Why Ancient Humans Could Run All Day Without Pain

Ancient humans could run long distances without pain because their natural barefoot running mechanics (forefoot strike) generated minimal impact forces, unlike modern heel-strike running which creates sharp impact spikes of 1.5-3 times body weight; this is supported by fossil evidence from 3.6 million-year-old footprints showing similar weight distribution, skeletal evidence from 1.5 million-year-old Turkana Boy showing no degenerative joint disease, and neurochemical research revealing that efficient forefoot running triggers endocannabinoid production (the 'runner's high') which reduces pain perception, while cushioned shoes that promote heel striking may actually make this natural pain-reduction mechanism harder to achieve.