Even small-scale or shifting agriculture can cause global change when considered at large scales and over long time periods.
Primitive food producers had transformed Earth's ecology as far back as 4,000 years ago, a study suggests, challenging prevailing notions that human-caused environmental change is only a recent phenomenon.
The findings, from a large international study by archaeologists and scientists, show the deep and previously underestimated impact on the planet of land cultivation and livestock breeding by ancient peoples.
Researchers say the "unique perspective" generated by the study may help them find ways of alleviating negative impacts on soils, vegetation and climate in the future.
Study author Andrea Kay, of the University of Queensland, said: "While modern rates and scales of anthropogenic global change are far greater than those of the deep past, the long-term cumulative changes wrought by early food producers are greater than many realise.
"Even small-scale or shifting agriculture can cause global change when considered at large scales and over long time periods."
Up to 40 percent of the Earth's land area had been affected by human cultivation and farming 4,000 years ago, the study suggests.
The findings challenge prevailing opinions of a mid-20th century starting date for the Anthropocene - the concept of an epoch in which human activity is the dominant influence on Earth's ecosystems.
They suggest dramatic changes in the Earth's landscape were started before even the domestication of animals or intensive agriculture - and well before the invention of the steam engine and motor car.
The study, published in the journal Science, was created by pooling the data-sets of 255 archaeologists with regional expertise around the world.
The resulting global-scale assessment, called the ArchaeoGLOBE Project, looks at land use from 10,000 to 170 years ago.
Nicole Boivin, a lead author on the study from the Max Planck Institute for the Science of Human History in Germany, said: "This novel crowd-sourcing approach to pooling archaeological data is extremely innovative, and has provided researchers with a unique perspective".
Erle Ellis, of the University of Maryland, Baltimore County, said: "It's time to get beyond the mostly recent paradigm of the Anthropocene and recognise that the long-term changes of the deep past have transformed the ecology of this planet, and produced the social-ecological infrastructures, agricultural and urban, that made the contemporary global changes possible.
Thomas Hornall is a reporter with PA.