Lucy, the 3.2 million-year-old hominin relative, couldn’t run very fast according to a new study. Researchers digitally modeled her muscles and tendons to determine that early human ancestors like Lucy were capable of running well but topped out around 11 mph (18 km/h).
The discovery was made by modeling the skeletal and muscular anatomy of Lucy, revealing her maximum running speed, energetic costs associated with running, and running endurance. The study compared Lucy’s performance to modern humans, who can run at speeds of over 27 mph (43 km/h).
Researchers found that Lucy used up between 1.7 and 2.9 times more energy than modern humans to run at her top speed. This suggests she would have required significantly more energy to travel a given distance than a modern human.
Australopithecines, like Lucy, had large upper bodies, long arms, and short legs, which limited their running speed. However, the researchers discovered that a differently shaped Achilles tendon and triceps surae might be the reason for Lucy’s slow running ability.
Modern humans have a long, spring-like Achilles tendon, providing efficient ankle movement crucial to high running performance. When modeling Lucy’s movement with human-like muscles, she was still slower but showed significant differences due to her smaller body size.
This study provides new insights into the evolution of human anatomy and key features that contribute to running performance. Further research is needed to fully understand the differences between australopithecine and human locomotion, including arm swing and torso rotations.
Source: https://www.livescience.com/archaeology/early-human-ancestor-lucy-was-a-bad-runner-and-this-one-tendon-could-explain-why