Excavation Iron Age Post-excavation The Cairns

Isotope analysis reveals an atypical Iron Age diet for The Cairn’s ‘elder’

Analysis of a woman’s jawbone deposited outside an Iron Age broch around AD200 has shown that seafood was major part of her diet throughout her life.

The analysis of a woman’s jawbone deposited outside an Iron Age broch around AD200 has shown that seafood was major part of her diet throughout her life.

The Eldery woman's jawbone from The Cairns, South Ronaldsay, Orkney.
The elderly woman’s jawbone from The Cairns, South Ronaldsay, Orkney. (UHI Archaeology Institute)

Being someone who lived in Orkney around 1,800 years ago that might not sound particularly strange. But it flies in the face of what we know about Iron Age Britain, where there is very little evidence for the exploitation of marine resources.

The elderly woman’s jawbone was discovered in 2016, during UHI Archaeology Institute excavations at The Cairns in South Ronaldsay, Orkney. It had been placed against the wall of the broch – perhaps to mark the end of its life – in a vessel carved from a whale vertebra.

Isotope analysis measures the ratios of different chemical isotopes in bones or teeth, which can then be used to investigate an individual’s diet and the environment they grew up in.

Previous isotopic analysis established there was marine protein in the woman’s diet, but this related only to the end of her life. “The Elder” – as she has been named – had very few teeth left and those that remained exhibited extensive, possibly painful, dental caries. This suggested the soft marine food had been consumed out of necessity.

You are what you ate

New studies completed this week as part of a research collaboration between the UHI Archaeology Institute and the University of York’s COMMIOS research project  have provided incredible new details about the diet of the old woman.

By peering into her diet at different stages in the development of her teeth, the new study has shown that she was consuming marine protein her entire life. The dentine of human teeth is laid down incrementally in layers as each tooth grows and develops, providing something of a clock – a little like the formation of growth rings in trees. As such dietary isotopes that are embedded in teeth at known growth points can be related to approximate periods in a person’s life.

The whalebone vessel and deer antler deposit where the human mandible was deposited. (UHI Archaeology Institute)

In collaboration with the National Environmental Isotope Facility (British Geological Survey) the woman’s tooth was sampled multiple times – when she was estimated to be three, seven, nine, eleven, thirteen, and fifteen years old.

The results show that in her infancy and teens she was indeed already consuming marine foodstuffs, and this was at a fairly consistent level throughout her life.

It is apparent that the marine portion of her diet was not eaten out of convenience or necessity only in later life but was, in fact, routinely consumed throughout her life.

Another view of the worked whalebone vessel. (UHI Archaeology Institute)

Further questions: A special role or more frequent Iron Age fish suppers?

The fact that seafood seems to have been avoided throughout the rest of Iron Age Britain opens up a new avenue of investigation. There are relatively few fishbones found in Iron Age middens and the analysis of human remains elsewhere suggests seafood was avoided, despite how ubiquitous and all-encompassing the sea was for communities in Atlantic Scotland.

This has led to suggestions that there may have been social restrictions, or taboos, on the consumption of seafood.

The latest analysis allows the archaeologists to question whether “the Elder” had a special role or status within society at The Cairns – one which might explain why her remains were singled-out for the special deposition that occurred towards the end of the broch’s life.

Or was seafood simply a more regular part of the Iron Age diet than previously thought? The ongoing work will hopefully start to make this clearer.

Looking across the broch interior at The Cairns.
Looking across the broch interior at The Cairns. (UHI Archaeology Institute)

Martin Carruthers is the site director of The Cairns excavations, and a lecturer in archaeology at the UHI Archaeology Institute.

He commented: “Thanks to our collaboration with the University of York’s COMMIOS project, it’s wonderful to be able to peer into the early, formative years of this older woman’s life and actually establish something of her biographical details.

The location of the whalebone vessel and human jawbone deposit against the outer wall face of The Cairn’s broch. (UHI Archaeology Institute)

“It was the COMMIOS project, in association with colleagues at Harvard University, that previously ascertained that she was genetically female, and the ongoing dietary and genetic studies are beginning to give her some real personality.

“It’s remarkable to be able to reach back and solve a problem like the question over her diet, which was previously unclear. Now we can see that the marine foodstuffs that she ate were after all a normal part of life for her, and this allows us to move on with further investigation of the mystery over the apparent lack of seafoods in Iron Age society at this time”.

The new study is part of an extensive raft of isotopic and ancient DNA analysis that has been undertaken on the human remains at The Cairns in a collaboration with the University of York’s COMMIOS project.

The ERC-funded research programme, led by Professor Ian Armit, uses a multidisciplinary approach to look into human mobility, kinship, and diet across Iron Age Britain and the Near Continent.

Anyone wishing to visit ‘the Elder’ and find out more about her life and times, can visit the Stromness Museum exhibition The Cairns: Living in the Landscape, until October 30, 2022.