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Manning JT, Fink B, Trivers R. Digit Ratio (2D:4D; Right-Left 2D:4D) and Multiple Phenotypes for Same-Sex Attraction: The BBC Internet Study Revisited. ARCHIVES OF SEXUAL BEHAVIOR 2024; 53:213-222. [PMID: 37847344 PMCID: PMC10794480 DOI: 10.1007/s10508-023-02703-6] [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: 02/20/2023] [Revised: 09/04/2023] [Accepted: 09/05/2023] [Indexed: 10/18/2023]
Abstract
Same-sex attraction may be linked to low prenatal androgen (in men) and high prenatal androgen (in women). Digit ratio (2D:4D) is thought to be a negative correlate of prenatal androgen and right-left 2D:4D (Dr-l) to reflect lateralized differences in sensitivity to prenatal androgen. Lower 2D:4D has been reported for lesbians compared to heterosexuals, but links to high 2D:4D in gay men are less clear. The largest study thus far (the BBC Internet study) found no significant difference between the 2D:4D of lesbians and heterosexual women but a higher 2D:4D in gay men compared to heterosexual men. Here we consider the possibility that low and high prenatal androgen is associated with same-sex attraction in men (n = 108,779) and women (n = 87,742), resulting in more than two phenotypes. We examined the associations between 2D:4D, Dr-l, and same-sex attraction scores in the BBC Internet study. In contrast to the earlier report, which considered sexual orientation in categories, there were positive linear associations in men (right and left 2D:4D, but not Dr-l) and negative linear associations in women (right 2D:4D and Dr-l, but not left 2D:4D). There were no curvilinear relationships for right and left 2D:4D. However, Dr-l showed a U-shaped association with same-sex attraction in men. Thus, (1) high prenatal androgen may be implicated in female homosexuality, while both low and high prenatal androgen may be implicated in male homosexuality, and (2) large side differences in sensitivity to androgen may be associated with elevated same-sex attraction in men.
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Affiliation(s)
- John T Manning
- Applied Sports, Technology, Exercise, and Medicine (A-STEM), Swansea University, Swansea, UK
| | - Bernhard Fink
- Biosocial Science Information, Biedermannsdorf, Austria.
- Department of Evolutionary Anthropology, University of Vienna, Djerassiplatz 1, 1030, Vienna, Austria.
- Human Evolution and Archaeological Sciences (HEAS), University of Vienna, Vienna, Austria.
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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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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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The effects of sex, nation, ethnicity, age and self-reported pubertal development on participant-measured right-left 2D:4D (Dr-l) in the BBC internet study. J Biosoc Sci 2023; 55:383-395. [PMID: 35088686 DOI: 10.1017/s0021932022000049] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Digit ratio (2D:4D) - a proxy for prenatal sex steroids - shows sex, nationality and ethnic differences and is linked to pubertal onset. It is unclear whether right-left 2D:4D (Dr-l) also correlates with prenatal sex steroids, as evidence of these differences has been less conclusive. The present study examined the effects of sex, nation, ethnicity, age and self-reported pubertal development (i.e. the rate of physical development and age at menarche [females] or first shave [males]) on Dr-l in a large online study (the BBC internet study). Digit lengths were self-measured in 201,865 adults (110,955 males) and the sample of nations included 41 countries. Participants reported the self-perceived rate of physical pubertal development on a five-point scale (from very slow to very fast) and provided information on the age at menarche or first shave. Adult (>17 years) males had lower Dr-l than females with weak effect size across 41 nations (males-females; d = -.065, p < .0001). There were sex and ethnicity effects on Dr-l across seven ethnic groups with males < females and lower Dr-l in Whites and Middle/Near Eastern participants compared to Asian, Black and Chinese respondents. Considering age effects, the authors focused on participants >12 years; there were stable sex differences and a weak positive effect of age on Dr-l. Dr-l showed a positive relationship with the rate of physical development and a negative relationship with age at menarche or first shave. Relationships were present in males and females with stronger effects in the latter. It is concluded that Dr-l shows a weak sex difference (males < females) independent of nation, ethnicity and age, and suggest that Dr-l is a proxy for prenatal sex steroids.
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An Investigation of the Relationship Between the Second-to-Fourth Digit Ratio and Sagittal Synostosis. J Craniofac Surg 2022; 33:1705-1708. [PMID: 35148529 DOI: 10.1097/scs.0000000000008512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 01/11/2022] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND The most common presentation of nonsyndromic craniosynostosis is that of the sagittal suture. Amongst this subgroup there is a significant male preponderance. Although the etiology is largely unknown, androgen exposure in utero has been suggested as a contributing factor. The second-to-fourth digit ratio (2D:4D) is a sexually dimorphic trait, reflective of the levels of androgen and estrogen exposure in utero, with a lower 2D:4D ratio associated with higher androgen exposure.This study aimed to examine the difference in 2D:4D ratio between participants with sagittal synostosis (SS) and gender-matched controls, hypothesizing that alterations in androgen exposure would be reflected in participants' 2D:4D ratio. METHOD Participants with nonsyndromic SS and gender-matched controls were prospectively recruited from outpatients clinics. Photographs were taken of the right hand, and 3 independent researchers measured the length of the fingers and 2D:4D ratio, with the mean 2D:4D ratio then calculated. RESULTS Fifty-six participants were recruited to both groups, with 35 males and 21 females in each. The mean age of the study and control groups were 5.6 and 6.3 years, respectively. There was no difference in the 2D:4D ratio between groups overall (P = 0.126). However, males with SS had a significantly higher 2D:4D ratio in comparison to male controls (0.969 ± 0.379 versus 0.950 ± 0.354, P = 0.038). CONCLUSIONS Our results suggest that 1 single hormonal pathway is not responsible for suture fusion. Subsequently we consider that an imbalance between testosterone and estrogen signaling may contribute to the development of sagittal craniosynostosis.
