In Europe, over the course of many centuries, the Catholic Church sent its best and brightest to be monks and priests, while the best and brightest Jews learned in the yeshivas and became Rabbis. The Rabbis went forth and multiplied, but the monks and priests did not.
As Charles Murray, co-author of The Bell Curve, explains, this is an oversimplification, though the process probably did play a role behind the obvious and undisputed phenomenon of Jewish people being disproportionately overrepresented in the various fields of intellectual and scientific and financial achievement.
One Jewish disproportionate overrepresentation I have long wondered about is that of the field of leftist politics. Why are people of Jewish origin so commonly found amongst the activist elements of the Communists, the Socialists, or just plain liberals? It is very perplexing!
My own Jewish upbringing was, politically speaking, centrist (for the times) Democrat, though quite frankly, my parents had other personal and family issues which diverted most of their attentions and energies from the political scene. But their social circles included, though by no means exclusively, people of decidedly leftist political orientation.
More recently, with my increased dabbling into genealogical research, I now have strong reason to suspect (read proof positive) that some relatives, of whom my parents and grandparents rarely if ever spoke, acted solidly on the left side of the political stage.
One thing which all humans find very difficult is to imagine that there are those who do not share their perspectives and beliefs. Justice and charity are very strongly ingrained Jewish cultural norms. Seeing someone in an "underdog" position naturally elicits empathy from a Jew. What most of these Jews on the Left have trouble realizing (and what I myself for many years could not conceptualize) was that not all ethnic or social cultures share the Jewish values of justice, truth, charity and societal order.
For example, if everyone shared those values, then opposition to capital punishment would be entirely sensible. The trouble is that there are those for whom justice, truth and charity are irrelevant, and whose very existence imperils order in society. It is all well and good that the limousine liberal can oppose capital punishment on humanitarian grounds, but such will do little to induce the criminal element to abolish their own perverse variety of the death penalty.
This, no doubt, does play a role in many Jews' propensity to embrace Leftist causes, but it is an oversimplification.
What does induce people of Jewish origin to religiously pick up the cudgels of the Left? The word "religiously" is a tip-off. There is a very, very strong correlation (with certain exceptions, of course) for Jews of the Left to have long abandoned the Jewish religious practices (and in many cases, beliefs). Many Leftist Jews are not merely non-religious, they are anti-religious! There are many, many religious Jews (myself among them) who are solidly on the Right side of the political spectrum.
Nor is this phenomenon peculiar to Jews; the experience with Finnish immigrants to America, and their descendants, has notably strong parallels. The "Church Finns" hold strongly Conservative political values, while the "Red Finns" who have abandoned the religious rituals have flocked to the Left (including Gus Hall, who was the quadrennial Communist Party candidate for President from 1976 through 1984).
This does shine some light on the phenomenon of the disproportionate numbers of Jews on the Left, but it is an oversimplification. Jewish accomplishment and achievement is phenomenon that is both perplexing and intimidating to the world -- and indeed, to the Jews themselves.
Could it be that we really are G-d's Chosen People? I believe so! But this explanation, too, is a severe oversimplification.