Cargando…

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

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 va...

Descripción completa

Detalles Bibliográficos
Autores principales: Krenn, Viktoria A., Webb, Nicole M., Fornai, Cinzia, Haeusler, Martin
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8986015/
https://www.ncbi.nlm.nih.gov/pubmed/35385483
http://dx.doi.org/10.1371/journal.pone.0264770
_version_ 1784682465228488704
author Krenn, Viktoria A.
Webb, Nicole M.
Fornai, Cinzia
Haeusler, Martin
author_facet Krenn, Viktoria A.
Webb, Nicole M.
Fornai, Cinzia
Haeusler, Martin
author_sort Krenn, Viktoria A.
collection PubMed
description 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.
format Online
Article
Text
id pubmed-8986015
institution National Center for Biotechnology Information
language English
publishDate 2022
publisher Public Library of Science
record_format MEDLINE/PubMed
spelling pubmed-89860152022-04-07 Sex classification using the human sacrum: Geometric morphometrics versus conventional approaches Krenn, Viktoria A. Webb, Nicole M. Fornai, Cinzia Haeusler, Martin PLoS One Research Article 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. Public Library of Science 2022-04-06 /pmc/articles/PMC8986015/ /pubmed/35385483 http://dx.doi.org/10.1371/journal.pone.0264770 Text en © 2022 Krenn et al https://creativecommons.org/licenses/by/4.0/This is an open access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Krenn, Viktoria A.
Webb, Nicole M.
Fornai, Cinzia
Haeusler, Martin
Sex classification using the human sacrum: Geometric morphometrics versus conventional approaches
title Sex classification using the human sacrum: Geometric morphometrics versus conventional approaches
title_full Sex classification using the human sacrum: Geometric morphometrics versus conventional approaches
title_fullStr Sex classification using the human sacrum: Geometric morphometrics versus conventional approaches
title_full_unstemmed Sex classification using the human sacrum: Geometric morphometrics versus conventional approaches
title_short Sex classification using the human sacrum: Geometric morphometrics versus conventional approaches
title_sort sex classification using the human sacrum: geometric morphometrics versus conventional approaches
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8986015/
https://www.ncbi.nlm.nih.gov/pubmed/35385483
http://dx.doi.org/10.1371/journal.pone.0264770
work_keys_str_mv AT krennviktoriaa sexclassificationusingthehumansacrumgeometricmorphometricsversusconventionalapproaches
AT webbnicolem sexclassificationusingthehumansacrumgeometricmorphometricsversusconventionalapproaches
AT fornaicinzia sexclassificationusingthehumansacrumgeometricmorphometricsversusconventionalapproaches
AT haeuslermartin sexclassificationusingthehumansacrumgeometricmorphometricsversusconventionalapproaches