Indicators of motherhood? Sacral preauricular extensions and notches in identified skeletal collections

Pany-Kucera, Doris; Spannagl-Steiner, Michaela; Desideri, Jocelyne; Rebay‐Salisbury, Katharina

doi:10.1002/oa.3044

Cited by 2 publications

(1 citation statement)

References 33 publications

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“…The inclusion of additional, potentially sexually dimorphic, discrete traits of the sacrum (e.g., sacral preauricular extensions and sacral preauricular notches) would not likely alter our findings. In fact, these features have been associated with multiple pregnancies and births before age 25 [ 59 ]. However, their rarity and their discrete nature makes it difficult to capture them with any of the investigated methods.…”

Section: Discussionmentioning

confidence: 99%

Sex classification using the human sacrum: Geometric morphometrics versus conventional approaches

et al. 2022

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The human pelvis shows marked sexual dimorphism that stems from the conflicting selective pressures of bipedal locomotion and parturition. The sacrum is thought to reflect this dimorphism as it makes up a significant portion of the pelvic girdle. However, reported sexual classification accuracies vary considerably depending on the method and reference sample (54%-98%). We aim to explore this inconsistency by quantifying sexual dimorphism and sex classification accuracies in a geographically heterogeneous sample by comparing 3D geometric morphometrics with the more commonly employed linear metric and qualitative assessments. Our sample included 164 modern humans from Africa, Europe, Asia, and America. The geometric morphometric analysis was based on 44 landmarks and 56 semilandmarks. Linear dimensions included sacral width, corpus depth and width, and the corresponding indices. The qualitative inspection relied on traditional macroscopic features such as proportions between the corpus of the first sacral vertebrae and the alae, and sagittal and coronal curvature of the sacrum. Classification accuracy was determined using linear discriminant function analysis for the entire sample and for the largest subsamples (i.e., Europeans and Africans). Male and female sacral shapes extensively overlapped in the geometric morphometric investigation, leading to a classification accuracy of 72%. Anteroposterior corpus depth was the most powerful discriminating linear parameter (83%), followed by the corpus-area index (78%). Qualitative inspection yielded lower accuracies (64–76%). Classification accuracy was higher for the Central European subsample and diminished with increasing geographical heterogeneity of the subgroups. Although the sacrum forms an integral part of the birth canal, our results suggest that its sex-related variation is surprisingly low. Morphological variation thus seems to be driven also by other factors, including body size, and sacrum shape is therefore likely under stronger biomechanical rather than obstetric selection.

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Section: Discussionmentioning

confidence: 99%

Sex classification using the human sacrum: Geometric morphometrics versus conventional approaches

et al. 2022

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Indicators of motherhood? Sacral preauricular extensions and notches in identified skeletal collections

Pany-Kucera

Spannagl-Steiner

Desideri

et al. 2021

Intl J of Osteoarchaeology

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The sacral preauricular extension (SPE) and sacral preauricular notch (SPN) are morphological changes at the ventral apex of the sacrum. We recently specified their shapes and appearances and suggested a scoring system based on prehistoric Austrian skeletal assemblages. We hypothesized that these specific pelvic changes relate to past pregnancies and parturitions, a hypothesis that we now tested on a subsample of individuals from the Simon Identified Skeletal collection in Geneva (n = 62) and the Christ Church, Spitalfields collection in London (n = 27) linked to historical information on deliveries. We found SPE and SPN in low frequencies and only in female individuals with at least two children in both collections, and a significant association between the emergence of SPE and first births by 25 years. SPN was found only in two females in the Simon collection, but both with a very high number of recorded parturitions including twin births. Based on these results, we are confident in our assumption that at least SPE, and possibly also SPN, result from increased compression forces at the sacroiliac joint, and especially at the ventrosuperior margin, in recurring (complicated) birth events, the interaction of enhanced pelvic joint mobility that is highest up to age 25, and postural changes related to weight gain during pregnancy. Pelvic shape, dimensions, body proportions, biomechanical issues and hormonal levels may also play a role in their emergence.

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Indicators of motherhood? Sacral preauricular extensions and notches in identified skeletal collections

Cited by 2 publications

References 33 publications

Sex classification using the human sacrum: Geometric morphometrics versus conventional approaches

Sex classification using the human sacrum: Geometric morphometrics versus conventional approaches

Indicators of motherhood? Sacral preauricular extensions and notches in identified skeletal collections

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