Study illuminates how human activity has transformed the Earth
Thousands of years before humans began burning fossil fuels, they had indelibly altered the natural world through foraging, herding animals, and farming, according to a new study by an international consortium of archaeologists.
The study, published Aug. 30 in the journal Science, synthesizes data from 255 archaeologists to provide the first global survey of the Earth’s transformation through human land use over the past 10,000 years. The findings challenge the commonly held view that large-scale, human-caused environmental change is a relatively recent phenomenon. It also shows how the overall impact of human behavior has been growing exponentially since the end of the last Ice Age.
“The industrial revolution and large-scale agriculture often spring to mind when people think about human impact on the environment, but these findings show that humans have been transforming the landscape going back at least 10,000 years,” said Yale anthropologist Jessica Thompson, a co-author of the study. “The line that separates the ‘pristine’ natural world from one transformed by people is blurrier and goes further back in time than what is commonly believed.”
The study was conducted by the ArcheoGLOBE Project, a consortium of archaeologists from institutions across the globe. Of the 255 archaeologists who contributed data, 120 are co-authors of the paper. The contributing researchers shared data on land use in 145 regional units — covering all the continents except Antarctica — from a period beginning 10,000 years ago to 1850 C.E. Thompson, whose research focuses on sub-Saharan Africa, contributed data from six regions in southern Africa.
The researchers concluded that foragers, farmers, and herders had transformed the planet by 3,000 years ago — much earlier than the timeframe derived from the most common land-use reconstructions used by Earth scientists. In some regions, the survey showed effects of intensive land-use more than 1,000 earlier than previous estimates.
The survey found that foraging, which includes hunting, gathering, and fishing, was commonplace 10,000 years ago in 120, or 82%, of the 145 regions. However, foragers were not passive occupants; they also drastically changed landscapes, such as through extensive burning, to improve conditions for hunting and gathering, according to the study.
“Certainly foragers had significant impacts on the plant and animal communities where they lived,” she said. “They manipulated the landscape to enhance their chances of survival. They might burn land to increase its productivity or influence how vegetation grows to attract animals to hunt. We need to start thinking more seriously about that activity when we consider what constitutes an environment or landscape transformed by people. And that requires archaeologists to be a part of the conversation about modern-day human impacts.”
The study also highlighted significant gaps in the archeological data, with some regions having been much more intensively studied than others. The most studied regions were concentrated in Europe, Southwest Asia, and portions of North and South America. Regions in Southeast Asia and Central and West Africa have received less attention from researchers, the study concluded.
The variability in data quality shows a striking need to focus attention on the less-studied regions, Thompson noted.
“Essentially, we know a lot more about places that have extensive histories of research,” she said. “That’s exciting because it demonstrates how little we know about much of the world in terms of long-term trends in human land use. It shows that there is much work that needs to be done and a lot of opportunities to produce impactful research.”
The study was funded by a grant from the National Science Foundation.