No one knows for certain how the Neanderthals went extinct. There are many theories propounded — climate change, resource competition with newly arriving anatomically modern humans, megafauna population declines, etc — all of which are plausible, and some of which are supported circumstantially by recent genetic evidence.
I’ll suggest another, uncomfortably familiar, extinction mechanism for the Neanderthals: Diversity™ killed off the loveable brutes.
I don’t mean, exclusively, Diversity™ in the usual senses — warfare, rape&pillage, territorial disputes, food shortages. I mean it in the Calhoun rat “behavioral sink” sense. That is, the flood of Vibrant AMH Diversity™ arriving from points south, who may or may not have mingled peaceably with Neanderthals in the latter’s homeland, (and occasionally shared beds), by their mere proximate presence and cultural dissimilarity induced immense psychic pressures on the locals until their native fertility rate plummeted to levels…
…not unlike what we are seeing today among white Westerners living in homelands rapidly populating with millions of alien world migrants.
Diversity™, itself, is what killed the Neanderthals.
Arguing against my speculation: Contraceptives, the Japs.
Neanderthals didn’t have the hedonism aids of condoms and Pills. If they were “secularizing”, relative to their race’s historical norm, and choosing to forfeit childbearing in favor of extracting the last bit of fun from a shrinking playground, they’d have a challenge trying to do all this to the beat of the rhythm method. Not that it couldn’t be done; Neanderthalettes might have stiff-armed a lot of horny men if they felt that conditions weren’t optimal for raising a family.
The Japanese. They have a very low TFR at the moment, and last I checked there wasn’t a ton of Diversity™ in Japan. But, it is an island nation, and there are a lot of Japanese living on it, living a neon-colored and optically-wired version of the Western lifestyle. Here, the mechanism is entirely raw numbers, rather than raw numbers + clash of cultures.
The Neanderthals, it now appears from genetic analysis, have gifted White Europeans with just enough of their DNA to make something of a difference to the trajectory of white history. Did Neanderthals also gift us with a warning for our own race’s future, or lack thereof?