Our First Famous Early Ancestor, Lucy, Was An Awful Runner
A new study suggests that “Lucy,” perhaps the world’s most famous early human ancestor, wasn’t able to run that fast.
The latest research analyzed our 3.2 million-year-old hominin relative, and the results have shed light on how human anatomy evolved to enhance running performance.
About 2 million years ago, our Homo erectus ancestors first got the ability to walk and run on two legs efficiently.
However, approximately 4 million years ago, other earlier relatives, such as the australopithecines, were actually already walking upright.
Species like Australopithecus afarensis had longer arms and different body proportions, though, which is why scientists believed they’d be less adept at bipedal walking compared to modern humans.
In a recent study, researchers used digital models of Lucy’s skeletal and muscular structure to analyze the energy required for running and her endurance capabilities, as well as her top running speed.
Using running gait simulations, the team found that Lucy’s maximum running speed was much slower than that of modern humans, reaching only about 11 miles per hour.
In contrast, recreational runners typically reach around 13.5 miles per hour, and Usain Bolt’s maximum running speed exceeds 27 miles per hour.
Despite this slower pace, Lucy also consumed 1.7 to 2.9 times more energy to run at that speed than humans do today. This indicates she would have needed considerably more energy to cover the same distance as a modern human.
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The limited running speeds of australopithecines, in general, were likely due to their short legs, long arms, and large upper bodies.
However, the team found another potential contributing factor by studying Lucy specifically: the differing shape of her Achilles tendon and the triceps surae.
Today, humans have a long Achilles tendon, which acts like a spring, linking the calf muscles to the heel bone. This structure helps create a strong and efficient ankle, which is key for running effectively.
So, the researchers adjusted Lucy’s model to include human-like Achilles and calf muscles. Now, even after that, she was still slower, but her lower speed was primarily due to her smaller body size.
“This wider context, therefore, emphasizes the crucial role of the Achilles tendon and triceps surae architecture in the evolution of hominin running energetics,” the team concluded.
“Key features in the human body plan evolved specifically for improved running performance.”
This study is the very first to use musculoskeletal modeling to estimate the running performance of Lucy’s species.
Nonetheless, more research is necessary and should include models that account for arm swing and torso rotation.
These added movements will help scientists gain a clearer picture of how australopithecine locomotion differs from that of modern humans.
To read the study’s complete findings, which have since been published in Current Biology, visit the link here.
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