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In reply to the discussion: Migrating humans may have killed off Neanderthals by accident [View all]Scootaloo
(25,699 posts)The major reason is simply that any diseases and ailments H. sapiens carried, were almost certainly shared with neanderthals - or at least the diseases were close enough that the neanderthals could have resisted them as well as sapiens did. Herpes, mentioned in the article, is almost certainly an example of such a pan-human disease. Worms? Absolutely pan-species.
Without livestock, the primary source of alien (nonhuman) disease would have been through butchering meat. Sort of like how HIV got its start through butchering primates for food. It's pretty much without doubt that we hunted the same animals as neanderthals. Further, such direct transfer diseases are usually not communicable - you might get sick if someone slapped a weird pigeon virus into your body, but you likely would not be infectious.
There's also the fact that the populations simply weren't there for pandemics. Assuming - a big assumption - that there were some pathogen that was minor to sapiens but highly lethal for neanderthals, what would happen is that the neanderthal group would rapidly die... and that would be the end of it. No lingering infections, no "Uncle Ugg has a bad cough, but let's go to the cave art festival anyway" 'cause Ugg and his whole family would be dead, before they could go anywhere. And for constant re-infection to happen would require that sapiens and neanderthals had frequent, prolonged contact all the time. While we clearly got together and partied, there doesn't seem to have been much by way of societal mingling. probably more like "hey, we're all hunting mammoth here, want to share a tent?"
And lastly... tropical disease? With what vectors? Most of these diseases are spead by insects... and such parasitic cycles are almost always extremely finicky. Only certain mosquitoes can harbor yellow fever. Only other kinds of mosquito carry malaria. only one kind of fly carries trypanosomiasis. Only certain species of assassin bug can carry chagas. And in the damn ice age, I kinda doubt that east african insect-borne pathogens are going to find their way into the middle of Europe - especially not when the human vectors in the life cycle of these diseases are walking, on foot, over a few hundred generations.
The plain fact is that neanderthals were already in decline by the time sapiens showed up in Europe - the last ice age hit them pretty hard, fragmenting their populations into small enclaves. The resulting inbreeding on top of everything else an ice age brought no doubt had several bad effects on their populations. These small, genetically weakened populations were simply out-competed for territory and later absorbed into H. sapiens.