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   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    First hominin muscle reconstruction shows 3.2 million-year-old 'Lucy'   
   could stand as erect as we can    
      
     Date:   
         June 14, 2023   
     Source:   
         University of Cambridge   
     Summary:   
         Digital modelling of legendary fossil's soft tissue suggests   
         Australopithecus afarensis had powerful leg and pelvic muscles   
         suited to tree dwelling, but knee muscles that allowed fully   
         erect walking.   
      
      
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   FULL STORY   
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   A Cambridge University researcher has digitally reconstructed the missing   
   soft tissue of an early human ancestor -- or hominin -- for the first   
   time, revealing a capability to stand as erect as we do today.   
      
   Dr Ashleigh Wiseman has 3D-modelled the leg and pelvis muscles of the   
   hominin Australopithecus afarensisusing scans of 'Lucy': the famous   
   fossil specimen discovered in Ethiopia in the mid-1970s.   
      
   Australopithecus afarensis was an early human species that lived in East   
   Africa over three million years ago. Shorter than us, with an ape-like   
   face and smaller brain, but able to walk on two legs, it adapted to both   
   tree and savannah dwelling -- helping the species survive for almost a   
   million years.   
      
   Named for the Beatles classic 'Lucy in the Sky with Diamonds', Lucy   
   is one of the most complete examples to be unearthed of any type of   
   Australopithecus - - with 40% of her skeleton recovered.   
      
   Wiseman was able to use recently published open source data on the Lucy   
   fossil to create a digital model of the 3.2 million-year-old hominin's   
   lower body muscle structure. The study is published in the journal Royal   
   Society Open Science.   
      
   The research recreated 36 muscles in each leg, most of which were   
   much larger in Lucy and occupied greater space in the legs compared to   
   modern humans.   
      
   For example, major muscles in Lucy's calves and thighs were over twice   
   the size of those in modern humans, as we have a much higher fat to   
   muscle ratio.   
      
   Muscles made up 74% of the total mass in Lucy's thigh, compared to just   
   50% in humans.   
      
   Paleoanthropologists agree that Lucy was bipedal, but disagree on how she   
   walked. Some have argued that she moved in a crouching waddle, similar to   
   chimpanzees -- our common ancestor -- when they walk on two legs. Others   
   believe that her movement was closer to our own upright bipedalism.   
      
   Research in the last 20 years have seen a consensus begin to emerge   
   for fully erect walking, and Wiseman's work adds further weight to   
   this. Lucy's knee extensor muscles, and the leverage they would allow,   
   confirm an ability to straighten the knee joints as much as a healthy   
   person can today.   
      
   "Lucy's ability to walk upright can only be known by reconstructing the   
   path and space that a muscle occupies within the body," said Wiseman, from   
   Cambridge University's McDonald Institute for Archaeological Research.   
      
   "We are now the only animal that can stand upright with straight   
   knees. Lucy's muscles suggest that she was as proficient at bipedalism   
   as we are, while possibly also being at home in the trees. Lucy likely   
   walked and moved in a way that we do not see in any living species today,"   
   Wiseman said.   
      
   "Australopithecus afarensis would have roamed areas of open wooded   
   grassland as well as more dense forests in East Africa around 3 to 4   
   million years ago.   
      
   These reconstructions of Lucy's muscles suggest that she would have been   
   able to exploit both habitats effectively."  Lucy was a young adult,   
   who stood at just over one metre tall and probably weighed around   
   28kg. Lucy's brain would have been roughly a third of the size of ours.   
      
   To recreate the muscles of this hominin, Wiseman started with some living   
   humans. Using MRI and CT scans of the muscle and bone structures of a   
   modern woman and man, she was able to map the "muscle paths" and build   
   a digital musculoskeletal model.   
      
   Wiseman then used existing virtual models of Lucy's skeleton to   
   "rearticulate" the joints -- that is, put the skeleton back together. This   
   work defined the axis from which each joint was able to move and rotate,   
   replicating how they moved during life.   
      
   Finally, muscles were layered on top, based on pathways from modern human   
   muscle maps, as well as what little "muscle scarring" was discernible (the   
   traces of muscle connection detectable on the fossilised bones). "Without   
   open access science, this research would not have been possible,"   
   said Wiseman.   
      
   These reconstructions can now help scientists understand how this human   
   ancestor walked. "Muscle reconstructions have already been used to gauge   
   running speeds of a T-Rex, for example," said Wiseman. "By applying   
   similar techniques to ancestral humans, we want to reveal the spectrum   
   of physical movement that propelled our evolution -- including those   
   capabilities we have lost."   
       * RELATED_TOPICS   
             o Fossils_&_Ruins   
                   # Early_Humans # Fossils # Human_Evolution # Anthropology   
                   # Origin_of_Life # Cultures # Evolution # Archaeology   
       * RELATED_TERMS   
             o Fossil o Petrified_wood o Evolution_of_cetaceans o   
             Homo_rudolfensis o Trace_fossil o Paralititan o Tyrannosaurus   
             o Evolution   
      
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   Story Source: Materials provided by University_of_Cambridge. The original   
   text of this story is licensed under a Creative_Commons_License. Note:   
   Content may be edited for style and length.   
      
      
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   Journal Reference:   
      1. Ashleigh L. A. Wiseman. Three-dimensional volumetric muscle   
         reconstruction of the Australopithecus afarensis pelvis and limb,   
         with estimations of limb leverage. Royal Society Open Science,   
         2023; 10 (6) DOI: 10.1098/rsos.230356   
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   Link to news story:   
   https://www.sciencedaily.com/releases/2023/06/230614220724.htm   
      
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