Mongolian visual IQ and throat singing
Last year I wrote up some suggestive evidence that in order for a group's musical style to emphasize harmony (or the "vertical" aspect of music), a necessary but not sufficient condition was a cognitive profile that either was lopsided toward Spatial rather than Verbal IQ or was balanced. Emphasis on melody (or the "horizontal" aspect) appears universal and is likely parasitic off of Verbal skills.
To reiterate the key groups and their exemplary musical genres: Africans with Hip-Hop and Jazz, Ashkenazi Jews with Klezmer and Jazz (and a little Hip-Hop), Germans with Baroque and Classical music, and Arctic peoples with throat singing. So, pretty much what I just said about Verbal-dominant groups pioneering more melodic genres and Spatial-dominant or balanced groups pioneering genres with a greater emphasis on harmony. Remember that I'm talking about composition, not performance / interpretation.
Now, throat singing is most strongly associated with Tuva and Central Asia in general (listen to an example), although data on the cognitive profiles of Central Asians was lacking at the time, so I made the obvious prediction that Central Asians must have IQ profiles favoring Spatial over Verbal skills. Richard Lynn has a new article out that reviews two large studies* of the IQs of Mongolians and Han Chinese in the regions of China near Mongolia. The first study used an IQ test that only tests raw pattern-recognition, without sub-tests for Verbal and Spatial skills. However, the second study did measure both, and they found that not only did Mongolians show the lopsidedness toward Spatial skills that characterizes East Asians broadly, but that on Spatial sub-tests they actually outperformed the Chinese on average by about 2 IQ points! This is despite scoring on average 10 points below the Chinese on Verbal and 5 points below the Chinese in overall IQ (combining both studies). So, it looks like the hypothesis about cognitive profiles and musical styles holds up for now.
* The studies were carried out by Chinese researchers and published in Chinese.