I do think Africa makes sense to treat as its own continent. Not because of anything to do with humans, but because aside from the Mediterranean margin it has its own distinctive Afrotropical flora and fauna. It also has its own separate geological prehistory before it ran into Eurasia…although by both standards the Arabian peninsula really should go with Africa instead of Asia.
India of course used to be its own island too, but it joined Asia not too long after the Mesozoic, and so far as I know is basically populated by Eurasian groups. If anyone knows anything left from its time on is own I would love to hear!
