New study offers insight into evolution of bipedal locomotion

Wednesday - January 31 2024, 23:10 UTC - 9 months ago

A new study using 3D CT scanning has revealed clues about the origins of bipedal locomotion. It suggests a three-step evolution, beginning with an ancestral locomotor repertoire similar to present-day gibbons, followed by a shared repertoire with Lufengpithecus, and finally leading to human bipedalism. This study also considers the potential impact of climate change on the evolution of ape and human locomotion.

Nearly a year and a half ago, scientists found that the act of chewing probably kick-started the evolution of our ancestors millions of years ago. Now, a study has found imperative clues about the origins of bipedal locomotion based on a recently discovered six-million-year-old fossil ape–Lufengpithecus, according to a new study published in The Innovation on January 29.

Scientists conducted an analysis using a new method. They employed three-dimensional CT scanning to examine the ape's bony inner ear region. This allowed them to visualize the internal structure of fossil skulls and study the anatomical details of the semicircular canals. Lead author Yinan Zhang, a doctoral student at the Chinese Academy of Sciences, explains that the size and shape of the semicircular canals can reveal how mammals, including apes and humans, move around in their environment.

Co-author Terry Harrison, an anthropologist at New York University, notes that the study suggests a three-step evolution of human bipedalism. The first step involved apes navigating through trees in a manner resembling how gibbons move today. The second step describes the last common ancestor of apes and humans, which had a similar locomotor repertoire to Lufengpithecus. This repertoire included a combination of climbing, clambering, forelimb suspension, bipedal walking in trees, and walking on all fours on the ground.

The third step is the evolution of human bipedalism itself. Harrison explains that it evolved from the broad ancestral repertoire seen in Lufengpithecus and our shared ancestor with other apes. This study sheds light on the evolution of bipedal locomotion and how it changed over time.

The fossils of Lufengpithecus were originally discovered in China's Yunnan Province in the early 1980s. This evidence not only delves into the evolutionary history but also discusses the potential impact of climate change, which began approximately 3.2 million years ago, on the evolutionary changes in ape and human locomotion. The researchers analyzed the rate of evolutionary change in the bony labyrinth, which is crucial for providing a sense of balance and position during movement. They discovered that cooler global temperatures, associated with the build-up of glacial ice sheets in the northern hemisphere, corresponded with an uptick in the rate of change of the bony labyrinth. This may indicate a rapid increase in the pace of ape and human locomotor evolution.

3D CT scanning has allowed scientists to reconstruct the locomotor repertoire of an extinct species and observe how it changed over time. This study provides valuable insights into the evolution of bipedal locomotion and its relationship to climate change and other environmental factors.