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Oguz B, Desdicioglu K, Tutuk V. Comparative morphometric analyses of the 2:4 finger ratio and nasal structure in young adults. Anat Sci Int 2024:10.1007/s12565-024-00792-4. [PMID: 39098845 DOI: 10.1007/s12565-024-00792-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Accepted: 07/23/2024] [Indexed: 08/06/2024]
Abstract
The 2:4 finger ratio (2D:4D ratio) refers to the length ratio of the second to the fourth finger of the hand. Studies on the 2D:4D ratio have long established that this ratio tends to be lower in males than in females. Our study aims to investigate the correlation between the 2.4 finger ratio and nasal structure among young adults aged 18-25 through detailed morphometric analysis. The study was conducted on 205 students (Female:127, Male:78) aged between 18 and 25 years studying at Ankara Yıldırım Beyazıt University Faculty of Medicine. Morphometric measurements of the hand and nose were also measured and recorded by the same researcher. The volunteers were divided into eight groups for age and four groups for BMI. Statistical analysis was performed and p < 0.05 was considered significant. The evaluation revealed significant differences between sexes and the 2D:4D ratio. While no significant relationship was found between age and the 2D:4D ratio, correlations were present with some nasal parameters. A significant relationship was found between the BMI and the right hand 2D:4D ratio (p < 0.05). A positive correlation was observed between the BMI and certain nasal parameters. Furthermore, significant relationships were identified between the 2D:4D ratio and certain nasal parameters (p < 0.05). The data obtained from our study will contribute to the understanding of nasal development, sex determination in forensic medicine, and the diagnosis and treatment of pathologies related to the nose. Additionally, it will assist clinicians involved in planning any nasal operations in describing anatomical points related to this region.
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Affiliation(s)
- Buket Oguz
- Faculty of Medicine, Department of Anatomy, Ankara Yıldırım Beyazıt University, Ankara, Turkey.
| | - Kadir Desdicioglu
- Faculty of Medicine, Department of Anatomy, Ankara Yıldırım Beyazıt University, Ankara, Turkey
| | - Vahide Tutuk
- Faculty of Medicine, Department of Anatomy, Ankara Yıldırım Beyazıt University, Ankara, Turkey
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2
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Ernsten L, Körner LM, Heil M, Schaal NK. The association between 2D:4D digit ratio and sex-typed play in children with and without siblings. Sci Rep 2024; 14:15231. [PMID: 38956189 PMCID: PMC11219774 DOI: 10.1038/s41598-024-65739-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Accepted: 06/24/2024] [Indexed: 07/04/2024] Open
Abstract
The 2D:4D digit ratio is commonly used as a surrogate possibly reflecting prenatal testosterone levels. Indirect evidence comes from studies investigating the association between 2D:4D and human characteristics that likely relate to prenatal testosterone. In children, sex-typed play reveals large sex differences early in development and an influence of prenatal testosterone is likely. Findings on the association between 2D:4D and children's sex-typed play are heterogeneous and other influences on the development of sex-typed play have been suggested, most of all social influences like siblings, their sex and birth order. The current study examined the association between right and left 2D:4D, a proposed surrogate for prenatal testosterone exposure, which was assessed in right and left hands of N = 505 6-month-old children, and sex-typed play behavior, which was evaluated 3.5 years later using the Pre-School Activities Inventory (PSAI), and the influence of siblings. To capture differential effects of siblings' sex and birth order, dummy-coded variables were used reflecting having no siblings as well as older or younger sisters or brothers. Multiple regression models were used to investigate the association between PSAI scores and sex, right and left 2D:4D, being a singleton as well as having an older or younger sister or brother. It was shown that sex and having an older brother were significant predictors for sex-typed play. Effects were further disentangled by conducting separate regression analyses in boys and girls. In boys, a significant association between PSAI scores and having an older brother was revealed, in girls, no significant associations were found. Results are discussed highlighting the non-significant association between 2D:4D and children's sex-typed play, which weakens the applicability of 2D:4D as a surrogate reflecting influences of prenatal T. Further, the importance of social factors like siblings on children's sex-typed play is discussed.
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Affiliation(s)
- Luisa Ernsten
- Faculty of Mathematics and Natural Sciences, Institute of Experimental Psychology, Heinrich Heine University, Düsseldorf, Germany.
| | - Lisa M Körner
- Faculty of Mathematics and Natural Sciences, Institute of Experimental Psychology, Heinrich Heine University, Düsseldorf, Germany
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, University Children's Hospital, Medical Faculty and University Hospital Düsseldorf, Heinrich Heine University, Düsseldorf, Germany
| | - Martin Heil
- Faculty of Mathematics and Natural Sciences, Institute of Experimental Psychology, Heinrich Heine University, Düsseldorf, Germany
| | - Nora K Schaal
- Faculty of Mathematics and Natural Sciences, Institute of Experimental Psychology, Heinrich Heine University, Düsseldorf, Germany
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3
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Osadchuk LV, Vasiliev GV, Osadchuk AV. Associations of CAG repeat polymorphism in the androgen receptor gene with steroid hormone levels and anthropometrics among men: the role of the ethnic factor. Vavilovskii Zhurnal Genet Selektsii 2024; 28:80-89. [PMID: 38469358 PMCID: PMC10926003 DOI: 10.18699/vjgb-24-10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 06/13/2023] [Accepted: 06/17/2023] [Indexed: 03/13/2024] Open
Abstract
Androgens are required for stimulation and maintenance of skeletal growth and bone homeostasis. Physiological functions of androgens are mediated through the androgen receptor (AR). The androgen receptor gene AR has a polymorphic trinucleotide CAG repeat and the length of AR CAG repeats determining the sensitivity of bone tissue to androgens is associated with skeleton formation and body proportions. This study aimed to investigate the relationship between AR CAG repeat polymorphism, circulating sex steroid hormones and the anthropometrics in males of different ethnic origins. Male volunteers of three ethnic groups (Slavs, Buryats, Yakuts) from urban Russian populations were recruited in a population-based study (n = 1078). Anthropometric indicators (height, arm span, leg length, the length of 2 and 4 digits of both hands) were measured and the following anthropometric indices were calculated: the ratio of height to leg length, the ratio of arm span to height, the ratio of lengths of second to fourth digit of the hand. Serum testosterone and estradiol were determined by enzyme immunoassay. Genotyping of the AR CAG repeats was performed using fragment analysis and capillary electrophoresis. Ethnic differences in all anthropometric and hormonal indicators have been established, with higher anthropometric indicators in Slavs than Buryats, and in most cases higher than in Yakuts. The testosterone level was higher among Slavs compared to Buryats, but did not differ from Yakuts; the estradiol level was lower among Slavs compared to Buryats, who did not differ from Yakuts. Buryats and Yakuts had a higher number of CAG repeats than Slavs (medians: Slavs, 23; Buryats, 24; Yakuts, 25). Positive correlations were found between the length of AR CAG repeats and estradiol levels in Buryats and testosterone levels in Yakuts, while longer CAG repeats were accompanied by higher estradiol levels in Buryats and testosterone levels in Slavs and Yakuts. Ethnic-specific correlations have been established between the steroid hormone levels and some anthropometric indicators in all ethnic groups. Available data suggest that the ethnic-specific associations of AR CAG repeats with anthropometrics can be mediated by sex steroid hormones as important regulators of skeletal growth and bone homeostasis.
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Affiliation(s)
- L V Osadchuk
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - G V Vasiliev
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - A V Osadchuk
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
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Banyeh M, Mayeem BN, Woli MK, Kolekang AS, Dagungong CB, Bure D, Wemegah RK, Azindow MI, Yakubu S, Seidu M, Baba MM, Essoun E, Owireduwaa N. Exploring Hematological and Biochemical Disparities in Same-Sex and Opposite-Sex Females: A Cross-Sectional Twin Study in a Ghanaian Population. Twin Res Hum Genet 2024; 27:50-55. [PMID: 38444332 DOI: 10.1017/thg.2024.7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2024]
Abstract
There are sex-dependent differences in hematological and biochemical variables in adulthood attributed to the predominant effects of testosterone in males and estrogen in females. The Twin Testosterone Transfer (TTT) hypothesis proposes that opposite-sex females may develop male-typical traits due to exposure to relatively higher levels of prenatal testosterone than same-sex females. Additionally, prenatal testosterone exposure has been suggested as a correlate of current circulating testosterone levels. Consequently, opposite-sex females might exhibit male-typical patterns in their hematological and biochemical variables. Despite this hypothesis, routine laboratory investigations assign the same reference range to all females. Our cross-sectional study, conducted in Tamale from January to September 2022, included 40 twins, comprising 10 opposite-sex (OS) males (25%), 10 OS females (25%), and 20 same-sex (SS) females (50%), all aged between 18 and 27 years. Fasting venous blood samples were collected and analyzed using automated hematology and biochemistry laboratory analyzers. Results indicated that levels of hemoglobin, serum creatinine, gamma-glutamyl transferase, total protein, globulins, and total testosterone were significantly higher in OS males than OS females. Conversely, total cholesterol and low-density lipoprotein cholesterol were significantly higher in OS females than OS males. Unexpectedly, levels of low-density lipoprotein cholesterol and total testosterone were significantly higher in SS females than OS females. Contrary to expectations, opposite-sex females did not exhibit male-typical patterns in their hematological and biochemical variables. This suggests that the TTT effect may not occur or may not be strong enough to markedly affect hematological and biochemical variables in OS females.
