A new study, published in the journal Proceedings of the National Academy of Sciences (PNAS), suggests that nearly all of the world’s unspoiled nature is entirely gone. In fact, most of it disappeared at least several thousand years ago, thanks to human activity, The Washington Post reports.

Nicole Boivin from the University of Oxford and the Max Planck Institute for the Science of Human History teamed up with scientists from the UK, U.S., and Australia to pore over archaeological, fossil, and ancient DNA data. The researchers concluded that humans began affecting the world’s natural ecosystems long before cars, housing developments, or factories existed. “Pristine’ landscapes simply do not exist and, in most cases, have not existed for millennia,” they said in a release.

The paper outlines the major phases when humans shaped the world and altered our world’s ecosystems: global human expansion during the Late Pleistocene; the Neolithic spread of agriculture; the era of humans colonizing islands; and the emergence of urban trading societies.

Here’s a rough timeline: modern humans arose in Africa roughly 190,000 years ago, and by 50,000–70,000 years ago (some say even earlier) had begun venturing out of the home continent. Human hunting is presumed to have helped drive the extinctions of some types of large or giant animals, called megafauna, in Australia, Tasmania, and later the Americas between 50,000 and 10,000 years ago. One example of our early impact occurred some 20,000 to 23,000 years ago, when humans introduced a new species—a marsupial that lived in New Guinea, now called the northern common cuscus—to Indonesia and other regions in the South Pacific.

Astoundingly enough, all this activity preceded the advent of agricultural societies during the Holocene period, which began about 11,700 years ago. (We still live in the Holocene.) By this time, the human species was widely dispersed throughout the world. Farmers began favoring certain animal, tree, and plant species, which thrive today thanks to our ancestors’ green thumbs. They used fire to burn land for agriculture, and to draw animals out into the open for easier hunting. Humans’ agricultural practices also affected everything from forests (after all, we had to clear land for planting food) to the atmosphere’s greenhouse gas composition. Sometime during this era, livestock and poultry were domesticated and spread from the Near East to across the globe.

Meanwhile, seafaring societies began spreading pests from one island to another, since various species of rats, mice, insects, and lizards stowed away onboard sailors’ boats. As humans colonized these new lands, they also threatened indigenous animals, contributed to deforestation, introduced new crops, generally altered these virgin landscapes for good.

As humanity’s become more advanced, our impact on our environment has grown. During the Industrial Revolution, factory emissions dramatically altered atmospheric carbon dioxide concentrations. In fact, researchers have even argued that these gases mark the end of the Holocene and the beginning of a new geological epoch called the Anthropocene.

In short, humans have a long, long history of affecting and changing the natural world. However, the study’s researchers don’t necessarily think that’s a bad thing. We’ll never be able to undo the damage, but we can mindfully monitor and shape the way we physically impact the world.

“The fact that we’ve been changing the planet for so long, with both positive and negative consequences, suggests that we can try to take control of the transformation, and make it less detrimental,” Boivin told The New Yorker

[h/t The Washington Post]