Research The Cairns Zooarchaeology

Whalebone genetics and the extraordinary closure of The Cairns broch

DNA investigations undertaken on a large collection of whale bone from the University of the Highlands and Islands Archaeology Institute Iron Age archaeological site of The Cairns, have afforded a glimpse into the complex relationship of Iron Age communities with whales.
A Fin Whale. Photo: Aqqa Rosing-Asvid. Creative Commons

New DNA results shed light on Iron Age use of whale bone and the remarkable process of decommissioning a broch in South Ronaldsay 2,000 years ago.

Genetic analysis of a large collection of whalebone from The Cairns has provided a window into the complex relationship of Iron Age communities with whales.

Vicki preparing one of the larger whalebone artefacts from The Cairns excavation.
(UHI Archaeology Institute)

In particular, the confirmation that multiple whale bone recovered from the site belonged to a single, large fin whale shows how its carcase was strategically, and even ceremonially, used and deposited at the closure of the monumental broch.

In 2019, Dr Vicki Szabo (Western Carolina University, North Carolina) and Dr Brenna Frasier (Saint Mary’s University, Nova Scotia) collaborated with Martin Carruthers, the site director at The Cairns, to examine the whalebone artefacts recovered from the Iron Age site. Their goal was to obtain genetic information to see what species of whale was present.

The research is part of an international project funded by the National Science Foundation which is investigating the past use of whales in North Atlantic society.

Brenna and Vicki are following up on work completed in Orkney in February 2018, when they examined the whale remains from another archaeological site in Sanday, Orkney, and other whalebone artefacts from the Orkney Museum.

The Cairns and the sea. Looking across Windwick Bay. (Bobby Friel @Takethehighview)

The project has sampled whalebone covering a time span of over 1,400 years and from Newfoundland, Greenland, Iceland, Faroes, Shetland, and Orkney. Orkney and Iceland are the primary centres of analysis, representing the eastern and western North Atlantic.

Orkney has many exceptional whalebone assemblages, from the Neolithic to the Norse period and thereafter. The types of objects produced in Orkney are remarkably stable over a long period of time, as well. The Cairns, though, has given Vicki and Brenna their first opportunity to sample at an ongoing excavation.

Their results show that some of the whalebone from The Cairns was from very large cetaceans, including sperm whale, North Atlantic right whale, minke, grey whale, and humpback. This raises questions on whether a site like The Cairns was able to stake a claim to the larger whale carcasses. And if so, is this indicative of status and the control of resources by the inhabitants of the broch?

One surprise, though, was the volume of fin whale bone in The Cairns assemblage.

One of the larger pieces of Fin whale bone found at The Cairns broch. (Andrew Hollingrake)

Fin whales are the second largest species on the planet and can grow to 27 metres long. They are also among the fastest whales in the sea, capable of bursts of 45KMH when hunting, or threatened. They can also dive fast and very deeply.

This meant that the fin whale was only really hunted in large numbers in modern times, after the invention of the explosive harpoon. This suggests the animals were unlikely to have been hunted in the Iron Age, so The Cairns whale bone must represent a stranded individual.

That, however, does not mean that other types of whale were not hunted, and the question of whether some were pro-actively sourced during the Iron Age remains unanswered.

In time, further study of patterns of whale bone and species recognition may shed light on this.

The end of two giants: the broch and a fin whale

The latest stage of the project allows us to connect an array of whalebone items.

The genetic and molecular study of 33 whalebone items shows that 20 pieces (vertebrae, ribs, scapulae, and other anatomical elements) were from the fin whale. Two key mitochondrial haplotype regions of the genome of each bone were examined, and it is likely that all the fin whale items (except one) came from the same animal.

This means that a single, large, fin whale may have been part of the final occupation and abandonment of the broch.

The Cairns broch looking across to the North Sea. (UHI Archaeology Institute)

The bones appear to relate to feasting that took place to mark the end of the broch.

Some have chop marks, suggesting butchery and perhaps bone-working. Others are slightly singed from being subjected to direct heat. The fin whale bones were found in a range of contexts across the broch – some came from the uppermost floor deposits while others were deposited into gaps in the walls.

Other fin whale bones came from the rubble used to infill the broch during the final abandonment.

The presence of this single animal, spread across these varied contexts, links these deposits very closely in time, much more tightly than is currently possible with radiocarbon dating alone.

It allows the excavators to closely connect several different contexts and stages within the finale of the broch and to appreciate what a relatively swift process the end of the broch was. The presence of the many bones from a single animal may also allow detailed consideration of the use of whalebone and how it was treated as a resource – both physically and perhaps also symbolically.

The Fin whale vessel just outside the broch entrance. (UHI Archaeology Institute)

The use of one of the fin whale bones is particularly remarkable.

A substantial vertebra had been used to make a container, which was deposited just outside the broch entrance at the end of the structure’s occupation. A remarkable assemblage of objects accompanied the vessel.

Two shed red deer antlers had been propped against the outside of the vessel, and a very large saddle quern was also placed snuggly against the vessel as though to pin it firmly against the broch. Inside the whalebone vessel were the remains of two newborn lambs and, most remarkably, the jawbone of an elderly human.

This entire collection was a very deliberate deposit that appears to have been one of the measures employed to formally “close” the broch.

Martin Carruthers said: “It’s just amazing to be able to say with confidence that so many of these whale bones, including the vessel with the human jawbone, actually belong to the same animal, especially as we’ve recovered them from the site over a number of different seasons, not knowing all along that the spread of bone belonged to one huge beast.

