Edit: Q&A is now closed. Thanks to everyone for participating, and thanks very much to Harpending and Cochran for their responses.
In response to Kaj's review, Henry Harpending and Gregory Cochran, the authors of the The 10,000 Year Explosion, have agreed to a Q&A session with the Less Wrong community.
If you have any questions for either Harpending or Cochran, please reply to this post with a question addressed to one or both of them. Material for questions might be derived from their blog for the book which includes stories about hunting animals in Africa with an eye towards evolutionary implications (which rose to Jennifer's attention based on Steve Sailer's prior attention).
Please do not kibitz in this Q&A... instead go to the kibitzing area to talk about the Q&A session itself. Eventually, this post will be edited to note that the process has been closed, at which time there should be no new questions.
I think education not becoming harder in the earlier grades is a strong misnomer. My parents did punctuation symbols in their grade 5 curriculum, I did it in grade 3, It's currently done in Kindergarten or Grade 1, and many other topics have similar track records.
As for high school math programs, many parts of the world have had a shift from a 13 grade program to a 12 grade program which compresses a lot of material.
I think a bigger factor may be we are better at recognizing and marketing talent. The kids who find high school mathematics a complete joke in grade 8 are getting scholarships elsewhere.
Many of my peers in undergraduate mathematics had done work with a professor at a university in their home city during their high school years, a sizable number had private school scholarships based on their talents. So perhaps these individuals are seldom present in ordinary standard math programs.