[2] Most certainly there was a gradual transition from hunter-gatherer to agricultural economies after a lengthy period when some crops were deliberately planted and other foods were gathered from the wild.
[3] In addition to the emergence of farming in the Fertile Crescent, agriculture appeared: by at least 6,800 BCE in East Asia (rice) and, later, in Central and South America (maize and squash).
[4] However, full dependency on domestic crops and animals, when wild resources contributed a nutritionally insignificant component to the diet, did not occur until the Bronze Age.
The ability of farmers to feed large numbers of people whose activities have nothing to do with material production was the crucial factor in the rise of surplus, specialization, advanced technology, hierarchical social structures, inequality, and standing armies.
[5] A rather different view is that as societies become larger and the movement of goods and people cheaper, they incorporate an increasing range of environmental variation within their borders and trade system.
[6] But environmental factors may still play a strong role as variables that affect the internal structure and history of a society in complex ways.
Archeological studies show that health deteriorated in populations that adopted cereal agriculture, returning to pre-agricultural levels only in modern times.
This is in part attributable to the spread of infection in crowded cities, but is largely due to a decline in dietary quality that accompanied intensive cereal farming.
These small states were highly urbanized, imported much food, and were centers of trade and manufacture to a degree quite unlike typical agrarian societies.
The use of crop breeding, better management of soil nutrients, and improved weed control have greatly increased yields per unit area.
[11] The rapid rise of mechanization in the 20th century, especially in the form of the tractor, reduced the necessity of humans performing the demanding tasks of sowing, harvesting, and threshing.
The main demographic consequences of agrarian technology were simply a continuation of the trend toward higher population densities and larger settlements.
Rome, for example, could obtain grain and other bulk raw materials from Sicily, North Africa, Egypt, and Southern France to sustain large populations, even by modern standards.
The populations of agrarian societies have historically fluctuated substantially around the slowly rising trend line, due to famines, disease epidemics and political disruption.
[16] The landowning strata typically combine government, religious, and military institutions to justify and enforce their ownership, and support elaborate patterns of consumption, slavery, serfdom, or peonage is commonly the lot of the primary producer.
[17] Caste systems, as found in India, are much more typical of agrarian societies where lifelong agricultural routines depend upon a rigid sense of duty and discipline.
The emphasis in the modern West on personal liberties and freedoms was in large part a reaction to the steep and rigid stratification of agrarian societies.