Fluctuating Asymmetry and Sexual Dimorphism in Human Facial Morphology: A Multi-Variate Study.
3D morphometrics
fluctuating asymmetry
sexual dimorphism
Journal
Symmetry
ISSN: 2073-8994
Titre abrégé: Symmetry (Basel)
Pays: Switzerland
ID NLM: 101580302
Informations de publication
Date de publication:
Feb 2021
Feb 2021
Historique:
entrez:
5
3
2021
pubmed:
6
3
2021
medline:
6
3
2021
Statut:
ppublish
Résumé
Fluctuating asymmetry is often used as an indicator of developmental instability, and is proposed as a signal of genetic quality. The display of prominent masculine phenotypic features, which are a direct result of high androgen levels, is also believed to be a sign of genetic quality, as these hormones may act as immunosuppressants. Fluctuating asymmetry and masculinity are therefore expected to covary. However, there is lack of strong evidence in the literature regarding this hypothesis. In this study, we examined a large dataset of high-density 3D facial scans of 1260 adults (630 males and 630 females). We mapped a high-density 3D facial mask onto the facial scans in order to obtain a high number of quasi-landmarks on the faces. Multi-dimensional measures of fluctuating asymmetry were extracted from the landmarks using Principal Component Analysis, and masculinity/femininity scores were obtained for each face using Partial Least Squares. The possible correlation between these two qualities was then examined using Pearson's coefficient and Canonical Correlation Analysis. We found no correlation between fluctuating asymmetry and masculinity in men. However, a weak but significant correlation was found between average fluctuating asymmetry and masculinity in women, in which feminine faces had higher levels of fluctuating asymmetry on average. This correlation could possibly point to genetic quality as an underlying mechanism for both asymmetry and masculinity; however, it might also be driven by other fitness or life history traits, such as fertility. Our results question the idea that fluctuating asymmetry and masculinity should be (more strongly) correlated in men, which is in line with the recent literature. Future studies should possibly focus more on the evolutionary relevance of the observed correlation in women.
Sections du résumé
BACKGROUND
BACKGROUND
Fluctuating asymmetry is often used as an indicator of developmental instability, and is proposed as a signal of genetic quality. The display of prominent masculine phenotypic features, which are a direct result of high androgen levels, is also believed to be a sign of genetic quality, as these hormones may act as immunosuppressants. Fluctuating asymmetry and masculinity are therefore expected to covary. However, there is lack of strong evidence in the literature regarding this hypothesis.
MATERIALS AND METHODS
METHODS
In this study, we examined a large dataset of high-density 3D facial scans of 1260 adults (630 males and 630 females). We mapped a high-density 3D facial mask onto the facial scans in order to obtain a high number of quasi-landmarks on the faces. Multi-dimensional measures of fluctuating asymmetry were extracted from the landmarks using Principal Component Analysis, and masculinity/femininity scores were obtained for each face using Partial Least Squares. The possible correlation between these two qualities was then examined using Pearson's coefficient and Canonical Correlation Analysis.
RESULTS
RESULTS
We found no correlation between fluctuating asymmetry and masculinity in men. However, a weak but significant correlation was found between average fluctuating asymmetry and masculinity in women, in which feminine faces had higher levels of fluctuating asymmetry on average. This correlation could possibly point to genetic quality as an underlying mechanism for both asymmetry and masculinity; however, it might also be driven by other fitness or life history traits, such as fertility.
CONCLUSIONS
CONCLUSIONS
Our results question the idea that fluctuating asymmetry and masculinity should be (more strongly) correlated in men, which is in line with the recent literature. Future studies should possibly focus more on the evolutionary relevance of the observed correlation in women.
Identifiants
pubmed: 33664983
doi: 10.3390/sym13020304
pmc: PMC7929517
mid: NIHMS1675279
pii:
doi:
Types de publication
Journal Article
Langues
eng
Subventions
Organisme : NIDCR NIH HHS
ID : R01 DE016148
Pays : United States
Organisme : NIDCR NIH HHS
ID : R01 DE027023
Pays : United States
Organisme : NIDCR NIH HHS
ID : U01 DE020078
Pays : United States
Déclaration de conflit d'intérêts
Conflicts of Interest: The authors declare no conflict of interest.
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