groid?
Intelligence is nature and nurture. Black people rarely have the nurture, and in most of the USA from what I've seen, intelligence is looked upon in the urban counter-culture like a weakness and showing it earns you degradation. Not so much in Africa in my experience, but access is limited in some cases.
I also knew an intelligent black guy who was extremely high society in Haiti, and he talks like "Haitians are dumb", but he's Haitian and not dumb, so obviously he's talking about the stereotype that makes up the majority.
The only thing that annoyed me a bit was calling a person an it, but like he got me here at the wrong time where I'm mad at that particular "groid" (?) so like I wasn't planning on saying anything.
Economically, muslim countries in Africa do worse than their black non-muslim neighbors, so yes muslims are statistically dumber, black or otherwise, than others.