How far did Neolithic communities travel to build Stonehenge? New strontium isotope analysis on some of the cremated remains buried during the first phases of the monument’s construction is hinting at intriguing answers. (IMAGE: Adam Stanford, Aerial-Cam)

Stonehenge is one of the most extensively researched monuments in Britain, but until recently little was known about the people who were buried on the site thousands of years ago. This is now beginning to change, thanks to isotopic analyses of some of the cremated human remains interred during the monument’s first phase of construction, around 3000 BC. The project’s findings are shedding light on the movements and burial practices of long vanished – and surprisingly far-flung – communities, as Kathryn Krakowka reports.

Across the centuries, the uniqueness of Stonehenge and the enigmatic nature of its construction have given rise to a number of outlandish theories – used by the Druids as a celestial observatory or by the Romans as a temple; built by Merlin or by aliens – ideas that flourished as antiquarians and early investigators struggled to provide more plausible explanations. Little by little, though, modern scientific investigations have uncovered clues to the monument’s true purpose. In particular, the last two decades of fieldwork focusing on the stones and their surrounding area (see CA 212, 219, 252, 311, and 334), combined with recent scientific advances in archaeological research, have revolutionised our understanding of Stonehenge. While we may not have all the answers yet – and debates still arise between archaeologists on some of the solutions that have been put forward – we are slowly beginning to fill in the pieces of the puzzle.

The latest of these pieces concerns not the stones themselves, but the people who were buried close to them – and their surprisingly diverse origins. In a research project originally published in Scientific Reports, Dr Christophe Snoeck and researchers from the University of Oxford, the Vrije Universiteit Brussel, the Université libre de Bruxelles, the Muséum national d’Histoire naturelle, and University College London have used isotope analysis to examine some of the cremated human remains excavated at Stonehenge, with fascinating results. Their findings highlight not only how mobile some Neolithic populations were, and how important Stonehenge was to them, but also the lengths to which they may have been willing to go to bury their dead on the site.

The Stonehenge Riverside Project re-excavated Aubrey Hole 7 in 2008, and once again unearthed the cremated remains originally discovered by Hawley. (PHOTO: Adam Stanford, Aerial-CAM)

EARLIER EXCAVATIONS

How did these remains first come to light? Cremated human bone was first discovered at Stonehenge during William Hawley’s excavations of 1919- 1926, primarily within what have come to be known as the Aubrey Holes (56 pits forming a circle around the monument, named after the antiquarian – John Aubrey – who first noted their presence in 1666), as well as in Stonehenge’s enclosure ditch and in scattered areas in the south-eastern half of the site.

The Aubrey Holes, which contained many of the cremated remains, were excavated by William Hawley and his team between 1919 and 1926. Pictured are trenches opened near the Heelstone during the season of 1923.

These fragments of human bone are thought to represent the remains of at least 58 individuals, but in the 1920s scientific techniques were not up to deducing much more about them, so they were all re-interred by Hawley’s team in Aubrey Hole 7. There the remains would lie undisturbed until more than eight decades later when, in 2008, the pit was re-excavated by the Stonehenge Riverside Project (CA 237). This revealed that the cremated remains were still present, but, unfortunately, they had not been reburied as individual parcels of bone. Rather, the team’s predecessors had created a haphazard heap of dumped remains, which were now thoroughly commingled. This severely impeded osteological analysis of the remains, but all was not lost – after painstaking analysis unpicking the fragments and identifying specific bones, osteoarchaeologists were able to identify the presence of at least 27 individuals, comprising 22 adults and five children.

Of these, 25 were selected for radiocarbon dating (the fragile remains of a foetus and another small infant were not sampled, as doing so would have completely destroyed them), and this analysis, carried out by the Oxford Radiocarbon Accelerator Unit (ORAU), dated the individuals to between c.3000-2800 BC (other dated individuals extend this range to c.2450 BC). In other words, they had died within the time of the earlier stages of Stonehenge’s lifespan, when the Aubrey Holes are thought to have been created. The amount of variation in the results within this broad span of dates, though, suggests that these people were unlikely to have been buried at the same time. Instead, their deaths and interments most likely took place over multiple generations: a period of decades, if not centuries. The Stonehenge cremation ‘cemetery’ had been strikingly long-lived. What else could be learned about the people buried within it?

