«Breeding for Brains:Why is the IQ of Ashkenazi Jews so High? - ImmortalLife.info
"Our Rabbis teach, Let a man sell all that he has and marry the daughter of a learned man. If he cannot find the daughter of a learned man, let him marry the daughter of one of the great men of his day. If he does not find such a one, let him marry the daughter of one of the heads of the congregation, or, failing this, the daughter of a charity collector, or even the daughter of a schoolmaster; but let him not marry the daughter of an illiterate man, for the unlearned are an abomination, as also their wives and their daughters." P'sachim, fol. 49, col. 2.
Judaic texts like the one above emphasize repeatedly that knowledge and intelligence are supreme virtues, with ignorance the grossest liability. Following this dictum, the Jews enhanced their gene pool for smartnesss. In A History of the Jews, author Paul Johnson notes that, "among the Jews the most intelligent people have always been very valued and sought after as husbands, so they procreate and spread their good genes." Charles Murray observed another matchmaking tendency, when he notes that "by marrying the children of scholars to the children of successful merchants, Jews were in effect joining those selected for abstract reasoning ability with those selected for practical intelligence."
Meanwhile, Catholics were marrying for "class" reasons, angling for blue-blood aristocrat gains that had no link to intelligence. Physical strength and valor was also desired, via brave knights on the battlefield - this exaltation of brawn over brains likewise did nothing to advance that religion's collective IQ.»