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Symmetry
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Symmetry in Human Evolutionary Biology
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Symmetry in Human Evolutionary Biology

A special issue of Symmetry (ISSN 2073-8994).

Deadline for manuscript submissions: closed (30 April 2017) | Viewed by 21634

Special Issue Editor

Prof. Dr. Stefan Van Dongen

E-Mail Website
Guest Editor
Evolutionary Ecology Group, Department of Biology, University of Antwerp, 2610 Antwerp, Belgium
Interests: evolutionary ecology; developmental instability; fluctuating asymmetry; biostatistics; fitness; stress

Special Issue Information

Dear Colleagues,

Evolutionary psychology, the study human behaviour in an evolutionary context, is a relatively young, but extremely exciting area of research. An aspect that has received a great deal of attention over the last few decades is the importance of developmental instability—the inability of an organism to withstand small random perturbations of development leading to asymmetric morphology (fluctuating asymmetry, FA)—in reflecting human health and quality, herewith potentially signalling ‘individual quality’. In addition, in humans with a high degree of lateralisation, some morphological variation is likely to be functional (and not related to developmental instability). Understanding the importance of morphological asymmetry in reflecting individual properties and serving as an honest signal in mate selection thus requires a very subtle approach from both a technical and experimental point of view. The aim of this Special Issue on “Symmetry in Human Evolutionary Biology” is to continue highlighting all aspects of (a)symmetry in the evolutionary history of humans. Research papers, comprehensive reviews, and discussions of theory are especially welcome, but also any other type of paper (communication, technical note, short overview, or comment) will be given attention.

Prof. Dr. Stefan Van Dongen
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Symmetry is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

 

Keywords

  • Developmental instability
  • Morphology
  • Fluctuating asymmetry
  • Directional asymmetry
  • Functional asymmetry
  • Human behavior
  • Evolutionary psychology
  • Mate selection
  • Attractiveness
  • Sexual dimorphism
  • Mating strategies
  • Health
  • Individual quality

Published Papers (5 papers)

