Malaria isn’t confined to Vietnam, and for all we know, it wasn’t even around 800K ago.
Large parts of the continental shelf has been ice-free for much of the past 2 milion years, and it’s not unlikely our ancestors grew up in now-submerged areas. Claiming that Africa *must be* the cradle of humanity is a little like looking around outdoors for the glasses you lost in the dark restaurant, just because the light’s better.
An argument can be made that mankind expanded into Africa rather than out. Wouldn't high genetic diversity accompany early settlers and would these earlies not be affected by the various genetic bottlenecks?
Remember, according to Herodotus, the Pygmies lived around Lake Chad in his time. Another interesting thing is the cluster of R1B DNA in central Africa.
Just musing.