Geography is fate,

 To find the general laws that explain the fate of human societies, the reasons some have triumphed and others become casualties in the last 13,000 years of human endeavour is a large endeavour.

So what is the explanation? Diamond argues that the causes of global inequality are ancient; they may go back 50,000 years to the time when modern humans began to fan out over the Earth. As continent after continent was settled, the earliest humans drew, as it were, tickets in a lottery. For the winners all would be movement: farms, draught animals, cities, kingdoms and, finally, empires. For the losers there would be stasis, or nearly so; millennia in the Stone Age which would cease only with their conquest and, sometimes, annihilation. The tickets they drew were the territories over which they strode; for Diamond, geography is fate.

Geography affects human societies in three ways. First, by the quantity and quality of plants and animals that are available for domestication. Some continents were biologically impoverished when humans arrived on them; others were swiftly made so by the action of early hunters (Diamond is a persuasive advocate of the ‘overkill’ hypothesis for the extinction of the Pleistocene megafauna in Australasia and the Americas). In such continents social evolution stalled until suitable domesticates arrived from elsewhere. Second, by size. The larger the territory, the more people it is likely to support, and the greater the chance that social and technological innovations will arise and be retained; there are numerous examples of isolated island populations simply forgetting the most rudimentary technological skills (Diamond cites the case of the Tasmanian Aborigines, who lost the art of making barbed spears, bone tools, boomerangs, ground stone tools, hooks, nets, pronged spears, traps and, most remarkably, fire – all skills found among continental Aborigines). Third, by the topography and orientation of landmasses. Domesticated plants and animals are necessarily suited to a limited range of climates, and climate is strongly influenced by latitude. Those landmasses, notably Eurasia, which are oriented on an east-west axis have vast areas suited to a given domesticate or cultivar, and such innovations spread rapidly across them. In contrast, north-south continents, such as South America, cross many climatic zones: a Meso-American crop is likely to be useless in the tropical Amazon basin and even more so on the Patagonian pampas. The importance of diffusion is nowhere more apparent than in the history of Europe, which received many domesticates from south-west Asia (emmer wheat, barley, rye, sheep, goats). Finally, there is the influence of geography on the spread of technology: China gave much to Europe; Egypt gave little to Great Zimbabwe.

• Guns, Germs and Steel by Jared Diamond
  Cape, 480 pp, £18.99, April 1997, ISBN 0 224 03809 5