Dental plaque helped reveal the dietary habits of ancient Europeans: they ate algae

Analysis of molecules preserved in fossilized dental plaque has revealed that seaweed and aquatic plants, virtually absent from most modern Western diets, were once staple foods of ancient Europeans, CNN reports.

Evidence of this hitherto hidden taste for nutrient-rich plants and algae has been difficult to detect in archaeological finds, according to a study published Tuesday in the journal Nature Communications. Previously, when researchers found evidence of seaweed, they explained its use as fuel, food packaging or fertilizer.

Previous research has suggested that the introduction of agriculture, which began around 8,000 years ago, prompted early humans to largely abandon eating seaweed. In Europe, by the 18th century, seaweed was considered food for very starving people or was only suitable for animal feed.

“It is very exciting to be able to definitively prove that seaweed and other native freshwater plants were eaten for a long period in our European past,” study author Karen Hardy, professor of prehistoric archeology at the University of Glasgow, said in a statement.

Karen Hardy and a team of archaeologists from the University of Glasgow and the University of York in the United Kingdom examined the teeth of 74 ancient people discovered at 28 archaeological sites across Europe, including the far north of Scotland, southern Spain and Lithuania.

The oldest sites examined in the study in Spain and Lithuania dated back more than 8,000 years ago, while the most recent was around 2,000 years old.

The researchers were able to detect identifiable chemical markers in tartar—bacterial plaque and food debris that accumulate on teeth over time—in 37 samples from 33 people. And of these, 26 samples were found to have seaweed or aquatic plants on the menu.

“Plaque… is very common, and once it forms, it can only be removed by scraping. This is what dentists do today as part of the cleaning process, explains Professor Hardy. “But in the past it just accumulated – especially in the small space between the tooth and the gum. This has been a common occurrence in most archaeological skeletal material throughout the past. It acts as a trap for material that enters and passes through the mouth. Since it is in the mouth, all the substances found in it are clearly associated with ingestion.”

According to the study, seaweeds, freshwater algae, and aquatic plants have “special, unusual, and complex organic chemistry” that has enabled the preservation and discovery of “highly potent biomarkers” of three types of organic compounds—lipids, amino acids, and alkylpyrroles.

“It’s a specific combination of biomarkers that allows us to identify seaweeds and aquatic plants,” said study co-author Stephen Buckley, a research fellow in the Department of Archeology at the University of York. – Other plants do have their own distinctive biomarkers, but they tend to survive less well in archaeological conditions compared to, for example, algae (e.g. seaweeds, macroalgae), so we can say that seaweeds and aquatic plants were exposed to organism and, therefore, were consumed as food.”

Analysis of the samples revealed that early humans ate, or at least chewed, red, green and brown seaweeds and various freshwater aquatic plants, such as species of algae and vegetation from the same genus as the water lily.

“This strongly suggests that the nutritional benefits of seaweed were well enough understood by these ancient populations that they maintained their dietary connection to the sea,” stresses Stephen Buckley.

The studied remains found in chambered pyramids or tombs in Orkney, an archipelago of islands off the coast of Scotland, also revealed biomolecular evidence of the consumption of seaweed, including most likely seaweed.

And, as the study notes, it wasn’t just coastal communities that consumed seaweed. At La Corona, a site in southeastern Spain that occupied the area from 6059 to 5849 BC, seaweed formed part of the diet, despite being 80 kilometers from the coast.

Buckley notes that it is impossible to be sure whether ancient Europeans cooked seaweed or ate it raw. However, he said it made sense that seaweed would be a staple food, given its nutritional properties and ease of obtaining along the seacoast.

Today, seaweed is considered a “superfood”, with around 145 species eaten, mostly in Asia, and known to have many health benefits.

The scientists said they hope their study will highlight the potential for including more seaweeds and freshwater plants in modern diets.