The accepted model of how archaic and modern humans relate has been accreted and patched rather than built, and is due for a simpler replacement.

Geneticist at Harvard Medical School

I think that, you know, the model that we've put together collectively about the relationships between archaic and modern humans is sort of accreted over time. There was this, you know, idea that modern humans are distinct and that Neanderthals and Denisovans are like sisters of each other. And then over time we developed and detected additional mixture events like this modern human into Neanderthal and then this other ones I didn't even talk about like super divergent lineage going into Denisovans and like all this other stuff.