According to a recent study just published in the journal Nature, early humans transitioned from quadrupedal to bipedal movement around seven million years ago, one million years earlier than previously thought.
Proofs Supporting the Claims that Early Humans are Bipeds
This claim is backed up by a thorough examination of fossils from the thigh (femur) and forearm (ulna) found in 2001 during excavations in Chad, Africa. The fossils belonged to an extinct ape known as Sahelanthropus tchadensis, a hominid type in North Africa during the Miocene era.
If the researchers behind the study are correct, this species was the first human ancestor to walk upright on the African continent. Take note that this species was unknown prior to its discovery at Toros-Menalla, Chad.
A Comparative Investigation of Sahelanthropus Tchadensis with Chimpanzees
In this latest study, researchers from the University of N'Djamena in Chad and the Paleontology Department at the University of Poitiers in France collaborated.
They conducted a new comparative investigation of fossils found more than 20 years ago. They contrasted the thigh and forearm bones of Sahelanthropus tchadensis with those of chimpanzees, gorillas, and contemporary humans.
They could make assumptions regarding the Sahelanthropus tchadensis' movement based on traits they already knew about. Through this, they could analyze the parallels and differences with other creatures' locomotion patterns and physiological traits.
The researchers studied the fossils to gather information on 20 different characteristics that may be used to establish if Sahelanthropus tchadensis could stand on two legs. They examined the fossils' external shapes. It also examined its internal features, accessed using microtomographic imaging equipment.
Researchers' Conclusion of Sahelanthropus Tchadensis Features
Despite some of its predecessors' abilities to climb trees, they concluded that the Sahelanthropus tchadensis fossils' anatomy was most compatible with a species that typically walked around on two feet.
Franck Guy, a paleoanthropologist at the University of Poitiers and the study's lead author, said the team's conclusion that Sahelanthropus tchadensis was a biped was based on the bones' total pattern of features rather than any particular magic trait.
The study suggests that an archaic human species existed in the woodlands around ancient Lake Chad at least one million years before two human ancestors, Orrogin tugensis or Ardipithecus. These species were previously thought to be the first to adapt to bipedal movement.
Approval Within The Scientific Community
It should be noted that not all scientific community members agree with Guy, Daver, and their team's claim. In actuality, there is currently a lot of skepticism around their findings.
Johns Hopkins University functional morphologist Chris Ruff stated in the Science paper that while the evidence is consistent with bipedality, it does not prove it. Meanwhile, paleoanthropologist Carol Ward of the University of Missouri, Columbia, appreciated the importance of any fossils that shed light on this, but she also noted that these don't offer the definitive answers we were hoping for.
However, the researchers respectfully disagree, writing that the postcranial morphology of Sahelanthropus is suggestive of bipedality and that any other theory would have less explanatory power for the combination of characteristics offered by the material from Chad.
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