After Hawley’s excavations, all the cremated remains were reinterred into Aubrey Hole 7, and buried with this inscribed stone, explaining when and where they were found. (PHOTO: Adam Stanford, Aerial-Cam)

RECREATING CREMATIONS

Until a few decades ago, most descriptions of excavated human remains were reserved for the appendices of site reports and rarely went into further details than the number of skeletons discovered. With cremated remains, this was historically exacerbated as the severe fragmentation and burnt nature of this material makes it even more difficult to examine. New research has provided a wealth of possibilities for what can be discerned from such remains, though, particularly in terms of chemical analysis such as the study of isotopes.

The Stonehenge Riverside Project re-excavated Aubrey Hole 7 in 2008, and once again unearthed the cremated remains originally discovered by Hawley. (PHOTO: Adam Stanford, Aerial-Cam)

These chemical signatures, preserved in our teeth and bones, contain a treasure trove of information about where someone grew up and the diet they ate. To study them, scientists normally take samples from tooth enamel; this is because the structure of enamel is highly crystalline and isotopes from the burial environment are, therefore, unable to leach into the enamel and contaminate the sample. Since teeth form in childhood and, unlike bone, do not subsequently remodel (which would allow for the integration of new isotopes), the analysis of enamel provides details of the diet and mobility of individuals during their early years.

In order to assess a person’s behaviour during adulthood, we must turn to bone, as it is constantly being remodelled – and taking up new isotopic signatures – throughout life. The structure of bone, however, also allows isotopes from the burial soil to be absorbed – what archaeologists call ‘diagenesis’ – which means that any subsequent isotopic analysis will not fully reflect an individual’s behaviours during life.

On re-excavation, it was discovered that the cremated remains had been heaped into one big pile, making it difficult to parse individual burials. (PHOTO: Adam Stanford, Aerial-Cam)

This is not the case with cremated bone, however. Recent research has shown that it is fundamentally different to unburnt bone. During the burning process, the structure of the bone changes, becoming highly crystallised and more similar in structure to tooth enamel. New research has shown that, because of this, the strontium isotopic signature in cremated remains does reveal aspects of the individual’s life, and not the environment in which they were buried. (We will see later that carbon and oxygen isotopes in cremated remains are also unaffected by the burial environment, but reflect something other than an individual’s behaviour.)

This is lucky for archaeologists, as the high heat that the body is exposed to during cremation usually completely destroys tooth enamel, so that it cannot be analysed. As mentioned above, our bones are completely remodelled throughout our lifetimes, meaning that cremated remains tell us about a person’s life and diet in the years leading up to their death. The exact amount of time is currently unknown, as it does vary by bone, with a rib turning over more quickly than a femur, but it is estimated at around ten years.

Recent research has revealed that cremated remains are structurally different to unburnt bone. This means that while normally archaeological bone is ill-suited to isotopic research – and tooth enamel is preferred – cremated bone can be successfully analysed. (PHOTO: Adam Stanford, Aerial-Cam)

FROM WALES TO WILTSHIRE

Isotope analyses had previously been conducted on the ‘Boscombe Bowmen’ – the Beaker period (c.2400-1800 BC) mass burial found at Boscombe Down (see CA 193) – as well as on animal remains from Durrington Walls, the Neolithic settlement near Stonehenge where the community responsible for building the main phase of the monument is thought to have lived (see CA 334).

The results from the Bowmen suggest that they may have hailed from west Wales or even northern France, while some of the animals being eaten at Durrington Walls appear to have been brought from as far away as western or northern Britain, suggesting that people had travelled some distances to get to Stonehenge. Both of these examples post-date the earliest phases of Stonehenge, though. What could strontium isotope analysis of the much earlier remains tell us about the people who were buried at the site during the first stages of the monument?

