Pathogenesis: A History of the World in Eight Plagues

by Jonathan Kennedy

When Homo sapiens gained immunity to Neanderthal diseases between 50,000 and 40,000 years ago, they were finally able to migrate northward out of Africa into areas inhabited by Neanderthals without getting horribly ill. The curse that had made the Eastern Mediterranean all but uninhabitable for tens of thousands of years was lifted. Our ancestors traveled deep into Eurasia, where they encountered Neanderthal and Denisovan communities that had never been exposed to African pathogens and hadn’t had the opportunity to build up any tolerance. Within a relatively short period of time all other human species died out and were replaced by the newly ubiquitous Homo sapiens. The world would never be the same again. It ceased to resemble Middle-earth, with its rich cast of human species, and quickly became the Homo sapiens–dominated planet that we still inhabit today. Skip