That’s a strange assertion seeing as how scientists attribute our adaptable immune system to our Neanderthal DNA.
Some people think there is something they are hiding about neanderthals, due to all the misinformation they keep putting out about them. For example, they keep making them look like cavemen, when in reality they looked more like Arnold Schwarzenegger and Tom Cruise. The evidence also looks like they were highly intelligent, and creative, and were genocided and eaten by modern humans. The mathematics and scientific (and musical) genes we have today are Neanderthal.
I just assume Neanderthals were more K-selected and intelligent, but modern humans reproduced faster, and the neanderthals couldn’t kill them fast enough and reproduce fast enough, and ended up out reproduced, with the women taken as breeding stock.
If you begin to look into it, there is a lot of academic strangeness around things relating to the history of the human species.