Portrait of Dr Julia Arias-Martorell

Dr Julia Arias-Martorell

Marie Curie Postdoctoral Fellow


Dr Julia Arias-Martorell is a paleoanthropologist interested in the evolution of locomotion in apes, including reconstructing locomotor behaviors at ancestral nodes to inform our evolutionary history and the origin of human bipedalism. Julia focuses primarily on the relationship between form and function across the forelimb bones of the extant and fossil primates, implementing analysis of external and internal morphology.

Dr Arias-Martorell is a Marie Curie Fellow at the School of Anthropology and Conservation, and her current project focuses on the analysis of the internal structure of forelimb bones of Miocene apes.

Julia's research interests include:

  • Primate locomotion
  • Hominoid evolution
  • Primate forelimb musculoskeletal adaptations to locomotion and biomechanics
  • Miocene ape and Hominin locomotor behavior reconstruction
  • External and internal morphology analyses of primate forelimb bones

Dr Arias-Martorell received her PhD from the University of Barcelona working on the functional external morphology of the glenohumeral (shoulder) joint of extant and fossil apes, using geometric morphometric analyses.



  • Potau, J. et al. (2018). Inter- and Intraspecific Variations in the Pectoral Muscles of Common Chimpanzees (Pan troglodytes), Bonobos (Pan paniscus), and Humans (Homo sapiens). BioMed Research International [Online] 2018:Article ID 9404508. Available at: https://doi.org/10.1155/2018/9404508?
    We have analyzed anatomic variations in the pectoralis major and pectoralis minor muscles of common chimpanzees (Pan
    troglodytes) and bonobos(Pan paniscus) and compared them to anatomic variations in these muscles in humans(Homo sapiens). We
    have macroscopically dissected these muscles in six adult Pan troglodytes, five Pan paniscus of ages ranging from fetus to adult, and
    five adult Homo sapiens. Although Pan troglodytes are thought to lack a separate pectoralis abdominis muscle, we have identified this
    muscle in three of the Pan troglodytes; none of the Pan paniscus, however, had this muscle. We have also found deep supernumerary
    fascicles in the pectoralis major of two Pan troglodytes and all five Pan paniscus. In all six Pan troglodytes, the pectoralis minor was
    inserted at the supraspinatus tendon, while, in Pan paniscus and Homo sapiens, it was inserted at the coracoid process of the scapula.
    Some of the anatomic features and variations of these muscles in common chimpanzees and bonobos are similar to those found
    in humans, therefore enhancing our knowledge of primate comparative anatomy and evolution and also shedding light on several
    clinical issues.
  • Arias Martorell, J. (2018). The morphology and evolutionary history of the glenohumeral joint of hominoids: A review. Ecology and Evolution [Online]:1-20. Available at: http://dx.doi.org/10.1002/ece3.4392.
    The glenohumeral joint, the most mobile joint in the body of hominoids, is involved in the locomotion of all extant primates apart from humans. Over the last few decades,our knowledge of how variation in its morphological characteristics relates to different locomotor behaviors within extant primates has greatly improved, including features of the proximal humerus and the glenoid cavity of the scapula, as well as the muscles that function to move the joint (the rotator cuff muscles). The glenohumeral joint is a region with a strong morphofunctional signal, and hence, its study can shed light on the locomotor behaviors of crucial ancestral nodes in the evolutionary history of hominoids (e.g., the last common ancestor between humans and chimpanzees). Hominoids, in particular, are distinct in showing round and relatively big proximal humeri with lowered tubercles and flattened and oval glenoid cavities, morphology suited to engage in a wide range of motions, which enables the use of locomotor behaviors such as suspension. The comparison with extant taxa has enabled more informed functional interpretations of morphology in extinct primates, including hominoids, from the Early Miocene through to the emergence of hominins. Here, I review our current understanding of glenohumeral joint functional morphology and its evolution throughout the Miocene and Pleistocene, as well as highlighting the areas where a deeper study of this joint is still needed.
  • Potau, J. et al. (2018). Structural and molecular study of the supraspinatus muscle of modern humans (Homo sapiens ) and common chimpanzees (Pan troglodytes ). American Journal of Physical Anthropology [Online] 166:934-940. Available at: https://doi.org/10.1002/ajpa.23490.
    To analyze the muscle architecture and the expression pattern of the myosin heavy chain (MyHC) isoforms in the supraspinatus of Pan troglodytes and Homo sapiens in order to identify differences related to their different types of locomotion.

    Materials and methods
    We have analyzed nine supraspinatus muscles of Pan troglodytes and ten of Homo sapiens. For each sample, we have recorded the muscle fascicle length (MFL), the pennation angle, and the physiological cross?sectional area (PCSA). In the same samples, by real?time quantitative polymerase chain reaction, we have assessed the percentages of expression of the MyHC?I, MyHC?IIa, and MyHC?IIx isoforms.

    The mean MFL of the supraspinatus was longer (p?=?0.001) and the PCSA was lower (p?<?0.001) in Homo sapiens than in Pan troglodytes. Although the percentage of expression of MyHC?IIa was lower in Homo sapiens than in Pan troglodytes (p?=?0.035), the combination of MyHC?IIa and MyHC?IIx was expressed at a similar percentage in the two species.