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Affiliation(s)
- Moses Banyeh
- Department of Biomedical Laboratory Science, University for Development Studies, Tamale, Ghana
| | - Benjamin N Mayeem
- Department of Medical Laboratory, Living Waters Hospital, Ejisu-krapa, Kumasi, Ghana
| | - Moses Kofi Woli
- Department of Medical Diagnostics, College of Health and Well-Being, Kintampo, Ghana
| | - Augusta S Kolekang
- Department of Epidemiology, Biostatistics and Disease Control, University for Development Studies, Tamale, Ghana
| | | | - David Bure
- Department of Biomedical Laboratory Science, University for Development Studies, Tamale, Ghana
| | - Romarick Kofi Wemegah
- Department of Biomedical Laboratory Science, University for Development Studies, Tamale, Ghana
| | - Mikail Ihsan Azindow
- Department of Biomedical Laboratory Science, University for Development Studies, Tamale, Ghana
| | - Suleman Yakubu
- Department of Biomedical Laboratory Science, University for Development Studies, Tamale, Ghana
| | - Musah Seidu
- Department of Biomedical Laboratory Science, University for Development Studies, Tamale, Ghana
| | - Mohammed Madde Baba
- Department of Biomedical Laboratory Science, University for Development Studies, Tamale, Ghana
| | - Elisha Essoun
- Department of Biomedical Laboratory Science, University for Development Studies, Tamale, Ghana
| | - Nancy Owireduwaa
- Department of Biomedical Laboratory Science, University for Development Studies, Tamale, Ghana
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Sorokowski P, Kowal M. Relationship between the 2D:4D and prenatal testosterone, adult level testosterone, and testosterone change: Meta-analysis of 54 studies. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2024; 183:20-38. [PMID: 37795916 DOI: 10.1002/ajpa.24852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 08/29/2023] [Accepted: 09/12/2023] [Indexed: 10/06/2023]
Abstract
The ratio between the hands' second to the fourth finger (2D:4D) is commonly hypothesized to result from prenatal testosterone. The 2D:4D has also been hypothesized to relate to adult-level testosterone and, more recently, to the testosterone response to a challenging situation. In the present work, we tested these core assumptions. Drawing from, in total, 54 studies and 8077 participants, we investigated whether the 2D:4D is related to adult level testosterone (44 studies), testosterone change (6 studies), and prenatal testosterone (10 studies). We found no evidence of the relationship between the above testosterone types and digit ratios. Furthermore, there was no relationship between testosterone and the right and left 2D:4D, male and female 2D:4D, and the 2D:4D and testosterone measurement (i.e., measured in blood or saliva). However, we found some evidence that prenatal testosterone measured in amniotic fluid (but not cord blood) might be related to the digit ratios-further studies are necessary to validate this observation. In summary, considering the current state of knowledge, any conclusions drawn from the assumption of the digit ratios as the proxy for testosterone (prenatal, adult level, or testosterone change under a challenging situation) warrant great caution.
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Affiliation(s)
| | - Marta Kowal
- IDN Being Human Lab, University of Wrocław, Wrocław, Poland
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Luoto S. Understanding the Biodevelopment of Sexual Orientation Requires a Multilevel Evolutionary Analysis. ARCHIVES OF SEXUAL BEHAVIOR 2023; 52:3001-3006. [PMID: 36575266 DOI: 10.1007/s10508-022-02515-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 12/19/2022] [Accepted: 12/20/2022] [Indexed: 06/17/2023]
Affiliation(s)
- Severi Luoto
- School of Population Health, University of Auckland, 1023, Auckland, New Zealand.
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7
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Siegmann EM, Eichler A, Buchholz VN, Gerlach J, Pontones CA, Titzmann A, Arnaud N, Consortium IMACM, Mühle C, Beckmann MW, Fasching PA, Kratz O, Moll GH, Kornhuber J, Lenz B. Effects of an App-Based Mindfulness Intervention during Pregnancy on the Infant's Prenatal Androgen Exposure: A Randomized Controlled Pilot Trial. J Clin Med 2023; 12:6142. [PMID: 37834786 PMCID: PMC10573842 DOI: 10.3390/jcm12196142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 09/18/2023] [Accepted: 09/20/2023] [Indexed: 10/15/2023] Open
Abstract
Prenatal androgen exposure modulates the development of the brain, with lasting effects on its function and behavior over the infant's life span. Environmental factors during pregnancy, in particular maternal stress, have been shown to influence the androgen load of the unborn child. We here addressed the research gap on whether a mindfulness intervention or a pregnancy education administered to pregnant women more affects the androgen exposure of the unborn child (quantified by the proxies of second-to-fourth digit length ratio (2D:4D) and anogenital distance assessed one year after delivery and at delivery, respectively). Moreover, we tested the mindfulness intervention's effects on maternal perceived stress, anxiety, depressiveness, and mindfulness. Pregnant women (gestation weeks 8-14) were randomized to a 15-week app-based mindfulness-oriented intervention (N = 72) or a pregnancy education intervention (control condition; N = 74). The mindfulness-oriented group did not significantly differ from the pregnancy education group in infants' 2D:4D or anogenital distance (partial η2 ≤ 0.01) or in maternal stress, anxiety, depressiveness, or mindfulness. However, the descriptive results indicate that across pregnancy, stress and anxiety decreased and mindfulness increased in both groups. Overall, this study did not show that the mindfulness intervention (relative to the pregnancy education) reduced the prenatal androgen exposure of the unborn children or improved the maternal outcomes significantly.
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Affiliation(s)
- Eva-Maria Siegmann
- Department of Psychiatry and Psychotherapy, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Anna Eichler
- Department of Child and Adolescent Mental Health, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Verena Nadine Buchholz
- Department of Psychiatry and Psychotherapy, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Jennifer Gerlach
- Department of Child and Adolescent Mental Health, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Constanza A. Pontones
- Department of Obstetrics and Gynecology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Adriana Titzmann
- Department of Obstetrics and Gynecology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Nicolas Arnaud
- German Centre for Addiction Research in Childhood and Adolescence, University Medical Centre Hamburg–Eppendorf, 20246 Hamburg, Germany
| | | | - Christiane Mühle
- Department of Psychiatry and Psychotherapy, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Matthias W. Beckmann
- Department of Obstetrics and Gynecology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Peter A. Fasching
- Department of Obstetrics and Gynecology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Oliver Kratz
- Department of Child and Adolescent Mental Health, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Gunther H. Moll
- Department of Child and Adolescent Mental Health, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Johannes Kornhuber
- Department of Psychiatry and Psychotherapy, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
| | - Bernd Lenz
- Department of Psychiatry and Psychotherapy, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany
- Department of Addictive Behavior and Addiction Medicine, Central Institute of Mental Health (CIMH), Medical Faculty Mannheim, Heidelberg University, 68159 Mannheim, Germany
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Kheloui S, Jacmin-Park S, Larocque O, Kerr P, Rossi M, Cartier L, Juster RP. Sex/gender differences in cognitive abilities. Neurosci Biobehav Rev 2023; 152:105333. [PMID: 37517542 DOI: 10.1016/j.neubiorev.2023.105333] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 07/09/2023] [Accepted: 07/27/2023] [Indexed: 08/01/2023]
Abstract
Sex/gender differences in cognitive sciences are riddled by conflicting perspectives. At the center of debates are clinical, social, and political perspectives. Front and center, evolutionary and biological perspectives have often focused on 'nature' arguments, while feminist and constructivist views have often focused on 'nurture arguments regarding cognitive sex differences. In the current narrative review, we provide a comprehensive overview regarding the origins and historical advancement of these debates while providing a summary of the results in the field of sexually polymorphic cognition. In so doing, we attempt to highlight the importance of using transdisciplinary perspectives which help bridge disciplines together to provide a refined understanding the specific factors that drive sex differences a gender diversity in cognitive abilities. To summarize, biological sex (e.g., birth-assigned sex, sex hormones), socio-cultural gender (gender identity, gender roles), and sexual orientation each uniquely shape the cognitive abilities reviewed. To date, however, few studies integrate these sex and gender factors together to better understand individual differences in cognitive functioning. This has potential benefits if a broader understanding of sex and gender factors are systematically measured when researching and treating numerous conditions where cognition is altered.
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Affiliation(s)
- Sarah Kheloui
- Department of Psychiatry and Addiction, University of Montreal, Montreal, Quebec, Canada; Department of Psychology, Université du Québec à Montréal, Montreal, Quebec, Canada; Centre de recherche de l'Institut universitaire en santé mentale de Montréal, Canada; Center on Sex⁎Gender, Allostasis and Resilience, Canada
| | - Silke Jacmin-Park
- Department of Psychology, University of Montreal, Montreal, Quebec, Canada; Department of Psychology, Université du Québec à Montréal, Montreal, Quebec, Canada; Centre de recherche de l'Institut universitaire en santé mentale de Montréal, Canada; Center on Sex⁎Gender, Allostasis and Resilience, Canada
| | - Ophélie Larocque
- Department of Psychology, University of Montreal, Montreal, Quebec, Canada; Department of Psychology, Université du Québec à Montréal, Montreal, Quebec, Canada; Centre de recherche de l'Institut universitaire en santé mentale de Montréal, Canada; Center on Sex⁎Gender, Allostasis and Resilience, Canada
| | - Philippe Kerr
- Department of Psychiatry and Addiction, University of Montreal, Montreal, Quebec, Canada; Department of Psychology, Université du Québec à Montréal, Montreal, Quebec, Canada; Centre de recherche de l'Institut universitaire en santé mentale de Montréal, Canada; Center on Sex⁎Gender, Allostasis and Resilience, Canada
| | - Mathias Rossi
- Department of Psychiatry and Addiction, University of Montreal, Montreal, Quebec, Canada; Department of Psychology, Université du Québec à Montréal, Montreal, Quebec, Canada; Centre de recherche de l'Institut universitaire en santé mentale de Montréal, Canada; Center on Sex⁎Gender, Allostasis and Resilience, Canada
| | - Louis Cartier
- Department of Psychiatry and Addiction, University of Montreal, Montreal, Quebec, Canada; Department of Psychology, Université du Québec à Montréal, Montreal, Quebec, Canada; Centre de recherche de l'Institut universitaire en santé mentale de Montréal, Canada; Center on Sex⁎Gender, Allostasis and Resilience, Canada
| | - Robert-Paul Juster
- Department of Psychiatry and Addiction, University of Montreal, Montreal, Quebec, Canada; Department of Psychology, Université du Québec à Montréal, Montreal, Quebec, Canada; Centre de recherche de l'Institut universitaire en santé mentale de Montréal, Canada; Center on Sex⁎Gender, Allostasis and Resilience, Canada.
