Some of the earliest steps of modern man have been discovered in Kenya, revealing that Homo Erectus would have worn a size 9. Assuming he didn't try to eat it. Or pass out in unholy terror of the insane "lighting" magicks of the modern shoe store.
Fossilized footprints were found in layers of sedimentary rock, and such clear images of feet can tell you a great deal about evolution. Since we came from the monkeys (good man, Scopes, and Butler be damned) the evolution of the lower extremity is an important element - it turns out that hanging around in trees and running along the ground, possibly wearing stiff office shoes and rushing to eight hours at an accounting database, require very different feet. Try not to think too hard about whether that's really progress.
Luckily early Erectus didn't know anything about invoice requisitions (or he likely wouldn't have bothered), and developed modern features such as the forward-facing big toe, arched foot and rounded heel. These turned the branch-gripping sole into a surface-distance system capable of carrying him much further afield than previous species. Other traces of early human culture support the idea of a spread around this time.
It remains to be seen what future forms of mankind will make of your tracks in the dirt - though considering how many pairs of non-biodegradable Nike TurboDynamic Sprintastic-Shoes they'll find in heavily built up urban areas where the maximum speed is "crowded", they might think us gullible.