All animals change their environment – most subtly, some dramatically. In recent years, humans have had an impact that is orders of magnitude larger than any other species. Although the scale of this is new, an assessment of the history of human impact shows that transformation of the landscape was widespread a lot earlier than most people realize, including even many scientists studying the topic.
Around the world, many people are investigating the appearance of agriculture and other practices that transformed the environment, such as the felling of forests for grazing land. Few, if any, are looking at the whole planet and are instead focused on a specific region or two they have made their academic niche.
The ArchaeoGLOBE Project seeks to bring this knowledge together, consulting 255 experts in the history of land use to combine their knowledge about each region and create a worldwide picture. The first results have been published in Science and surprised even many of those involved.
Although the oldest noticeable human impacts began not long after the ending of the Ice Age, with agriculture leading to the first cities, the paper concludes that changes accelerated around 4,000 years ago. By about 3,000 years ago, human effects were widespread, the authors conclude.
Dr Tim Denham of the Australian National University was one of the authors. His primary expertise is in early human impact on New Guinea, but he also contributed knowledge of South East Asia and tropical agriculture more broadly. He told IFLScience the patchy nature of our knowledge, with more than 10 experts contributing on some regions and two in others, means these dates may change, but the important lesson to be drawn is that assessments of human impact need a longer historical perspective.
“The thing is to acknowledge agricultural practice had a major impact on land use by 3,000 years ago,” Denham said. “When people think of the Anthropocene they think about the last few hundred years.” On the other hand, Denham added we know little about the consequences of these land use changes, for example how many species were driven to extinction.
"Understanding how humans interact with the environment over the long-term past is one of the best things we can do to help us understand how people will deal with this in the future," said Professor Michael Barton of Arizona State University in a statement. "We're not starting from zero. We're starting from a long history."
Denham added that one path to sustainable agriculture is to draw on some of the crops that were once heavily used but have now been discarded as the world concentrates on a narrow range considered most profitable. Greater knowledge about the historical impacts of heritage plants could help feed the world in less damaging ways.