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Lenz B, Gerhardt S, Boroumand-Jazi R, Eichler A, Buchholz VN, Fasching PA, Kornhuber J, Banaschewski T, Flor H, Guldner S, Prignitz M, Nees F. Sex-specific association between prenatal androgenization (second-to-fourth digit length ratio) and frontal brain volumes in adolescents. Eur Arch Psychiatry Clin Neurosci 2023; 273:1243-1254. [PMID: 36449103 PMCID: PMC10449726 DOI: 10.1007/s00406-022-01515-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 10/26/2022] [Indexed: 12/03/2022]
Abstract
Prenatal androgenization associates sex-dependently with behavior and mental health in adolescence and adulthood, including risk-taking, emotionality, substance use, and depression. However, still little is known on how it affects underlying neural correlates, like frontal brain control regions. Thus, we tested whether prenatal androgen load is sex-dependently related to frontal cortex volumes in a sex-balanced adolescent sample. In a cross-sectional magnetic resonance imaging study, we examined 61 adolescents (28 males, 33 females; aged 14 or 16 years) and analyzed associations of frontal brain region volumes with the second-to-fourth digit length ratio (2D:4D), an established marker for prenatal androgenization, using voxel-based morphometry in a region-of-interest approach. Lower 2D:4D (indicative of higher prenatal androgen load) correlated significantly with smaller volumes of the right anterior cingulate cortex (r-ACC; β = 0.45) in male adolescents and with larger volumes of the left inferior frontal gyrus orbital part (l-IFGorb; β = - 0.38) in female adolescents. The regression slopes of 2D:4D on the r-ACC also differed significantly between males and females. The study provides novel evidence that prenatal androgenization may influence the development of the frontal brain in a sex- and frontal brain region-specific manner. These effects might contribute to the well-known sex differences in risk-taking, emotionality, substance use, and depression. Future research is needed to elucidate the role of prenatal androgenization within the biopsychosocial model.
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Affiliation(s)
- Bernd Lenz
- Department of Addictive Behavior and Addiction Medicine, Central Institute of Mental Health (CIMH), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
| | - Sarah Gerhardt
- Department of Addictive Behavior and Addiction Medicine, Central Institute of Mental Health (CIMH), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Rafat Boroumand-Jazi
- Department of Addictive Behavior and Addiction Medicine, Central Institute of Mental Health (CIMH), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Anna Eichler
- Department of Child and Adolescent Mental Health, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Verena Nadine Buchholz
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Peter A Fasching
- Department of Obstetrics and Gynecology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Johannes Kornhuber
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Tobias Banaschewski
- Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health (CIMH), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Herta Flor
- Institute of Cognitive and Clinical Neuroscience, Central Institute of Mental Health (CIMH), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Stella Guldner
- Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health (CIMH), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Institute of Cognitive and Clinical Neuroscience, Central Institute of Mental Health (CIMH), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Maren Prignitz
- Institute of Cognitive and Clinical Neuroscience, Central Institute of Mental Health (CIMH), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Frauke Nees
- Department of Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health (CIMH), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Institute of Cognitive and Clinical Neuroscience, Central Institute of Mental Health (CIMH), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Institute of Medical Psychology and Medical Sociology, University Medical Center Schleswig Holstein, Kiel University, Kiel, Germany
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10
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Banyeh M, Kangkpi T, Bani SB, Zogli KE, Tanko MM, Atuahene PE, Iddrisu AY, Ekor C, Akoto EO, Amidu N. Are sex differences in blood cell count and hemoglobin moderated by the 2D:4D ratio? A cross-sectional study in a Ghanaian population. Health Sci Rep 2023; 6:e1547. [PMID: 37670848 PMCID: PMC10476464 DOI: 10.1002/hsr2.1547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 08/02/2023] [Accepted: 08/22/2023] [Indexed: 09/07/2023] Open
Abstract
Background and Aims There are sex differences in blood cell count and hemoglobin (HGB) in adulthood due to differences in the levels of circulating sex hormones. The second-to-fourth digit ratio (2D:4D) is the putative marker of prenatal hormone exposure. The 2D:4D or the right-left difference (Dr-l) are sexually dimorphic and are correlates of sex hormones in adulthood. The study sought to determine whether sex differences in adult blood cell count and HGB can be partly explained by the 2D:4D or Dr-l. Methods The study was cross-sectional between June and December 2021 at the University for Development Studies. The study involved 207 healthy participants (females = 113) aged from 18 to 32 years. The right-hand (2D:4DR), and the left-hand (2D:4DL) digit ratio and their difference (Dr-l) were measured using Computer-assisted analysis. Blood cell count, HGB, testosterone, and estradiol were measured from venous blood samples using an automated HGB analyzer and ELIZA technique. Results The platelet count was inversely related to the 2D:4DR in the total sample with the 2D:4DR accounting for about 0.2% (adjR 2 = 0.002) of the variability in platelet count. However, there was a sex difference as indicated by the significant interaction between sex and the 2D:4DR on platelet count (p = 0.03). The relationship between platelet count and the 2D:4DR was negative in females but positive in males. Also, there was a positive relationship between HGB concentration and the Dr-l in the total study sample, where the Dr-l accounted for about 0.6% (adjR 2 = 0.006) of the variability in HGB concentration. Sex interacted significantly with the Dr-l on HGB concentration (p = 0.01) such that the relationship between HGB and the Dr-l was positive in females but negative in males. Conclusion Prenatal hormone exposure, as indexed by the 2D:4D ratio, may partly account for the observed sex differences in platelet count and HGB levels in adulthood.
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Affiliation(s)
- Moses Banyeh
- Department of Biomedical Laboratory ScienceUniversity for Development StudiesTamaleGhana
| | - Thea Kangkpi
- Department of Biomedical Laboratory ScienceUniversity for Development StudiesTamaleGhana
| | - Simon B. Bani
- Department of Biomedical Laboratory ScienceUniversity for Development StudiesTamaleGhana
| | - Kervin Edinam Zogli
- Department of Biomedical Laboratory ScienceUniversity for Development StudiesTamaleGhana
| | - Muniru Mohammed Tanko
- Department of Biomedical Laboratory ScienceUniversity for Development StudiesTamaleGhana
| | - Peter Eugene Atuahene
- Department of Biomedical Laboratory ScienceUniversity for Development StudiesTamaleGhana
| | - Aisha Yaaba Iddrisu
- Department of Biomedical Laboratory ScienceUniversity for Development StudiesTamaleGhana
| | - Christine Ekor
- Department of Biomedical Laboratory ScienceUniversity for Development StudiesTamaleGhana
| | - Emmanuel Osei Akoto
- Department of Biomedical Laboratory ScienceUniversity for Development StudiesTamaleGhana
| | - Nafiu Amidu
- Department of Biomedical Laboratory ScienceUniversity for Development StudiesTamaleGhana
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Siegmann EM, Olm P, Lenz B, Mühle C, Oberstein TJ, Maler JM, Kornhuber J. Digit Ratio (2D:4D) Is Not Associated with Alzheimer's Disease in the Elderly. Brain Sci 2023; 13:1229. [PMID: 37759830 PMCID: PMC10526128 DOI: 10.3390/brainsci13091229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 08/15/2023] [Accepted: 08/19/2023] [Indexed: 09/29/2023] Open
Abstract
The development of Alzheimer's disease (AD) is influenced by sex hormones-estrogens and androgens in particular. However, the impact of prenatal sex hormone exposure is less clear; very few investigations have examined the relationship between the second-to-fourth digit length ratio (2D:4D), a putative proxy for the ratio of prenatal estrogens to androgens, and AD, with inconsistent results among the few that have. Therefore, we aimed to investigate this relationship using methodologically robust metrics. In a 2 (sex) × 4 (group) MANOVA incorporating 108 participants (30 AD patients, 19 patients with tauopathy but no amyloidopathy, 31 clinical and 28 healthy age- and education-matched controls), the effects of sex and group on the dependent variables right and left 2D:4D were examined. We also explored the association between 2D:4D and the severity of AD symptoms assessed via neuropsychological examination. We did not find any significant differences in the right- and left-hand 2D:4D between patients with AD and the other groups; no significant associations between 2D:4D and neuropsychological task performances were found in the dementia groups. The 2D:4D of healthy women was significantly lower than that of depressed women without AD, i.e., clinical controls, but not significantly different from depressed female patients with AD. This investigation does not support the role of 2D:4D in the development or severity of AD in general, but suggests a potential role of 2D:4D for depression in women. Future studies are warranted to clarify whether 2D:4D can distinguish between early- and late-onset depression in women.
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Affiliation(s)
- Eva-Maria Siegmann
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 6, 91054 Erlangen, Germany
| | - Pauline Olm
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 6, 91054 Erlangen, Germany
| | - Bernd Lenz
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 6, 91054 Erlangen, Germany
- Department of Addictive Behavior and Addiction Medicine, Central Institute of Mental Health (CIMH), Medical Faculty Mannheim, Heidelberg University, 68159 Mannheim, Germany
| | - Christiane Mühle
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 6, 91054 Erlangen, Germany
| | - Timo Jan Oberstein
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 6, 91054 Erlangen, Germany
| | - Juan Manuel Maler
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 6, 91054 Erlangen, Germany
| | - Johannes Kornhuber
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 6, 91054 Erlangen, Germany
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12
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Lupu DC, Monedero I, Rodriguez-Ruiz C, Pita M, Turiegano E. In support of 2D:4D: More data exploring its conflicting results on handedness, sexual orientation and sex differences. PLoS One 2023; 18:e0280514. [PMID: 37607180 PMCID: PMC10443882 DOI: 10.1371/journal.pone.0280514] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 12/28/2022] [Indexed: 08/24/2023] Open
Abstract
In the last few years, several studies have questioned the value of the second-to-fourth digit ratio (2D:4D) as a measure of exposure to sex hormones before birth. Controversy has also extended to the 2D:4D association with individual features previously related to this exposure such as handedness and sexual orientation. Given that it has been argued that sex differences in 2D:4D could be a consequence of body-size differences, we have tested in a large sample the allometric relationship between finger lengths and body size. Our results show that the association is either allometric or isometric, depending on the analyses performed. In any case, the deviation from isometry is not large enough to explain the typically observed sex difference in this trait. We have also tested the association between sexual orientation and 2D:4D, finding a relationship between 2D:4D and sexual orientation in men but not in women. We attribute this discordance with previously published meta-analysis to differences in genetic background, a variable that has gained relevance in recent years in studies involving 2D:4D. Finally, we did not find any relationship between 2D:4D and handedness, evaluated through self-reported preference and hand performance. Our main conclusion is that 2D:4D shows differences between sexes beyond their disparity in body size. In our opinion, 2D:4D can be used cautiously as an indicator of intrauterine exposure to sex hormones taking into account some considerations, such as analysing a very large sample and taking careful measurements of the ethnicity of the sample.