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Research

649 KiB  
Article
p-Curve and Selection Methods as Meta-Analytic Supplements for Biologists: A Demonstration of Effect Size Estimation in Studies of Human Fluctuating Asymmetry
by Nicholas M. Grebe, Rachael G. Falcon and Steven W. Gangestad
Symmetry 2017, 9(7), 98; https://doi.org/10.3390/sym9070098 - 27 Jun 2017
Cited by 4 | Viewed by 4091
Abstract
Fluctuating asymmetry is hypothesized to predict developmental instability (DI) and fitness outcomes. While published studies largely support this prediction, publication bias remains an issue. Biologists have increasingly turned to meta-analysis to estimate true support for an effect. Van Dongen and Gangestad (VD&G) performed [...] Read more.
Fluctuating asymmetry is hypothesized to predict developmental instability (DI) and fitness outcomes. While published studies largely support this prediction, publication bias remains an issue. Biologists have increasingly turned to meta-analysis to estimate true support for an effect. Van Dongen and Gangestad (VD&G) performed a meta-analysis on studies of fluctuating asymmetry (FA) and fitness-related qualities in humans. They found an average robust effect size, but estimates varied widely. Recently, psychologists have identified limitations in traditional meta-analyses and popular companion adjustments, and have advocated for alternative meta-analytic techniques. P-curve estimates true mean effects using significant published effects; it also detects the presence of p-hacking (where researchers exploit researcher “degrees of freedom”), not just publication bias. Alternative selection methods also provide a means to estimate average effect size correcting for publication bias, but may better account for heterogeneity in effect sizes and publication decisions than p-curve. We provide a demonstration by performing p-curve and selection method analyses on the set of effects from VD&G. We estimate an overall effect size range (r = 0.08–0.15) comparable to VD&G, but with notable differences between domains and techniques. Results from alternative estimation methods can provide corroborating evidence for, as well as insights beyond, traditional meta-analytic estimates. Full article
(This article belongs to the Special Issue Symmetry in Human Evolutionary Biology)
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254 KiB  
Article
Androgen Levels and Body Size Are Associated with Directional as Well as Fluctuating Asymmetry Patterns in Adult !Kung San and Kavango Males from Northern Namibia
by Sylvia Kirchengast and Kerrin Christiansen
Symmetry 2017, 9(5), 72; https://doi.org/10.3390/sym9050072 - 15 May 2017
Cited by 10 | Viewed by 4789
Abstract
Fluctuating asymmetry is mainly interpreted as an indicator of developmental instability, while directional asymmetry of the upper limbs is associated with handedness. The association patterns between adult androgen levels and fluctuating as well directional asymmetry patterns are still unclear. In the present study, [...] Read more.
Fluctuating asymmetry is mainly interpreted as an indicator of developmental instability, while directional asymmetry of the upper limbs is associated with handedness. The association patterns between adult androgen levels and fluctuating as well directional asymmetry patterns are still unclear. In the present study, the association between adult androgen levels, body size and directional as well as fluctuating asymmetry pattern was tested among !Kung San and Kavango males from northern Namibia. Serum concentrations of testosterone (Tser) and 5α-dihydrotestosterone (DHT) as well as salivary testosterone (Tsal) concentrations were obtained from 114 !Kung San and 136 Kavango men aged 18–40 years. Fluctuating and directional asymmetry were determined from eight paired traits. Signed and unsigned asymmetry, composite fluctuating and directional asymmetry were calculated. !Kung San males surpassed their Kavango counterparts in the directional asymmetry but also in composite directional asymmetry (CDA) significantly. Among !Kung San males, DHT correlated significantly negatively with parameters of fluctuating asymmetry as well as with parameters of directional asymmetry. Free testosterone of the saliva correlated significantly negatively with asymmetry of hand length. Among Kavango males, DHT is negatively associated with foot breadth asymmetry, but positively associated with wrist asymmetry. Although the correlations between asymmetry patterns and androgen levels are weak, it can be concluded that among !Kung San males adult androgen levels are negatively associated with a high quality phenotype. Full article
(This article belongs to the Special Issue Symmetry in Human Evolutionary Biology)
718 KiB  
Article
Developmental Origins of Limb Developmental Instability in Human Fetuses: Many Abnormalities Make the Difference
by Clara M. A. ten Broek, Jessica Bots, Marianna Bugiani, Frietson Galis and Stefan van Dongen
Symmetry 2017, 9(4), 51; https://doi.org/10.3390/sym9040051 - 28 Mar 2017
Cited by 3 | Viewed by 3651
Abstract
Fluctuating asymmetry (FA) is the small random deviation from perfect symmetry in bilateral traits and is often used to assess developmental instability (DI) experienced by organisms. In this study, with a unique dataset of 1389 deceased human fetuses, we investigated the relationship between [...] Read more.
