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Shape Variation in the Growing Non-Adult Tibia

  • Author / Creator
    Swaters, Sean Gordon
  • The degree of diaphyseal curvature in the human tibia has been shown to significantly correlate with activity levels in archaeological populations. Specifically, tibial anteroposterior curvature is greatest in physically active populations and decreases in less active populations. Interestingly, recent research has shown that the tibial anterior crest’s sigmoid curvature increases as diaphyseal anteroposterior decreases. Tibial curvature is theorized to be the product of developmental plasticity during non-adult growth. This hypothesis was tested with 3D geometric morphometrics to determine if the non-adult anterior crest demonstrates age-related shape variation, and if a consistent pattern of shape change is identifiable during growth. A cross-sectional sample of non-adults (n = 41) from four archeological populations was analyzed. A second cross-sectional sample of adults (n = 24) from the four populations was included for two reasons. First, as an endpoint in a maturation analysis of anterior crest size and shape, and second, to determine if sexual dimorphism was present in the adult anterior crest. Age estimates were calculated from dental age atlases. A portion of the anterior crest was traced between 70-40% of tibial diaphyseal length. This portion overlapped the diaphyseal area previously observed to display the greatest degree of morphological change in the tibia. Twelve sliding 3D semi-landmarks were then derived from these traces to capture the shape and outline of the anterior crest. Statistical tests of age (dental age) and size (Csize) were conducted on the semi-landmark data to determine the possible presence of growth-related shape variation. For the results, non-adult anterior crest shape variation was observed to primarily occur in the mediolateral and anteroposterior planes, which coincided with previous research on the adult anterior crest. Age had a non-significant correlation with non-adult anterior crest shape variation. Further, a consistent pattern of shape change during growth was not observed. Age and size were significantly correlated. No significant differences were detected between adult male and female anterior crests. Regarding the maturation analysis, non-adult shape maturation continued into adulthood as size maturation leveled off during adolescence. From the results of this thesis, non-adult anterior crest shape variation was not significantly correlated with dental age, despite shape maturation continuing into adulthood. This suggests that non-adult anterior crest shape variation may be influenced by other factors of developmental plasticity.

  • Subjects / Keywords
  • Graduation date
    Fall 2021
  • Type of Item
    Thesis
  • Degree
    Master of Arts
  • DOI
    https://doi.org/10.7939/r3-811g-8j66
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.