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Affiliation(s)
| | - Ignacio Monedero
- Departamento de Fisiología, Universidad Autónoma de Madrid, Madrid, España
| | | | - Miguel Pita
- Departamento de Biología, Universidad Autónoma de Madrid, Madrid, España
| | - Enrique Turiegano
- Departamento de Biología, Universidad Autónoma de Madrid, Madrid, España
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Yan X, Zhu A, Li Y, Yang Z, Wang Y, Liu L, Liu W, Liu D, Li F, Du J, Cheng F, Gao X, Zhao J. Systematical assessment of digit ratio in a female masculinization disease: polycystic ovary syndrome. Front Endocrinol (Lausanne) 2023; 14:1146124. [PMID: 37223048 PMCID: PMC10202172 DOI: 10.3389/fendo.2023.1146124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 03/30/2023] [Indexed: 05/25/2023] Open
Abstract
Background In recent years, the right ratio of 2nd and 4th digit length (2D:4D) is regarded as an anatomical marker of prenatal testosterone exposure. Polycystic ovary syndrome (PCOS) is a female masculinized disease and is determined by prenatal testosterone exposure. Whether the ratio in the right hand of PCOS women is reduced or not compared with non-PCOS women is under debate. To further investigate the relationship between PCOS and digit ratio, we systematically measured all the digit ratios. Methods We recruited 34 non-PCOS women, 116 PCOS women, and 40 men and systematically measured all the ratios of digit length (2D:3D, 2D:4D, 2D:5D, 3D:4D, 3D:5D, and 4D:5D) of right hands and left hands. Results Left 2D:3D, 2D:4D, and 2D:5D in men were significantly lower than those in non-PCOS women. Significantly lower digit ratios of left 2D:3D and 2D:4D were observed in PCOS compared with non-PCOS women. In the subgroup analysis, the left ratio of digit length in 2D:3D and 2D:5D of the hyperandrogenism subgroup was lower than that of the non-hyperandrogenism subgroup without statistical significance. The logistic regression model of PCOS revealed that 2D:3D, 2D:4D, 2D:5D, and 3D:4D of left hands were statistically related to the diagnosis of PCOS among all the digit ratios. Conclusion Not only 2D:4D but also other digit ratios, such as 2D:3D and 2D:5D, are a marker of prenatal testosterone exposure and may be an anatomical marker of PCOS. The majority of these significant differences included left 2D, with the following order: non-PCOS women > PCOS women > men.
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Affiliation(s)
- Xueqi Yan
- Center for Reproductive Medicine, Shandong University, Jinan, Shandong, China
- Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, Shandong, China
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Shandong University, Jinan, Shandong, China
- Shandong Technology Innovation Center for Reproductive Health, Shandong University, Jinan, Shandong, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, China
| | - Aiqing Zhu
- Center for Reproductive Medicine, Shandong University, Jinan, Shandong, China
- Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, Shandong, China
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Shandong University, Jinan, Shandong, China
- Shandong Technology Innovation Center for Reproductive Health, Shandong University, Jinan, Shandong, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, China
| | - Yexing Li
- Center for Reproductive Medicine, Shandong University, Jinan, Shandong, China
- Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, Shandong, China
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Shandong University, Jinan, Shandong, China
- Shandong Technology Innovation Center for Reproductive Health, Shandong University, Jinan, Shandong, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, China
| | - Ziyi Yang
- Center for Reproductive Medicine, Shandong University, Jinan, Shandong, China
- Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, Shandong, China
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Shandong University, Jinan, Shandong, China
- Shandong Technology Innovation Center for Reproductive Health, Shandong University, Jinan, Shandong, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, China
| | - Yuteng Wang
- Center for Reproductive Medicine, Shandong University, Jinan, Shandong, China
- Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, Shandong, China
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Shandong University, Jinan, Shandong, China
- Shandong Technology Innovation Center for Reproductive Health, Shandong University, Jinan, Shandong, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, China
| | - Li Liu
- Department of Reproductive Medicine, Yinchuan Maternal and Child Health Hospital, Yinchuan, Ning xia, China
| | - Wei Liu
- Department of Reproductive Surgery, Northwest Women’s and Children’s Hospital, Xi’an, Shanxi, China
| | - Dan Liu
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, Tang Du Hospital, The Air Force Military Medical University, Xi’an, Shanxi, China
| | - Fenghua Li
- Department of Reproductive Medicine, Yuhuangding Hospital Affiliated to Qingdao University, Yantai, Shandong, China
| | - Juan Du
- Center for Reproductive Medicine, Shandong University, Jinan, Shandong, China
| | - Fang Cheng
- Department of Reproductive Medicine, Yinchuan Maternal and Child Health Hospital, Yinchuan, Ning xia, China
| | - Xueying Gao
- Center for Reproductive Medicine, Shandong University, Jinan, Shandong, China
- Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, Shandong, China
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Shandong University, Jinan, Shandong, China
- Shandong Technology Innovation Center for Reproductive Health, Shandong University, Jinan, Shandong, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, China
- Center for Reproductive Medicine, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Shanghai, China
| | - Junli Zhao
- Reproductive Medicine Center, General Hospital of Ningxia Medical University, Yinchuan, Ningxia, China
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education, Ningxia Medical University, Yinchuan, Ningxia, China
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14
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Ertuğrul B, Aydık MF. No association between developmental instability as a general measure of stress and 2D:4D digit ratios in a non-western sample. Am J Hum Biol 2023; 35:e23860. [PMID: 36602102 DOI: 10.1002/ajhb.23860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2022] [Revised: 12/22/2022] [Accepted: 12/23/2022] [Indexed: 01/06/2023] Open
Abstract
OBJECTIVE Random deviation from perfect symmetry of organisms is defined as fluctuating asymmetry. Fluctuating asymmetry is widely considered to be a marker of developmental instability, developmental noise and phenotypic quality at the population level. In this study, we investigated hypothesized relationship between 2D:4D digit ratios as a proxy measure of prenatal sex hormones and developmental instability levels in young adult humans. MATERIALS AND METHODS In the study, seven bilateral traits were measured for fluctuating asymmetry, as well as second and fourth digit lengths on both hands of 185 individuals, 87 men (mean age: 22.42 ± 3.37) and 97 women (mean age: 22.88 ± 3.87). The second digit length was divided by the fourth digit length and the resulting value was used as the digit ratio (2D:4D). Composite fluctuating asymmetry was calculated using five bilateral traits displaying fluctuating asymmetry. RESULTS Only the right hand 2D:4D ratio is lower in men than in women. However, this difference disappears when the effect of digit lengths is controlled. Composite fluctuating asymmetry results reveal that men are more asymmetrical than women. There was no significant relationship between digit ratios and composite fluctuating asymmetry. CONCLUSION In this study, the 2D:4D digit ratios appear to be influenced (at least in humans) by different digit lengths. This study also confirms previous studies that digit ratios as a proxy measure of exposure to either high testosterone or estrogen levels during early development does not appear to affect levels of developmental instability.
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Affiliation(s)
- Berna Ertuğrul
- Faculty of Literature, Department of Anthropology, İstanbul University, İstanbul, Turkey
| | - Muhammet Fatih Aydık
- Faculty of Literature, Department of Anthropology, İstanbul University, İstanbul, Turkey
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15
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Ernsten L, Körner LM, Schaper ML, Lawrenz J, Richards G, Heil M, Schaal NK. The association of prenatal amniotic sex hormones and digit ratio (2D:4D) in children aged 5 to 70 months: A longitudinal study. PLoS One 2023; 18:e0282253. [PMID: 36952430 PMCID: PMC10035896 DOI: 10.1371/journal.pone.0282253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 02/07/2023] [Indexed: 03/25/2023] Open
Abstract
The sex difference of the 2D:4D digit ratio (female > male)-a proposed marker for prenatal testosterone exposure-is well established. Studies suggest it already exists in utero and is of moderate effect size in adulthood. However, evidence for the claim that 2D:4D reflects prenatal androgen action is limited, and the sex difference may exhibit lability during childhood. In the present study, 244 mothers were recruited in the course of an amniocentesis examination (performed between gestational weeks 14 and 18). Prenatal testosterone (T) and estradiol (E) levels were determined from amniotic fluid for boys and girls. The majority (97.4%, n = 114) of available female T levels (n = 117) were found below the level of quantification. Therefore, only male amniotic fluid data (n = 117) could be included for the analysis of associations between amniotic sex hormones (T levels and T to E ratio (T/E)) and 2D:4D. The families were then invited to each of the five consecutive follow-ups (ages: 5, 9, 20, 40, and 70 months) where children's 2D:4D was measured for both hands. The alternative marker D[r-l] reflects the directional asymmetry of 2D:4D (right subtracted by left 2D:4D) and was subsequently calculated as an additional measure for prenatal T exposure. No significant correlations between amniotic T or the T/E ratio (measured between week 14 and 18 of gestation) with 2D:4D respectively D[r-l] were observed for any time point. There was a significant sex difference (females > males) and a significant age effect with moderate correlations of 2D:4D between time points. 2D:4D increased between 20 and 40 months and between 40 and 70 months of age. The findings raise questions regarding the applicability of 2D:4D as a marker for prenatal androgen action and are discussed in terms of the reliability of obtained digit ratio data as well as in terms of the developmental timing of amniocentesis.
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Affiliation(s)
- Luisa Ernsten
- Department of Experimental Psychology, Heinrich-Heine-University, Düsseldorf, Germany
| | - Lisa M Körner
- Department of Experimental Psychology, Heinrich-Heine-University, Düsseldorf, Germany
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, University Children's Hospital, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Marie Luisa Schaper
- Department of Experimental Psychology, Heinrich-Heine-University, Düsseldorf, Germany
| | - Judith Lawrenz
- Department of Experimental Psychology, Heinrich-Heine-University, Düsseldorf, Germany
| | - Gareth Richards
- School of Psychology, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Martin Heil
- Department of Experimental Psychology, Heinrich-Heine-University, Düsseldorf, Germany
| | - Nora K Schaal
- Department of Experimental Psychology, Heinrich-Heine-University, Düsseldorf, Germany
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16
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Banyeh M, Appiah SK, Abubakari A, Issah M, Amidu N. Sex-moderated relationship between the 2D:4D ratio and circulating hormones in an adult Ghanaian population. Physiol Rep 2023; 11:e15578. [PMID: 36695786 PMCID: PMC9875815 DOI: 10.14814/phy2.15578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 01/02/2023] [Accepted: 01/03/2023] [Indexed: 06/17/2023] Open
Abstract
The second-to-fourth digit ratio (2D:4D) is the putative marker of prenatal hormone exposure. The 2D:4D ratio or the right-left difference (Dr-l) are said to be negative and positive correlates, respectively, of circulating testosterone and estrogen in both adult males and females. However, previous studies on the subject have reported mixed results. This study aimed to determine the sex-moderated relationship between the 2D:4D ratio and adult circulating testosterone, estradiol, testosterone-to-estradiol ratio and the free androgen index. This was a cross-sectional study from January to June 2021 at the University for Development Studies, Ghana. The study involved 62 participants (Female = 28; Male = 34), aged between 20 and 26 years. The right (2D:4DR), the left (2D:4DL), and their difference (Dr-l) were measured by computer-assisted analysis. Fasting venous samples were assayed for total testosterone (T), estradiol (E2 ), and sex hormone-binding globulin (SHBG) using ELISA. The free androgen index (FAI) was then calculated (T/SHBG) and the data were analyzed using moderated and/or weighted regression. Males had significantly higher T and FAI than females while females had significantly higher E2 than males, which were independent of age and body mass index (p < 0.001). There was a significant SEX*Dr-l interaction on FAI (p = 0.007). The Dr-l correlated negatively with FAI in males but positively in females and accounted for about 94.0% of the variability of FAI in males (adjR2 = 0.940) and only 0.2% in females (adjR2 = 0.002). The 2D:4D ratio, a putative marker of prenatal hormone exposure, may have an impact on sex differences in adult free androgen index.
