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Stanford archaeologist embraces technology to trace the origins of agriculture

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Li Liu at the late Neolithic fortified site of Shimao, Shaanxi, China. Photo credit: Hao Zhao.
The group from Stanford was in a traditional house in Inner Mongolia, on hard beds that were made of bricks. There was no running water and they were the only foreigners in the village. 
 
“For me it was no big deal and nothing new,” says Li Liu, professor of Chinese Archeology at Stanford, who has been studying Chinese archeology and the origins of civilization for 35 years. 
 
They were there to collect residue samples from excavated artifacts to analyze in her labs in China and the Stanford Archeology Center. Liu’s research has pushed back the date of the origins of agriculture in two sites in northern China to 23,000 years ago. 
 
“Food production is really the economic foundation for almost everything in civilization, which is why I began to search for the origins of agriculture.”
 
By focusing her analysis on artifacts from some of the oldest centers of global civilization located in modern-day China, her research has deepened understanding of human history in the region.
 
“We have evidence now that shows people began to collect and consume wild millet 23,000 years ago, during the last ice age. This was the first step leading to cultivating and domesticating millet some 13,000 years later in this region.”
 
On the broadest level, her research is interested in human history and state formation, using archeology to study agricultural development and the rise of civilization.
 
“Rather than looking at specific moments in history, we want to develop a coherent understanding of the long term development of subsistence economy to better understand the emergence of civilization in China and its position in world history.” 
 
There are human-focused questions that guide her research: “How did this society evolve from simple to complex? How is it different from and similar to other regions? And what does this mean in a broader context of the growth of human civilization?” 
 
The work she does is not solitary. Instead, it relies on a team made up of other archeologists, students and specialists. They have a lab in China and a lab in the Stanford Archeology Center, and both graduate students and undergraduates assist with projects. Moreover, she has a collaboration with the Institute of Archeology in China, and her team often co-author articles.
 

 
The timeframe that is the focus of her research stretches from 23,000 years ago until 2,000 years ago. 
During this period it is possible, she says, to track the slow transformation from the collection of wild ancestors of cereals, through the cultivation and domestication of these plants, up until the establishment of intensive multi-cropping farming.
 
“We are looking at what plants were explored and when. The earliest grinding stones we look at date from 23,000 to 19,500 years ago, during the coldest period of the last ice age. They were used to process wild plants including millet, tubers, and beans. But, the earliest archaeological evidence for millet cultivation in China is about 10,000 years old, suggesting that farming was slow to emerge from ancient traditions of plant use.” 
 
Some tubers used 23,000 years ago later became important ingredients in traditional Chinese herb medicine, suggesting that Chinese medicinal knowledge can be traced back to a very deep antiquity.  
 
The beginning of the Holocene, around 11,000 years ago, saw the development of more complex tools and techniques. During the period that Liu studies, humans became less nomadic and developed early traits of sedentary villages. The origins and rise of agriculture marked a key moment in human history.
 
Modern technology, ancient artifacts
Liu has done excavations focusing on certain archaeological sites to uncover details of the social organization of a particular society. Now she analyzes artifacts from many sites, which were excavated by other archaeologists. This method allows her to see the bigger picture over a broad region. These artifacts often have been kept in museums and storage rooms for decades, and are holding great potential to reveal the secret of ancient people’s foodways.
 
Her team studies artifacts from more than 30 sites within the Yellow River and North East regions of China, where they travel each summer to collect samples for analysis. Collecting from various sites allows her to make comparisons to establish a more comprehensive picture of agricultural development in these areas.
 
She is careful to preserve these important ancient artifacts. “It is not like I take the grinding stones or the sickles and bring them to my lab. It is also not very easy to transport artifacts like that.”
 
Liu uses new technology in order to build up a better picture of how agriculture developed, adopting two analytical methods in her research. One is residue analysis of the samples, which looks at what remains are on the tools, and the other is use-wear analysis, which examines how the tools were used.

To obtain her samples from objects for residue analysis, she collects residue from tools, pottery vessels, and human teeth using a complex washing process that helps to extract small particles – starch, phytoliths, and other microfossils – from the surface. She then uses microscopic analysis in the lab to establish what is in the residue.

 
“Through seeing what was being ground for nutrition and how the tools were used, we can have a better picture of food consumption at the time, and therefore how early agriculture developed.”
 
The combination of traditional archeological methods and recently developed scientific technology makes her research stand out. “Through using advanced microscopic techniques we have been able to make the invisible visible, and revise the date surrounding the origins of agriculture – and the rise of civilization – in the area.”
 
Into the future, she aims to investigate the change of foodways on a greater spatial and temporal scale. “By applying scientific method to archeology I am hoping to answer big questions in human evolution.”
 
“Archeologists have a fundamental role to play in searching for the origins of civilizations. We use and study objects that can produce meaningful results for my research and for our understanding of human history.”
 
 
Tom Winterbottom is a doctoral candidate in Iberian and Latin American cultures at Stanford.
 
Media Contact: Corrie Goldman, Director of Humanities Communication:  (650) 724-8156, corrieg@stanford.edu