UM Researcher Reveals How People in Ancient Asia Adapted to Climate Change

November 01, 2018

UM researcher Kyle Bocinsky (Photo by Eric Sorensen/Washington State University)MISSOULA – A University of Montana researcher recently co-authored a new paper that combines changes in ancient Asian farming practices with state-of-the-art computer modeling to offer insights into the ways people adapt to climate change.

When the climate cooled in ancient Asia, making it increasingly difficult to grow certain crops, agrarian societies responded by moving away, turning to pastoralism, increasing trade or diversifying the types of crops they planted, suggests new research by Kyle Bocinsky of the University of Montana and Jade d’Alpoim Guedes of the University of California, San Diego.

These strategies eventually coalesced into the development of the Silk Road, d’Alpoim Guedes and Bocinsky argue. Their paper, published Oct. 31 in Science Advances, describes a computer model the co-authors developed that shows for the first time when and where in Asia staple crops would have thrived or failed between 5,000 and 1,000 years ago.

Bocinsky is a computational archaeologist who uses computer-based, analytical methods to study the past. He is a research associate with the Montana Climate Office in the W.A. Franke College of Forestry and Conservation and is part of the Montana Drought and Climate project, which works to transform climate forecasts into useful and relevant information for agricultural producers across the state.

D’Alpoim Guedes is an assistant professor in the Department of Anthropology and Scripps Institution of Oceanography at UC San Diego and is an archaeologist specializing in paleoethnobotany – the science of analyzing ancient plant remains – to understand how human subsistence strategies changed over time.

The co-authors developed their model by combining weather station data from across Asia with a global reconstruction of past temperatures to create a simulation of how temperature in Asia changed through time. Then they combined their reconstruction with a database of different grains recovered from archaeological sites across Asia. The result is a model that shows how changes in temperature affected what agricultural crops could and couldn’t grow in certain areas over time, and it offers insight into the ways people adapted to those fluctuations.

“It’s currently the only such model for this region and time period,” Bocinsky said.

The climate cooled dramatically in the region around 3,000 to 3,700 years ago, and the effects were most pronounced in high-latitude and high-altitude areas. In Mongolia and the Tibetan Plateau around 3,500 years before the present, broomcorn and foxtail millet would have failed about half of the time, and people eventually abandoned the crops in favor of more cold-tolerant wheat and barley.

The researchers also argue that cooling temperatures made it increasingly difficult to grow key grain crops across Northern China between AD 291 and 360 – something that may have ended up playing an important role in the relocation of the Chinese capital from Xi’an to what is now Nanjing, in the south of the country. Climate change also stimulated the development of transportation infrastructure across Asia, the co-authors state, including the later Sui Dynasty’s creation of China’s Grand Canal, now a UNESCO World Heritage Site.

The code used to create the model is open-source, and any user of the free statistical software R can download the package and run the analysis themselves. Researchers also are welcome to extend d’Alpoim Guedes and Bocinsky’s findings by running analyses on other crops and in other locations.

“It is even possible to modify the code and potentially project for future crop failures,” Bocinsky said. “We developed this simulation using open-source software and published in an open-access journal because we hope researchers will make use of it and even improve it.”

The study can be found online at http://bit.ly/2Den6Py.

This research was supported by National Science Foundation grants BCS-1632207 (to d’Alpoim Guedes) and SMA-1347973 (to Bocinsky). D’Alpoim Guedes also received support from the Chiang Ching-kuo Foundation for Scholarly Exchange (JS027-A-15). Bocinsky, who is also affiliated with Washington State University and the Crow Canyon Archaeological Center in Colorado, received additional support as the William D. Lipe Chair in Research at the Crow Canyon Archaeological Center.

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Video:

https://umt.box.com/s/sp6d9bfquviz0wiqup9x3ehdtbfdhwe1

This model output shows how temperature changes in ancient Asia affected where people could grow broomcorn millet, historically one of the most important crops in Northern China. The graphic represents the crop’s probability of being in niche – the likelihood that under a given climatic scenario people would be able to grow this crop. Areas below 75 percent represent a high likelihood of failure that may have been intolerable to farmers. This particular map tells several interesting stories: for example, at 3,500 years before present, millets could no longer be cultivated in high-altitude areas like the Tibetan Plateau or Mongolia. In these areas, people abandoned millets and replaced them with more cold-tolerant crops like wheat and barley during this time period.

Contact: Kyle Bocinsky, research associate, Montana Climate Office, Montana Forest and Conservation Experiment Station, 770-362-6659, kyle.bocinsky@umontana.edu.