    The longer MFL in the human supraspinatus is associated with a faster contractile velocity, which reflects the primary function of the upper limbs in Homo sapiens—the precise manipulation of objects—an adaptation to bipedal locomotion. In contrast, the larger PCSA in Pan troglodytes is related to the important role of the supraspinatus in stabilizing the glenohumeral joint during the support phase of knuckle?walking. These functional differences of the supraspinatus in the two species are not reflected in differences in the expression of the MyHC isoforms.
  • Potau, J. et al. (2018). Quantification of Myosin Heavy Chain Isoform mRNA Transcripts in the Supraspinatus Muscle of Vertical Clinger Primates. Folia Primatologica [Online] 88:497-506. Available at: https://doi.org/10.1159/000485246.
    Vertical clinging is a specialized form of locomotion characteristic of the primate family Callitrichidae. Vertical clinging requires these pronograde primates to maintain a vertical posture, so the protraction of their forelimbs must resist gravity. Since pronograde primates usually move as horizontal quadrupeds, we hypothesized that the supraspinatus muscle of vertical clingers would present specific characteristics related to the functional requirements imposed on the shoulder area by vertical clinging. To test this hypothesis, we quantified by real-time quantitative polymerase chain reaction the mRNA transcripts of myosin heavy chain (MHC) isoforms in the supraspinatus muscle of 15 species of pronograde primates, including vertical clingers. Our results indicate that the supraspinatus of vertical clingers has a specific expression pattern of the MHC isoforms, with a low expression of the transcripts of the slow MHC-I isoform and a high expression of the transcripts of the fast MHC-II isoforms. We conclude that these differences can be related to the particular functional characteristics of the shoulder in vertical clingers, but also to other anatomical adaptations of these primates, such as their small body size.
  • Ciurana, N. et al. (2017). Expression of myosin heavy chain isoforms mRNA transcripts in the temporalis muscle of common chimpanzees (Pan troglodytes). Annals of Anatomy - Anatomischer Anzeiger [Online] 214:80-85. Available at: https://doi.org/10.1016/j.aanat.2017.08.001.

    The common chimpanzee (Pan troglodytes) is the primate that is phylogenetically most closely related to humans (Homo sapiens). In order to shed light on the anatomy and function of the temporalis muscle in the chimpanzee, we have analyzed the expression patterns of the mRNA transcripts of the myosin heavy chain (MyHC) isoforms in different parts of the muscle.

    Basic procedures

    We dissected the superficial, deep and sphenomandibularis portions of the temporalis muscle in five adult P. troglodytes and quantified the expression of the mRNA transcripts of the MyHC isoforms in each portion using real-time quantitative polymerase chain reaction.

    Main findings

    We observed significant differences in the patterns of expression of the mRNA transcripts of the MyHC-IIM isoform between the sphenomandibularis portion and the anterior superficial temporalis (33.6% vs 47.0%; P = 0.032) and between the sphenomandibularis portion and the anterior deep temporalis (33.6% vs 43.0; P = 0.016). We also observed non-significant differences between the patterns of expression in the anterior and posterior superficial temporalis.

    Principal conclusions

    The differential expression patterns of the mRNA transcripts of the MyHC isoforms in the temporalis muscle in P. troglodytes may be related to the functional differences that have been observed in electromyographic studies in other species of primates. Our findings can be applicable to the fields of comparative anatomy, evolutionary anatomy, and anthropology.
  • Ciurana, N. et al. (2017). Expression of MyHC isoforms mRNA transcripts in different regions of the masseter and medial pterygoid muscles in chimpanzees. Archives of Oral Biology [Online] 83:63-67. Available at: https://doi.org/10.1016/j.archoralbio.2017.07.003.
    The aim of this study is to examine the expression pattern of the different myosin heavy chain (MyHC) isoforms in the masseter and medial pterygoid muscles by real time quantitative polymerase chain reaction (RT-qPCR) to obtain information at molecular level which can be related to the functional characteristics of these two muscles.

    The masseter, deep and superficial portion, and medial pterygoid muscles of five adult Pan troglodytes were dissected in order to obtain samples of the anterior and posterior regions of each portion of the
    masseter and of the medial pterygoid. The expression of MyHC isoforms mRNA transcripts was analyzed by RT-qPCR.

    No significant differences in expression of MyHC isoforms between the masseter and the medial pterygoid were found. In contrast, when comparing the superficial and the deep portion of the masseter, we found that the MyHC-IIM isoform was expressed at a significantly higher level in the superficial portion.

    The superficial portion of the masseter and the medial pterygoid muscle have the same expression pattern regarding the different MyHC isoforms. On the other hand, the deep portion of the masseter, which is activated mainly during lateral and repositioning movements of the mandible, has a lower MyHC-IIM isoform expression than the superficial portion. Our findings provide new data on functional aspects of the masseter and medial pterygoid that can complement results obtained by other techniques.

Conference or workshop item

  • Arias-Martorell, J. et al. (2017). Trabecular architecture of the hominoid humerus. in: Annual Meeting of the American Association for Physical Anthropology.
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