http://www.metafilter.com/mefi/42501

That's a mefi thread about Ashkenazi Jews and their superior intellect, which contains some links to research into this matter. I don't generally buy that different ethnicities are genetically different in any meaningful way, but there's a good case for that being so with the Ashkenazi Jews and their intelligence, in that their survival depended on their intelligence; in a sense they were bred to be smart. I even have a little experience: my woman is an Ashkenazi-descended Jew, and she is damn smart, as is her entire family. It's not a win-win situation for them though: Ashkenazi Jews often have genetic deficiencies as a result of inbreeding in the past.