Acorn Oil Rendering and the Adoption of Pottery in the Upper Great Lakes
School of Anthropology
As an abundant and easily storable source of fats and carbohydrates, acorns represent a significant, yet often overshadowed, element of the human diet. Hanson’s recent research in the Laboratory for Traditional Technology (2017) has sought to add one more product to the acorn’s growing resume: oil. Acorn oil would have provided a nutritionally rich product for overwintering and may have been an important impetus for adopting pottery in the region.
Organic residue analysis of pottery sherds from two Woodland period sites on Grand Island, Michigan yielded lipid profiles consistent with nut oil (Skibo et al. 2009). Skibo et al. (2016) have since argued that the adoption of pottery in the Upper Great Lakes region was intended to facilitate acorn oil rendering, largely replacing stone boiling techniques as the predominant cooking technology. While ethnographic sources confirm that oil was rendered from acorns (e.g. Densmore 1928), the mechanics of this process had not been systematically investigated.
Hanson’s research sought to evaluate this argument by establishing experimental parameters for rendering acorn oil. Put simply, does simmering in ceramic vessels offer a more efficient mechanism for rendering oil than stone boiling techniques?
To address this, northern red oak acorns (Q. rubra) were first shelled and simmered in water to remove harmful tannins . Leached acorns were then processed into a thin paste using groundstone tools and the addition of a small amount of water. Once processed, acorn fats separate within minutes and can be poured off for immediate use or into smaller containers for storage . This process was repeated with boiling temperatures to replicate stone boiling and no separation of fats occurred. This suggests that acorn oil cannot be rendered at boiling temperatures and could only be accomplished with simmering temperatures afforded by ceramic vessels.
These preliminary results indicate that acorn oil can be effectively rendered using ceramic technology, which conditionally supports the claim that the adoption of pottery in the Upper Great Lakes region was intended to facilitate acorn oil rendering.
1928 Uses of Plants by the Chippewa Indians. Bureau of American Ethnology Annual Report 44:275-
Skibo, James M., Mary E. Malainey, and Eric C. Drake
2009 Stone Boiling, Fire-Cracked Rock and Nut Oil: Exploring the Origins of Pottery Making on
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Skibo, James M., Mary E. Malainey, and Susan M. Kooiman
2016 Early Pottery in the North American Upper Great Lakes: Exploring Traces of Use. Antiquity