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Kobus M, Sitek A, Antoszewski B, Rożniecki J, Pełka J, Żądzińska E. Prenatal oestrogen-testosterone balance as a risk factor of migraine in adults. J Headache Pain 2021; 22:119. [PMID: 34620097 PMCID: PMC8499432 DOI: 10.1186/s10194-021-01326-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 09/07/2021] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Migraine is a common neurological disease with extremely debilitating, but fully reversible symptoms. Women suffer from migraine more often than men. It was assumed that fluctuation of oestrogen level during menstrual cycle is one of many factors responsible for more frequent migraine attacks. The second-to-fourth digit ratio (2D:4D) is considered as an indicator of prenatal sex steroids. Balance of prenatal androgens (testosterone) and oestrogen has been studied in numerous diseases that are affected by hormones. However, the relationship between migraine and the sex steroids balance in prenatal development is still unexplained. The aim of this paper is to provide an evidence of relationship between prenatal oestrogen and testosterone exposure following 2D:4D digit ratio, and migraine prevalence in adults. METHODS We examined a group of 151 adults (33 males, 118 females) with migraine and a control group of 111 adults (45 males, 66 females). 2D:4D digit ratio of both hands was measured using sliding Vernier calliper. RESULTS Significant differences were found in the right hand. Female migraineurs had lower value of 2D:4D ratio than the control group and the right 2D:4D was lower than left 2D:4D (Δ2D:4D), suggesting prenatal testosterone dominance. The opposite relationship was observed in males. Male migraineurs had higher value of 2D:4D ratio and Δ2D:4D was greater than the control group, suggesting prenatal oestrogen dominance. CONCLUSIONS Our results suggest that depending on sex, different proportion of prenatal sex steroids might be a risk factor of migraine in adults. Women with migraine were presumably exposed in prenatal life to higher testosterone levels relative to oestrogen, while men with migraine were probably exposed in prenatal life to higher levels of oestrogen relative to testosterone.
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Affiliation(s)
- Magdalena Kobus
- Department of Anthropology, Faculty of Biology and Environmental Protection, University of Lodz, 90-237, Lodz, Poland.
| | - Aneta Sitek
- Department of Anthropology, Faculty of Biology and Environmental Protection, University of Lodz, 90-237, Lodz, Poland
| | - Bogusław Antoszewski
- Department of Plastic, Reconstructive and Aesthetic Surgery, Institute of Surgery, Medical University of Lodz, Lodz, Poland
| | - Jacek Rożniecki
- Department of Neurology, Stroke and Neurorehabilitation, Medical University of Lodz, Lodz, Poland
| | - Jacek Pełka
- Department of Neurology, Norbert Barlicki Memory University Teaching Hospital, Lodz, 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, South Australia, 5005, Australia
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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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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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10
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Effects of hand preference on digit lengths and digit ratios among children and adults. Early Hum Dev 2020; 151:105204. [PMID: 33059164 DOI: 10.1016/j.earlhumdev.2020.105204] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 09/28/2020] [Accepted: 09/29/2020] [Indexed: 01/21/2023]
Abstract
BACKGROUND Prenatal sex hormones may not exclusively determine effects of hand preference on digit ratios. Genetic determination is an alternative possibility. AIM To study the likelihood of similar effects of hand preference on digit lengths and digit ratios. METHODS We selected similar numbers of left-handers and right-handers in samples of kindergarten children (N = 101, age range: 3.5-7 years) and adults (N = 189, age range: 17-28 years) and measured digit lengths (excluding the thumb) directly on the palmar hand. RESULTS Compared to right-handers, left-handers had longer digits and lower third-to-fourth (3D:4D) digit ratios among children, whereas an opposite pattern of handedness differences occurred among adults. CONCLUSIONS Effects of hand preference on digit lengths and ratios might be genetically/ontogenetically determined. Also discussed are implications of this set of findings for digit ratio research.
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11
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Gazioglu S, Alkan I, Karaman AG, Boz C. Decreased second to fourth digit ratios in female multiple sclerosis patients. Early Hum Dev 2020; 144:105039. [PMID: 32304983 DOI: 10.1016/j.earlhumdev.2020.105039] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 03/27/2020] [Accepted: 03/31/2020] [Indexed: 01/10/2023]
Abstract
BACKGROUND Sex-related differences in multiple sclerosis (MS) suggest a possible role of prenatal sex hormones in the pathogenesis. The aim of this study was to investigate whether the 2D:4D ratio, considered a predictor of prenatal hormonal exposure, in MS patients differ from that in healthy controls. METHODS Two hundred MS patients and one hundred seventy healthy control subjects with similar age and sex distribution enrolled. All participants were right-handed. The right hands of all participants were scanned using a digital scanner. Measurements of second and fourth digit lengths were made from digital scans. The 2D:4D ratio was calculated by dividing the length of the second digit by the length of the fourth digit. RESULTS A total of 171 MS patients' and 159 healthy controls' digit scans included in the study. The MS group consisted of 94 females (mean age 38.32 ± 10.5) and 77 males (mean age 42.06 ± 11.8) and the control group of 86 females (mean age 40.24 ± 9.7) and 73 males (mean age 38.49 ± 11.6). 2D:4D ratios of female MS patients were significantly lower than those of healthy females (p=0.004). Although 2D:4D ratios of male patients with MS were lower than those of healthy males, this difference was not statistically significant (p=0.33). There was no significant correlation between the 2D:4D ratio, EDSS levels or duration of the disease in male or female MS patients (p<0.05). CONCLUSION Although our results suggest that a prenatal hormonal balance in favor of androgenic activity may be a risk factor for MS, complex factors mediating the actions of sex hormones on target cells should always be considered when evaluating the effects of sex hormones.
