GO-NAD!, I'm pretty sure diet was never mentioned in terms of joint longevity. I think it had to do more with energy and nutrition (and hydration if you asked Scott Jurek).
I think the point is that some people have learned HOW to run. A hardcore barefooter might believe that a running shoe will atrophy the foot's muscles. edit: I remember the book says that over 1/4 of all our human bones reside in our feet. I don't recall if they mentioned the number of muscles and ligaments.
The thought why certain shoes are bad for us was sorta explained in my first post, I think anyways, but maybe I can expound. Our feet, when going through squishy stuff, are searching for that tactile ground information. The bones push through, searching. Our feet are also super sensitive, on the level of face, hands, genitalia.
The thought is also that impact is not reduced at all (only immediate pain, but if we were running properly, it wouldn't be painful anyways: pain teaches us), and if we never learned to run properly, that we might be incorrectly dealing with the impact. I think at one point in the book someone explained it as if you are chasing your child into the street, you will have an upright back, on the balls of your feet, and when I think of it this way, we would be extremely balanced; ready to dart our body instantly in any direction in front of us. I imagined something like this on a run last week, but the problem for me was the sense of urgency and quickening of pace, which would seem natural of course.
From my very very short time on running forums, there seem to be quite a few people who are going both/hybrid. They either do the first half of the run barefeet, or the second. The first would be to make sure proper form/technique is used, and finish with shoes. Those who do the second part say it's then when their form/technique is finally failing, and the barefeet get them back in shape, or something.
You really shouldn't be asking me though, I know nothing really. I am excited about running now, for the very first time in my life. I honestly thought it was the most boring thing one could do as far as exercise, ok outside of being in a gym, etc.
The book eschews the old idea of "no pain no gain". The author and others suspect this kind of attitude has caused countless injuries of countless types. The idea for running, even at insane lengths, is supposed to be truly of fun. Maybe that's why these Indians always look stupidly happy or something.
If you feel good, then obviously you're doing something right. There is that old adage, don't fix it if it ain't broke. How long have you been doing your running regimen?
I know that the Tarahumara play this game with a wooden ball. I also remember that these Indians in other regions with different terrain will use a different size ball, maybe even with differing rules. The ball will just act so randomly on the very rocky terrain, and so their feet must be able to quickly dart and know. The region where they live has extremely* dangerous terrain, yet they fly up and down it. I can't remember for certain, but maybe in that game, and in other running situations, the best runner might hang in the back. This may relate to the idea of hunting technique (it might have been a hypothesis of the Harvard prof, IIRC, or maybe that's in fact how the Bushmen do it) as a whole clan in that the elderly have the youngsters trailing them, teaching them first hand how to track. The most fit of the men are in the back, saving the energy bursts of continuously tracking, saving the energy for the kill. Unlike a race, they would never know how long the hunt would be, whether one hour, or five hours.
BTW, my "tracker friend" has already seen that running hunt DVD, is poor, and says it would be worth every penny if I could figure out the region coding (yes he's willing to purchase it). Maybe I'll splurge $50 on such a DVD player. The courses in tracking he takes (and btw, he is a professional survival course teacher, adults, but even teaching kids to stay warm sleeping in the outdoors with no tent no sleeping bag, even as young as five in areas with mountain lions; yes he makes lifelong friends), the teacher's assignment to you would be any specific animal, can be even a snake, or a large creature, maybe even a bird for all I know. Your assignment is finished when you touch the creature.