As a result, infectious diseases created an “invisible barrier”: it was impossible for Homo sapiens to migrate out of Africa because sooner or later they would encounter Neanderthals and their pathogens and get ill, and the same was true when Neanderthals pushed southward.[60] For early humans, the Eastern Mediterranean region must have seemed like a cursed realm, the Paleolithic equivalent of Tolkien’s Mordor.[*3]
