There is quite a lot of space between being a couch potatoe and a marathon runner, on both cases probably the extreme is bad for you. Professional athlethes tend to have severe problems, injuries, joints operated once or several times by the time they retire in their forties. It's a hazard of the job, but should try to achieve the same hazards? I wouldn't.
People tend to think that primitive hunter-gatherers had so good health since they were excercising or were on the run all the time, but it isn't necessarily true. Hunter-gatherers actually had leisure times to sit by the fire telling stories, creating art or tools. Some todays tribes actually have lower or the same activity levels than us westeners(some studies: http://wholehealthsource.blogspot.com/2009/01/exercise-and-b...)
Oh I agree, but most Marathon runners are doing 1 Marathon a year, if that. For many people a Marathon is a once-in-a-lifetime thing that they do and move onto the next challenge or goal. That list is ridiculous, you could make a list of worst-case risks for any activity and not do it.
The top athletes in any sport won the genetic lottery to be well-adapted for that sport. Basketball players don't train to get that tall... It's not reasonable to compare their training and competition volumes with average people. Even a full time professional Marathon runner only competes a few times a year.
Incidentally, if you show up to a Marathon (or a half-Marathon or even a 10k) and look around you, you'll see that 99% of the crowd look perfectly ordinary. If you saw them (us!) in street clothes, you wouldn't think they were anything unusual, certainly not super-athletes. A Marathon is not at all out of reach for the average person.
I think the ability of any person to jog a marathon even after being couch potato for long periods of life shows how well genetically predisposed people are for running.
Karno has amazing endurance and recovery but he's not a competitive Marathon runner - his best Marathon time is 3:00:30, compare that to Haile Gebrselassie in 2:03:59. Geb competes once every couple of months on average.
When you say professional athletes, are you referring to those exclusively in endurance sports? Surely you cannot directly compare runners with tackle football players, etc.
As I understand him, DeVany is against long, constant-paced runs, of which marathons are the most extreme example. He likes short, varied sprints, as in competitive sports.
Chasing prey across mixed terrain likely had more pacing variety than a marathon. Just navigating around plants and rocks could provide more rhythmic variation than a modern marathon on a paved course. The optimal chase may have also involved trying to drive the prey to a convenient final resting location, so some of the chase would involve overtaking the prey from different angles at different times.
