An analysis of the feet of a recently-discovered extinct human relative suggests the beings walked on two feet, but were also exceptional tree climbers.
Remains of the human ancestor were first discovered in a South Africa cave and were introduced only last month. The bones of Homo naledi reveal the ancient ancestor's feet were the most human-like part of its body, but even this feature had some distinct differences, the American Museum of Natural History reported.
"Homo naledi's foot is far more advanced than other parts of its body, for instance, its shoulders, skull, or pelvis," said William Harcourt-Smith, lead author of the new paper, resident research associate in the American Museum of Natural History's Division of Paleontology, and assistant professor at CUNY's Lehman College. "Quite obviously, having a very human-like foot was advantageous to this creature because it was the foot that lost its primitive, or ape-like, features first. That can tell us a great deal in terms of the selective pressures this species was facing."
To make their findings, the researchers looked at 107 foot bones believed to be composed of two juveniles and three adults. The findings revealed the ancient feet looked more like humans' than what is seen in modern chimpanzees. There were two major differences between H. naledi and human feet: the toes of H. naledi's foot were more curved and their feet were flatter than the modern human's. Fossils from other parts of the hominin's body suggest the ancestor had a much different gait than today's humans.
"This species has a unique combination of traits below the neck, and that adds another type of bipedalism to our record of human evolution," Harcourt-Smith said. "There were lots of different experiments happening within hominins--it wasn't just a linear route to how we walk today. We are a messy lineage, and not just in our skulls and our teeth. We're messy in the way we moved around."
In the future, the researchers hope to date the recently-discovered fossils to learn how this bipedalism fits into the human family tree.
"Regardless of age, this species is going to cause a paradigm shift in the way we think about human evolution, not only in the behavioral implications--which are fascinating--but in morphological and anatomical terms," Harcourt-Smith said.
The findings were published in the journal Nature Communications.
