New carbon-14 dating approach corrects age of prehistoric burial site

How old are these bones? This classic question in archeology can in many cases be answered quite precisely using the carbon isotope. ¹⁴C. But there are exceptions. Certain lifestyle habits, such as those of prehistoric hunter-gatherer-fisher communities, can distort ¹⁴C dating, because carbon in aquatic ecosystems generally contains less ¹⁴C as carbon from land plants and animals.

An international team led by researchers from the Leibniz-Zentrum für Archäologie (LEIZA), the ROOTS cluster of excellence and the University of Kiel (CAU) was able for the first time to accurately date Neolithic tombs at the important site of Sakhtysh (Russia). , thus identifying new models in the cultural development of the time.

“At the same time, the method used here also allows more precise dating of human remains in other regions with similar environmental conditions,” explains Dr. John Meadows. He is the lead author of the study, published in Scientists progress.

One of the largest known prehistoric burial sites in northeastern Europe

In Sakhtysh, about 200 kilometers northeast of Moscow, about 180 prehistoric burials were excavated between 1962 and 1992. Pottery remains show that they date from around 5,000 to 3,000 BC. This makes Sakhtysh one of the largest known burial sites from this period in northeastern Europe.

However, the exact dating of the different burials and therefore their chronological order remains uncertain until now. One reason: the people buried ate a lot of fish during their lives.

“We know that this diet reduces the level of carbon 14 compared to carbon 12 in the bones. As a result, the bones appear much too old. These discrepancies are also very variable and until now difficult to correct,” explains John Meadows, who conducts research at the Leibniz-Zentrum für Archäologie du Schleswig (LEIZA-ZBSA) and the University of Kiel and is a member of the ROOTS network.

Carbon-14 dating is off by 900 years

The current study team compared isotopic analyzes of two samples from people excavated at Sakhtysh: one from a tooth and one from petrous bone. Teeth and petrous bone are the only mineralized parts of the human body that are not remodeled after they are formed, and they form at different ages.

“If diet changed during childhood and adolescence, differences in isotopic values ​​between an individual’s tooth and petrous bone allow us to draw conclusions about the extent of consumption. ¹⁴The C dating of the individual needs to be corrected,” says Meadows.

A mathematical model of these differences indicated a lag of up to 900 years for some burials. The corrections lead to a completely new burial site chronology, which allows for new interpretations of the cultural context. For example, one anomalous tomb turned out to be the most recent, dating from the beginning of the 3rd millennium BC. On the other hand, the oldest burials date from the beginning of the 5th millennium BC.

New timeline provides new insights into prehistoric communities

“When properly arranged, the tombs show changes in trade networks, which tended to move from the east to the Baltic region between 3,500 and 3,000 BCE. Another result of the investigations is that there are often more than one generation between individual burials, which means that the burial site was only used sporadically and for a long period of time,” explains Anastasia Khramtsova from the ROOTS Center of Excellence.

“We can only correctly interpret findings if we can place them in the correct chronological order. Being able to determine environmental influences on ¹⁴C dating is therefore fundamental. If there are no terrestrial organic burial objects such as animal bones, our method can help reduce corresponding uncertainties at other sites in the future,” Meadows summarizes.