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How Did Humans Learn to WaHlk? Ancient Ape's Inner Ear Holds Secrets to Balance, Scientists Say 

The mystery as to how human beings learned how to walk may be hiding in a strange place: a 6-million-year-old ape's ear.

According to researchers at New York University, the ancient ape called Lufengpitchecus' bony inner ear region is the key to how humans learned to walk, Knewz.com has learned.

 

Researchers say the Lufengpitchecus' ears can give clues as to how humans began walking on two feet. By: Chinese Academy of Sciences© Knewz (UK)

The researchers used three-dimensional CT scanning technology to make the conclusion.

“The semicircular canals, located in the skull between our brains and the external ear, are critical to providing our sense of balance and position when we move, and they provide a fundamental component of our locomotion that most people are probably unaware of,” Yinan Zhang, a doctoral student at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences (IVPP) and the lead author of the paper, said in a news release.

 

The researchers created a computer model of the ape's ear. By: Unsplash© Knewz (UK)

“The size and shape of the semicircular canals correlate with how mammals, including apes and humans, move around their environment. Using modern imaging technologies, we were able to visualize the internal structure of fossil skulls and study the anatomical details of the semicircular canals to reveal how extinct mammals moved.” 

The researchers note that previous studies of the evolution of ape locomotion focused on comparisons of the bones of the limbs, shoulders, pelvis and spine.

The NYU researchers believe the ear, rather, is at the center of humans' equilibrium when it comes to walking on two feet.

 

Tiny bones in the ear are key to humans' ability to walk on two legs, researchers say. By: Unsplash© Knewz (UK)

“Our study points to a three-step evolution of human bipedalism,” Terry Harrison, a New York University anthropologist and one of the paper’s co-authors, said.

“First, the earliest apes moved in the trees in a style that was most similar to aspects of the way that gibbons in Asia do today. Second, the last common ancestor of apes and humans was similar in its locomotor repertoire to Lufengpithecus, using a combination of climbing and clambering, forelimb suspension, arboreal bipedalism, and terrestrial quadrupedalism. It is from this broad ancestral locomotor repertoire that human bipedalism evolved.” 

The Lufengpithecus skulls, which were originally discovered in China’s Yunnan Province in the early 1980s, have been at the center of the study. However, researchers found that the heavy compression and distortion of the skulls made it so the semicircular canals were not preserved.

 

The researchers say climate change may have played a factor in humans' evolution to walking on two legs. By: Unsplash© Knewz (UK)

Therefore, Zhang, Ni and Harrison, along with other researchers at IVPP and the Yunnan Institute of Cultural Relics and Archaeology (YICRA), used three-dimensional scanning technologies to virtually reconstruct the inner ear's bony canals.

They then compared the computer model to fossils from apes and humans from Asia, Europe and Africa. 

“Our analyses show that early apes shared a locomotor repertoire that was ancestral to human bipedalism,” IVPP Professor Xijun Ni, who led the project, said. “It appears that the inner ear provides a unique record of the evolutionary history of ape locomotion that offers an invaluable alternative to the study of the postcranial skeleton.” 

The study appeared in the journal The Innovation. By: Unsplash© Knewz (UK)

“Most fossil apes and their inferred ancestors are intermediate in locomotor mode between gibbons and African apes,” Ni added. “Later, the human lineage diverged from the great apes with the acquisition of bipedalism, as seen in Australopithecus, an early human relative from Africa.” 

The researchers also concluded that climate change may have played a role in the locomotor diversification of apes and humans.

“Cooler global temperatures, associated with the buildup of glacial ice sheets in the northern hemisphere approximately 3.2 million years ago, correspond with an uptick in the rate of change of the bony labyrinth and this may signal a rapid increase in the pace of ape and human locomotor evolution,” Harrison said.

The study appeared in the journal The Innovation. Story by David Wetzel: Knewz