Editing Guns, Germs, and Steel (section)

=== Agriculture ===
[[File:Jared Diamond's big five.jpg|thumb|The five most significant domesticated animals: clockwise, cattle, pigs, goats, sheep and horses]]
''Guns, Germs, and Steel'' argues that [[urbanization|cities]] require an ample supply of food, and thus are dependent on agriculture. As farmers do the work of providing food, division of labor allows others freedom to pursue other functions, such as mining and literacy.

The crucial trap for the development of agriculture is the availability of wild edible plant species suitable for domestication. Farming arose early in the [[Fertile Crescent]] since the area had an abundance of wild wheat and pulse species that were nutritious and easy to domesticate. In contrast, American farmers had to struggle to develop corn as a useful food from its probable wild ancestor, [[teosinte]].

Also important to the transition from hunter-gatherer to city-dwelling agrarian societies was the presence of "large" domesticable animals, raised for meat, work, and long-distance communication. Diamond identifies a mere 14 domesticated large mammal species worldwide. The five most useful (cow, horse, sheep, goat, and pig) are all descendants of species [[Endemic (ecology)|endemic]] to [[Eurasia]]. Of the remaining nine, only two (the [[llama]] and [[alpaca]] both of South America) are indigenous to a land outside the temperate region of Eurasia.

Due to the [[Anna Karenina principle]], surprisingly few animals are suitable for domestication. Diamond identifies six criteria including the animal being sufficiently docile, gregarious, willing to breed in captivity and having a social dominance hierarchy. Therefore, none of the many African mammals such as the [[zebra]], [[antelope]], [[cape buffalo]], and [[African elephant]] were ever domesticated (although some can be tamed, they are not easily bred in captivity). The [[Holocene extinction event]] eliminated many of the [[megafauna]] that, had they survived, might have become candidate species, and [[Holocene extinction event#North America|Diamond argues]] that the pattern of extinction is more severe on continents where animals that had no prior experience of humans were exposed to humans who already possessed advanced hunting techniques (such as the Americas and Australia).

Smaller domesticable animals such as dogs, cats, chickens, and [[guinea pig]]s may be valuable in various ways to an agricultural society, but will not be adequate in themselves to sustain a large-scale agrarian society. An important example is the use of larger animals such as cattle and horses in plowing land, allowing for much greater crop productivity and the ability to farm a much wider variety of land and soil types than would be possible solely by human muscle power. Large domestic animals also have an important role in the transportation of goods and people over long distances, giving the societies that possess them considerable military and economic advantages.