suitable to be made into beads. At Porc-Epic, collecting the opercula was a deliberate choice, as only the opercula were found at the site and not the corresponding snail shell. Additionally, MSA people needed to have the landscape and ecological knowledge to collect the specific opercula in such high frequencies, which embeds the act of collection within a broader set of interactions with the environment.

Commodification and perforating opercula

Studying the perforated opercula at Porc-Epic requires researchers to make certain assumptions about the intentions and cognitive processes of the ancient human(s) that created the assemblage. Following Knappett’s discussions of commodification, we can think about the role of practice, standardization, and routine play in meaning making, both for the creator of the perforated opercula and for the archaeologist. The presence of 400 perforated opercula allow researchers to assign intent to the practice. One perforated opercula at a site could be naturally occurring, but such a large collection shows purposeful, repeated actions and choice. The opercula, whether they were ultimately used as beads or not, were gathered in large quantities and perforated. While perforating the opercula may not have been a technically difficult task, the perforator needed to understand how to perforate the central portion of the opercula without cracking it. The use of tools and the embodied knowledge of creation involves practice.

Assigning significance to the perforated opercula by simply labeling it as a “bead” is a problematic process, since the function of the perforated opercula is unknown. While we will never know exactly what the ancient human(s) that gathered and perforated the opercula at Porc-Epic were thinking, by focusing on the materiality of the opercula, we can understand that these objects were meaningful to them in some way.

Cindy H. Huang is a doctoral student in the School of Human Evolution and Social Change at Arizona State University and an affiliated graduate student of the Institute of Human Origins. Her research interests include biocultural evolution and the impact of technological and cultural innovation on human evolution.

John K. Murray is a doctoral student in the School of Human Evolution and Social Change at Arizona State University and an affiliated graduate student of the Institute of Human Origins. His research focuses on the origins of modern humans and heat treatment technology in the Middle Stone Age.

Sandra L. López Varela is contributing editor for the Archaeology Division’s section news column.

Cite as: Huang, Cindy H. and John K. Murray. 2020. “What the (Prehistoric) Shell?” Anthropology News website, September 29, 2020. DOI: 10.14506/AN.1509

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