A 7,000-year-old Neolithic settlement in modern-day Greece has, for the first time, been accurately dated down to the precise years it was built, and findings may provide a reference point in time in dating other archaeological sites in southeastern Europe.
Archaeologists from the University of Bern in Switzerland managed to date the site, called Dispilio, by a combination of annual growth ring measurements on wooden building components and another slightly stranger method—cosmic rays. Their research on Greece’s neolithic site is published in the journal Nature Communications.
Methods used in dating Neolithic sites
There are two methods used when dating prehistoric wooden elements. The first is dendrochronology, which is the analysis of tree rings. A wooden object’s growth rings are altered by climatic and regional conditions over time. This can be compared to other known examples.
“In central Europe, there is a tree-ring chronology that goes back almost 12,500 years into the past—to the year 10,375 BC,” lead author, Andrej Maczkowski from the Institute of Archaeological Sciences at the University of Bern, told Live Science. “However, this chronology only applies to certain regions. There is no consistent chronology for the Mediterranean region.”
The second method is radiocarbon dating, which measures the presence of radioactive carbon isotope 14C, or carbon-14. This isotope is absorbed by living organisms throughout their lifespan. When they die, carbon-14 radioactively decays into other atoms.
“However, the accuracy of such classifications is, in the best case, within the range of decades,” Maczkowski adds.
“Until recently, it was therefore believed that dendrochronological dating to the [exact] year was only possible if a continuous regional tree-ring chronology was available, which is the case for prehistoric periods in just 3 regions worldwide: this is the southwestern United States, the northern Alpine foothills and England/Ireland,” explains senior author Albert Hafner.
However, in 2012, Japanese physicist Fusa Miyake suggested that a huge influx of cosmic rays, such as those produced by solar flares, may increase the amount of 14C in the atmosphere. Such events today would likely have major impacts on telecommunications and electronics.
These monumental, global events throughout history could be used as “markers” in tree rings. Several have been identified, including two found in 2022—one in 7,176 BC and another in 5,259 BC.
How researchers applied markers to Greece’s Neolithic site
Using the latter of these markers, the archaeologists evaluated 787 pieces of timber from Dispilio at Lake Orestiada in what is today northern Greece. The team identified 303 years of growth ring chronology for the region and could show settlement and housebuilding at the site for over 188 years between the years 5,328 and 5,140 BC.
“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,” said Hafner.