“We had some suspicions that something particularly interesting was going on with the amount of whalebone that was emerging, but we’d never have managed to get to this level of specificity without the input and collaboration with Brenna and Vicki”.

Martin added: “One of the most important things, from my point of view, is how this research helps us to recognise the significant role that the treatment of the fin whale had in the dramatic procedures of deliberately ending of the monumental broch.”

What circumstances led to the use and deposition of the fin whale?

Whale bone seems to have been a highly important material for Iron Age communities.

The appearance of these ocean giants on beaches, when stranded, must have occasioned opportunities to recover a large volume of meat, oil (fuel for lamps), as well as a substantial resource for making objects. Whalebone work clearly included things like our big vessel (The Cairns has also yielded several more whale bone vessels from across the site), but also toolmaking (e.g. weaving “batons”, chopping-boards, soft anvils, and much more), and even for architectural purposes such as large ribs used as roof rafters.

The whalebone distribution across the site which has been DNA tested. (UHI Archaeology Institute)

It is possible that a stranding of an animal, like a massive fin whale, would have represented an exponential contribution to the community’s resources.

Vicki Szabo suggested: “As a free and scavenged resource, whale provides a large volume of high value protein. Large whales are generally 14 plus per cent body weight bone, which means that a fin whale represents a massive quantity of soft tissue, meat and blubber at around 70 per cent.”

This amount of food from a stranged whale may have energised productive capacity, providing additional assurance of a successful year for the community. Perhaps, by making them more manageable, a stranding permitted endeavours and projects that might otherwise have been considered risky.

At The Cairns, this whale boon could have included support for a major undertaking such as decommissioning the broch, – a structure that had dominated the landscape, and society, for generations. It would have been no minor activity to demolish the upper parts of the structure and it is likely that the work of taking it down would have had serious consequences for the surrounding settlement.

It would have been a physically arduous and time-consuming process, probably involving many people, taking them away from other important tasks, in particular, food production.

That is not to say that the stranding of a single whale led to the demise of the broch.

There is growing evidence that the period around the 2nd Century AD was a time when many brochs were coming to their end – at least in their initial form as high-walled, tower-like buildings. Things were changing, more generally, across Iron Age society in northern Scotland and that at that time and the waning importance of monumental broch architecture was part of that.

However, we may still wonder if occurrences, such as the stranding of a significantly large whale, might encourage a community, perhaps already considering a radical break with the past, to go for it.

Just some of the whale bone unearthed at The Cairns. (UHI Archaeology Institute)

There was a very practical bonus to be had in the harvesting of a very large whale, but we may also wonder if the appearance of such a large beast stranded on the foreshore meant more to Iron Age communities than just a practical resource.

In many non-Western societies, and, indeed, many ancient European ones, sudden natural phenomena, such as the highly prominent death of a significant type of animal, may be seen as a conspicuous indication of arcane and esoteric forces, taken as a sign, an auspicious, or inauspicious, omen.

Even though stranding may have been more common in prehistory, when there was a larger whale population, it might be that both the practical impact, and the potential ideological and psychological effects of the appearance of a massive whale was the impetus for a major change.

Other offerings? Animal bone groups at The Cairns

Whales were not the only animals present in the final stages of the broch’s life. Across the site there are what are known as animal bone groups (ABGs) present that date to the broch period and afterwards.

These are articulated animals, or articulated parts of animals, apparently deliberately deposited and derive from cattle, sheep, and red deer as well as cat, pig, otter. There is even, in one case, an articulated seal flipper!

To date, around 20 ABGs have been recognised from The Cairns. Probably many more await discovery.

In many, or most, cases they may well represent butchered joints of meat. But if so, they were not discarded in middens as one might normally expect and seen elsewhere on the site.

Instead, they were left in certain locations within the buildings and across floors, and infills, as if they were actually posed. Indeed, many look like they have been displayed. Some of the bones reveal traces of weathering on their surfaces, indicating a period of exposure prior to being covered in soil, rubble or new house floors.

Whale bone from The Cairns…showing cut marks. (UHI Archaeology Institute)

Why formally place animal bones?

What did these deposits mean for the people of the Iron Age?

Martin Carruthers explained: “At the Cairns, I wonder if many, or all, of these deposits followed on from activities that celebrated the end of the broch and the beginning of new things for the community, who by no means just disappeared thereafter.”

Human occupation of the site lasted at least another 800 years after the end of the broch.

Martin continued: “They might also be acts of propitiation, an assuagement of the decision to end a major building that had been highly valued for so long, by many previous generations of inhabitants.

“Perhaps the inclusion of our elderly human jawbone as part of the process was also a nod in the direction of the past of the broch, when it was in its hey-day? When that person was in their youth the broch would still have been the major symbol of authority in the landscape, and the jawbone may well have belonged to someone who had been a member of the broch household.”

Another possibility is that these depositional acts were a source of comfort and reconciliation, especially in the face of major transitions under way on site, and in wider society.

Whatever the truth, the process of ending the broch was measured, carefully planned and required resources of people as well as of materials. It was physically difficult and probably quite dangerous. It also seems to have entailed serious ideological input and consideration, not least indicated by the deposition of human remains like our jawbone inside the fin whale vessel.

The end of the broch seems also to have involved the butchery, and perhaps sacrifice, of animals, feasting, and especially, perhaps, reflection on the past, present, and future of the community.