A new study analyzing ancient DNA has uncovered the primary ingredient in the famous ancient Roman sauce garum. The findings point to European sardines, preserved at a Roman-era salting site in Spain, as the key fish used in this widely consumed condiment.
Although often linked with Roman cuisine, garum was not a Roman invention. The sauce traces back to Ancient Greece, where a similar fermented fish sauce known as “garos” (Greek: γάρος) was widely used. However, the sauce has Babylonian origins and arrived on the coasts of Mediterranean lands thanks to the voyages of the Phoenicians.
The Romans adopted and adapted the recipe, eventually turning garum into a staple of their diet and a key product in their food trade.
Fermented fish was central to Roman food culture
Garum was made by fermenting small fish in salt at coastal processing centers called cetariae. These sites helped preserve large quantities of fish, allowing producers to create sauces and pastes that added intense flavor to Roman meals.
Although garum gradually disappeared, its culinary legacy lives on in modern fermented sauces such as Worcestershire and those used widely in Southeast Asia.
Identifying the fish was long a challenge
While fish remains are common at ancient salting facilities, identifying which species were used in garum has proven difficult. The fermentation process, along with crushing and acidic conditions, often destroyed the physical features needed for visual identification.
To overcome this, an international research team turned to DNA analysis. They extracted and sequenced genetic material from fish bones found at the Adro Vello site in northwest Spain, a Roman-era cetaria. Despite the degradation, the team identified the remains as belonging to European sardines.
The study, published in the journal Antiquity, is the first to confirm the species used in ancient Roman sauce garum through genetic analysis.
Ancient sardines closely match today’s population
Paula Campos, a specialist in ancient DNA at the University of Porto, led the research. Her team compared the ancient sequences with DNA from modern sardines in the same region. They found strong genetic similarities, although sardines are known to migrate over long distances. This suggests remarkable genetic continuity in local fish populations over centuries.
A new tool for studying ancient diets
The researchers say fish-salting vats hold rich archaeological material, but the tiny size of fish bones has limited their study. The success of this DNA approach opens new possibilities for examining how ancient people fished, ate, and traded.
They also note that such research can reveal changes in marine life that modern fishing data cannot capture.
By unlocking the DNA of the fish behind ancient Roman sauce garum, researchers have opened a new chapter in archaeological science—one where even the remnants at the bottom of a vat can offer a glimpse into daily life thousands of years ago.