East Asian IQ variation: Over at iSteve, there is a discussion about why cultures stagnate, with quite a bit of attention devoted to Chinese stasis at the time when Europe was flowering.
One standard HBD explanation for higher Chinese IQ combined with lower cultural accomplishment is less IQ diversity. I haven't made a systematic study of it, but the IQ studies I have read do not indicate a smaller East Asian standard deviation.
Using GSS data, I combined Chinese and Japanese Americans (only those born in this country) and got a standard deviation (SD) of 2.04 across 50 respondents. For whites born in the country, the SD is 2.08--not different, basically. SD tends to increase along with higher means, so if we take that into account by using the coefficient of variation (CV), we get .30 for Asians and .33 for whites. No difference, or a trivial difference at best.
It would be better to have a sample from China, and even better to have samples from the period when Europe was surging ahead, but I take the GSS data as evidence that other kinds of theories are necessary to explain why China has not been on top. IQ, as important as it is, is far from everything.