New analysis of obsidian blades reveals dynamic Neolithic social networks


An analysis of obsidian artifacts discovered in the 1960s at two important archaeological sites in southwestern Iran suggests that the networks formed by Neolithic people in the region as they developed agriculture are more vast and more complex than previously thought, according to a new study by Yale researchers.

The study, published Oct. 17 in the journal Proceedings of the National Academy of Sciences, is the first to apply cutting-edge analytical tools to a collection of 2,100 obsidian artifacts housed at the Yale Peabody Museum. The artifacts were unearthed more than 50 years ago at Ali Kosh and Chagha Sefid, sites in Iran’s Deh Luran plain that yielded significant archaeological finds from the Neolithic era – the period beginning there. around 12,000 years ago when people began farming, domesticating animals and establishing permanent sites. settlements.

Original analyzes carried out shortly after the artifacts were discovered had suggested that people first acquired obsidian – volcanic glass – from Nemrut Dağ, a now dormant volcano in eastern Turkey, and then relied on a second unknown source for the material. This new elemental analysis showed that the obsidian came from seven distinct sources, including Nemrut Dağ, in present-day Turkey and Armenia, which are about 1,000 miles on foot from the excavation sites.

Ellery Frahm

It wasn’t a simple scheme of getting obsidian from one source and then moving on to the next,” said Ellery Frahm, an archaeologist in the Department of Anthropology at the Faculty of Arts and Sciences at Yale and lead author of the study. “Rather, our analysis shows that they were acquiring obsidian from an increasingly diverse number of geological sources over time – a trend that was impossible to detect with the technology and methods available there. 50 years old.”

The new analysis, combined with computer modeling, indicates that there was an intensification of the links between Neolithic peoples, suggesting the presence of a greater number of colonies between the source volcanoes and the two sites where the artifacts were unearthed. thousands of years later, Frahm said.

The artifacts were collected in the 1960s during multiple excavations of the two sites led by Frank Hole, professor emeritus of anthropology CJ MacCurdy at Yale. Initial analyzes were based largely on the appearance of artifacts, particularly their color when exposed to sunlight. A subset of 28 artifacts was then subjected to an elemental analysis method common at the time which involved grinding them into powder.

Frahm and co-author Christina M. Carolus, a doctoral student in the Department of Anthropology, are the first researchers to study the elemental composition of obsidian artifacts since these early analyses. They used state-of-the-art portable X-ray fluorescence instruments, which allowed them to examine the entire collection without damaging the artifacts.

Every aspect of the finds made at these sites has been revisited since the 1960s, except for the elemental composition and origin of the obsidian artifacts,” Carolus said. “Much more is known about source volcanoes today than 50 years ago, and we know that sorting obsidian by color will miss a lot of nuance. Fortunately, we have instruments the size of drills without wire which, in a few seconds and without destroying any material, gives us a more precise elemental signature than anything possible in the past.

Scientists widely believed that mankind’s transition from the hunter-gatherer lifestyle to agriculture produced a period of rapid population growth due to rising birth rates made possible by improved food supply and permanent settlements. Finding evidence of this demographic change often requires excavating places that include burial sites, which can indicate the population of a given settlement and provide a clearer picture of how agriculture enabled people to settle. disperse in a landscape, said Frahm.

Researchers’ analysis of obsidian provided similar evidence.

Tracing these obsidian artifacts from their sources to their extremities offers insight into how they moved from hand to hand over time, helping us to better understand population changes in the region during the Neolithic era,” said Frahm. “This suggested that there were larger social networks and more colonies between source volcanoes and excavation sites than we previously thought.”


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