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Affiliation(s)
- Sibel Gazioglu
- Department of Neurology, Karadeniz Technical University Medical Faculty, 61080 Trabzon, Turkey.
| | - Ismail Alkan
- Department of Neurology, Karadeniz Technical University Medical Faculty, 61080 Trabzon, Turkey
| | - Ayse Gul Karaman
- Department of Neurology, Karadeniz Technical University Medical Faculty, 61080 Trabzon, Turkey
| | - Cavit Boz
- Department of Neurology, Karadeniz Technical University Medical Faculty, 61080 Trabzon, Turkey
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12
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Manning J, Cook C, Crewther B. Digit ratio (2D:4D) and testosterone supplementation. Early Hum Dev 2019; 139:104843. [PMID: 31493670 DOI: 10.1016/j.earlhumdev.2019.104843] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 08/16/2019] [Accepted: 08/20/2019] [Indexed: 01/21/2023]
Abstract
BACKGROUND Testosterone (T) is taken or prescribed to enhance appearance, increase athletic performance and libido and to treat hypogonadism. Digit ratio (2D:4D) is thought to be a negative correlate of prenatal T. Here we consider the relationship between 2D:4D and T supplementation. AIMS Our sample was taken from the BBC internet study. Respondents were asked (y/n) if they were taking; (i) T, (ii) hormone replacement therapy with T (HRTwT). We removed extreme 2D:4D values and age and considered the most numerous ethnic group (i.e. "Whites"). Analyses were performed with a two-factor (sex*T) analysis of variance with covariate age and dependent variables 2D:4D or right-left 2D:4D (Dr-l). RESULTS Out of 197,589 respondents, 793 (598 males) reported taking T. There was a significant main effect for right 2D:4D such that T supplementing males had higher 2D:4D than those who did not. The sex*T interaction was significant, but the effect reversed in females. There were 22,576 (661 males) participants who reported taking HRTwT. We found a significant main effect for right 2D:4D, males taking HRTwT had higher 2D:4D than those who did not. This was reversed in females. The sex*HRTwT interaction was significant, a high Dr-l was also found in males reporting HRTwT. CONCLUSION Males who reported taking T or HRTwT had high right 2D:4D and/or Dr-l. The situation with females may be the reverse of that found in males but effect sizes are less. The health implications of an association between high (feminized) 2D:4D and T supplementation in males are discussed.
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Affiliation(s)
- John Manning
- Applied Sports, Technology, Exercise, and Medicine (A-STEM), Swansea University, Swansea, United Kingdom.
| | - Christian Cook
- Hamlyn Centre, Imperial College, United Kingdom; Biomedical Science, School of Science and Technology, University of New England, Armidale, NSW, Australia
| | - Blair Crewther
- Institute of Sport - National Research Institute, Warsaw, Poland
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13
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Paukner A. Digit ratio (2D:4D) and its behavioral correlates in infant rhesus macaques (Macaca mulatta). Dev Psychobiol 2019; 62:992-998. [PMID: 31512755 DOI: 10.1002/dev.21917] [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: 03/29/2019] [Revised: 08/16/2019] [Accepted: 08/17/2019] [Indexed: 11/11/2022]
Abstract
2D:4D ratios are typically lower in adult human males than females and are linked to numerous sex-differentiated behaviors. 2D:4D ratios are considered an indicator of prenatal androgen exposure; if so, children's 2D:4D ratios would arguably be even better indicators of prenatal androgen exposure since children have experienced fewer postnatal influences than adults. However, sex differences in 2D:4D ratios as well as associations between 2D:4D ratios and sex-typed behaviors in children have been inconsistent. Several studies also report sex differences and behavioral correlates of 2D:4D ratios in adult non-human primates, but little is known about 2D:4D ratios in infant non-human primates. This study examined sex differences in 2D:4D ratios over the first month of life, and associations with behavioral outcomes at 12-24 weeks of age, in N = 304 infant rhesus macaques. An increase in 2D:4D ratios over the first month of life was found, as well as associations with aggression and play behaviors, but no sex differences in 2D:4D ratios were observed. These results highlight the need for future developmental studies of 2D:4D ratios in order to determine not only their stability and predictive value, but also to discern the mechanism connecting prenatal androgen exposure, 2D:4D ratios, and behavioral outcomes.
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Affiliation(s)
- Annika Paukner
- Psychology Department, Nottingham Trent University, Nottingham, UK
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14
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Klapprodt KL, Fitzgerald JS, Short SE, Manning JT, Tomkinson GR. Relationships between the digit ratio (2D:4D) and game-related statistics in professional and semi-professional male basketball players. Am J Hum Biol 2018; 30:e23182. [PMID: 30251289 DOI: 10.1002/ajhb.23182] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 07/20/2018] [Accepted: 08/21/2018] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVES The primary aim of this study was to examine relationships between digit ratio (2D:4D) and game-related statistics in professional and semi-professional male basketball players. The secondary aim was to quantify differences in mean 2D:4Ds between starting and reserve players. METHODS Using a cross-sectional design, 93 male basketball players from the professional Australian National Basketball League and the semi-professional South Australian Premier League were measured in-season for height, mass, and 2D:4D, with game-related statistics collected end-season. Linear relationships between right and left 2D:4Ds and game-related statistics were quantified using nonparametric partial correlations, and differences in mean 2D:4Ds between starting and reserve players were quantified using analysis of covariance (ANCOVA). All partial correlations and ANCOVAs were adjusted for playing experience, body size, and competitive standard. RESULTS 2D:4D was a weak to moderate negative correlate of points scored and assists-to-turnovers ratio, indicating that males with lower 2D:4Ds were generally better offensively as they recorded more points and assists relative to turnovers. The difference in mean 2D:4D between starting and reserve players was negligible. CONCLUSIONS 2D:4D was favorably correlated with open-skill sports performance, as evidenced by the better offensive statistics of male basketball players with lower 2D:4Ds. These results probably reflect the organizational benefits of prenatal testosterone and indicate that 2D:4D may be a useful complement to traditional physical, physiological, skill, and behavioral predictors of basketball success.
