A new study questions if Bronze Age dishes really do have traces of olive oil.

Rethinking Ancient Olive Oil: New Study Challenges Long-Held Assumptions

Olive oil has long been celebrated as a staple of Mediterranean cuisine—and archaeologists often report finding its residue on ancient pottery. Humans have been using it for around 8,000 years, but a new study suggests that its historical prevalence may have been overstated in some regions.

Cornell archaeologist Rebecca Gerdes and her team found that organic residues from plant oils, like olive oil, degrade rapidly in calcium-rich Mediterranean soils. This means that earlier identifications of olive oil on ceramics could actually be other plant oils—or even mistaken for animal fats.

Washing Ancient Dishes

Gerdes describes her work as “washing ancient dirty dishes,” collecting the rinse water to analyze molecules left behind on pottery. Partnering with chemical engineer Jillian Goldfarb, she developed an experiment to test how soil chemistry affects residue preservation.

Ceramic pellets were made from terracotta clay, coated with olive oil, and buried in two types of moistened soil—one from Cyprus and one from agricultural fields in New York. After up to a year in incubators at 122°F (50°C), the team analyzed the residues.

Surprising Results

The pellets buried in Cyprus soil—common in the eastern Mediterranean—showed significantly degraded olive oil markers, including a loss of key plant oil biomarkers. In contrast, pellets in mildly acidic New York soil preserved more of the olive oil signature. These results suggest that previous archaeological claims of olive oil may need reevaluation.

Gerdes notes that the assumption archaeologists often make—that finding olive oil molecules automatically means olive oil was present—can be misleading. Degraded olive oil can resemble other plant oils or even animal fats, complicating identification.

Looking Ahead

While this study did not re-examine ancient pottery directly, it highlights the need to revisit existing artifacts. Olive oil may not have been as ubiquitous as previously thought, and other oils or fats could have been used in the Mediterranean world. For Gerdes, the work continues: washing “ancient dirty dishes” to better understand the culinary past.