Do these observations have some validity or is this just racist nonsense?
vThere is no doubt that these earlier authors had observed something imporetant, but they had no  interpretational framework to make sense of it. Correctly understood, both archaeological and rock art evidence can be integrated into the model.
v
vHowever, it should be said;
v
ØEvidence for Semitic influence is zero
ØEvidence that the Khoi migrated from elsewhere is Zero
ØEvidence that the Bantu herders of Southern Angola migrated with their present culture from NE Africa is zero
ØThere is no genetic connection between Khoesan languages and Afroasiatic or other groups
Ø
ØThis paper will present some examples of potential evidence and interpret it in the light of modern archaeological evidence