Looking into the past, researchers can see that human populations have not always collapsed in the face of climate change. In fact, a new study from Washington University in St. Louis reveals that during the early Bronze Age, people in the central plains of China responded quite successfully to long-term environmental changes.
The experts found that when a new climate emerged, humans turned to innovation, including advancement in agriculture and increasingly complex social structures. Such innovations set the stage for a dramatic increase in the human population around 3,900 to 3,500 years ago.
“In China, especially, there has been a relatively simplistic view of the effects of climate,” said Professor Tristram R. Kidder. “Our work shows that we need to have a nuanced appreciation of human resilience as we consider the effects of climate and its effects on human societies.”
“We have remarkable capacity to adapt. But part of the lesson here is that our social, political and technological systems have to be flexible. People in the past were able to overcome climate adversity because they were willing to change.”
The researchers set out to quantify the types of demographic and subsistence changes that took place over the course of thousands of years in the central plains of China.
Based on pollen data from a lake sediment core collected in Henan Province, the experts determined that a warm and wet climate about 9,000 to 4,000 years ago shifted to a cool and dry climate during the Neolithic-Bronze Age transition.
The team used radiocarbon dating and archaeological data to analyze what people were growing and eating during periods of significant population surges and declines throughout the time when the climate was stable and when it shifted.
The researchers discovered that as resources began to fluctuate and become more limited in drier conditions, people expanded the number of plants they cultivated for food. They embraced new diversity, including foxtail millet, broomcorn millet, wheat, soybean and rice.
The time when the climate was changing is also marked by innovations in water management approaches for irrigation and new metal tools.
“Certainly, by 4,000 years ago, which is when we see this change in the overall environmental condition, this is a society with complicated political, social and economic institutions,” said Professor Kidder.
“And what I think we are seeing is the capacity of these institutions to buffer and to deal with the climatic variation. When we talk about changes in subsistence strategies, these changes didn’t happen automatically. These are human choices.”
According to study co-author Michael Storozum, the fact that climate change does not always equal collapse is an important point in both a prehistoric and modern context.
“Humans have been heavily modifying their environments for thousands of years, often in the pursuit of increasing food production which grants societies a higher degree of social resilience,” said Storozum.
“As more environmental scientists and archaeologists work together, I expect that our understanding of what makes a society resilient to climate change in prehistoric and historical times will grow as well.”
The study is published in the journal Environmental Research Letters.