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Affiliation(s)
- Katelyn L Klapprodt
- Department of Education, Health and Behavior Studies, University of North Dakota, Grand Forks, North Dakota
| | - John S Fitzgerald
- Department of Education, Health and Behavior Studies, University of North Dakota, Grand Forks, North Dakota
| | - Sandra E Short
- Department of Education, Health and Behavior Studies, University of North Dakota, Grand Forks, North Dakota
| | - John T Manning
- Applied Sports, Technology, Exercise, and Medicine (A-STEM), Swansea University, Swansea, United Kingdom
| | - Grant R Tomkinson
- Department of Education, Health and Behavior Studies, University of North Dakota, Grand Forks, North Dakota.,Alliance for Research in Exercise, Nutrition and Activity (ARENA), School of Health Sciences and Sansom Institute for Health Research, University of South Australia, Adelaide, South Australia, Australia
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15
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Bönte W, Procher VD, Urbig D, Voracek M. Digit Ratio (2D:4D) Predicts Self-Reported Measures of General Competitiveness, but Not Behavior in Economic Experiments. Front Behav Neurosci 2017; 11:238. [PMID: 29276479 PMCID: PMC5728070 DOI: 10.3389/fnbeh.2017.00238] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 11/15/2017] [Indexed: 11/29/2022] Open
Abstract
The ratio of index finger length to ring finger length (2D:4D) is considered to be a putative biomarker of prenatal androgen exposure (PAE), with previous research suggesting that 2D:4D is associated with human behaviors, especially sex-typical behaviors. This study empirically examines the relationship between 2D:4D and individual competitiveness, a behavioral trait that is found to be sexually dimorphic. We employ two related, but distinct, measures of competitiveness, namely behavioral measures obtained from economic experiments and psychometric self-reported measures. Our analyses are based on two independent data sets obtained from surveys and economic experiments with 461 visitors of a shopping mall (Study I) and 617 university students (Study II). The correlation between behavior in the economic experiment and digit ratios of both hands is not statistically significant in either study. In contrast, we find a negative and statistically significant relationship between psychometric self-reported measures of competitiveness and right hand digit ratios (R2D:4D) in both studies. This relationship is especially strong for younger people. Hence, this study provides some robust empirical evidence for a negative association between R2D:4D and self-reported competitiveness. We discuss potential reasons why digit ratio may relate differently to behaviors in specific economics experiments and to self-reported general competitiveness.
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Affiliation(s)
- Werner Bönte
- Jackstädt Center of Entrepreneurship and Innovation Research, University of Wuppertal, Wuppertal, Germany.,Schumpeter School of Business and Economics, University of Wuppertal, Wuppertal, Germany.,Institute for Development Studies, School of Public and Environmental Affairs, Indiana University, Bloomington, IN, United States
| | - Vivien D Procher
- Jackstädt Center of Entrepreneurship and Innovation Research, University of Wuppertal, Wuppertal, Germany.,Schumpeter School of Business and Economics, University of Wuppertal, Wuppertal, Germany.,RWI-Leibniz-Institut für Wirtschaftsforschung, Essen, Germany
| | - Diemo Urbig
- Jackstädt Center of Entrepreneurship and Innovation Research, University of Wuppertal, Wuppertal, Germany.,Schumpeter School of Business and Economics, University of Wuppertal, Wuppertal, Germany
| | - Martin Voracek
- Department of Basic Psychological Research and Research Methods, School of Psychology, University of Vienna, Vienna, Austria
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16
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Schmitz J, Metz GA, Güntürkün O, Ocklenburg S. Beyond the genome—Towards an epigenetic understanding of handedness ontogenesis. Prog Neurobiol 2017; 159:69-89. [DOI: 10.1016/j.pneurobio.2017.10.005] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 09/18/2017] [Accepted: 10/26/2017] [Indexed: 12/13/2022]
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17
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Kaneoke Y, Donishi T, Iwahara A, Shimokawa T. Severity of Premenstrual Symptoms Predicted by Second to Fourth Digit Ratio. Front Med (Lausanne) 2017; 4:144. [PMID: 28936432 PMCID: PMC5595152 DOI: 10.3389/fmed.2017.00144] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 08/14/2017] [Indexed: 12/25/2022] Open
Abstract
Women of reproductive age often experience a variety of unpleasant symptoms prior to the onset of menstruation. While genetics may influence the variability of these symptoms and their severity among women, the exact causes remain unknown. We hypothesized that symptom variability originates from differences in the embryonic environment and thus development caused by variation in exposure to sex hormones. We measured the second to fourth digit ratios (2D:4D) in 402 young women and investigated the potential relationships of this ratio premenstrual symptoms using a generalized linear model. We found that two models (one with two predictors such as both hands' digit ratios and the other with the difference between the two digit ratios, Dr-l) were significantly different from the constant model as assessed by chi-square test. The right digit ratio and Dr-l were negatively related to the symptom scores, and the left digit ratio was related to the scores. When premenstrual symptoms were classified into eight categories, five categories, including pain, concentration, autonomic reaction, negative affect, and control were associated with the digit ratios and Dr-l. Behavioral changes and water retention were not predicted by them. Arousal was predicted by Dr-l. The right 2D:4D is thought to be determined by the balance of testosterone and estrogen levels during early embryogenesis and is not affected by postpartum levels of sex hormones, while the left 2D:4D might be affected by the other prenatal environmental factors. We conclude that the embryonic environment, including the relative concentration of sex hormones an embryo is exposed to, is associated with the severity of premenstrual symptoms once menarche is reached.
