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The preauricular sulcus in relation to sexual dimorphism, pregnancy and parturition in humans

Canty, S (2020) The preauricular sulcus in relation to sexual dimorphism, pregnancy and parturition in humans. Doctoral thesis, Liverpool John Moores University.

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Abstract

The present thesis proposes a new grading system for the examination of the preauricular sulcus (PAS) in humans. Previous studies concerning the variables affecting the development of the preauricular sulcus often provided conflicting results. The new grading system was developed to better describe the wide range of morphology exhibited in the trait, rather than just present or absent. It is hoped that this will lead to a better understanding of this trait. The new method ranges from grade 0 for the absence of a PAS, through to grade 4 for sulci that are deeply pitted. The main aim of the thesis was to examine the relationship between the trait and sexual dimorphism, pregnancy and parturition. This examination was carried out by the study of 894 specimens from the seven samples. The analysis indicated that sexual dimorphism has a significant effect on both the occurrence and morphology of the PAS. Females in all samples exhibited more frequent and severe expressions of the trait. The research further showed that parity status did not appear to have an effect and that there was no significant difference in either occurrence or morphology between parous and nulliparous females. Two pilot studies were also carried out as part of the thesis. A further examination of the CT Scans was performed with additional biographical information (e.g. diet, activity level, smoking history etc.) to see their relationship with the PAS. However, the majority of variables were found to have no effect. The second pilot study performed was an examination of how a selection of effect of pelvic dimensions. Four of these measurements (Maximum Sacral Width, Sacral Width Inferior, Transverse Diameter and Bispinous Diameter) were found to be the best predictors. All these measurements are wider in females, and there was a positive correlation between their width and both the frequency of the PAS and higher grades. The results of this thesis suggest that the development of a sulcus occurs more in females than males as a result of wider pelvic dimensions in response to evolutionary selection pressures for pregnancy and parturition. The method proposed has been tested and validated on both skeletal remains (Poulton, St Owens, Spitalfields, St Brides, Pretoria Bone Collection and Raymond A. Dart Collection) and CT Scans (from living subjects).

Item Type: Thesis (Doctoral)
Uncontrolled Keywords: Biological Anthropology; Preauricular Sulcus
Subjects: Q Science > QH Natural history > QH301 Biology
Q Science > QM Human anatomy
Divisions: Biological & Environmental Sciences (new Sep 19)
Date Deposited: 07 Aug 2020 13:27
Last Modified: 07 Aug 2020 13:28
DOI or Identification number: 10.24377/LJMU.t.00013460
Supervisors: Borrini, M, Gonzalez, S and Eliopoulos, C
URI: http://researchonline.ljmu.ac.uk/id/eprint/13460

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