Is IQ lower on average in Africa than Europe and Asia?

It is sometimes suggested that IQ varies across the world and that those in Japan have IQs some twenty points higher than people in most African countries. What grounds are there for such a belief? A look at the work of Richard Lynne, J. Phillippe Rushton, Arthur Jensen, Hans Eysenck and Ed Dutton.
https://en.wikipedia.org/wiki/Richard_Lynn
https://en.wikipedia.org/wiki/J._Philippe_Rushton#Race_and_intelligence
https://en.wikipedia.org/wiki/Edward_Dutton_(author)
https://en.wikipedia.org/wiki/Arthur_Jensen
https://en.wikipedia.org/wiki/Hans_Eysenck

loweraverageAfrica