The Spanish Conquistador, Pizarro, led a contingent of only 169 men 1,000 miles from potential Spanish reinforcements. A little treachery plus the advantage of metal swords, daggers, and horses amounted to the slaughter of Incas and the capture of Atahuallapa. This same story repeated itself throughout the Spanish conquest of the Americas. Even more devastating to indigenous Americans were the contagious diseases brought by the Europeans. The Fates of Human Societies.
Diamond begins by quickly dismissing the possibility of genetic differences between peoples.
Diamond argues, may have dysgenic effect on intelligence. A hunter-gatherer existence is unforgiving to low intelligence. In contemporary society, stupidity is not nearly so lethal. It might even get you elected to public office. Diamond argues for a geographic determinism.