According to a 1972 study of mental ability among ethnic groups by Margaret E. Backman, the average intelligence scores of American Jews in various aspects of mental ability, with the average performance of White non-Jews taken as the point of reference (i.e. as "100"), were as follows:
verbal knowledge: 107.8
perceptual speed and accuracy: 102.2
English language: 99.5
(short-term) memory: 95.1
visual reasoning: 91.3
I was particularly intrigued by the finding that Jews are above average in mathematical and verbal reasoning ability but just as much below average in visual reasoning (and below average in short-term memory too).
This finding supports a certain stereotype about Jews being inept at physical tasks. The low scores in visual reasoning and short-term memory both point in this direction, since it is necessary both to have a good visual comprehension and to remember what stage you are at in the process and what difficulties have appeared while performing a mechanical task.
Jews are well adapted for accountancy and law, but you would not want a Jew typically to be the one working on your car or doing any complex operation on your body.
The specialization of Jewish intelligence represents the evolution of the Jews into a parasitic niche where they rely on other races to take care of building things and keeping things working while the Jews focus on manipulating symbols: buying, selling, banking, and negotiating.
It also occurs to me that the Jewish disdain for realistic, representative art may be related to their below-average visual reasoning skills, which would put them at a disadvantage in creating and perhaps appreciating such art.
One could even argue that poor visual reasoning ability means a poor grasp of physical reality. The Jews tend to live in an artificial world of symbols.
These scores put the Jews roughly on a par with the Germans in overall intelligence, except that the Germans have a much better reputation for mechanical ability.