Osteoarchaeologists were able to identify at least 27 individuals out of the commingled remains buried in Aubrey Hole 7. Here we can see occipital fragments from three of the individuals. (IMAGE: Christie Wills)

The results were intriguingly mixed. Some 15 of the 25 individuals were deemed to be probably ‘local’, in as much as their isotope values reflected the chalk geology of Stonehenge and the surrounding area. This means that for the last decade or so of their lives, they probably obtained most of their diet from the area in and around Salisbury Plain. The remaining ten had isotope ratios that were inconsistent with the surrounding area, however, meaning that they could not have solely sourced their food from around Stonehenge and probably either got all of their food from further afield or lived somewhere else entirely.

What does this mean? Delving deeper into the results, the picture becomes even more interesting. For seven of this group of ten, the team obtained intermediate isotope values that could reflect a mixed diet which came from both the west – either south-west England or west Wales – and the chalk areas in and around Salisbury Plain. This suggests that these individuals might have moved between these regions sometime within the last decade or so of their lives – perhaps hinting at a history of contact and movement in both directions between the two locations.

For the remaining three, the strontium values were so high that they probably did not obtain any of their diet from the Wessex chalk. Instead, the majority of their diet seems to have come from regions with older lithologies, such as Devon or west Wales. The team labelled these individuals as ‘non-local’, since their results indicate that they are unlikely to have lived in the Stonehenge area for any meaningful period of time. The ratios are also in keeping with origins in parts of Scotland, Ireland, and continental Europe, but the team suggests that west Wales may be the most likely candidate. As it has been established that a key component of Stonehenge, the bluestones, came from the Mynydd Preseli region of Pembrokeshire, they argue that it seems more than coincidence that the people buried at the monument have isotopic signatures that could indicate that they may have originated there as well.

Many of the Stonehenge bluestones have been linked to the Mynydd Preseli region of Wales (pictured is Carn Goedog, where the bluestones made of dolerite are believed to have originated; see CA 311). Recent isotope analysis on the cremated remains buried at Stonehenge suggests that some of the individuals could have lived nearby in the years leading up to their deaths. (PHOTO: Adam Stanford, Aerial-Cam)

This seems plausible in light of the hypothesis of Mike Parker Pearson and his colleagues that the bluestones were brought to Salisbury Plain sometime between 3015 and 2935 BC – the period to which the cremations analysed in this study have been dated. This link also seems to lend credence to suggestions that the bluestones may have originally been placed in the Aubrey Holes, effectively on top of these cremated burials, to mark their burial locations. Might these ‘non-local’ people have travelled to Salisbury Plain with the bluestones? If so, could this feat have been repaid with burial at the prestigious site? It is an evocative idea, but it seems that the scenario could have been more surprising still.

 


ESTABLISHING A BASELINE

Strontium isotope analysis is based on the fact that the bedrock of the earth is comprised of various geologies. Certain regions are defined by unique characteristics that are formed of specific strontium isotopic compositions. As these isotopes become soluble in water, they are taken up by plants, and then enter the bones or teeth of the humans and animals that eat those plants. When analysing the bones or teeth of archaeological specimens, their isotope values will reflect the chemical composition of the region where they sourced their food. In order to establish these sources, a baseline knowledge of the amount of strontium available in the surrounding biosphere, known as ‘biologically available strontium’ (BASr), is required in order to match the archaeological results with a specific area. As isotope studies have advanced, detailed maps of varying isotope signatures have been developed, and are constantly being refined.

As regards the study of the Stonehenge cremations, the isotopic ratios of the Cretaceous chalk that dominates the Wessex landscape have been well defined, but the geology of west Wales is more variable and so required additional sampling of modern plants to understand the range of variation there. This is relevant as the team suspected that some of the individuals may have originated from this region (based on the strong connection it appears to have with Stonehenge, see opposite page). Accordingly, they sampled the isotope ratios of 17 modern plant samples from eight locations in west Wales. This showed that the isotopic ranges from each location are completely different from each other – an important point, as it means that the two regions can be easily distinguished using isotopic analysis.

The project team then combined their new data with that already mapped by the British Geological Survey in order to create an updated plot of biosphere strontium isotope variation across Britain. They now had a robust map with which to compare the strontium isotope values from the cremated remains of Stonehenge.

