Thursday, March 25, 2021

Responding To The 5.2 Kya Event In Anatolia

There aren't many studies demonstrating the impact of the 5.2 kiloyear climate event on historic communities of people, in part, because the civilizations impacted by it at the Neolithic-Copper Age transition didn't have the same scale of urban areas, empires, architecture and sophisticated goods to collapse from, and writing was much more limited then, making the impact less obvious. 

But this study deserves kudos for using clever methods to observe these subtle impacts on human communities on a quite fine grained time scale which other methods can't always resolve nearly as finely.

Just as the 4.2 kya event was pivotal in ushering in the Bronze Age and creating a political vacuum into which Indo-Europeans could expand in Europe, Central Asia and South Asia, the 5.2 kya event was pivotal in creating a political vacuum in Neolithic society into which copper age cultures could expand. 

This (or the 5.9 kya event) is probably the climate event that was the proximate cause of the demographic transition from the Sardinian-like Anatolian first farmers of the Fertile Crescent Neolithic Revolution to copper age people with a different genetic makeup who migrated to Anatolia from elsewhere in the West Asian highlands who partially replaced them in Anatolia.

It is also one of the first documented iterations of a pattern that would repeat itself many times in history. When rain is ample and temperatures are comfortable, agriculture flourishes and sophisticated sedentary civilizations arise. When drought strikes and it gets too hot or too cold, herding civilizations replace the farming civilizations that flourished in better times.
"People would build a mud brick structure, and over the years the structure is either abandoned or collapses and the people just build on top of it," Smith says. "Eventually these villages look like they have been built on hills, but they're really just occupations going up and up."

Just as the occupants built new layers up, the archaeologists excavate down to get a glimpse of history and how lives changed over the millennia. Within the layers, archaeobotanists like von Baeyer and Smith look for ancient plant remains; for instance, intentionally or unintentionally charred plant matter. Though wood was often used, much can be learned by looking at the remains of fires fueled by livestock dung, says Smith: "The dung contains seeds that give clues about what the animals were eating." 
. . .

The focus was on a time period called the Late Chalcolithic, roughly 3700-3200 years before the common era (BCE). By referencing paleo-climatic data and Steadman's very detailed phasing at Çadır Höyük, the researchers were able to discern how lifestyles changed as the climate rapidly shifted in what is called the 5.2 kya event, an extended period of aridity and drought at the end of the fourth millennium BCE.

With climate change, there are lots of strategies that can be used to adapt says Smith, "They could have intensified, diversified, extensified, or abandoned the region entirely. In this case they extensified the area of land used and diversified the herds of animals they relied upon."

Zooarchaeologists on the site examined the bones to further demonstrate the shift in the types of animals herded, while the seeds from the dung-fueled fires at the dig site gave clues to what the animals were eating.

Smith says, "We know they were herding cattle, sheep, goats, and pigs, and we saw a shift to animals that are grazers. They all have a different diet, and by diversifying you are maximizing the range of potential calories that can eventually be consumed by humans."

By employing this mixed strategy, the people of Çadır Höyük were ensuring their survival as the climate became increasingly dry. Smith says that at the same time they continued to grow wheat, barley, chickpeas, and lentils, among other crops for humans, while the animals grazed on crops not suitable for human consumption -- a strategy to maximize resources and resilience.
From here. The paper and its abstract are as follows:
This study examines how the population at Çadır Höyük on the north central Anatolian plateau modified agricultural and fuel use practices in response to rapid social and environmental change between 3600 and 2900 BCE (Late Chalcolithic and Transitional to Early Bronze periods). 
Using descriptive and multivariate statistics to explore data from 60 archaeobotanical samples spanning three periods of occupation (3600–3200 BCE, 3300–3100 BCE, and 3100–2900 BCE) the results reveal that the inhabitants of Çadır relied heavily on barley, emmer, lentils, and flax throughout the Late Chalcolithic. Both dung and wood were used as fuel, although dung fuel appears to have been preferentially used. 
The most significant change throughout this period was a shift from foddering animals to grazing animals on the steppe. This shift corresponded with the 5.2 kya event, a period of increased aridity at the very end of the 4th millennium BCE. By diversifying their agricultural strategies to more risk adverse practices, the population at Çadır demonstrated their ability to be resilient in the face of climate change.
Madelynn von Baeyer, Alexia Smith, Sharon R. Steadman. "Expanding the plain: Using archaeobotany to examine adaptation to the 5.2 kya climate change event during the Anatolian Late Chalcolithic at Çadır Höyük." 36 Journal of Archaeological Science: Reports 102806 (2021). DOI: 10.1016/j.jasrep.2021.102806

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