3D Simulations Reveal Ancient Humans' Limited Running Speed and Endurance

A new study from researchers at Duke University in the United States has shed light on the running abilities of Australopithecus afarensis, a small ancient human relative who lived over 3 million years ago. Through 3D computer simulations, the researchers discovered that this early human ancestor, despite walking on two legs like modern humans, exhibited significant differences in speed and endurance.

The simulation provided detailed insights into the running speed and muscle adaptation characteristics of these ancient humans, which are crucial for modern humans' long-distance running capabilities. The findings of the study have been published in the latest issue of the journal Current Biology.

Using advanced technology, the researchers created a 3D digital model of the skeleton of "Lucy", an almost complete specimen of Australopithecus afarensis discovered in Ethiopia nearly half a century ago, dating back approximately 3.2 million years. By combining muscle features of modern apes with the surface area of Lucy's bones, they estimated the muscle mass of the ancient humans. They then simulated "Lucy running" and compared her performance to a digital model of a modern human.

The results revealed that Lucy had the ability to run on two legs but lacked the elongated Achilles tendon and shortened muscle fibers necessary for endurance running in modern humans. Even with the reshaped model using human muscles, her maximum speed was only 5 meters per second, while the modern human model could reach 8 meters per second. Even when adjusting for body size differences, Lucy's speed still fell short, indicating that her body proportions were a significant limiting factor.

Further simulations highlighted the critical role of ankle muscles. When the researchers added human-like ankle muscles to the Lucy model, her energy consumption was comparable to animals of similar size; however, using ape-like ankle muscles made running more strenuous. This suggests that the adaptation of the Achilles tendon and surrounding muscles in modern humans provides a significant advantage for long-distance running.