4,900 years ago, a Neolithic people on the Danish island Bornholm sacrificed hundreds of stones engraved with sun and field motifs. Archaeologists and climate scientists from the University of Copenhagen can now show that these ritual sacrifices coincided with a large volcanic eruption that made the sun disappear throughout Northern Europe.
Throughout history, volcanic eruptions have had serious consequences for human societies such as cold weather, lack of sun, and low crop yields. In the year 43 BC when a volcano in Alaska spewed large quantities of sulphur into the stratosphere, harvests failed the following years in the countries around the Mediterranean, causing famine and disease. This is well-documented in written sources from ancient Greece and Rome.
We do not have written sources from the Neolithic. But climate scientists from the Niels Bohr Institute at the University of Copenhagen have analysed ice cores from the Greenland ice sheet and can now document that around 2,900 BC a similar volcanic eruption took place. An eruption that must have had equally devastating consequences for the Neolithic peoples who lived in Northern Europe at the time and who were deeply dependent on agriculture.
The so-called sun stones, which are small flat shale pieces with finely incised patterns and sun motifs, are known only from the island of Bornholm in the Baltic Sea, where they appear at two locations on the southern part of the island, Rispebjerg and Vasagård, around 2,900 BC.
Both sites belong to the late part of the Neolithic Funnel Beaker Culture, which, among other things, was responsible for the many dolmens and passage tombs found across Denmark.
This new insight into a climate episode in the Neolithic period has led archaeologists from the University of Copenhagen, the National Museum of Denmark and the Museum of Bornholm to view their findings of so-called "sun stones" from the Neolithic Vasagård site on Bornholm in a new light, and they have just published a scientific article on the phenomenon in the journal Antiquity:
"We have known for a long time that the sun was the focal point for the early agricultural cultures we know of in Northern Europe. They farmed the land and depended on the sun to bring home the harvest. If the sun almost disappeared due to mist in the stratosphere for longer periods of time, it would have been extremely frightening for them," says archaeologist Rune Iversen from the University of Copenhagen, who has participated in the excavations at the site led by the Museum of Bornholm and the National Museum. He adds:
"One type of find that is completely unique to Bornholm is the so-called sun stones, which are flat shale pieces with engraved patterns and sun motifs. They symbolized fertility and were probably sacrificed to ensure sun and growth. Sun stones were found in large quantities at the Vasagård West site, where residents deposited them in ditches forming part of a causewayed enclosure together with the remains of ritual feasts in the form of animal bones, broken clay vessels, and flint objects around 2,900 BC. The ditches were subsequently closed."
Rune Iversen and his colleagues believe that there is a very high probability that there is a connection between the volcanic eruption, the subsequent climate changes and the discovery of the ritual sun stone sacrifices.
"It is reasonable to believe that the Neolithic people on Bornholm wanted to protect themselves from further deterioration of the climate by sacrificing sun stones - or perhaps they wanted to show their gratitude that the sun had returned again."
Major cultural changes
The researchers can document reduced radiation from the sun and consequent cooling, which can be traced in both the United States and Europe around 2,900 BC.
Dendrochronological analyses of fossil wood show signs of frost in the spring and summer months both before and after 2,900 BC.
And ice cores from the Greenland ice cap and the Antarctica contain sulphur, which is a sign of the occurrence of a strong volcanic eruption.
As if an acute climate deterioration around 2,900 BC was not enough, Northern European Neolithic cultures were also affected by other disasters; New DNA studies of human bones have shown that the plague was very widespread and fatal.
During the same period when the Neolithic people were affected by both climate change and disease, archaeologists can also document a shift in the traditions they had held on to for a long time. The so-called Funnel Beaker Culture, which had been dominant until about 5,000 years ago with its characteristic ceramics and passage graves, was gradually disappearing.
"At the causewayed enclosure we have excavated on Bornholm, we can also see that, after the sacrifice of the sun stones, the residents changed the structure of the site so that instead of sacrificial ditches it was provided with extensive rows of palisades and circular cult houses. We do not know why, but it is reasonable to believe that the dramatic climatic changes they had been exposed to would have played a role in some way, Rune Iversen concludes.
Sun stones to be exhibited in Copenhagen
Four of the sun stones from Vasagård on Bornholm can be experienced from 28 January in the prehistoric exhibition at The National Museum of Denmark in Copenhagen. They probably exemplify one of the earliest depositional practices connected to a Neolithic sun-cult in South Scandinavia, which are also known from the Nordic Bronze Age with objects like the sun chariot.
"The sunstones are completely unique, also in a European context. The closest we get to a similar sun-cult in the Neolithic is some passage graves in southern Scandinavia or henge structures like Stonehenge in England, which some researchers associate with the sun. With the sun stones, there is in my mind no doubt. It is quite simply an incredible discovery, which demonstrates that depositions honouring the sun is an ancient phenomenon, which we encounter again in South Scandinavia during the climate disaster caused by a volcanic eruption in the year 536 AD, where several large gold hoards were deposited as sacrifices," says Lasse Vilien Sørensen, who is senior researcher at The National Museum of Denmark and co-author of the research paper.
