This has been circulating the birb-site. It's about specific adaptations Homo Sapiens has for persistence-hunting. Specifically, how we're engineered to chase our prey until they fall down from heat-prostration. This explains much of our psyche.

http://thumbnails-visually.netdna-ssl.com/possible-endurance-running-adaptations-in-human_533c2e4998e45_w1500.png