Fluctuating Asymmetry and Sexual Dimorphism in Human Facial Morphology: A Multi-Variate Study
(1) 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 qualit...
Main Authors: | , , , , , , , |
---|---|
Format: | Article |
Language: | English |
Published: |
MDPI AG
2021-02-01
|
Series: | Symmetry |
Subjects: | |
Online Access: | https://www.mdpi.com/2073-8994/13/2/304 |
id |
doaj-961e0671e1b04ab8a2c497e920ee4eca |
---|---|
record_format |
Article |
spelling |
doaj-961e0671e1b04ab8a2c497e920ee4eca2021-02-11T00:07:42ZengMDPI AGSymmetry2073-89942021-02-011330430410.3390/sym13020304Fluctuating Asymmetry and Sexual Dimorphism in Human Facial Morphology: A Multi-Variate StudyOmid Ekrami0Peter Claes1Ellen Van Assche2Mark D. Shriver3Seth M. Weinberg4Mary L. Marazita5Susan Walsh6Stefan Van Dongen7Evolutionary Ecology Group, Department of Biology, University of Antwerp, 2610 Antwerp, BelgiumDepartment of Electrical Engineering, ESAT/PSI, KU Leuven, 3000 Leuven, BelgiumEvolutionary Ecology Group, Department of Biology, University of Antwerp, 2610 Antwerp, BelgiumDepartment of Anthropology, Pennsylvania State University, University Park, PA 16801, USACenter for Craniofacial and Dental Genetics, Department of Oral and Craniofacial Sciences, University of Pittsburgh, Pittsburgh, PA 15261, USACenter for Craniofacial and Dental Genetics, Department of Oral and Craniofacial Sciences, University of Pittsburgh, Pittsburgh, PA 15261, USADepartment of Biology, Indiana University Purdue University Indianapolis (IUPUI), Indianapolis, IN 46202, USAEvolutionary Ecology Group, Department of Biology, University of Antwerp, 2610 Antwerp, Belgium(1) 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. (2) Materials and 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. (3) 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. (4) 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.https://www.mdpi.com/2073-8994/13/2/304fluctuating asymmetry3D morphometricssexual dimorphism |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Omid Ekrami Peter Claes Ellen Van Assche Mark D. Shriver Seth M. Weinberg Mary L. Marazita Susan Walsh Stefan Van Dongen |
spellingShingle |
Omid Ekrami Peter Claes Ellen Van Assche Mark D. Shriver Seth M. Weinberg Mary L. Marazita Susan Walsh Stefan Van Dongen Fluctuating Asymmetry and Sexual Dimorphism in Human Facial Morphology: A Multi-Variate Study Symmetry fluctuating asymmetry 3D morphometrics sexual dimorphism |
author_facet |
Omid Ekrami Peter Claes Ellen Van Assche Mark D. Shriver Seth M. Weinberg Mary L. Marazita Susan Walsh Stefan Van Dongen |
author_sort |
Omid Ekrami |
title |
Fluctuating Asymmetry and Sexual Dimorphism in Human Facial Morphology: A Multi-Variate Study |
title_short |
Fluctuating Asymmetry and Sexual Dimorphism in Human Facial Morphology: A Multi-Variate Study |
title_full |
Fluctuating Asymmetry and Sexual Dimorphism in Human Facial Morphology: A Multi-Variate Study |
title_fullStr |
Fluctuating Asymmetry and Sexual Dimorphism in Human Facial Morphology: A Multi-Variate Study |
title_full_unstemmed |
Fluctuating Asymmetry and Sexual Dimorphism in Human Facial Morphology: A Multi-Variate Study |
title_sort |
fluctuating asymmetry and sexual dimorphism in human facial morphology: a multi-variate study |
publisher |
MDPI AG |
series |
Symmetry |
issn |
2073-8994 |
publishDate |
2021-02-01 |
description |
(1) 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. (2) Materials and 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. (3) 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. (4) 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. |
topic |
fluctuating asymmetry 3D morphometrics sexual dimorphism |
url |
https://www.mdpi.com/2073-8994/13/2/304 |
work_keys_str_mv |
AT omidekrami fluctuatingasymmetryandsexualdimorphisminhumanfacialmorphologyamultivariatestudy AT peterclaes fluctuatingasymmetryandsexualdimorphisminhumanfacialmorphologyamultivariatestudy AT ellenvanassche fluctuatingasymmetryandsexualdimorphisminhumanfacialmorphologyamultivariatestudy AT markdshriver fluctuatingasymmetryandsexualdimorphisminhumanfacialmorphologyamultivariatestudy AT sethmweinberg fluctuatingasymmetryandsexualdimorphisminhumanfacialmorphologyamultivariatestudy AT marylmarazita fluctuatingasymmetryandsexualdimorphisminhumanfacialmorphologyamultivariatestudy AT susanwalsh fluctuatingasymmetryandsexualdimorphisminhumanfacialmorphologyamultivariatestudy AT stefanvandongen fluctuatingasymmetryandsexualdimorphisminhumanfacialmorphologyamultivariatestudy |
_version_ |
1724274705763926016 |