The Flynn effect is dubious and always has been, so this is not much of a counter-argument. No one has demonstrated a meaningful increase in overall intelligence, just on one or two types of subtests, and if you've been following the latest research - since you've surely been reading up on these topics and following Thompson's blog if you are going to authoritatively sweep HBD to the ash heap of history, doubtless - the gains seem to reflect an attitude or conceptual shift rather than any sort of real intelligence gain. These hollow gains are why we see nothing on backwards digit span, nothing on reaction time, nothing on all the other aspects of intelligence, no 10x+ increase in tails/genius as expected from a +1.3SD in means...

Yes. IQ is pretty obviously at least partially a trainable skill. This doesn't support HBD - and in fact argues against a substantial part of the evidence.

And yet, those geographic areas are still generally closer to each other and the island populations than they are to East Asia, say, and so my point stands, there will be more gene flow between them than more distant populations. They will be correlated and not as variable as one would expect. Which of the African groups will be highest genetically? I dunno, and it'll be interesting to see what the refined polygenic scores indicate; disease and parasite load might be a red herring and the relevant evolutionary environmental condition completely different.

Yet Africa has more genetic diversity than anywhere else.

Who said it fails to appear anywhere else in the world? There are a lot of undeveloped countries which have serious problems. Look at Brazil for a highly dysfunctional country on the equator with similar issues and which has continually failed to develop well despite considerable apparent potential.

You mean a country which LBJ deliberately helped destabilize? The fingerprints of the US are clear on the civil wars which tore apart South America, just as much as the fingerprints of Europe are all over the civil wars which tore apart Africa.

Yes, it was, because it was further north and colder and had different ecologies.

You realize portions of Africa are as far South as Europe is North from the equator?

Again, since populations are phylogenetic trees, there are going to be clusters of more and less related populations which will have less variability than expected, so what we see with Europe and East Asia could well be the two clusters which drifted highest and won the race to the Great Divergence. In an African cluster, there are enough that we can expect some to go near Europe/Asia levels, but if they exceeded Europe/Asia levels, they would have broken out before or at some point shortly afterwards. But there is no South Korea of Africa.

If we go back further in history, of course, we see a previous "Great Divergence", between North Africa and far Southern Europe and everywhere else. The northern Europeans were primitive savages during this era. Further back, and North Africa and the Middle East were the seat of civilization.