An ancient volcano blotted out the sun, killing crops. People likely reacted by making "sun stones"

Almost five millennia ago, hundreds of engraved, disc-shaped stones were deposited in a giant pit at the Neolithic Vasagård site on the small Danish island of Bornholm. For decades the so-called “sun stones” mystified researchers, but now scientists report in the journal Antiquity reveal that they may have served a very specific purpose: A ritualistic attempt by Neolithic humans to protect themselves from climate change and disease.

Climate scientists from the Niels Bohr Institute at the University of Copenhagen in Bornholm analyzed ice cores from Greenland’s ice sheets and demonstrated that a major volcanic eruption occurred on the island 2,900 years ago. Because this roughly corresponds with the date of the sun stones, it follows that the stones would have been created as part of a religious or other supernatural ritual to address the weather changes.

"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," archaeologist Rune Iversen from the University of Copenhagen, who previously participated in site excavations led by the Museum of Bornholm and the National Museum, said in a statement. "The ditches were subsequently closed.”

Speaking with Salon, Iversen brought the Neolithic rituals to life by describing the elaborate ceremonies that would have been practiced by the ancient humans.

“Causewayed enclosures were large ritual gathering sites with a significance to a larger community,” Iversen said. “People returned to these sites and made depositions (offerings) and at many of these we see traces of feasting indicating that many people came together and participated in the ceremonies that took place there. I imagine that such gatherings also were of social significance and served to facilitate social integration of the communities.”

This can be seen from the engravings on the stones themselves, which the researchers divide into six types. There are sun motifs, which have many varieties but usually include, as the study authors put it, “incised lines (rays), including concentric circles, emanating from a circular central motif”; bands that either run up like a ladder or follow a transverse and longitudinal pattern; lines and strokes in geometric patterns such as patchworks and crosses, or being merely random; plants; blank spaces; and figures that cannot yet be categorized.

The sun and plant motifs were by far the most prevalent on the sun stones. Now that we know they were made during a time of weather-related crises, this makes sense.

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“Neolithic societies relied on the sun for the successful growth of their crops and thus for the continued prosperity of the families dependent upon each harvest,” the authors write. “It does not, therefore, seem unreasonable to consider the engraved stones as fertility offerings, their deposition at Vasagård an invocation to secure the growth of crops. The virtual absence of figurative imagery in the archaeological record of the north-west European Neolithic highlights the exceptional nature of the stone plaques from Vasagård.”

The sun stones correspond with the decline of the so-called Funnel Beaker tradition in European Neolithic culture, or the era in which the pottery-using hunter-gatherers in the north began to adopt farming and husbandry for food.

“At Vasagård the deposition of the engraved stones correlates with a change from activities centred on the causewayed enclosure to new rituals taking place in small, circular cult houses inside wooden palisades,” the authors write. “The effects of the climate crisis may have resulted in increased competition and conflicts at a time when the classical Funnel Beaker tradition was dissolving and was soon to be followed by new cultural changes resulting from migrations impacting eastern, central and northern Europe and beyond.”

In addition to the volcanic eruption, Northern Europeans during the Neolithic period would have also worried about infectious disease. Archaeologists and DNA scientists studying bones from the region and time found evidence of widespread plague. While this does not seem to be reflected on the stones themselves, that does not mean there are not more enigmas about the sun stones which need to be cracked.

“​​The sun stones are completely unique, also in a European context,” Lasse Vilien Sørensen, senior researcher at The National Museum of Denmark and co-author of the research paper, said in a statement. ”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.”

Sørensen added, “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.”

Iversen compared the Neolithic reactions to their era’s climate changes with humanity’s own climate changes today. The latter are primarily caused by human activity such as the use of fossil fuels.

“The Neolithic people didn’t know why the sun was shrouded so they tried to handle the situation by communal efforts to bring back the sun,” Iversen said. “If we can learn from this, it might be that we as individuals are not alone in facing climatic changes and challenges and a communal effort is indeed needed today.”