we already know European and East Asian populations are probably the smartest genetically because they are the smartest now phenotypically; this has already been conditioned on, so it's illogical to say 'well, we should expect an African subpopulation to be higher'. The race has already been run and the first and second place prizes handed out, it makes no sense to say 'there were a lot of other runners so maybe one of them is in first place'.

It's likely, but I think it's important to remember that there are a lot of environmental factors which can depress IQ, and some populations may have high genetic potential which is being depressed by circumstance.

The Dutch are the tallest nationality in the world today, but 150 years ago, they were among the shorter ones; as average height has risen in Western nations, the Dutch significantly overtook various populations that used to be much taller than they were.