Guns, Germs, and Steel

Diamond asks why Eurasian societies conquered others rather than the reverse, and answers with geography rather than with any claim about the people involved. His argument runs through the availability of domesticable plants and animals, which was concentrated in the Fertile Crescent, and through the east-west orientation of Eurasia, which allowed crops and livestock to spread across similar latitudes while the north-south axes of Africa and the Americas blocked diffusion.

Food surpluses produced dense populations, occupational specialisation, writing, centralised states and standing armies. Dense populations living beside domesticated animals also produced epidemic diseases and the partial immunity that comes from long exposure. Diamond argues that these diseases, rather than weapons, killed the large majority of indigenous Americans, and he uses the encounter at Cajamarca between Pizarro and Atahualpa as the concentrated illustration of all three factors.

The evidence draws on archaeology, linguistics, epidemiology and biogeography. Diamond was trained in physiology and ornithology and worked in New Guinea, where the question was put to him by Yali, a local politician.

The book is heavily contested by specialists. Anthropologists and historians accuse Diamond of environmental determinism, of compressing complex regional histories, and of underweighting institutions, contingency and agency. Acemoglu and Robinson in Why Nations Fail argue directly against the geographic thesis. Others note that geography cannot explain why Europe rather than China industrialised, since both sit on the same continent. Diamond's answer, about European political fragmentation, is the weakest part. Read it as a strong argument for one factor rather than as a settled account.