I am currently reading the book "Coming Apart" by Charles Murray, who was mentioned by another posting in this thread.
In the part of the book I am currently reading, he is outlining the reasons for the increasing economic gap among whites from the 1960s to the present.
One of the reasons listed is that the elite schools have become more selective over time (in 1960, the average IQ of students in the Ivy League wasn't much different from other schools, but just 10 years later it was much different).
He calls this the "college sorting machine" and per his statistics, the top tier (~50 colleges) absorb almost 80% of the top students (numbers are approximate, as I don't have the book in front of me).
He couples this statement with three others: (1) There has been an increasing reward for high IQ, and (2) Many college students find their mates among other college students at the same college (or at least same academic tier), and (3) IQ is significantly inheritable. The last reason is particularly important, as it suggests that the advantage can last across many generations.
To summarize what I have read so far, the rich-poor divide starts with talent. I have heard that later parts of the book are more controversial, and I will provide an update as I read further.
