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To protect Earth, humans need to redefine what is the "best" nature

Only 17 percent of Earth’s land has actually been uninhabited over the past 12,000 years.

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If you think the best way to protect nature is to keep humans away from it, you’re not alone. Most people see the world’s ecosystems as existing separate from human society — something either decimated by industrial society or sustained by the hands-off approach used by traditional cultures.

But this narrative assumes Indigenous societies of the past didn’t have an impact on the world around them, and it assumes that humans’ impact on nature is a relatively new, predominantly negative, phenomenon.

Neither is true. Even when global populations were relatively low, people from all types of societies were influencing their surroundings in ways that seriously altered the systems and shaped them into the ecosystems we know today. In a study out Monday in the Proceedings of the National Academy of Sciences, an international team of anthropologists and ecologists quantified the full extent of this influence, finding it goes back at least 12,000 years.

If that’s the case, we may need to rethink how we view the relationship between humans and nature when it comes to conserving both for the future. Not only can nature handle certain types of human interventions — these interventions may actually be critical for maintaining the ecosystems as we know them today.

“The idea that you’re going to conserve biodiversity by keeping people out of nature doesn’t have any real scientific standing,” ecologist and lead author Erle Ellis tells Inverse.

The background — The idea to map global human land use over time isn’t a new one — it’s a tactic that’s been widely used in climate change modeling. These types of models use a process called back-casting, or hind-casting, to backward-forecast human population distributions based on where people live now.

In the past, many of these models assumed much of Earth was relatively uninhabited until about 1500, Ellis explains. This type of idea both feeds off of and contributes to, widespread assumptions that the “best” nature occurs where it’s been untouched — pure, pristine wilderness; free of humans.

“The idea that you’re going to conserve biodiversity by keeping people out of nature doesn’t have any real scientific standing.”

But there are plenty of examples of how Indigenous and traditional peoples shaped the landscape throughout history. For instance, it’s been well documented that the distribution of Brazil nuts throughout the Amazon rainforest was intentional; systematically shaped by humans who intentionally scattered the nuts through the landscape. Likewise, many North American grasslands were maintained by fires intentionally set by Indigenous groups.

It’s also well understood how the presence of top predators can shape entire ecosystems, a phenomenon ecologists call trophic cascades. Perhaps the most-studied cascade is that caused by wolves in areas like Yellowstone National Park, where the carnivores were completely extirpated and then later re-introduced. Wolves keep populations of prey like elk and deer in check, which benefits the plant communities those grazers can decimate when left to their own devices. The presence of hunters can change the behavior of other animals in a way that has positive trickle-down effects on the whole system.

Perhaps the most-studied cascade is that caused by wolves in areas like Yellowstone National Park. Sandy Huffaker/Corbis via Getty Images

Given the story of the wolves, it makes sense that certain types of human presence could have a similar, if not greater, contribution toward the success of the environment. “You can imagine what happens when a social mega-omnivore shows up with fire and projectiles which are extremely effective at hunting,” Ellis says, referring to humans.

What’s new — In this study, Ellis and colleagues found that very little of what we today think of as “wilderness” has actually been uninhabited throughout history. They estimate that three-quarters of Earth was inhabited by 10,000 B.C. While the global population was still relatively low, people were already shaping the landscape.

Compared to previous models, the new analyses incorporated a better representation of how hunter-gatherers would have used and affected the land. In the end, only 17 percent of Earth’s land has actually been truly uninhabited over the past 12,000 years — probably less. And for some ecosystems, like temperature woodlands, the number falls closer to 5 percent.

Why this matters — “The idea that hunter-gatherer societies don’t transform ecology, that they kind of just live in harmony and nothing changes, is incorrect,” says Ellis. This has implications for what we consider to be wild, to be “nature” — especially when it comes to areas currently prioritized for conservation and how we manage them.

“Nature as we know it has all been shaped by earlier histories of land use by different societies,” Ellis says. “The biodiversity that we have now came to us through these long histories of people living in the landscape and shaping the landscape. You can’t look at biodiversity and think, the only reason this is here is because people left it alone. People curated it.”

“I think that this idea is very much accepted in fields of Indigenous studies, but a lot of these [old] paradigms about wilderness still influence research into conservation and restoration practices,” says Cleo Woelfle-Erskine, an eco-hydrologist at the University of Washington who was not involved in the study. “It’s really important for this type of research to be published in natural science journals.”

“We think about the Anthropocene starting with settlement, but Native engineering caused pretty fundamental changes in the structure of the landscape that had feedback throughout ecosystems,” Woelfle-Erskine says.

Conservation and restoration initiatives typically don’t include traditional land stewardship as a component. For instance, in fire-prone landscapes, many Indigenous cultures would have regularly conducted prescribed burns to maintain a sustainable system. Today, these areas are instead “protected” from fires as much as possible — think: Smokey the Bear — and the result is an extremely flammable landscape.

“If you’re going to restore land without people in it, that’s not really restoring it.”

Likewise, there are examples of how traditional hunting and gathering practices act to keep systems in balance. For instance, the digging required to harvest tubers underground can cause important soil turnover in forest ecosystems. Humans harvesting seeds can disperse plant species throughout the landscape. Hunting grazing species can boost the plant populations across

“Indigenous practices, including hunting, gathering, traditional burning practices, are actually good for the landscape. All these things need to be brought back,” says Ellis. “If you’re going to restore land without people in it, that’s not really restoring it.”

What’s next — Ellis says that technically, conservation practitioners can just figure out how people of the past were using the land, and just copy the practices. But that seems unethical.

“To be fair, you really need to restore people’s rights to do what they used to do,” he says.

The elephant in the room is the clear history of humans who are not good stewards of the land. Worldwide biodiversity and habitat loss continues at an alarming rate, and people are to blame.

How can we prevent further degradation and destruction? By avoiding an all or nothing approach, this study suggests. Traditional stewardship practices are not only safe for nature — they’re essential. At this point, the only way to let nature take its course may be to guide it along the way.

Abstract: Archaeological and palaeoecological evidence shows that by 10,000 BCE, all human societies employed varying degrees of ecologically transformative land-use practices, including burning, hunting, species propagation, domestication, cultivation, and others that have left long term legacies across the terrestrial biosphere. Yet a lingering paradigm among natural scientists, conservationists, and policymakers is that human transformation of terrestrial nature is mostly recent and inherently destructive. Here we use the most up-to-date spatially-explicit global reconstruction of historical human populations and land use to show that this paradigm is likely wrong. Even 12,000 years ago, nearly three-quarters of Earth’s land was inhabited and therefore shaped by human societies, including more than 95% of temperate and 90% of tropical woodlands. Lands now characterized as “natural”, “intact”, and “wild” generally exhibit long histories of use, as do protected areas and Indigenous lands, and current global patterns of vertebrate species richness and key biodiversity areas are more strongly associated with past patterns of land use than with present ones in regional landscapes now characterized as natural. The current biodiversity crisis can seldom be explained by the loss of uninhabited wildlands, resulting instead from the appropriation, colonization, and intensifying use of the biodiverse cultural landscapes long shaped and sustained by prior societies. Recognizing this deep cultural connection with biodiversity will therefore be essential to resolve the crisis.
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