Pretty darned good topic, thanks to everyone.
A problem with DNA research, that isn’t backed up by physical evidence, is that there are the rare beneficial mutations that can change genes in a species without contact with other groups. And there isn’t likely to be physical evidence remaining of crude humanoids from so long ago.
I guess when there is enough knowledge that will be addressed. Seems, for now, everyone just assume the changes come from contact with ‘new’ groups.