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Affiliation(s)
- Moses Banyeh
- Department of Biomedical Laboratory ScienceUniversity for Development StudiesTamaleGhana
| | - Samuel Kwasi Appiah
- Department of Biomedical Laboratory ScienceUniversity for Development StudiesTamaleGhana
| | - Abdul‐Malawi Abubakari
- Department of Biomedical Laboratory ScienceUniversity for Development StudiesTamaleGhana
| | - Musah Issah
- Department of Biomedical Laboratory ScienceUniversity for Development StudiesTamaleGhana
| | - Nafiu Amidu
- Department of Biomedical Laboratory ScienceUniversity for Development StudiesTamaleGhana
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Levin RN, Erickson-Schroth L, Mak K, Edmiston EK. Biological studies of transgender identity: A critical review. JOURNAL OF GAY & LESBIAN MENTAL HEALTH 2022. [DOI: 10.1080/19359705.2022.2127042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Rachel N. Levin
- Departments of Biology and Neuroscience, Pomona College, Claremont, CA, USA
| | | | - Kristie Mak
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - E. Kale Edmiston
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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Pickering GJ, Anger N, Baird J, Dale G, Tattersall GJ. Use of crowdsourced images for determining 2D:4D and relationship to pro-environmental variables. Acta Ethol 2022; 25:165-178. [PMID: 36097527 PMCID: PMC9452876 DOI: 10.1007/s10211-022-00401-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 06/28/2022] [Accepted: 08/16/2022] [Indexed: 01/02/2023]
Abstract
The primary purpose of this study was to examine whether 2D:4D ratios (a putative measure of prenatal androgen exposure) could be determined using participant-submitted hand images. The secondary purpose was to examine whether 2D:4D ratio was associated with pro-environmental behaviors, attitudes, and empathy, given the recent literature linking sex to environmental attitudes and actions. Participants (N = 1065) were asked via an online survey to submit a clear photograph of their right hand, palm side up. Participants also completed a questionnaire to assess (a) demographics, (b) dispositional empathy, and (c) environmental attitudes and behavior. A 2D:4D ratio was calculated for each participant, and the quality of each image was classified as poor, moderate, or good. We then examined the reliability of the 2D:4D image measurements, and the relationship between 2D:4D and our environmental measures. 2D:4D ratios fell somewhat outside of previously reported ranges, but the measurements did show acceptable intra-rater consistency. Although we did not find a sex difference in 2D:4D, we did find a sex by ratio interaction for both empathy and the number of pro-environmental behaviors in which individuals had engaged. Specifically, as 2D:4D ratio increased, males reported lower empathy and less engagement in pro-environmental behaviors, whereas females reported more engagement in pro-environmental behaviors (but no differences in empathy). These findings were contrary to expectations, as we anticipated that greater digit ratios (i.e., feminized) would be associated with greater empathy and pro-environmental behaviors. Overall, the findings of this study present a preliminary examination of the utility of measuring digit ratio with online samples. Furthermore, our results provide information regarding the complex relationship between sex and pro-environmental behaviors.
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Affiliation(s)
- Gary J. Pickering
- Department of Biological Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON L2S 3A1 Canada
- Psychology Department, Brock University, St. Catharines, Canada
- Environmental Sustainability Research Centre, Brock University, St. Catharines, Canada
- Sustainability Research Centre, University of the Sunshine Coast, Sippy Downs, Australia
| | - Nicholas Anger
- Centre for Digital Humanities, Brock University, St. Catharines, Canada
| | - Julia Baird
- Environmental Sustainability Research Centre, Brock University, St. Catharines, Canada
- Sustainability Research Centre, University of the Sunshine Coast, Sippy Downs, Australia
- Department of Geography and Tourism Studies, Brock University, St. Catharines, Canada
| | - Gillian Dale
- Environmental Sustainability Research Centre, Brock University, St. Catharines, Canada
| | - Glenn J. Tattersall
- Department of Biological Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON L2S 3A1 Canada
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Maternal Age and Behavior during Pregnancy Affect the 2D:4D Digit Ratio in Polish Children Aged 6–13 Years. BIOLOGY 2022; 11:biology11091286. [PMID: 36138765 PMCID: PMC9527011 DOI: 10.3390/biology11091286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 08/23/2022] [Accepted: 08/27/2022] [Indexed: 11/16/2022]
Abstract
Background: The length of the second and fourth finger calculated as a ratio (2D:4D) is a marker of prenatal exposure to sex hormones. Higher exposure to testosterone is related to a lower 2D:4D digit ratio, and inversely, higher exposure to estrogen is related to a higher 2D:4D. The digit ratio in humans (prenatally determined by sex hormone levels and androgen receptor activity) is associated with multiple biological, cognitive, and behavioral traits, as well as health in later life. The aim of this study was to verify if maternal traits during pregnancy are associated with 2D:4D among their children. Methods: We investigated 537 boys, 646 girls, and their mothers. The investigation consisted of a questionnaire and a measurement part. In the questionnaire, we included questions about maternal traits during pregnancy such as: illnesses, active and passive smoking, work activity, psychological trauma (death or serious illness of a loved one, divorce, job loss), and age. We performed length measurements of the second and fourth fingers on both hands for both study groups. Results: The GLM analysis showed that children of smoking mothers were characterized by a higher 2D:4D R as compared to their peers whose mothers did not smoke (β = 0.10, p = 0.0008). In turn, the offspring of women who worked during pregnancy exhibited lower 2D:4D R values than the children of women who did not work (β = −0.07, p = 0.0233). It should be noted, however, that the effects of those maternal factors were small, as each of them explained less than 1% of 2D:4D R in the population, adjusted for child age and sex. Pearson’s linear correlation revealed that maternal age was negatively correlated with 2D:4D R in daughters (r = −0.11, p = 0.0137), but not in sons (r = 0.02, p = 0.6908). The negative correlation of 2D:4D R with maternal age indicates that the daughters of older mothers exhibited lower values of that ratio relative to the same-age daughters of younger mothers. Conclusions: For both study groups, the right-hand digit ratio was positively correlated with maternal smoking and negatively with maternal work during pregnancy. Maternal age during pregnancy was negatively related to right hand 2D:4D only among girls.
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Digit ratio (2D:4D) and maternal testosterone-to-estradiol ratio measured in early pregnancy. Sci Rep 2022; 12:13586. [PMID: 35945232 PMCID: PMC9363442 DOI: 10.1038/s41598-022-17247-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 07/22/2022] [Indexed: 11/09/2022] Open
Abstract
The ratio of index to ring finger (2D:4D) has been hypothesised to indicate prenatal androgen exposure, yet evidence for its validity is lacking. We report the first pre-registered study to investigate mothers' early pregnancy sex hormone concentrations in relation to their children's digit ratios measured at 18-22-month follow-up. Although the testosterone (T) to estradiol (E) ratio correlated negatively with right hand digit ratio (R2D:4D) and directional asymmetry (right-minus-left) in digit ratio (D[R-L]), neither effect remained statistically significant once demographic and obstetric covariates were controlled for. Nevertheless, the multivariate level of analysis did reveal that T correlated positively with left hand digit ratio (L2D:4D) and negatively with D[R-L]. However, the first of these effects is in the opposite direction to that predicted by theory. Taken together, the results of our study suggest research with larger samples is required to determine whether digit ratios are valid proxies for maternal sex hormone exposure.
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21
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Sexual Dimorphism and Sex-2D : 4D Interactions on Fasting Lipid Variables in an Adult Ghanaian Population. J Lipids 2022; 2022:3303588. [PMID: 35782294 PMCID: PMC9246597 DOI: 10.1155/2022/3303588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Accepted: 06/04/2022] [Indexed: 11/17/2022] Open
Abstract
Prenatal hormone exposure has been suggested as a correlate of adult circulating estrogen and testosterone. If this observation is true, then prenatal hormone exposure may have an association with lipid homeostasis in adulthood. The study sought to investigate sexual dimorphism and the interactions between the putative marker of prenatal hormone exposure (2D : 4D) and sex on adult fasting plasma lipid variables. The study was cross-sectional from June to December 2021 at the University for Development Studies. The participants were between 18 and 30 years of age and consisted of 206 healthy persons (female = 93, male = 113). The right hand (2D : 4DR), the left hand (2D : 4DL), and the right-left 2D : 4D difference (Dr-l) were measured using computer-assisted analysis. Fasting venous blood samples were collected and analyzed for lipid variables including total cholesterol (TCHOL) and high-density lipoprotein cholesterol (HDL-C). There were no significant differences in the 2D : 4D ratio and lipid variables between males and females. However, after adjusting for age and BMI, the 2D : 4DR (P = 0.014) and the 2D : 4DL (P = 0.007) increased with increasing fasting plasma HDL-C on average. Moreover, there were significant interactions between sex and the 2D : 4DR (P = 0.002) and also, the 2D : 4DL (P = 0.005) on fasting plasma HDL-C. The relationship between HDL-C and the 2D : 4D ratio was positive in females but negative in males. The 2D : 4DR accounted for about 54.9% and 46.0% while the 2D : 4DL accounted for about 48.2% and 14.0% of the variabilities in fasting plasma HDL-C in females and males, respectively. Prenatal hormone exposure may partly account for the sexual dimorphism in adult lipid homeostasis.
