People have shaped most of terrestrial nature for at least 12,000 years

View ORCID ProfileErle C. Ellis, View ORCID ProfileNicolas Gauthier, View ORCID ProfileKees Klein Goldewijk, View ORCID ProfileRebecca Bliege Bird, Nicole Boivin, Sandra Díaz, View ORCID ProfileDorian Q. Fuller, View ORCID ProfileJacquelyn L. Gill, View ORCID ProfileJed O. Kaplan, View ORCID ProfileNaomi Kingston, View ORCID ProfileHarvey Locke, View ORCID ProfileCrystal N. H. McMichael, View ORCID ProfileDarren Ranco, View ORCID ProfileTorben C. Rick, M. Rebecca Shaw, Lucas Stephens, View ORCID ProfileJens-Christian Svenning, and James E. M. Watson


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PNAS April 27, 2021 118 (17) e2023483118; https://doi.org/10.1073/pnas.202348311

Edited by B. L. Turner, Arizona State University, Tempe, AZ, and approved March 4, 2021 (received for review November 13, 2020)


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The current biodiversity crisis is often depicted as a struggle to preserve untouched habitats. Here, we combine global maps of human populations and land use over the past 12,000 y with current biodiversity data to show that nearly three quarters of terrestrial nature has long been shaped by diverse histories of human habitation and use by Indigenous and traditional peoples. With rare exceptions, current biodiversity losses are caused not by human conversion or degradation of untouched ecosystems, but rather by the appropriation, colonization, and intensification of use in lands inhabited and used by prior societies. Global land use history confirms that empowering the environmental stewardship of Indigenous peoples and local communities will be critical to conserving biodiversity across the planet.

Abstract

Archaeological and paleoecological 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 y 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.

agriculture
hunter-gatherer
extinction
conservation
Anthropocene

Multiple studies confirm that ecosystems across most of the terrestrial biosphere, from 75 to 95% of its area, have now been reshaped to some degree by human societies (1⇓–3). With a few exceptions (e.g., refs. 4⇓⇓⇓–8), this global anthropogenic transformation of terrestrial nature has been described by natural scientists as mostly recent: the product of the industrial era (9⇓⇓⇓–13). This is partly because previous global reconstructions of early populations and land use systematically ignored these earlier transformations (1, 5, 14) and partly due to the conservation community’s focus on recent industrial changes (2, 3, 9, 15). There has also been a history of natural scientists and conservation practitioners interpreting terrestrial ecosystems as uninfluenced by long-sustained interactions with human societies, ignoring prior histories of land use, especially by Indigenous societies (16⇓–18). While this paradigm has increasingly been questioned with respect to long-term global changes in climate (19), fire regimes (20), and biodiversity (7, 8, 21), it continues to have real-world consequences, including failed policies of fire suppression, wildlife management, and ecological restoration, as well as the repression and removal of Indigenous peoples from traditional lands and waters and the erasure of their extensive knowledge of effective ecosystem management practices, thereby undermining their sovereignty over these ecosystems (17, 22⇓–24).

Here, we examine contemporary global patterns of biodiversity and conservation in relation to the spatial history of human populations and land use over the past 12,000 y. Specifically, we use spatially explicit global datasets to visualize histories of human use in areas identified as biodiversity-rich and high-priority for conservation, including those specifically labeled as more “natural” or “wild,” and test the degree to which global patterns of land use and population at different times are associated statistically with contemporary global patterns of high biodiversity value and vertebrate species richness and threat within areas prioritized for conservation. Through this examination, we assess the early and sustained global significance of cultural landscapes as a basis for better understanding and conserving terrestrial nature.

Anthropological, archaeological, and paleoecological evidence indicate that, at least since the start of the current interglacial interval 11,600 y ago, all human societies were interacting with biota and environments in ways that shaped evolutionary dynamics, ecosystems, and landscapes (25⇓⇓–28). We use the term transformations to describe system-level changes in the social-ecological systems shaped by these interactions, including their initial formation by human inhabitation and the adoption of cultural practices leading to changes in ecosystem state, sensu 5, 27. While the focus is often on negative outcomes relating to these interactions, including extinctions of island endemics (29) and megafauna (21, 30, 31) with cascading ecological consequences (32), there is increasing evidence that human cultural practices can also produce sustained ecological benefits through practices that expand habitat for other species (33, 34), enhance plant diversity (17, 34⇓⇓–37), increase hunting sustainability (38), provide important ecological functions like seed dispersal (39), and improve soil nutrient availability (40, 41).

Hunter-gatherers, early farmers, and pastoralists often shared regional landscapes, which they shaped through a wide array of low-intensity subsistence practices, including hunting, transhumance, residential mobility, long- and short-fallow cultivation, polycropping, and tree-fallowing that created diverse, dynamic, and productive mosaics of lands and novel ecological communities in varying states of ecological succession and cultural modification (34, 37, 42). In many regions, these diverse cultural landscape mosaics were sustained for millennia (17, 24, 25, 27, 33, 34, 37, 43⇓–45), contrasting sharply with the more homogenous and continuously used landscapes of larger-scale agricultural societies employing annual tillage, irrigation, continuous grazing, and the extractive and colonial use of land, labor, and other resources to support elites (1, 5, 44). The emergence and spread of increasingly globalized and industrial societies only accelerated this trend toward today's ever more intensively used and homogeneous cultural landscapes shaped by global supply chains, mechanization, chemical nutrients and pest control, leading to ecologically simplified habitats and biotic homogenization through species transported around the world intentionally and unintentionally (1, 44, 46).

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