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Affiliation(s)
- Yoshiki Kaneoke
- Department of System Neurophysiology, Wakayama Medical University, Wakayama, Japan
| | - Tomohiro Donishi
- Department of System Neurophysiology, Wakayama Medical University, Wakayama, Japan
| | - Akihiko Iwahara
- School of Health and Nursing Science, Wakayama Medical University, Wakayama, Japan
| | - Toshio Shimokawa
- Clinical Research Center, Wakayama Medical University, Wakayama, Japan
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18
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Papadatou-Pastou M, Martin M. Cerebral laterality for language is related to adult salivary testosterone levels but not digit ratio (2D:4D) in men: A functional transcranial Doppler ultrasound study. BRAIN AND LANGUAGE 2017; 166:52-62. [PMID: 28088127 DOI: 10.1016/j.bandl.2016.12.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 11/07/2016] [Accepted: 12/12/2016] [Indexed: 06/06/2023]
Abstract
The adequacy of three competing theories of hormonal effects on cerebral laterality are compared using functional transcranial Doppler sonography (fTCD). Thirty-three adult males participated in the study (21 left-handers). Cerebral lateralization was measured by fTCD using an extensively validated word generation task. Adult salivary testosterone (T) and cortisol (C) concentrations were measured by luminescence immunoassay and prenatal T exposure was indirectly estimated by the somatic marker of 2nd to 4th digit length ratio (2D:4D). A significant quadratic relationship between degree of cerebral laterality for language and adult T concentrations was observed, with enhanced T levels for strong left hemisphere dominance and strong right hemisphere dominance. No systematic effects on laterality were found for cortisol or 2D:4D. Findings suggest that higher levels of T are associated with a relatively attenuated degree of interhemispheric sharing of linguistic information, providing support for the callosal and the sexual differentiation hypotheses rather than the Geschwind, Behan and Galaburda (GBG) hypothesis.
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Affiliation(s)
- Marietta Papadatou-Pastou
- Cognition and Health Research Group, Department of Experimental Psychology, University of Oxford, 9 South Parks Road, Oxford OX1 3UD, UK.
| | - Maryanne Martin
- Cognition and Health Research Group, Department of Experimental Psychology, University of Oxford, 9 South Parks Road, Oxford OX1 3UD, UK.
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19
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Jeevanandam S, Muthu PK. 2D:4D Ratio and its Implications in Medicine. J Clin Diagn Res 2016; 10:CM01-CM03. [PMID: 28208851 DOI: 10.7860/jcdr/2016/21952.9000] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 09/20/2016] [Indexed: 11/24/2022]
Abstract
Digit ratios, especially 2D:4D ratio, a potential proxy marker for prenatal androgen exposure shows sexual dimorphism. Existing literature and recent research show accumulating evidence on 2D:4D ratio showing correlations with various phenotypic traits in humans. Ratio of 2D:4D is found to correlate negatively to testosterone and positively to oestrogen in the foetus. Interestingly, it is constant since birth and not influenced by the adult hormone levels. Usually, males have lower ratios when compared to females. Prenatal androgen exposure and therefore, digit ratios have been reported to be associated with numerical competencies, spatial skills, handedness, cognitive abilities, academic performance, sperm counts, personalities and prevalence of obesity, migraine, eating disorders, depression, myopia, autism etc. The authors have attempted to write a brief account on the digit ratios and the dimorphism observed in various physiological, psychological and behavioural traits. Also, the authors have discussed the relevant molecular basics and the methods of measurement of digit ratios.
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Affiliation(s)
| | - Prathibha K Muthu
- Associate Professor, Department of Physiology, Saveetha Medical College and Hospital , Thandalam, Chennai, India
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20
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Left with Raging Hormones. Laterality 2016. [DOI: 10.1016/b978-0-12-801239-0.00005-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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21
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Apicella CL, Tobolsky VA, Marlowe FW, Miller KW. Hadza hunter-gatherer men do not have more masculine digit ratios (2D:4D). AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2015; 159:223-32. [PMID: 26354727 DOI: 10.1002/ajpa.22864] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 08/23/2015] [Accepted: 08/30/2015] [Indexed: 12/17/2022]
Abstract
OBJECTIVES The ratio between the length of the second and the length of the fourth digit (2D:4D) is sexually dimorphic such that males of many species possess a lower ratio than females, particularly in the right hand. Still, men and women often exhibit overlapping 2D:4D ranges and the ratio is highly variable between populations. In order to further explore populational variability, we chose to analyze 2D:4D in the Hadza, a population of hunter-gatherers living in Tanzania. MATERIALS AND METHODS Data were collected separately by two researchers over the course of three years (1998, 2001, 2006) from 152 adult participants (male: n = 76, female: n = 76). Independent samples t-tests were used to explore sex differences, paired samples t-tests were used to explore directional effects within each sex, and linear regression and one-way ANOVA were used to test possible age effects. RESULTS In none of the years, or pooled (n = 152), did we find evidence that adult men have a lower 2D:4D than adult women. If anything, the data suggest that women in this population have a significantly lower right hand 2D:4D than men (P < 0.001, d = 0.57). In contrast, left hand 2D:4D did not exhibit a sex difference (P = 0.862, d = 0.03). DISCUSSION These findings challenge the current view that lower 2D:4D in men is a uniform characteristic of our species. Cross-populational variance in 2D:4D may be related to known patterns of hormonal variation resulting from both genetic and environmental mechanisms, though this relationship merits further investigation.
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Affiliation(s)
- Coren L Apicella
- Department of Psychology, University of Pennsylvania, Philadelphia, PA, 19104
| | - Victoria A Tobolsky
- Department of Psychology, University of Pennsylvania, Philadelphia, PA, 19104.,Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, 02138
| | - Frank W Marlowe
- Division of Biological Anthropology, Department of Archaeology and Anthropology, Cambridge, CB2 3QG, UK
| | - Kathleen W Miller
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, 02138
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22
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Abstract
It is reported that a canonical and cultural finger counting habit influences the spatial-numerical association. The digit ratio (the ratio between the lengths of the index and ring fingers as a putative indicator of prenatal androgen exposure) also plays an effect on space-number representation, reflecting a stronger left-to-right number representation in people with a short index finger and longer ring finger (i.e., 2D:4D ratio). It is unknown whether the finger counting habit and digit ratio have an effect on spatial-numerical association independently from each other or whether they interact with each other. In Study 1, the digit ratio and finger counting mapping were recorded in right handers. The participants performed number-to-position, digit string bisection, and physical line bisection tasks. In the number-to-position task, a finger counting effect was found, as well as a significant interaction between factors. A digit ratio effect was observed in the digit string bisection task. In Study 2, digit ratio and finger counting mapping were recorded in right and left handers. The results showed that the finger counting habit influenced the spatial biases in both numerical tasks. A significant interaction between finger counting and digit ratio was found in both numerical tasks when only the left hand was considered. The results are discussed considering the embodied nature of the spatial-numerical association.
