The first modern humans appeared on the African plains 200,000 years ago. As our ancestors spread across the globe, they changed their environment, wiping out many of the large animals in their paths. Yet the arrival of agriculture, which sprang up independently in several places as the last ice age receded 8-10,000 years ago, accelerated this change beyond recognition.
Agriculture bound people to the land, leading to permanent settlements. Settlements grew into villages, and then into cities, countries and empires; relatively equal societies gave way to the rule of a few.
People domesticated plants and animals, breeding them to make them more productive and inventing new tools to help plant and harvest crops. Ever-increasing areas of wild land came under human control; forests were cut down, grasslands ploughed up and rivers diverted for irrigation.
Now humans commandeer 75% of the global land surface outside of the Greenland and Antarctic ice sheets, and we’re bringing more wild land under our control every day.
A situation in which processes that affect the state of a system precisely balance out so that the system does not change. An equilibrium is 'stable' if the system returns to it after a small perturbation and is 'unstable' if the system moves away from the equilibrium point after such a perturbation.