It is recommended to get this upgrade before building any farms, as the upgrade cannot improve the productivity of farms that were already built. To research more farming upgrades such as the Plow and Irrigation, this economic upgrade must be researched beforehand.
The revolution in agriculture involved both the development of animals. The ability to control and manage herds of milk- and meat- producing animals also served to free humans from the drudging and desperation of continual hunting and gathering. Herding did not lead necessarily to a sedentary village life, however. The need to find pasture often meant that herding societies remained nomadic, at least for part of the year. Domesticated sheep and goats first appear in the archaelogical record around 7500 B.C. in the Zagros Mountains to the east of the Tigro and Euphrates River valleys. Cattle were domesticated around 600 B.C. in both the Sahara and Egypt, perhaps near simultaneously. Domestication of cattle alone may have been for responsible for a doubling of world human population in a few generations.