Implicit in much, if not all, modern environmental sentiment is the idea that the natural world has been despoiled by humans — and if we could just leave it alone, things would get better. But new research suggests that in reality, humans have been altering the natural world for millennia, long before the 15th century dawn of the Age of Discovery, when European societies mastered long-distance ocean navigation and began to spread their cultures, animals and diseases to new continents.
The result of these changes, accumulating over time, has been “the creation of extensively altered, highly cosmopolitan species assemblages on all landmasses,” the authors write in a study published earlier this week in the Proceedings of the National Academy of Sciences. “Pristine landscapes simply do not exist and, in most cases, have not existed for millennia.” Conservationists often have the goal of “let’s get back to that natural environment with humans out of the picture,” said Melinda Zeder, one of the study’s authors and an anthropologist with the National Museum of Natural History at the Smithsonian Institution. “And that’s a chimera; that’s a false hope. It’s too late for that.”
“People have been modifying their environments for tens of thousands of years,” added Jon Erlandson, an archeologist, professor and director of the University of Oregon Museum of Natural and Cultural History, and another of the study’s co-authors. “Humans have literally impacted everything from mammoths to microbes. Most people have no idea how heavily we’ve altered things — and for how long.
“When anatomically modern humans appeared about 200,000 years ago, there’s what I think was a continual acceleration of technological change,” he said. As humans spread across the globe, he said, they invented things such as the bow and arrow, fishing spears, ceramics and agricultural advancements that made life easier but also impacted the environment. Based on a large synthesis of archaeological, fossil and ancient DNA data, the researchers conclude that humans started dramatically changing the world’s natural ecosystems well before 12,000 years ago. By that time, the species had emerged from Africa and colonised much of the globe. And already, mega-scale human impacts on the landscape and the creatures living on it included changing the regime of burning on lands from Africa to New Guinea, as early humans exploited fire for purposes of agriculture and hunting.
And that’s only one type of change already afoot. By between 20,000 and 23,000 years ago, the study notes, one of the earliest human introductions of a species from one region to another had already occurred — when the northern common cuscus, a marsupial, was spread from New Guinea to Indonesia and other locations. Erlandson said that it’s tempting to think that people thousands of years ago weren’t smart or technologically wasn’t sophisticated, but that’s not necessarily the case.
“The story we’re putting together is that for many, many thousands of years, people have basically been like us,” he said. “They were ingenious in developing new technologies and modifying their local environments.” But as humans have evolved and proliferated, that innovation — and the subsequent effect on the environment — has sped up.