This map shows the variations in biologically available strontium across Britain. It highlights the different strontium values present between Stonehenge and Craig Rhos-yfelin, where some of the bluestones are likely to have originated. (IMAGE: C. Snoeck et al, 2018, Scientific Reports 8, article number: 10790)


 

ACCOMPANIED BY ANCESTORS?

Once again, the quirks of analyzing cremated remains held the key to understanding. Although cremated bone retains the strontium values of the living individual that they came from, carbon and oxygen isotopes appear to be altered during the burning process. In unburnt bone, these isotopes are used to determine an individual’s diet and mobility, but recent research has shown that after cremation their values instead mainly reflect the fuel used for the funeral pyre.

Given the apparently diverse origins of the people cremated at Stonehenge, it is perhaps unsurprising that their carbon and oxygen isotope values were also seemingly quite wide-ranging. This suggests that these individuals were cremated under variable conditions. Those who were identified as ‘local’ had higher carbon isotope values than the ‘non-local’ group, suggesting that the wood used in their funeral pyres had come from trees grown in an open landscape consistent with the Wessex chalk surrounding Stonehenge. Conversely, the lower values found in the ‘non-locals’ points to a different fuel source, with the wood used in their pyres most likely coming from dense woodlands – an environment more in keeping with areas including Neolithic Wales.

During the cremation process, carbon and oxygen isotopes appear to be altered. Instead of reflecting an individual’s diet, they take on the isotopic values of the fuel used for the funeral pyre. Because of this, the team was able to determine that the cremated remains from Stonehenge were burned using wood from different locations – some were more in keeping with Salisbury Plain, while others were similar to the characteristics of areas including west Wales. (PHOTO: Christophe Snoeck)

What does this mean? The stark difference in results suggests that cremations were being carried out in different places. The individuals who probably spent the last decade or so of their lives in and around Salisbury Plain seem to have been cremated in the area. So far, so unsurprising – but some of those who are likely to have spent the last years of their lives in western Britain appear to have been cremated there instead. It seems that at least some of the ‘non-locals’ had died and been cremated far from their final resting place, and that their burnt remains had been deliberately brought to the monument to be buried.

If this is the case, it brings us full circle to the original discovery of the cremations. Back in the 1920s, Hawley noted that many of the Aubrey Hole burial deposits had circular margins, suggesting that the remains may have been deposited in organic containers like leather bags. He even states in his initial observations that ‘in every case [the burials] had apparently been brought from a distant place for interment’. It appears that modern science is proving Hawley’s words remarkably prescient – and the implications are exciting. If Neolithic people were carrying the remains of their cremated ancestors over many miles to be buried at Stonehenge, this signifies just how important the location was to these people at the time of the monument’s construction – and how far its renown reached from Salisbury Plain, even in its earliest days.

The more data from Stonehenge we collect, the tighter its possible ties with west Wales seem to become, with tantalising evidence of a link between the two locations and Neolithic people moving between them. We may never know exactly why Neolithic Preseli communities seemingly chose to transport dozens of two-tonne stones over a distance of about 150 miles, but whatever their motivation it now seems increasingly possible that they may have done so with some of their dead in tow.

We may never know why Neolithic people chose to haul the bluestones some 150 miles to Salisbury Plain, but this isotope research suggests that they may have done so accompanied by some of their dead. (PHOTO: Adam Stanford, Aerial-Cam)


FURTHER READING

Snoeck et al. (2018) ‘Strontium isotope analysis on cremated human remains from Stonehenge supports links with west Wales’, Scientific Reports 8, article no.10790.

Snoeck et al. (2015) ‘Calcined bone provides a reliable substrate for strontium isotope ratios as shown by an enrichment experiment’, Rapid Communications in Mass Spectrometry 29: 107-114.

Parker Pearson et al. (2009) ‘Who was buried at Stonehenge?’, Antiquity 83(319): 23-39.

Willis et al. (2016) ‘The dead of Stonehenge’, Antiquity 90(350): 337-356.

This feature appeared in CA 344

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