Sometimes I really wonder if people on this forum even understand what Darwin meant when he wrote about 'natural selection.'
The general point behind the article is (in my opinion) that our species is so different from other apes because we evolved a trait that other apes DID NOT evolve (namely: running). Why not? Because they didn't need it to survive. Chimpanzees do not need to run to survive (neither do gorillas or orangoutangs), but -apparently- our direct ancestors did. Since both humans and chimps have a common ancestor, this article tries to pin-point WHERE the big difference originated.
That's what I interpret at least.