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Affiliation(s)
- Marco Fabbri
- Department of Psychology, Second University of Naples, Italy
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23
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Crewther B, Cook C, Kilduff L, Manning J. Digit ratio (2D:4D) and salivary testosterone, oestradiol and cortisol levels under challenge: Evidence for prenatal effects on adult endocrine responses. Early Hum Dev 2015; 91:451-6. [PMID: 26025335 DOI: 10.1016/j.earlhumdev.2015.04.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 04/23/2015] [Accepted: 04/25/2015] [Indexed: 01/09/2023]
Abstract
BACKGROUND Digit ratio (2D:4D) is a marker for prenatal sex steroids and a correlate of sporting performance. This association may exist because low 2D:4D is linked to high prenatal levels of testosterone (T) and low oestrogens (E). It was recently suggested that low 2D:4D, and particularly low right-left 2D:4D (or Dr-l), is a marker for T changes in response to physical and aggressive challenges. If correct, this link may in part explain the association between 2D:4D and sports performance. AIMS We tested this hypothesis in adults. STUDY DESIGN Three experimental treatments were completed using a randomised, cross-over design; (i) cycle sprints plus an aggressive video (S+V), (ii) aggressive video plus cycle sprints (V+S), and (iii) a control session. SUBJECTS 24 healthy adults (12 men and 12 women). OUTCOME MEASURES Salivary T, oestradiol (E2) and cortisol (C) levels were measured on six occasions across each session and pooled for analysis. RESULTS The S+V treatment was associated with a rise in T and C levels, and Dr-l was significantly and negatively correlated with T and E2 with these effects confined to men. The right 2D:4D and Dr-l were also negatively correlated with the T/C ratio and Dr-l negatively related to the E2/C ratio in men during the S+V treatment. CONCLUSIONS We suggest that the hormonal responses to a challenge are programmed by prenatal levels of T and E with possible links to sporting performance in adulthood.
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Affiliation(s)
| | - Christian Cook
- The Hamlyn Centre, Imperial College, London, UK; School of Sport, Health and Exercise Science, Bangor University, Gwynedd, UK
| | - Liam Kilduff
- Applied Sports Technology, Exercise and Medicine Research Centre, Swansea University, Swansea, UK
| | - John Manning
- Department of Psychology, Northumbria University, Newcastle-upon-Tyne, UK
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24
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Kishida M, Rahman Q. Fraternal Birth Order and Extreme Right-Handedness as Predictors of Sexual Orientation and Gender Nonconformity in Men. ARCHIVES OF SEXUAL BEHAVIOR 2015; 44:1493-1501. [PMID: 25663238 DOI: 10.1007/s10508-014-0474-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 12/01/2014] [Accepted: 12/06/2014] [Indexed: 06/04/2023]
Abstract
The present study explored whether there were relationships between number of older brothers, handedness, recalled childhood gender nonconformity (CGN), and sexual orientation in men. We used data from previous British studies conducted in our laboratory (N = 1,011 heterosexual men and 921 gay men). These men had completed measures of demographic variables, number and sex of siblings, CGN, and the Edinburgh Handedness Inventory. The results did not replicate the fraternal birth order effect. However, gay men had fewer "other siblings" than heterosexual men (even after controlling for the stopping-rule and family size). In a sub-sample (425 gay men and 478 heterosexual men) with data available on both sibling sex composition and handedness scores, gay men were found to show a significantly greater likelihood of extreme right-handedness and non-right-handedness compared to heterosexual men. There were no significant effects of sibling sex composition in this sub-sample. In a further sub-sample (N = 487) with data available on sibling sex composition, handedness, and CGN, we found that men with feminine scores on CGN were more extremely right-handed and had fewer other-siblings compared to masculine scoring men. Mediation analysis revealed that handedness was associated with sexual orientation directly and also indirectly through the mediating factor of CGN. We were unable to replicate the fraternal birth order effect in our archived dataset but there was evidence for a relationship among handedness, sexual orientation, and CGN. These data help narrow down the number of possible neurodevelopmental pathways leading to variations in male sexual orientation.
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Affiliation(s)
- Mariana Kishida
- Department of Psychology, Institute of Psychiatry, King's College London, 5th Floor, Bermondsey Wing, Guy's Hospital Campus, London, SE1 9RT, UK,
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Is Foot Asymmetry a Correlate of Hand Performance Asymmetry? Evidence from the Jamaican Symmetry Project. EVOLUTIONARY PSYCHOLOGICAL SCIENCE 2015. [DOI: 10.1007/s40806-014-0002-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Beaton AA, Kaack IH, Corr PJ. Handedness and behavioural inhibition system/behavioural activation system (BIS/BAS) scores: A replication and extension of Wright, Hardie, and Wilson (2009). Laterality 2015; 20:585-603. [DOI: 10.1080/1357650x.2015.1016530] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Montag C, Bleek B, Breuer S, Prüss H, Richardt K, Cook S, Yaruss JS, Reuter M. Prenatal testosterone and stuttering. Early Hum Dev 2015; 91:43-6. [PMID: 25460256 DOI: 10.1016/j.earlhumdev.2014.11.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 11/04/2014] [Accepted: 11/06/2014] [Indexed: 11/25/2022]
Abstract
BACKGROUND The prevalence of stuttering is much higher in males compared to females. The biological underpinnings of this skewed sex-ratio is poorly understood, but it has often been speculated that sex hormones could play an important role. AIMS The present study investigated a potential link between prenatal testosterone and stuttering. Here, an indirect indicator of prenatal testosterone levels, the Digit Ratio (2D:4D) of the hand, was used. As numerous studies have shown, hands with more "male" characteristics (putatively representing greater prenatal testosterone levels) are characterized by a longer ring finger compared to the index finger (represented as a lower 2D:4D ratio) in the general population. STUDY DESIGN, SUBJECTS, OUTCOME MEASURES We searched for differences in the 2D:4D ratios between 38 persons who stutter and 36 persons who do not stutter. In a second step, we investigated potential links between the 2D:4D ratio and the multifaceted symptomatology of stuttering, as measured by the Overall Assessment of the Speaker's Experience of Stuttering (OASES), in a larger sample of 44 adults who stutter. RESULTS In the first step, no significant differences in the 2D:4D were observed between individuals who stutter and individuals who do not stutter. In the second step, 2D:4D correlated negatively with higher scores of the OASES (representing higher negative experiences due to stuttering), and this effect was more pronounced for female persons who stutter. CONCLUSIONS The findings indicate for the first time that prenatal testosterone may influence individual differences in psychosocial impact of this speech disorder.