Fluctuating asymmetry (FA) is the small random deviation from perfect symmetry in bilateral traits and is often used to assess developmental instability (DI) experienced by organisms. In this study, with a unique dataset of 1389 deceased human fetuses, we investigated the relationship between abnormal development and human limb FA in different ways, using a more fundamental approach than usually done. We studied whether there is an underlying developmental basis of DI, as measured by FA, by investigating, first, whether limb FA can be attributed to developmental abnormalities associated with specific organ systems, germ layers or patterning processes, and second, whether limb FA increases with increasing number of developmental abnormalities either gradually, or in a threshold-like fashion. Limb FA was found to increase in fetuses with cardiovascular and nervous system abnormalities. Fetuses with ectoderm-derived abnormalities were also found to have significantly higher limb FA, but no other germ layers were found to be associated. We found no significant correlation between specific developmental processes, such as neural crest development, segmentation, midline and left-right patterning and limb FA. Although only some congenital abnormalities were correlated with limb FA, our results do suggest that limb FA increases when an increasing number of organ systems, germ layers or developmental pathways are disrupted. Therefore, we conclude that limb FA is mainly a good indicator for DI in the case of particularly severe perturbations of development and that FA does not reflect the subtler deviations from developmental stability. Full article
(This article belongs to the Special Issue Symmetry in Human Evolutionary Biology)
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1159 KiB  
Communication
Changes of Fluctuating Asymmetry with Age in Human Fetuses and Young Infants
by Stefan Van Dongen, Claartje Ten Broek, Jessica Bots and Frietson Galis
Symmetry 2017, 9(3), 44; https://doi.org/10.3390/sym9030044 - 21 Mar 2017
Cited by 3 | Viewed by 4130
Abstract
(1) Background: Developmental instability (DI), often measured by fluctuating asymmetry (FA), increases with stress in humans, yet little is known about how stress affects the changes of asymmetry with age. More specifically, it is unknown if fetuses experiencing a major congenital abnormality will [...] Read more.
(1) Background: Developmental instability (DI), often measured by fluctuating asymmetry (FA), increases with stress in humans, yet little is known about how stress affects the changes of asymmetry with age. More specifically, it is unknown if fetuses experiencing a major congenital abnormality will express higher FA already during early development or only at a later age; (2) Methods: We combine two datasets to study associations between age and asymmetry in human fetuses and young infants. One population consists of fetuses from spontaneous abortions and early deceased infants where many experienced major congenital abnormalities, and a second from elicited abortions for social reasons; (3) Results: While the occurrence of major abnormalities did not seem to affect the way asymmetry decreased with age, differences between the two populations were observed; and (4) Conclusions: In one population where fetuses and young infants deceased of natural causes, asymmetry decreased rapidly until 20 weeks of age and then leveled off. Over the entire timespan (week 15–49), individuals with major congenital abnormalities showed higher FA, suggesting that developmental perturbations increase FA rapidly. In the second, more normal population with abortions solicited for social reasons, the decrease in asymmetry with age was less profound and not statistically significant, calling for further research toward understanding regional differences. Full article
(This article belongs to the Special Issue Symmetry in Human Evolutionary Biology)
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2839 KiB  
Article
Age-Dependent Sexually-Dimorphic Asymmetric Development of the Ferret Cerebellar Cortex
by Kazuhiko Sawada and Ichio Aoki
Symmetry 2017, 9(3), 40; https://doi.org/10.3390/sym9030040 - 14 Mar 2017
Cited by 5 | Viewed by 4367
Abstract
A three-dimensional (3D) T1-weighted Magnetic Resonance Imaging (MRI) at 7-Tesla system was acquired with a high spatial resolution from fixed brains of male and female ferrets at postnatal days (PDs) 4 to 90, and their age-related sexual difference and laterality were [...] Read more.
A three-dimensional (3D) T1-weighted Magnetic Resonance Imaging (MRI) at 7-Tesla system was acquired with a high spatial resolution from fixed brains of male and female ferrets at postnatal days (PDs) 4 to 90, and their age-related sexual difference and laterality were evaluated by MRI-based ex vivo volumetry. The volume of both left and right sides of cerebellar cortex was larger in males than in females on PD 10 and thereafter. When the cerebellar cortex was divided into four transverse domains, i.e., anterior zone (AZ; lobules I–V), central zone (CZ; lobules VI and VII), posterior zone (PZ; lobules VIII–IXa), and nodular zone (NZ; lobules IXb and X), an age-related significantly greater volume in males than in females was detected on either side of all four domains on PD 42 and of the AZ on PD 90, but only on the left side of the PZ on PD 90. Regarding the volume laterality, significant leftward asymmetry was obtained in the CZ and PZ volumes in males, but not in females on PD 90. From asymmetry quotient (AQ) analysis, AQ scores were rightward in the AZ in both sexes already on PD 21, but gradually left-lateralized only in males in the CZ, PZ, and NZ during PDs 42 to 90. The present study suggests that a characteristic counterclockwise torque asymmetry (rostrally right-biased, and caudally left-biased or symmetrical) is acquired in both sexes of ferrets during PDs 42 to 90, although the leftward laterality of the posterior half of the cerebellum was more enhanced in males. Full article
(This article belongs to the Special Issue Symmetry in Human Evolutionary Biology)
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