Is that something well established?

We’re talking about neanderthals who went extinct like 40k years ago…

Nothing is really “well established”.

But yeah, them having a lower reproductive rate has been pretty widely accepted for a while. They were as smart as us and waaaay stronger and with better immune system.

About the only thing modern humans have going for us is we’re basically the sapian equivalent of cancer. Neanderthals barely reproduced enough to keep their own numbers up, so when humans showed up and added a bunch of new mouths, it was just a numbers game.

It’s never going to be just one thing tho. Another big theory is the neanderthal Y chromosome triggered an immune response in human females which resulted in male hybrids not being carried to term, while female hybrids could be.

I just glanced over this article, but it ignores a lot of prior research and most importantly:

The article is confusing successful reproductive rates with boning…

Who knows who was choosing who back then or why. The best we can tell is whose babies went on to have more babies, and sometimes with who.