They’re approximately 1.5 million years old and they prove that the ancestral humans to whom they belonged (most likely Homo erectus) walked like we do. Prints Show a Modern Foot in Prehumans.

An international team of scientists, in a report on Friday in the journal Science, said the well-defined prints in an eroding bluff east of Lake Turkana “provided the oldest evidence of an essentially modern humanlike foot anatomy.” They said the find also added to evidence that painted a picture of Homo erectus as the prehumans who took long evolutionary strides — figuratively and, now it seems, also literally. […]

Studying the more than a dozen prints, scientists determined that the individuals had heels, insteps and toes almost identical to those in humans, and that they walked with a long stride similar to human locomotion.

That means they could walk and run over long distances much like we do today, something scientists have suspected from examining fossilized Homo erectus skeletons. Since those skeletons were incomplete and no foot bones had been found, the question of how they walked and ran was still an open one.

The footprints discovered in Kenya, researchers said, indicated that the erectus foot functioned much as a human foot does: the heel contacts the ground first; weight transfers along the arch to the ball of the foot; and the push-off is applied by the forefoot. In apes and apparently earlier hominids, this force comes from the midfoot.

These are the first prints found that were made by members of our genus Homo. The only earlier set we have are 3.7 million years ago and were left in what is now Tanzania by Lucy’s species, Australopithecus afarensis.