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22
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Banyeh M, Yeboah NA, Seidu L, Doglikuu AF. Sex estimation accuracies from variables of the index and ring fingers in a Ghanaian population: Absolute lengths versus length ratios. FORENSIC SCIENCE INTERNATIONAL: REPORTS 2022. [DOI: 10.1016/j.fsir.2022.100277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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23
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Richards G, Browne WV. Prenatal testosterone and sexually differentiated childhood play preferences: a meta-analysis of amniotic fluid studies. CURRENT PSYCHOLOGY 2022. [DOI: 10.1007/s12144-021-02386-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
AbstractSexually differentiated behaviour appears to emerge from a complex interaction of biological and socio-cultural factors, with prenatal exposure to steroid hormones such as testosterone thought to play a key role. Due to large sex differences being present from a very early age, much research has focussed on the influence these hormones may have on play preferences during childhood. We present an overview of the literature and a random-effects meta-analysis linking amniotic testosterone with sexually differentiated play preferences (k = 9, n = 493). The overall effect size estimate was in the theory-consistent direction (i.e., with higher levels of testosterone associated with more male-typical play preferences), though not statistically significant (r = 0.082, p = 0.274). However, after three hypothesised missing studies were imputed via the trim and fill procedure, a significant correlation emerged (r = 0.166, p = 0.014). Nevertheless, one sample was observed to exert a particularly large influence on the outcome of the analysis. Notably this was the second biggest sample and related to the largest effect size estimate. Though far from conclusive, the overall findings are consistent with the idea that individual differences in prenatal testosterone within the typical range predict sexually differentiated play preferences in early life. However, these effects may be small in magnitude and appear to vary considerably across studies.
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24
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Fonseca CDAD, Martelli DRB, Maia CMF, Dias VO, Carvalho AA, Júnior HM. Digital biomarker 2D:4D as a predictor of cancer: A systematic review. Early Hum Dev 2022; 164:105521. [PMID: 34922146 DOI: 10.1016/j.earlhumdev.2021.105521] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 11/27/2021] [Accepted: 11/30/2021] [Indexed: 01/05/2023]
Abstract
BACKGROUND The digital ratio between the second and fourth digits of the hands, known as 2D:4D, is sexually dimorphic. It has been suggested that a low 2D:4D indicates high exposure to prenatal testosterone and low estrogen exposure while a high 2D:4D indicates the inverse. The 2D:4D may be predictive of cancer susceptibility, and this may be particularly true in cancers that show differences between sexes in their occurrence. AIM To conduct a systematic review of published epidemiological literature examining the association between 2D:4D and cancer. METHOD This review was carried out according to criteria recommended for the systematic review of Statement PRISMA. We enrolled 25 papers involving eleven cancer topographies with 4,569 cases and 19,416 controls from Europe, America, Asia and Australia. RESULTS We noticed variations and discrepancies in the results of the association between 2D:4D and cancer among the studies, either in those that had evaluated the same or different types of cancer, or in the same or distinct lateralities. However, a high 2D:4D was considered a likely predictor of cancer risk in 11 of 25 studies, a low 2D:4D was suggested as a predictor of risk in eight papers, and five of the twenty-five studies did not demonstrate any association. CONCLUSIONS Although this biomarker has the advantage of being easy to measure, it is noted that its relationship with sex hormone levels at specific stages of life has not yet been well quantified, and it has still been questioned. Hence, it is suggested that those findings from studies involving 2D:4D as a proxy for foetal hormone exposure should be interpreted with caution, as well as those studies which claim its association with cancer. Thus, this review shows the need for a greater number of epidemiological studies using more homogeneous methodology and techniques to better investigate the strength of the findings.
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Affiliation(s)
- Cláudia de A D Fonseca
- Health Science Program, State University of Montes Claros, Unimontes, Minas Gerais, Brazil; Medicine School, State University of Montes Claros, Montes Claros, Minas Gerais, Brazil.
| | - Daniella R B Martelli
- Dental School, State University of Montes Claros, Montes Claros, Minas Gerais, Brazil
| | - Célia M F Maia
- Health Science Program, State University of Montes Claros, Unimontes, Minas Gerais, Brazil
| | - Verônica O Dias
- Dental School, State University of Montes Claros, Montes Claros, Minas Gerais, Brazil
| | - Adriana A Carvalho
- Health Science Program, State University of Montes Claros, Unimontes, Minas Gerais, Brazil; Medicine School, State University of Montes Claros, Montes Claros, Minas Gerais, Brazil
| | - Hercílio Martelli Júnior
- Health Science Program, State University of Montes Claros, Unimontes, Minas Gerais, Brazil; Dental School, State University of Montes Claros, Montes Claros, Minas Gerais, Brazil; Center for Rehabilitation of Craniofacial Anomalies, University of José Rosario Vellano, Alfenas, Minas Gerais, Brazil
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25
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Banyeh M, Amidu N, Quaye L. The relationship between offspring's 2D:4D ratio and postpartum maternal circulating testosterone, estradiol, and their indices in a Ghanaian population. Am J Hum Biol 2021; 34:e23684. [PMID: 34558765 DOI: 10.1002/ajhb.23684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 09/12/2021] [Accepted: 09/13/2021] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVES The 2D:4D ratio is influenced by prenatal testosterone (PT) and estrogen (PE) exposure in utero. This study sought to determine whether evidence of Manning's hypothesis can still be observed even in the postpartum period. We hypothesize that the offspring 2D:4D ratios will be inversely correlated with maternal postpartum circulating testosterone but positively correlated with estradiol. METHODS This study was conducted between December 2020 and April 2021 and was cross-sectional in nature. There were 272 mother-offspring pairs; the mothers were aged between 18 and 36 years while the median (IQR) age of their offspring was 111 (44-210) days. Offspring right (2D:4DR) and left (2D:4DL) digit ratios were measured using computer-assisted analysis. Sampling was done at 111 (44-210) days postpartum and blood was analyzed for total testosterone (TT), estradiol (E2) and sex hormone-binding globulins using the enzyme-linked immunosorbent assay technique. RESULTS The 2D:4DR of sons was significantly lower compared to daughters (p = .031). Mothers with sons had significantly increased levels of serum TT (p = .001) while mothers with daughters had significantly increased levels of E2 (p = .000). As hypothesized, the maternal serum free testosterone (FT%) was inversely correlated with their daughters' (r = -0.320, p = .003), and also with their sons' (r = -0.213, p = .047), 2D:4DL. Unexpectedly, daughters' 2D:4DL was inversely correlated with maternal circulating free E2 (r = -0.255, p = .015). CONCLUSIONS In humans, evidence of the relationship between maternal testosterone levels and their offspring's 2D:4D ratio may persist even into the postpartum period.
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Affiliation(s)
- Moses Banyeh
- Department of Biomedical Laboratory Science, School of Allied Health Sciences, University for Development Studies, Tamale, Ghana
| | - Nafiu Amidu
- Department of Biomedical Laboratory Science, School of Allied Health Sciences, University for Development Studies, Tamale, Ghana
| | - Lawrence Quaye
- Department of Biomedical Laboratory Science, School of Allied Health Sciences, University for Development Studies, Tamale, Ghana
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26
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Vorsatz M, Sanchez-Pages S, Turiegano E. Masculinity and Lying. Front Psychol 2021; 12:684226. [PMID: 34393911 PMCID: PMC8360853 DOI: 10.3389/fpsyg.2021.684226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 06/21/2021] [Indexed: 11/13/2022] Open
Abstract
Dishonesty in communication has important economic implications. The standing literature has shown that lying is less pervasive than predicted by standard economic theory. We explore whether biology can help to explain this behavior. In a sample of men, we study whether masculine traits are related to (dis)honesty in a sender-receiver game. We study three masculine physical traits: the second-to-fourth digit ratio, facial morphometric masculinity and the facial width-to-height ratio. These biomarkers display significant associations with lying and deception in the game. We also explore the extent to which these effects operate through social preferences or through beliefs about the behavior of receivers.
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Affiliation(s)
- Marc Vorsatz
- Department of Economic Analysis, National University of Distance Education (UNED), Madrid, Spain
| | | | - Enrique Turiegano
- Department of Biology, Autonomous University of Madrid, Madrid, Spain
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27
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Butovskaya M, Burkova V, Apalkova Y, Dronova D, Rostovtseva V, Karelin D, Mkrtchyan R, Negasheva M, Batsevich V. Sex, population origin, age and average digit length as predictors of digit ratio in three large world populations. Sci Rep 2021; 11:8157. [PMID: 33854119 PMCID: PMC8046776 DOI: 10.1038/s41598-021-87394-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 03/25/2021] [Indexed: 02/06/2023] Open
Abstract
Recently, a number of authors have claimed that sexual dimorphism in the second-to-fourth digit ratio (2D:4D) is simply dependent on digit length and is an artifact of allometry. The goal of our study is to verify the validity of these assumptions. The study sample comprised 7,582 individuals (3,802 men and 3,780 women) from three large world populations: Europeans (n = 3043), East Africans (n = 2844), and Central Asians (n = 1695). The lengths of the second and fourth digits on both hands were measured. Digit ratios were computed according to standard procedures. Analyses were conducted separately for each hand for the whole sample and in succession for the three large populations. Additionally, we separately tested four age cohorts (≤ 13, 14-18, 19-30, and 31 ≥ years) to test the effect of developmental allometry. The second and fourth digits showed strong positive linear relationships on both hands, and demonstrated an increase with age; digit length in women from the youngest age cohort was longer or equal to that of men, and shorter than men in older age cohorts. However, the 2D:4D magnitude and its sexual dimorphism remained stable throughout the ontogeny. To test for an allometric effect on 2D:4D, the average digit lengths were calculated. Both sex and population origin were permanent reliable predictors of 2D:4D, whereas average digit length was not. Height was applied as another measure of allometric effect on the limited sample (≤ 30 years) from the European population, along with sex and age. No allometric effect was observed in this case. We conclude that sex differences in 2D:4D are not an artifact of allometry.
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Affiliation(s)
- Marina Butovskaya
- Institute of Ethnology and Anthropology, Russian Academy of Sciences, Leninsky pr., 32a, Moscow, Russia, 119991.
- National Research University Higher School of Economics, Moscow, Russia.
