Tonal languages are most common in Southeast Asia and East Asia. However, the Negritos and Australians predate forty thousand years by quite a bit. That would suggest two or more large “ waves” of settlement which is more than likely. Interesting that the Hobbits of Flores Island are thought by some to be microcephalic.
Also, Herto man from the Afar had a larger than average by modern standards brain some one hundred sixty thousand years ago. Yet the Afar region has not yielded up more than stone tools for that period. The South Africans seemed clearly ahead at that point (shell fish diet rather than genes?).
I just like reading about this and I ask questions. I’m by no means “expert”.
Actually there are many tonal languages in Africa. A couple of them are highly tonal and lend themselves to being whistled, which they are over distances too great for vocal conversation.