// "Factors Underlying the Broadest Patterns of History" from
// "Guns, Germs, and Steel", figure 4.1.

// Different presentation of basic ideas from the book.

digraph world_history {

size="8.5,11"; // U.S. letter size
margin="0.5,0.5";
ratio="fill";

key [label="Factors underlying History\nfrom 'Guns, Germs, and Steel'\nby Jared Diamond" shape="box"]

axis [label="East/west axis of continent"]
spreading [label="Ease of species spreading"]
wild [label="Many suitable wild species"]
many [label="Many domesticated\nplant and animal species"]
surpluses [label="Food surpluses\nand food storage"]
societies [label="Large, dense, sedentary,\nstratefied societies"]
technology [label="Technology"]
guns [label="Guns" shape="none"]
steel [label="Steel swords" shape="none"]
ships [label="Ocean-going ships" shape="none"]
organization [label="Political organization\nand writing" shape="none"]
disease [label="Epidemic diseases\n(germs)" shape="none"]
horses [label="Horses" shape="none"]

// proximate [style=invisible]


axis->spreading
wild->many
spreading->many
many->surpluses
surpluses->societies
societies->technology
technology->societies [style=dotted]
technology->guns
technology->steel
technology->ships
societies->organization
many->disease
societies->disease

many->horses




}