- Russian State University for the Humanities, Moscow, Russia.
| | - Valentina Burkova
- Institute of Ethnology and Anthropology, Russian Academy of Sciences, Leninsky pr., 32a, Moscow, Russia, 119991
- National Research University Higher School of Economics, Moscow, Russia
| | - Yulia Apalkova
- Institute of Ethnology and Anthropology, Russian Academy of Sciences, Leninsky pr., 32a, Moscow, Russia, 119991
| | - Daria Dronova
- Institute of Ethnology and Anthropology, Russian Academy of Sciences, Leninsky pr., 32a, Moscow, Russia, 119991
| | - Victoria Rostovtseva
- Institute of Ethnology and Anthropology, Russian Academy of Sciences, Leninsky pr., 32a, Moscow, Russia, 119991
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28
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Pruszkowska-Przybylska P, Sitek A, Rosset I, Sobalska-Kwapis M, Słomka M, Strapagiel D, Żądzińska E, Morling N. Associations between second to fourth digit ratio, cortisol, vitamin D, and body composition among Polish children. Sci Rep 2021; 11:7029. [PMID: 33782473 PMCID: PMC8007693 DOI: 10.1038/s41598-021-86521-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 03/16/2021] [Indexed: 01/17/2023] Open
Abstract
Associations between body characteristics (body composition: fat mass, muscle mass, cell, and water mass as well as body proportion—BMI), the 2D:4D digit ratio, and the concentrations of cortisol and vitamin (25-OH)D among Polish children have not been studied before. A total of 133 (73 girls and 60 boys) healthy Polish children aged 7–11 years were examined. The investigation was divided into three parts: measuring (the length of the second and fourth fingers in both hands, body composition, and body height and mass), questionnaires (socioeconomic status), and laboratory investigations (25-OH vitamin D and cortisol concentrations in saliva measured with ELISA methods). Boys with digit ratios below 1 had lower vitamin D concentration than those with digit ratios equal to or higher than 1 (Z = − 2.33; p = 0.019). Only boys with the male-typical pattern of 2D:4D digit ratio tended to have a lower 25-OH vitamin D concentration in saliva. Thus, it might indicate an effect of prenatal programming on the concentrations of steroid hormones in later life. Neither vitamin D, 2D:4D digit ratio nor the cortisol level was associated with the body components or proportions. More studies are needed to evaluate the molecular and genetic background of this phenomenon.
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Affiliation(s)
| | - Aneta Sitek
- Department of Anthropology, Faculty of Biology and Environmental Protection, University of Lodz, 90-237, Lodz, Poland
| | - Iwona Rosset
- Department of Anthropology, Faculty of Biology and Environmental Protection, University of Lodz, 90-237, Lodz, Poland
| | - Marta Sobalska-Kwapis
- The Biobank Lab, Department of Molecular Biophysics, Faculty of Biology and Environmental Protection, University of Lodz, Lodz, Poland.,BBMRI.Pl Consortium, Wrocław, Poland
| | - Marcin Słomka
- The Biobank Lab, Department of Molecular Biophysics, Faculty of Biology and Environmental Protection, University of Lodz, Lodz, Poland.,BBMRI.Pl Consortium, Wrocław, Poland
| | - Dominik Strapagiel
- The Biobank Lab, Department of Molecular Biophysics, Faculty of Biology and Environmental Protection, University of Lodz, Lodz, Poland.,BBMRI.Pl Consortium, Wrocław, Poland
| | - Elżbieta Żądzińska
- Department of Anthropology, Faculty of Biology and Environmental Protection, University of Lodz, 90-237, Lodz, Poland.,Biological Anthropology and Comparative Anatomy Research Unit, School of Medicine, The University of Adelaide, Adelaide, SA, 5005, Australia
| | - Niels Morling
- Section of Forensic Genetics, Department of Forensic Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Frederik V's Vej 11, 2100, Copenhagen, Denmark
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29
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Zhang J, Yang M, Luan P, Jia W, Liu Q, Ma Z, Dang J, Lu H, Ma Q, Wang Y, Mu C, Huo Z. Associations Between Cytochrome P450 (CYP) Gene Single-Nucleotide Polymorphisms and Second-to-Fourth Digit Ratio in Chinese University Students. Med Sci Monit 2021; 27:e930591. [PMID: 33723203 PMCID: PMC7980499 DOI: 10.12659/msm.930591] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Accepted: 02/22/2021] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Cytochrome P450 (CYP) genes are necessary for the production or metabolism of fetal sex hormones during pregnancy. The second-to-fourth digit ratio (2D: 4D) is formed in the early stage of human fetal development and considered an indicator reflecting prenatal sex steroids levels. We explored the association between 2D: 4D and single-nucleotide polymorphisms (SNPs) of CYP. MATERIAL AND METHODS Correlation analysis between 2D: 4D and 8 SNPs, rs2687133 (CPY3A7), rs7173655 (CYP11A1), rs1004467, rs17115149, and rs2486758 (CYP17A1), and rs4646, rs2255192, rs4275794 (CYP19A1), was performed using data from 426 female and 412 male Chinese university students. SNP genotyping was conducted using PCR. Digit lengths were photographed and measured by image processing software. RESULTS rs2486758 (CYP17A1) correlated with left hand 2D: 4D in men (P=0.026), and rs1004467 (CYP17A1) correlated with right hand 2D: 4D in men (P=0.008) and the whole population (P=0.032). In men, allele G rs1004467 decreased right hand 2D: 4D, while allele C of rs2486758 increased left hand 2D: 4D. In women, left hand 2D: 4D was higher in genotypes with allele A of SNP rs4646 (CYP19A1) under the dominant genetic model; female DR-L was higher in genotypes with allele T of rs17115149 (CYP11A1). SNPs rs2687133 (CYP3A7) and rs1004467 (CYP17A1) were significantly correlated with right hand 2D: 4D (P=0.0107). CONCLUSIONS SNPs rs1004467 and rs2486758 of CYP17A1 are significant in the relationship between 2D: 4D and CYP gene polymorphisms under different conditions. SNP interactions between CYP genes probably impact 2D: 4D. The correlation between 2D: 4D and some sex hormone-related diseases may be due to the effect of CYP variants on the 2 phenotypes.
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Affiliation(s)
- Jing Zhang
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
- Ningxia Key Laboratory of Cerebrocranial Diseases, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
| | - Mengyi Yang
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
| | - Pengfei Luan
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
| | - Wei Jia
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
| | - Qiujun Liu
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
| | - Zhanbing Ma
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
| | - Jie Dang
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
| | - Hong Lu
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
| | - Qian Ma
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
| | - Yanfeng Wang
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
| | - Chunlan Mu
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
| | - Zhenghao Huo
- Key Laboratory of Fertility Preservation and Maintenance of Ministry of Education/Key Laboratory of Reproduction and Genetics/Basic Medical College, Ningxia Medical University, Yinchuan, Ningxia, P.R. China
- Department of Biology, Gansu Medical College, Pingliang, Gansu, P.R. China
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30
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An association between body image dissatisfaction and digit ratio among Chinese children and adolescents. Sci Rep 2021; 11:5217. [PMID: 33664410 PMCID: PMC7970844 DOI: 10.1038/s41598-021-84711-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 02/19/2021] [Indexed: 12/04/2022] Open
Abstract
Body image dissatisfaction (BID) is a negative evaluation of personal physical characteristics, including dissatisfaction with body shape, gender, sexual organs, appearance and so forth, and it plays an important role in growth and development. The second-to-fourth digit ratio (2D:4D) is recognized as a putative indicator of intra-uterine testosterone to estrogen ratio exposure, and it has been observed that higher levels of fetal testosterone exposure are associated with a lower 2D:4D. The present paper contributes to a better understanding of the biological underpinnings of BID by analyzing BID and the digit ratio (2D:4D). We found that the 2D:4D was positively related to appearance dissatisfaction in boys with first spermatorrhea, which means that low prenatal androgen exposure may increase boys’ dissatisfaction with their appearance. In girls with breast development being lower than Tanner stage II, their 2D:4D was negatively related to their body shape dissatisfaction, which means that high prenatal androgen exposure may increase girls’ dissatisfaction with their body shape. These results suggest that the prenatal androgen exposure level might play an important role in the body image dissatisfaction of the offspring.
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31
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Richards G, Beking T, Kreukels BPC, Geuze RH, Beaton AA, Groothuis T. An examination of the influence of prenatal sex hormones on handedness: Literature review and amniotic fluid data. Horm Behav 2021; 129:104929. [PMID: 33454315 DOI: 10.1016/j.yhbeh.2021.104929] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 12/30/2020] [Accepted: 12/31/2020] [Indexed: 01/27/2023]
Abstract
Competing theories have posited roles for foetal androgen exposure in the development of human handedness. However, due to practical and ethical considerations, few studies have used hormonal measures to examine this possibility. The current paper reviews this literature and reveals a generally inconsistent pattern of results. We also present data from a longitudinal study of prenatal sex hormone exposure and subsequent handedness. More specifically, we examine correlations between testosterone and estradiol measured from second trimester amniotic fluid and hand preference (Dutch language version of the Edinburgh Handedness Inventory) and hand skill asymmetry (pegboard task) measured at 15 years of age. Prenatal sex hormone exposure was not associated with the direction of hand preference in either males or females. However, in females, high levels of prenatal testosterone were associated with weaker lateralisation of hand skill, and high levels of prenatal estradiol were associated with weaker hand preference. In addition, high levels of prenatal testosterone were associated with increased task duration (i.e., slow hand speed) for the right and left hands of males. The pattern of results observed here is not entirely consistent with any of the main theories linking sex hormones with handedness, suggesting that an association between these variables may be more complex than initially thought.
