Ancient DNA Uncovers the Dietary Preferences of the Roman Empire

Garum, a type of fermented fish sauce, was a favored condiment throughout the Roman Empire. Recent analyses of ancient DNA extracted from the production vats have uncovered the specific fish species used in this staple seasoning.

This Roman fish sauce was widely appreciated for its intense salty and umami flavors. However, philosopher Seneca famously remarked that one variant had a price “as audacious as that of rotten fish.” There were various types, including a liquid known as Garum or Liquamen, and a thicker paste called Allec. The preparation involved fermenting fish and plant materials, complicating the identification of the fish species used.

According to Paula Campos from the University of Porto, Portugal, “The small, fractured bones and the acidic conditions contribute significantly to the degradation of DNA.”

Campos and her team conducted DNA sequencing on bone samples dating back to the 3rd century AD, sourced from a Roman fish sauce production facility in northwestern Spain. They compared numerous overlapping DNA sequences against the complete fish genome, allowing them to confidently identify the species involved.

This analysis revealed that the remaining fish was predominantly European sardines, aligning with previous visual identifications at other Roman fish processing sites. Additional fish species such as herring, whiting, mackerel, and anchovy have also been identified in various garum production locales.

This finding indicates that “even degraded fish remains” can yield identifiable DNA, suggesting that “it could enhance our understanding of regional variations in the main ingredients of historical fish sauces and pastes,” noted Analisa Marzano, a colleague from the University of Bologna, Italy, who was not involved in the study.

The research shows a comparison of ancient and modern sardines, indicating less genetic mixing among sardine populations across different marine regions in ancient times. This knowledge “may help us gauge the impact of human-environment interactions over the centuries,” Marzano explained.

For future studies, Campos and her colleagues intend to analyze additional fish species from other Roman garum production sites. “We’re broadening our sampling to verify if the results are consistent throughout the Roman Empire,” she added.