Ancient Hominin “Lucy” Stood Fully Upright, New 3D Muscle Reconstruction Reveals

by Hiroshi Tanaka
5 comments
3D Muscle Reconstruction

Using a blend of muscle scarring data and MRI scans, a new study illustrates a polygonal muscle modeling technique. This study, conducted by Dr. Ashleigh Wiseman, suggests that the 3.2 million-year-old Australopithecus afarensis, famously known as “Lucy”, could stand as erect as contemporary humans.

Through digital reconstruction of Lucy’s soft tissue, it became evident that she possessed robust leg and pelvic muscles, indicative of tree-living. Still, her knee muscles showed the capability for completely erect ambulation. This ground-breaking reconstruction of a hominin’s soft tissue is a first for a researcher from the University of Cambridge.

“Lucy’s muscular structure implies that she was as adept at two-legged walking as modern humans are,” noted Dr. Wiseman.

Lucy’s muscles were 3D-rendered by Dr. Wiseman, focusing particularly on her leg and pelvis, utilizing scans of the famous hominin specimen, Australopithecus afarensis. This specimen, discovered in the 1970s in Ethiopia, represents an early human species that resided in East Africa over three million years ago. This species was shorter and exhibited an ape-like face and smaller brain but had the ability to walk bipedally. They adapted to both tree and grassland environments, contributing to their survival for nearly a million years.

The most complete Australopithecus fossil found to date, Lucy, had about 40% of her skeleton recovered and was named after the Beatles song, ‘Lucy in the Sky with Diamonds’.

Using open-source data about Lucy, Dr. Wiseman generated a digital representation of the hominin’s lower body musculature, a finding published in the Royal Society Open Science journal.

This study yielded digital reconstructions of 36 muscles in each of Lucy’s legs, revealing that most of these were considerably larger and occupied more leg space compared to those of modern humans.

It’s well-established that Lucy was bipedal, but experts have long debated her walking style. Some suggest she walked in a squatting waddle, like our common ancestor the chimpanzee, while others argue that her gait mirrored our upright bipedalism. However, recent studies have pointed towards completely erect walking, and Dr. Wiseman’s work further corroborates this.

The muscle paths and spaces reconstructed by Dr. Wiseman show that Lucy could straighten her knees as fully as modern humans, suggesting her proficiency in bipedalism.

“Lucy would likely have had a unique way of walking and moving, one we don’t see in any existing species today. She would have been quite capable of exploiting both grasslands and dense forests in East Africa around 3 to 4 million years ago,” said Wiseman.

To digitally reproduce Lucy’s muscles, Wiseman began with modern humans. By mapping the “muscle paths” from the MRI and CT scans of a man and woman’s muscle and bone structures, she developed a digital musculoskeletal model. She then used Lucy’s skeletal models to rearticulate the joints, determining each joint’s axis of movement. Finally, she added muscles based on modern human muscle maps and the discernable “muscle scarring” on the fossilized bones.

These reconstructions now serve as valuable tools for understanding how our ancient ancestor moved. “Muscle reconstructions have already been used to estimate a T-Rex’s running speed. By applying similar techniques to early humans, we aim to uncover the spectrum of physical movement that drove our evolution – including capabilities we no longer possess,” Dr. Wiseman added.

Reference: Wiseman, Ashleigh L. A. “Three-dimensional volumetric muscle reconstruction of the Australopithecus afarensis pelvis and limb, with estimations of limb leverage”. Royal Society Open Science, 14 June 2023. DOI: 10.1098/rsos.230356.

Frequently Asked Questions (FAQs) about 3D Muscle Reconstruction

What is the significance of the 3D muscle reconstruction of Lucy?

The 3D muscle reconstruction of Lucy, a 3.2 million-year-old hominin, reveals that she could stand fully erect just like modern humans. This new insight deepens our understanding of human evolution, specifically regarding the development of bipedalism.

Who conducted the research on Lucy’s muscle reconstruction?

The research on Lucy’s muscle reconstruction was carried out by Dr. Ashleigh Wiseman, a researcher at the University of Cambridge.

Where was the research on Lucy’s muscle reconstruction published?

The research findings were published in the Royal Society Open Science journal.

What does the study suggest about Lucy’s ability to walk?

The study suggests that Lucy was proficient at bipedalism – she had the ability to walk on two legs just like modern humans.

How was the 3D muscle reconstruction of Lucy performed?

Dr. Wiseman started with modern humans, using MRI and CT scans to map the “muscle paths” and create a digital musculoskeletal model. Existing virtual models of Lucy’s skeleton were then used to rearticulate the joints, replicating their natural movement. Finally, muscles were added based on pathways from modern human muscle maps and discernible “muscle scarring” on Lucy’s fossilized bones.

Why is Lucy important in the study of human evolution?

Lucy, an Australopithecus afarensis, represents an early stage in human evolution. Her skeletal structure exhibits both human-like and ape-like characteristics. As one of the most complete Australopithecus fossils, Lucy provides valuable insight into our ancestors’ adaptive capacities and locomotion.

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5 comments

EvoGirl June 14, 2023 - 7:01 pm

This is really cool. It’s amazing to think about how far we’ve come. Human evolution is just mindblowing!!

Reply
Ape2Man June 14, 2023 - 8:57 pm

Lucy stood upright huh… Evolution is just fascinating, its like a journey into the past. Never ceases to amaze me.

Reply
HistoryBuff101 June 14, 2023 - 11:37 pm

Oh wow, did’t knw that Lucy was so similar to us. Crazy how technology can help us learn so much about the past…

Reply
PaleoPaul June 15, 2023 - 12:34 am

Have to say, this is pretty impressive stuff. And it’s not just about the past – it’s about understanding our evolution too. Great work, Dr. Wiseman!

Reply
ScienceLover22 June 15, 2023 - 7:45 am

I love how they are using modern human scans to map Lucy’s muscles. Really brings our ancient history to life, doesn’t it?

Reply

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