The interesting question is not if, but why. That is, was it environmental or genetic factors that created superior IQ? The case for environment is 2,000 years of oppression, including prohibitions against owning real estate. The net result was that Js were forced into city centers and non-capital intensive trades such as media, finance, retail, etc. - areas which they still exert significant influence.
On the other hand, the Js were one of the first to popularize the notion of a monolithic God around 5,000 yrs ago. This in itself could point to an early ability to sythensize complex philosophical concepts while the rest of the known civilized world was still attributing natural causes to individual dieties.
I myself lean more towards the environmental explanation. If over 40+ generations you periodically directed murder, theft, emmigration, etc at a specific targeted group, they would either (a) die out, or (b) become incredibly hardy with diverse survival skills.