Understanding the evolution of bipedal locomotion in humans is of paramount importance to paleoanthropologists. Such endeavor requires well-preserved dynamic evidence of fossil human locomotion we are short of. Physical models of modern human locomotion predict individuals would perform voluntary step length adjustment as a function of slope gradient in order to minimize the energetic cost of locomotion while maintaining balance and reasonably comfortable gait. The famous Roccamonfina volcano “Devil’s trails”, which are Middle Pleistocene Homo fossilized trackways, provide unique opportunity to validate such predictions for fossil human individuals. We studied the best-preserved Roccamonfina Devil’s trail to ascertain the dynamic behavior of the individual who left the trackway. We found Roccamonfina’s individual moved in a way which is dynamically equivalent to modern humans, adjusting gait as to minimize energy expenditure. We derived body mass and stature estimates for such individual, which fit perfectly with previously published figures for Middle Pleistocene hominins outside Africa.