Quantitative modeling of human-environment interactions in the preindustrial world

Over the past 10,000 years, a series of agricultural and technological developments revolutionized land use by societies on most continents. The spread of crop plants, the use of fire for land management, the adoption of animal traction, the invention of the plow and the wheel, of metal agricultural implements, and the application of organic fertilizers all led to the intensification agricultural land use. This intensification allowed both growing human populations to be supported by a stable land base, and opened up new frontiers for agriculture that were previously undesirable for cultivation. In some cases, growing populations further developed macro-levels of social organization that facilitated collective undertakings that influenced land use, such as irrigation and terracing. All of these phenomena occurred heterogeneously in space and time, and their importance for anthropogenic land cover change over the Holocene is strongly debated. Here we quantify human influence on global landscapes using a numerical model describing preindustrial agriculture. The model is driven by archaeological information describing agriculture, technology, and social organization, and with environmental constraints from climate and soils. We simulate the environmental impact of changing land use systems over the early agricultural era. At least since the 3000 BP, agricultural land use is substantial enough to have had a significant impact on the distribution of forests and wetlands across large parts of Eurasia, Africa, and the Americas.