A photograph of the entrance to the Isbister Chambered Cairn on a blue sunny day.

The calculus of 15 individuals from the 5000-year-old Isbister Chambered Cairn in the Orkney Islands was analysed as part of the project. Image © Karen Hardy.

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From staple to superfood: how seaweed fed prehistoric Europeans

Seaweed may have helped to feed early Europeans while farming found its feet.

Chemical traces found in the remains of ancient Europeans suggest that algae once provided many of the nutrients and protein they needed to survive.

Dental plaque may help to reveal what prehistoric humans ate.

Chemical traces locked within the hardened plaque, or calculus, of ancient Europeans suggests that seaweed was high on the menu. Far from being a fad, new research suggests that eating seaweed was much more common around 8,000 years ago than it is today.

It’s not entirely sure when seaweed fell out of favour, but it’s thought that a shift to growing wheat and other crops spelled the end for the algae.

Professor Karen Hardy, who co-authored the paper, says, ‘Today, seaweed and freshwater aquatic plants are virtually absent from traditional, western diets. Their marginalisation as they moved from food to famine resource and animal fodder probably occurred over a long period of time.’

‘This research highlights the potential for the rediscovery of alternative, sustainable food resources that may contribute to addressing the negative health and environmental effects of the western diet’s over-dependence on a small number of mass-produced agricultural products.’

The findings of the study were published in the journal Nature Communications.

A pot of the chutney-like laverbread next to two wooden forks.

Laver seaweed is washed and boiled to make laverbread, a traditional Welsh delicacy. Image © David Pimborough/Shutterstock.

The fall and rise of seaweed suppers

While seaweed and other aquatic plants may not be commonly eaten in Europe today, they have historically been an important source of food and resources for coastal communities.

Despite the remains of 14,500-year-old chewed seaweed surviving elsewhere in the world, the charred fragments that are often found in Europe tend to point towards other uses, such as fertiliser, fuel, or salt production, an industry which continued until very recently.

Europeans seemed to stop eating seaweed almost entirely by the 1800s, and as a result seaweed is now uncommon as a food in Europe, with laverbread from Wales being one of the few exceptions.

That’s not to say that prehistoric Europeans weren’t eating seaweed, just that there’s not enough evidence to prove it. Seaweed would have been a good source of vitamins, nutrients and protein for ancient humans before animal agriculture became widespread.

To overcome this lack of evidence, the researchers looked to identify what makes seaweed unique. Previous research has suggested that traces of algae can survive as ‘chemical fossils’ which can be detected through the presence of certain compounds known as biomarkers.

If prehistoric Europeans were eating seaweed in large amounts, then these chemicals should have ended up in the calculus that built up on their teeth. While no one biomarker can prove if a person ate seaweed, a combination of biomarkers can build a strong case that they probably did.

A patch of dental calculus covers a fragment of human jaw containing teeth.

Chemical traces of seaweeds remained in the calculus thousands of years later. Image © Buckley et al., licensed under CC BY 4.0 via Nature Communications

After looking through the calculus on teeth from 28 different archaeological sites from the Baltic Sea to southern Spain, the researchers found that over half showed a unique set of biomarkers associated with seaweed.

One of these sites was La Corona, a site in Spain located more than 80 kilometres away from the coast. While 8,000 years ago it was likely closer to the sea, it still would have been a considerable distance away, suggesting that seaweed was an important food source for the people living there.

But even after farming arrived in Europe seaweed appears to have retained its importance as a food source. Calculus from Orkney suggests that people were still eating seaweed and other aquatic plants alongside meat and dairy products around 4,800 years ago.

First author Dr Stephen Buckley adds, ‘The fact that seaweed consumption continued into the Neolithic, by which point it was thought to have been abandoned, strongly suggests that its nutritional benefits were sufficiently well understood that they maintained their dietary link with the sea.’

By around 2,000 years ago, however, traces of seaweed consumption appear to have largely disappeared, with most Europeans switching to other plants instead.

However, with traditional agriculture now recognised as one of the leading causes of biodiversity loss, seaweed might be due a comeback. Providing a sustainable source of protein whilst not relying on land for growth, it’s hoped that seaweed could help to feed the world’s growing population without costing the planet.

A report from the European Commission estimates that globally seaweed could provide more than 100 million tonnes of extra food by the 2040s. While less than 1% of the world’s seaweed is currently grown in Europe, it’s hoped that the development of aquaculture in the region will dramatically increase the continent’s production.

If this happens, then Europeans may once again be eating many of the seaweeds that their ancestors once enjoyed.