Editing Guns, Germs, and Steel (section)

=== Germs ===
In the later context of the [[European colonization of the Americas]], 95% of the indigenous populations are believed to have been [[Population history of indigenous peoples of the Americas|killed off by diseases]] brought by the Europeans. Many were killed by infectious diseases such as smallpox and measles. Similar circumstances were observed in [[History of Australia (1788–1850)|Australia]] and [[History of South Africa|South Africa]]. Aboriginal Australians and the Khoikhoi population were devastated by smallpox, measles, influenza, and other diseases.<ref>{{cite book|last1=Blainey|first1=Geoffrey|title=A short history of the world|url=https://archive.org/details/shorthistoryofwo00blai|url-access=registration|date=2002|publisher=Dee|location=Chicago|isbn=978-1566635073}}</ref><ref>{{cite web|title=Smallpox Epidemic Strikes at the Cape|url=http://www.sahistory.org.za/dated-event/smallpox-epidemic-strikes-cape|website=South Africa History Online|date=16 March 2011|access-date=April 14, 2017|archive-url=https://web.archive.org/web/20190428140710/https://www.sahistory.org.za/dated-event/smallpox-epidemic-strikes-cape|archive-date=April 28, 2019|url-status=live}}</ref>

Diamond questions how diseases native to the American continents did not kill off Europeans, and posits that most of these diseases were developed and sustained only in large dense populations in villages and cities. He also states most epidemic diseases evolve from similar diseases of domestic animals. The combined effect of the increased population densities supported by agriculture, and of close human proximity to domesticated animals leading to animal diseases infecting humans, resulted in European societies acquiring a much richer collection of dangerous pathogens to which European people had acquired immunity through [[natural selection]] (such as the [[Black Death]] and other epidemics) during a longer time than was the case for [[Indigenous peoples of the Americas|Native American]] [[hunter-gatherers]] and farmers.

He mentions the tropical diseases (mainly [[malaria]]) that limited European penetration into Africa as an exception. Endemic infectious diseases were also barriers to European colonisation of Southeast Asia and New Guinea.