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Affiliation(s)
| | - Benjamin Bleek
- Department of Psychology, University of Bonn, Bonn, Germany
| | - Svenja Breuer
- Department of Psychology, University of Bonn, Bonn, Germany
| | - Holger Prüss
- Department for the Treatment of Stuttering, LVR Clinic Bonn, Bonn, Germany
| | - Kirsten Richardt
- Department for the Treatment of Stuttering, LVR Clinic Bonn, Bonn, Germany
| | | | - J Scott Yaruss
- Department of Communication Science & Disorders, University of Pittsburgh, PA, USA
| | - Martin Reuter
- Department of Psychology, University of Bonn, Bonn, Germany; Center for Economics & Neuroscience, University of Bonn, Bonn, Germany
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Baker J, Kungl AM, Pabst J, Strauß B, Büsch D, Schorer J. Your fate is in your hands? Handedness, digit ratio (2D:4D), and selection to a national talent development system. Laterality 2013; 18:710-8. [DOI: 10.1080/1357650x.2012.755992] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Romero-Martínez Á, Lila M, Catalá-Miñana A, Williams RK, Moya-Albiol L. The contribution of childhood parental rejection and early androgen exposure to impairments in socio-cognitive skills in intimate partner violence perpetrators with high alcohol consumption. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2013; 10:3753-70. [PMID: 23965927 PMCID: PMC3774467 DOI: 10.3390/ijerph10083753] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 08/05/2013] [Accepted: 08/09/2013] [Indexed: 11/16/2022]
Abstract
Alcohol consumption, a larger history of childhood parental rejection, and high prenatal androgen exposure have been linked with facilitation and high risk of recidivism in intimate partner violence (IPV) perpetrators. Participants were distributed into two groups according to their alcohol consumption scores as high (HA) and low (LA). HA presented a higher history of childhood parental rejection, prenatal masculinization (smaller 2D:4D ratio), and violence-related scores than LA IPV perpetrators. Nonetheless, the former showed poor socio-cognitive skills performance (cognitive flexibility, emotional recognition and cognitive empathy). Particularly in HA IPV perpetrators, the history of childhood parental rejection was associated with high hostile sexism and low cognitive empathy. Moreover, a masculinized 2D:4D ratio was associated with high anger expression and low cognitive empathy. Parental rejection during childhood and early androgen exposure are relevant factors for the development of violence and the lack of adequate empathy in adulthood. Furthermore, alcohol abuse plays a key role in the development of socio-cognitive impairments and in the proneness to violence and its recidivism. These findings contribute to new coadjutant violence intervention programs, focused on the rehabilitation of basic executive functions and emotional decoding processes and on the treatment of alcohol dependence.
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Affiliation(s)
| | - Marisol Lila
- Department of Social Psychology, University of Valencia, Valencia 46010, Spain; E-Mails: (M.L.); (A.C.-M.)
| | - Alba Catalá-Miñana
- Department of Social Psychology, University of Valencia, Valencia 46010, Spain; E-Mails: (M.L.); (A.C.-M.)
| | - Ryan K. Williams
- Criminal Justice Department, University of Illinois Springfield, Springfield, IL 62703, USA; E-Mail:
| | - Luis Moya-Albiol
- Department of Psychobiology, University of Valencia, Valencia 46010, Spain; E-Mail:
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +34-96-386-4635; Fax: +34-96-386-4668
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Trabert B, Graubard BI, Erickson RL, Zhang Y, McGlynn KA. Second to fourth digit ratio, handedness and testicular germ cell tumors. Early Hum Dev 2013; 89:463-6. [PMID: 23623693 PMCID: PMC3684556 DOI: 10.1016/j.earlhumdev.2013.04.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 03/29/2013] [Accepted: 04/04/2013] [Indexed: 11/23/2022]
Abstract
BACKGROUND Research on early life exposures and testicular germ cell tumors (TGCT) risk has focused on a possible perinatal etiology with a well-known hypothesis suggesting that hormonal involvement during fetal life is associated with risk. Second-to-fourth digit ratio (2D:4D) and left-hand dominance have been proposed as markers of prenatal hormone exposure. AIM To evaluate associations between 2D:4D digit ratio, right minus left 2D:4D (ΔR-L), and left-hand dominance and TGCT in the U.S. Servicemen's Testicular Tumor Environmental and Endocrine Determinants Study. METHODS A total of 246 TGCT cases and 236 non-testicular cancer controls participated in the current study, and completed a self-administered questionnaire. Associations between digit ratio, hand dominance and TGCT were estimated using unconditional logistic regression adjusting for identified covariates. RESULTS Right 2D:4D was not associated with TGCT [odds ratio (OR) for a one-standard deviation (SD) increase in right-hand 2D:4D: 1.12, 95% confidence interval (CI): 0.93-1.34]. The results were consistent when evaluating the association based on the left hand. The difference between right and left-hand 2D:4D was also not associated with TGCT risk [OR for a one-SD increase in ΔR-L: 1.03, 95% CI: 0.87-1.23]. Compared to men who reported right-hand dominance, ambidexterity [OR (95% CI)=0.65 (0.30-1.41)] and left-hand dominance [OR (95% CI)=0.79 (0.44-1.44)] were not associated with risk. CONCLUSIONS These results do not support the hypothesis that prenatal hormonal imbalance is associated with TGCT risk. Given the limited sample size, further evaluation of the relationship between TGCT and prenatal hormonal factors using digit ratio, ΔR-L, or left-hand dominance and larger sample size are warranted.
