I saw a fascinating article recently that calls the human body our ancestors' first real weapon. We could run faster and longer than any of the four-legged creatures we hunted, including Cheetahs. And our body's unique ability to regulate its heat allowed us to chase our prey until it collapsed from heat exhaustion. This is called persistence hunting and it was still done until comparatively recently by tribes in Australia and Ethiopa among other places.
The article also got into the dangers of "modern footwear" for running and says that considering how our bodies have evolved, and how they're designed, the 8+ hour/day desk jockey is actually more "extreme" when it comes to stresses on the system — even more extreme than running a marathon.
This is all leading up to a little series on running, covering these points and more through the Nature of Things and the CBC. Click this link for more info (and to read the article -- don't forget to click through the tabs as well!):