Finished this excellent book a couple weeks ago. Christopher McDougall has written a classic. Some very good insights into the errors of the shoe industry, ultrarunning, the Tarahumara or Raramuri people of northern Mexico, and discussions on the evolutionary theory of running.
McDougall interviewed and discussed some of the same researchers that I cited in my post Running a few months back.
An entertaining book with lots of insightful philosophical gems.
Some may think it is impossible or insane, but if it's part of your culture to run like the Tarahumara... logging 600 miles in 5 days, really is no big deal.
Nature, nurture, and culture.