3.7-Million-Year-Old Mysterious Footprints in Tanzania Were From Humans, Not Bears; Evidence Shows Earliest Proof Of Hominin Bipedalism

A new study has uncovered the actual origins of the 3.7 million-year-old footprints found at the nearby site in Laetoli, Tanzania, previously identified as footprints from bears walking upright.

The mysterious ancient footprints were discovered in 1976, which showed a big toe and large heel in the fossilized impressions. Scientists have now classified the footprints to an unidentified bipedal hominin that may have had a strange cross-stepping gait. Researchers said that this is the earliest evidence of bipedalism of hominins.

3.7-Million-Year-Old Footprints in Tanzania Were From Humans, Not Bears; Evidence Shows Earliest Proof Of Hominin Bipedalism

(Photo : Wikimedia Commons)
Footprint of an unknown hominin species from Laetoli / site A (top); footprint of Australopithecus afarensis from Laetoli / site G (below) — oroginal

Re-Analysis of Footprints Showed It Was Made By a Bipedal Hominin

According to Science Daily, the footprints at a site in Tanzania discovered in 1978 by paleontologist Mary Leaky and her team are believed to be the oldest unequivocal evidence of a bipedal hominin.

But an earlier set of footprints partially excavated at a nearby Site A in 1976 are now believed to have come from unidentified bipedal hominins. It was previously thought to have come from a bear, but comparative re-analysis revealed that an early human indeed made it.

Assistant professor and lead author Ellison McNutt from the Heritage College of Osteopathic Medicine at Ohio University said that the unusual footprints deserved another look, given the increasing evidence for bipedalism and species diversity in hominin fossils in the last three decades.

McNutt's work focuses on bipedal footprints at Lateoli, famous for the impressive trackway of hominin footprints at Sites G and S. Those footprints are believed to have come from Australopithecus afarensis, which is the hominin species of the famous partial skeleton "Lucy."

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Unidentified Hominin May Have Walked Like Modern Catwalk Model

The New York Times reported that the unusual shape of the footprints, which is shorter and more stout version of a human's footprint, showed a cross-step walking movement that is almost similar to a model on a catwalk wherein each of the feet crosses the midline of the body to touch down in front of the other foot.

Based on the size of the footprints, researchers conclude that they are a different species from Lucy. They believe that this hominin species did not share an evolutionary trajectory with chimpanzees.

Moreover, researchers said that the foot is wider than the typical foot of the early human, and the cross-walk pattern can only happen if the species walk on two legs with help from the hips. McNutt added that this kind of motion could occur when trying to re-establish their balance as the hominin might have been walking across an unleveled surface.

To prove their claims, Mail Online reported that researchers had some wild American black bears walk but observed that they hardly ever walk on two feet. It suggests that it is unlikely bears made the footprints at Laetoli. Bears are unable to walk on two feet for long because their hip musculature and knee shape do not allow that kind of motion and balance, unlike a hominin species.

Through this research, scientists now have conclusive evidence that a bipedal hominin walked on this landscape and was not from the same species as Lucy.

They published their study, titled "Footprint Evidence of Early Hominin Locomotor Diversity at Laetoli, Tanzania," in the journal Nature.