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Affiliation(s)
- Gareth Richards
- Newcastle University, School of Psychology, Ridley Building 1, Queen Victoria Road, Newcastle upon Tyne NE1 7RU, UK; University of Cambridge, Autism Research Centre, Department of Psychiatry, Douglas House, 18b Trumpington Road, Cambridge CB2 8AH, UK.
| | - Tess Beking
- University of Groningen, Faculty of Behavioural and Social Sciences, Department Clinical & Developmental Neuropsychology, Grote Kruisstraat 2/1, 9712 TS Groningen, the Netherlands; Amsterdam University Medical Center, location VUmc, Department of Medical Psychology, Center of Expertise on Gender Dysphoria, PO Box 7057, 1007 MB Amsterdam, the Netherlands; University of Groningen, Groningen Institute for Evolutionary Life Sciences, Nijenborgh 7, 9747 AG Groningen, the Netherlands
| | - Baudewijntje P C Kreukels
- Amsterdam University Medical Center, location VUmc, Department of Medical Psychology, Center of Expertise on Gender Dysphoria, PO Box 7057, 1007 MB Amsterdam, the Netherlands
| | - Reint H Geuze
- University of Groningen, Faculty of Behavioural and Social Sciences, Department Clinical & Developmental Neuropsychology, Grote Kruisstraat 2/1, 9712 TS Groningen, the Netherlands
| | - Alan A Beaton
- Swansea University, Department of Psychology, School of Human & Health Sciences, Swansea SA2 8PP, UK; Aberystwyth University, Department of Psychology, Aberystwyth SY23 3UX, UK
| | - Ton Groothuis
- University of Groningen, Groningen Institute for Evolutionary Life Sciences, Nijenborgh 7, 9747 AG Groningen, the Netherlands
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Nave G, Koppin CM, Manfredi D, Richards G, Watson SJ, Geffner ME, Yong JE, Kim R, Ross HM, Serrano-Gonzalez M, Kim MS. No evidence for a difference in 2D:4D ratio between youth with elevated prenatal androgen exposure due to congenital adrenal hyperplasia and controls. Horm Behav 2021; 128:104908. [PMID: 33279508 PMCID: PMC8591085 DOI: 10.1016/j.yhbeh.2020.104908] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 11/22/2020] [Accepted: 11/23/2020] [Indexed: 12/27/2022]
Abstract
The second-to-fourth digit ratio (2D:4D) has been associated with sexual dimorphism, with a lower 2D:4D in males. A large body of research has relied on the 2D:4D as a proxy for prenatal androgen exposure, and includes reports of relationships between 2D:4D and a wide range of human traits. Here, we examine the validity of the 2D:4D proxy by studying the association between 2D:4D and classical Congenital Adrenal Hyperplasia (CAH) due to 21-hydroxylase deficiency, a condition characterized by excessive prenatal exposure to androgens during most of the gestational period. To this end, we retrospectively examine 513 serial radiographs of the left hand obtained clinically in 90 youth with classical CAH (45 female) and 70 control youth (31 female). Replicating previous reports, we observe associations of the 2D:4D with sex (lower 2D:4D in males) and age (increase of 2D:4D through development). However, we find no evidence for differences in 2D:4D between CAH and controls (full sample: β = -0.001 (-0.008, 0.006); females: β = -0.004 [-0.015, 0.007]; males: β = 0.001, [-0.008, 0.011]). Although our findings do not rule out a small association between the 2D:4D and CAH, they cast doubt on the usefulness of the 2D:4D as a biomarker for prenatal androgen exposure in behavioral research.
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Affiliation(s)
- Gideon Nave
- Marketing Department, The Wharton School, University of Pennsylvania, United States of America.
| | - Christina M Koppin
- Center for Endocrinology, Diabetes, and Metabolism, Children's Hospital Los Angeles, United States of America
| | - Dylan Manfredi
- Marketing Department, The Wharton School, University of Pennsylvania, United States of America
| | - Gareth Richards
- School of Psychology, Faculty of Medical Sciences, Newcastle University, UK
| | - Steven J Watson
- Department of Psychology of Conflict, Risk and Safety, University of Twente, Netherlands
| | - Mitchell E Geffner
- Center for Endocrinology, Diabetes, and Metabolism, Children's Hospital Los Angeles, United States of America; The Saban Research Institute at Children's Hospital Los Angeles, United States of America; Keck School of Medicine of University of Southern California, United States of America
| | - Jillian E Yong
- Center for Endocrinology, Diabetes, and Metabolism, Children's Hospital Los Angeles, United States of America
| | - Robert Kim
- Center for Endocrinology, Diabetes, and Metabolism, Children's Hospital Los Angeles, United States of America
| | - Heather M Ross
- Center for Endocrinology, Diabetes, and Metabolism, Children's Hospital Los Angeles, United States of America
| | - Monica Serrano-Gonzalez
- Hasbro Children's Hospital, Warren Alpert Medical School of Brown University, United States of America
| | - Mimi S Kim
- Center for Endocrinology, Diabetes, and Metabolism, Children's Hospital Los Angeles, United States of America; The Saban Research Institute at Children's Hospital Los Angeles, United States of America; Keck School of Medicine of University of Southern California, United States of America
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Richards G, Medland SE, Beaton AA. Digit ratio (2D:4D) and handedness: A meta-analysis of the available literature. Laterality 2021; 26:421-484. [PMID: 33517845 DOI: 10.1080/1357650x.2020.1862141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The Geschwind-Behan-Galaburda and sexual differentiation models predict an association between elevated foetal androgen exposure and left-handedness whereas the callosal hypothesis predicts the opposite. We present a meta-analysis of correlations between handedness and digit ratio (2D:4D), a putative marker of prenatal testosterone. Left-handedness predicted low (male-typical) right-hand digit ratio (R2D:4D), high (female-typical) left-hand digit ratio (L2D:4D), and low R2D:4D-L2D:4D directional asymmetry (D[R-L]). Effect sizes were extremely small and not moderated by sex or method of measuring handedness or 2D:4D. The same general pattern was observed after excluding the very large study (110,329 males, 90,412 females) of Manning and Peters ([2009]. Digit ratio (2D:4D) and hand preference for writing in the BBC Internet Study. Laterality: Asymmetries of Body, Brain and Cognition, 14(5), 528-540. doi:10.1080/13576500802637872); however, no significant effects for R2D:4D were observed once these samples were removed. The results do not confirm any theory linking prenatal androgens with handedness, so we speculate they instead reflect the mechanical action of writing causing subtle changes in the musculature and/or fat pads of the fingers. Gripping a pen/pencil might cause an increase in 2D relative to 4D (and/or decrease in 4D relative to 2D) resulting in higher ratios on the writing-hand; furthermore, this could differ between left- and right-handers due to writing in the left-to-right direction (as in English) having asymmetrical effects depending on which hand is used.
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Affiliation(s)
- Gareth Richards
- School of Psychology, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.,Autism Research Centre, Department of Psychiatry, University of Cambridge, Cambridge, UK.,Centre for Research on Play in Education, Development & Learning, Faculty of Education, University of Cambridge, Cambridge, UK
| | - Sarah E Medland
- Psychiatric Genetics, QIMR Berghofer Medical Research Institute, Brisbane, Australia.,School of Psychology, University of Queensland, St Lucia, Australia.,School of Psychology and Counselling, Queensland University of Technology, Brisbane, Australia
| | - Alan A Beaton
- Department of Psychology, School of Human & Health Sciences, Swansea University, Swansea, UK.,Department of Psychology, Aberystwyth University, Aberystwyth, UK
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Digit ratio (2D:4D) and amniotic testosterone and estradiol: an attempted replication of Lutchmaya et al. (2004). J Dev Orig Health Dis 2021; 12:859-864. [PMID: 33472723 DOI: 10.1017/s2040174420001294] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The ratio of length between the second (index) and fourth (ring) fingers (digit ratio or 2D:4D) is frequently employed as a retrospective marker of prenatal sex hormone exposure. Lutchmaya et al. (2004) reported that the ratio of testosterone (T) to estradiol (E) present in second-trimester amniotic fluid was negatively correlated with digit ratios for the right hand (but not the left hand) in a sample of 29 children at 2-year follow-up. This observation is frequently cited as evidence for the measure's validity but has not been replicated. We therefore present the findings of another study of amniotic T and E that did not find evidence for these effects at 4½-year follow-up. The confidence intervals were large, the direction of correlations observed was generally erratic, and the overall findings question the premise that second-trimester sex hormones affect the development of digit length ratios in humans.
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Osu T, Lechler-Lombardi J, Butler A, Newman M, Miłkowska K, Galbarczyk A, Richards G. Fluctuating asymmetry of finger lengths, digit ratio (2D:4D), and tattoos: A pre-registered replication and extension of Koziel et al. (2010). Early Hum Dev 2021; 152:105273. [PMID: 33227633 DOI: 10.1016/j.earlhumdev.2020.105273] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Revised: 11/06/2020] [Accepted: 11/10/2020] [Indexed: 10/23/2022]
Abstract
BACKGROUND Tattoos bring risks yet no obvious evolutionary benefit. Koziel et al. (2010) reported increased fluctuating symmetry (a proxy for low developmental instability) in tattooed men, suggesting they could serve as fitness indicators. AIMS We replicate and extend the findings of Koziel et al. by examining fluctuating asymmetry of finger lengths and digit ratio (2D:4D) (a putative indicator of prenatal testosterone exposure) as predictors of adult tattoo prevalence. STUDY DESIGN We used an online survey with a correlational design. SUBJECTS Participants were recruited from the UK and Poland via university participant pools and social media. Data were available for presence/absence of tattoos and at least one predictor variable (composite Fluctuating Asymmetry [cFA], right-hand digit ratio [R2D:4D] and left-hand digit ratio [L2D:4D]) for n = 186 males and n = 997 females. OUTCOME MEASURES We firstly assessed presence/absence of tattoos; when at least one tattoo was present, we also examined overall number and highest visibility. RESULTS Greater cFA was associated with lower likelihood of having tattoos in males, though in females greater cFA was associated with higher numbers of tattoos. R2D:4D and L2D:4D correlated negatively with number of tattoos in males, and a positive correlation between L2D:4D and number of tattoos was observed in females. However, these latter findings did not remain significant after controlling for covariates. CONCLUSIONS Tattoos may act as fitness indicators in males, though this explanation appears not to extend to females. Prenatal testosterone may also play a role, though doubt is cast on this premise because 2D:4D effects did not remain statistically significant after controlling for covariates.
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Affiliation(s)
- Tinisha Osu
- School of Psychology, Faculty of Medical Sciences, Newcastle University, UK
| | | | - Amy Butler
- School of Psychology, Faculty of Medical Sciences, Newcastle University, UK
| | - Miles Newman
- School of Psychology, Faculty of Medical Sciences, Newcastle University, UK
| | - Karolina Miłkowska
- Department of Environmental Health, Faculty of Health Science, Jagiellonian University Medical College, Poland
| | - Andrzej Galbarczyk
- Department of Environmental Health, Faculty of Health Science, Jagiellonian University Medical College, Poland
| | - Gareth Richards
- School of Psychology, Faculty of Medical Sciences, Newcastle University, UK.
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