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Cosmic rays help archaeologists determine the age of prehistoric settlements

Dating prehistoric discoveries is a crucial aspect of archaeology, as it allows researchers to understand the timeline of human history and the development of civilizations. However, before the use of cosmic rays, determining the age of such finds has always been a challenge.

Recently, a team of researchers from the University of Bern has made an amazing discovery that could revolutionize the way we date archaeological sites in Southeast Europe, especially in regions without consistent tree-ring chronologies.

The research team, led by Andrej Maczkowski and Professor Albert Hafner from the Institute of Archaeological Sciences at the University of Bern, has successfully dated timber from the archaeological site of Dispilio in northern Greece to different building activities between 5328 and 5140 BC.

This precise dating was made possible by combining annual growth ring measurements on wooden building elements with a sudden spike in cosmogenic radiocarbon in 5259 BC, caused by a massive influx of prehistoric cosmic rays.

Challenges of prehistoric archaeology

Dendrochronology and radiocarbon dating are the two primary methods used for determining the age of prehistoric finds.

Dendrochronology uses characteristic patterns of broad and narrow annual growth rings in wood, which are influenced by climatic conditions, to date wooden objects.

However, this method requires a consistent regional tree-ring chronology, which is not available for the Mediterranean region.

Radiocarbon dating, on the other hand, relies on the decay rate of the radioactive carbon isotope 14C contained in tree rings to calculate the approximate age of the finds. While this method can provide a general timeframe, its accuracy is limited to the range of decades.

Prehistoric cosmic rays as a game-changer

In 2012, Japanese physicist Fusa Miyake discovered that a massive influx of cosmic rays, presumably due to solar flares, can cause an uptick in the atmosphere’s 14C content, which is deposited in the respective years’ tree rings.

These spikes, known as Miyake events, can be accurately dated on the basis of long tree-ring chronologies and serve as important anchor points for regions without consistent annual growth ring chronologies.

“Miyake recognized the first anchor points of this kind and thus brought about a paradigm shift in prehistoric archaeology,” says Professor Albert Hafner.

Establishing the Dispilio chronology

The research team from the EXPLO project, led by the University of Bern, analyzed 787 pieces of timber from the archaeological site of Dispilio on Lake Orestida in northern Greece.

By establishing an annual growth ring chronology spanning 303 years, which ends in 5140 BC, they were able to identify various house building activities over 188 years between 5328 and 5140 BC.

This precise dating was made possible by the detection of a Miyake event in 5259 BC by researchers at ETH Zurich. By reproducing this peak in the annual growth ring chronology from Dispilio and connecting it to the anchor point 5259 BC, the team was able to establish the “Dispilio Chronology.”

“The Balkans is therefore the first region in the world to benefit from this paradigm shift and to be able to successfully determine absolute dating independently of a consistent calendar,” says Professor Albert Hafner.

Tree rings and cosmic rays at the regional level

The establishment of the Dispilio Chronology is a significant step forward in the development of a regional dendrochronology for the southern Balkans.

As Andrej Maczkowski notes, “We expect that other chronologies for the region from this period can now be linked to the ‘Dispilio Chronology’ in rapid succession.”

The Balkans hold a special place in the history of human civilization, as it is home to the oldest lakeside settlements in Europe, dating back to just after 6000 BC.

The region played a key role in the expansion of agriculture in Europe, and the ability to precisely date archaeological sites in this area will undoubtedly shed new light on the development of early farming communities.

Potential impact of Miyake Events on modern society

While the discovery of Miyake events has revolutionized prehistoric archaeology, it also serves as a reminder of the potential impact of solar flares on modern society.

As the researchers point out, if an event of similar magnitude to the one in 5259 BC were to occur today, it would likely have a disastrous effect on telecommunications and electronics.

This highlights the importance of understanding the complex interplay between cosmic events and our planet, not only for the sake of uncovering the mysteries of the past but also for preparing for the challenges of the future.

Cosmic rays spawn new era in prehistoric archaeology

In summary, this fascinating research conducted by the team at the University of Bern marks the beginning of a new era in prehistoric archaeology.

By combining the power of dendrochronology, radiocarbon dating, and the detection of Miyake events, researchers now have a powerful tool for precisely dating archaeological sites in regions previously thought to be inaccessible to such methods.

As more chronologies are linked to the Dispilio Chronology and a regional dendrochronology for the southern Balkans is developed, we can expect to gain unprecedented insights into the lives of early farming communities and the expansion of agriculture in Europe.

This research not only sheds light on our past but also paves the way for a better understanding of the complex forces that shape our world today.

The full study was published in the journal Nature Communications.


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