New research shows that land use by human societies has reshaped ecology across most of Earth's land for at least 12,000 years. Researchers, from over a dozen institutions around the world, assessed biodiversity in relation to global land use history, revealing that the appropriation, colonization, and intensified use of lands previously managed sustainably is the main cause of the current biodiversity crisis.

The new data overturn earlier reconstructions of global land use history, some of which indicated that most of Earth's land was uninhabited even as recently as 1500 CE. Further, this new PNASstudy supports the argument that an essential way to end Earth's current biodiversity crisis is to empower the environmental stewardship of Indigenous peoples and local communities across the planet.1

  • 1. "Our work shows that most areas depicted as 'untouched,' 'wild,' and 'natural' are actually areas with long histories of human inhabitation and use," says UMBC's Erle Ellis, professor of geography and environmental systems and lead author. He notes that they might be interpreted like this because in these areas, "societies used their landscapes in ways that sustained most of their native biodiversity and even increased their biodiversity, productivity, and resilience."

Erle C. Ellis, Nicolas Gauthier, Kees Klein Goldewijk, Rebecca Bliege Bird, Nicole Boivin, Sandra Díaz, Dorian Q. Fuller, Jacquelyn L. Gill, Jed O. Kaplan, Naomi Kingston, Harvey Locke, Crystal N. H. McMichael, Darren Ranco, Torben C. Rick, M. Rebecca Shaw, Lucas Stephens, Jens-Christian Svenning, James E. M. Watson. People have shaped most of terrestrial nature for at least 12,000 years. Proceedings of the National Academy of Sciences, 2021; 118 (17): e2023483118 DOI: 10.1073/pnas.2023483118

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.

Fig. 1. Global changes in anthromes and populations 10,000 BCE to 2017 CE.
Fig. 1. Global changes in anthromes and populations 10,000 BCE to 2017 CE. - (A) Anthrome map at 2017 CE (Eckert IV projection). (B) Global changes in anthrome areas, with population changes indicated by red line. Anthromes are classified using population densities and dominant intensive land use. Wildlands are defined by zero population and no intensive land use (urban + crops + grazing), Cultured anthromes have low populations and <20% intensive use, and Intensive anthromes are ≥20% intensive. Cultured and Intensive anthromes are further stratified by population densities, in persons km−2, as Remote (>0 to <1), Populated (1 to <10), Residential (10 to <100), Inhabited (>0 to <100), Villages and Mixed settlements (100 to <2,500), and Urban ( ≥2,500). Intensive anthromes are further stratified based on their dominant intensive land use area ≥20% in order of most intensive use (urban > rice > irrigated > cropped > pastured). Woodlands combine all forest and woodland biomes (73); drylands comprise the remaining biomes, from savanna to tundra, excluding permanent ice.