Understanding how extinct species moved presents a significant challenge for palaeontologists. While skeletons offer valuable information, they rarely preserve the soft tissues crucial for reconstructing movement. However, recent advancements in three-dimensional polygonal modelling, guided by imaging scan data and muscle scarring, have opened new avenues for reconstructing the missing soft tissues.
This article explores the application of this technique to the Australopithecus afarensis specimen AL 288-1, otherwise known as ‘Lucy’ one of the most complete hominin skeletons, shedding light on the debate surrounding its bipedal movement.
The examination conducted on Lucy's fossil over the previous two decades has indicated that she and individuals of her species exhibited bipedal locomotion. However, Dr Ashleigh L.A. Wiseman, the principal author of the study and a research associate affiliated with the University of Cambridge in the United Kingdom, sought to undertake a more comprehensive approach by reconstructing a non-fossilized aspect of Lucy: her muscular system.
“The defining aspect of what makes us human is the ability to walk on two legs, but understanding how and why this evolved has been debated for a long time”
Dr Wiseman also adds, “With recent advances in computational modelling, it is now possible to investigate these questions. Of course, in the fossil record we are left looking at the bare bones. But muscles animate the body — they allow you to walk, run, jump and even dance. So, if we want to understand how our ancestors moved, we first need to reconstruct their soft tissues.”
Capacity For an Upright Posture
In the study, a meticulous reconstruction of the muscular configuration in the pelvis and lower limb of Lucy has been unveiled, offering invaluable insights into the motion abilities of Australopithecus afarensis. The comprehensive analysis encompasses 36 muscles, meticulously mapped to their spatial distribution within each body segment.
The findings of this investigation, based on the examination of muscle leverage, indicate that Au. Afarensis possessed the capacity for an upright posture, thus suggesting the potential for bipedal locomotion. However, the research also suggests that these early hominins were capable of a diverse range of motions beyond habitual terrestrial bipedalism, reminiscent of the behaviours observed in chimpanzees and bonobos.
“I was very surprised to find that the knee extensors (those muscles that produce and maintain a straight knee when you stand upright) were so comparable to the human,” Wiseman said. “This means that Lucy could stand and likely walk as efficiently as we can.”
It is important to note that while the current results do not definitively confirm the efficiency of bipedalism in Lucy, they do establish that upright walking was indeed a viable option. Moving forward, the employment of the polygonal muscle modelling approach demonstrates significant promise in reconstructing the soft tissues of hominins and providing crucial information on muscle configuration and shape filling.
For future studies delving into muscular function in hominins, several key factors must be considered. Firstly, researchers should give due attention to the space occupied within a desired body segment, including a detailed analysis of muscle paths and masses. Secondly, the significance of digitizing the complete attachment site surface cannot be overstated, as this step allows for a more accurate determination of a realistic centroid. Lastly, it is imperative to consider the collective impact of all muscles acting upon a given body segment, rather than focusing solely on an individual muscle.
To facilitate further investigation and potentially aid in the teaching of human evolutionary anatomy, an interactive three-dimensional Autodesk Maya scene showcasing the entire musculature is provided alongside this paper. This invaluable resource will serve as a valuable tool for future research endeavours and may even contribute to enhancing the understanding of human evolution.
The insights garnered from this study shed new light on the locomotion capabilities of Au. afarensis and emphasize the importance of examining the muscular structure in our understanding of human evolution. With the advancement of muscle reconstruction techniques, we are poised to gain further knowledge about the soft tissue configurations of our early ancestors, unravelling the mysteries surrounding our evolutionary past.
ALSO READ| 100 million-years-old bones of Sauropods dinosaur found in Meghalaya
Comments
All Comments (0)
Join the conversation