This is a welcome surprise and also calls into the question the African IQ problem which may after all not be real at all and something to be hoped for. IQ tests are weighted in terms of two obvious factors. One is language of education and the second is nutrition throughout ones education.
It seems reasonable that Nigeria has had the full use of English in its overall education system and this has promoted maximum access. I am equally aware that South Africa has had a history of starving the blacks in terms of educational support and also in terms of calories and mostly this has come about from a learned prejudice. This is also were IQ tests were done easiest.
What this does underline though is that all African countries developing their populations need to combine education with calories. We all did the same back in the day without necessarily knowing why.