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Affiliation(s)
- Britton Trabert
- Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD 20852-7234, USA.
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Kalmady SV, Agarwal SM, Shivakumar V, Jose D, Venkatasubramanian G, Reddy YCJ. Revisiting Geschwind's hypothesis on brain lateralisation: A functional MRI study of digit ratio (2D:4D) and sex interaction effects on spatial working memory. Laterality 2013; 18:625-40. [DOI: 10.1080/1357650x.2012.744414] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Lin Y, Ma X, Deng W, Han Y, Li M, Liu X, Loh EW, Li T. Minor physical anomalies in patients with schizophrenia in a Chinese population. Psychiatry Res 2012; 200:223-7. [PMID: 22884216 DOI: 10.1016/j.psychres.2012.07.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2012] [Revised: 06/15/2012] [Accepted: 07/13/2012] [Indexed: 02/05/2023]
Abstract
Studies have shown that minor physical anomalies (MPAs) may be associated with schizophrenia. However, it remains unclear whether any items of MPAs are more associated with schizophrenia than the others. We aimed to examine which specific MPAs are more associated with schizophrenia than others. A total of 154 patients with schizophrenia and 152 healthy controls were assessed using candidate MPAs items along with items from the Waldrop scale. Significant differences were found between the patients and controls in inner canthal distance, epicanthus, adherent ear lobe, cuspidal ear and length difference from section index to ring finger (2D:4D length difference) as well as gap between the first and the second toes. These six items were selected by the logistic regression model, which correctly classified 89.0% of patients with schizophrenia (sensitivity) and 96.7% of healthy controls (specificity). The overall classification success rate was 92.8%. MPAs are associated with neurodevelopment, especially 2D:4D associated with cerebral lateralisation. Hence, our present findings support that it is necessary to evaluate MPAs beyond the Waldrop scale, as some item, such as 2D:4D length difference may reflect the more detailed aberrant neurodevelopment of schizophrenia.
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Affiliation(s)
- Yin Lin
- The Psychiatric Laboratory & the Mental Health Center, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, China
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Motofei IG, Rowland DL, Georgescu SR, Baconi DL, Dimcevici NP, Paunica S, Constantin VD, Balalau C. A pilot study on the sexual side effects of finasteride as related to hand preference for men undergoing treatment of male pattern baldness. BJU Int 2012; 111:E221-6. [DOI: 10.1111/j.1464-410x.2012.11580.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Venkatasubramanian G, Arasappa R, Rao NP, Gangadhar BN. Digit ratio (2D:4D) asymmetry and Schneiderian first rank symptoms: implications for cerebral lateralisation theories of schizophrenia. Laterality 2012; 16:499-512. [PMID: 21128162 DOI: 10.1080/1357650x.2010.499910] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Schneiderian first rank symptoms (FRS) in schizophrenia have been hypothesised to be secondary to aberrant cerebral lateralisation over the course of human evolution. The ratio of length of second digit to fourth digit (2D:4D) has been put forward as a potential indicator of cerebral lateralisation. This study examined 2D:4D and its asymmetry in antipsychotic-naïve schizophrenia patients (N=79) in comparison with healthy controls (N=75). Psychopathology was assessed using Scales for Assessment of Positive and Negative Symptoms. FRS assessment was performed as per established descriptions. The digit lengths (2D & 4D) were measured using a digital vernier caliper with good inter-rater reliability. Female schizophrenia patients showed significantly lower 2D:4D than female healthy controls. Mean 2D:4D asymmetry index was significantly lower in male schizophrenia patients than male healthy controls. FRS status had significant effect on left 2D:4D as well as 2D:4D asymmetry index, the patients with FRS having the lowest values. Our study findings support association between schneiderian FRS and low 2D:4D as well as low 2D:4D asymmetry index. Since 2D:4D is linked with limbic asymmetry, our study findings offer further support to the cerebral lateralisation theories of schizophrenia.
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Affiliation(s)
- Ganesan Venkatasubramanian
- Metabolic Clinic in Psychiatry, Department of Psychiatry, National Institute of Mental Health & Neurosciences, Bangalore 560029, Karnataka, India.
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Abbott AD, Colman RJ, Tiefenthaler R, Dumesic DA, Abbott DH. Early-to-mid gestation fetal testosterone increases right hand 2D:4D finger length ratio in polycystic ovary syndrome-like monkeys. PLoS One 2012; 7:e42372. [PMID: 22927929 PMCID: PMC3425513 DOI: 10.1371/journal.pone.0042372] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 07/05/2012] [Indexed: 01/03/2023] Open
Abstract
A smaller length ratio for the second relative to the fourth finger (2D:4D) is repeatedly associated with fetal male-typical testosterone (T) and is implicated as a biomarker for a variety of traits and susceptibility to a number of diseases, but no experimental human studies have been performed. The present study utilizes the rhesus monkey, a close relative of humans, and employs discrete gestational exposure of female monkeys to fetal male-typical T levels for 15-35 days during early-to-mid (40-76 days; n = 7) or late (94-139 days; n = 7) gestation (term: 165 days) by daily subcutaneous injection of their dams with 10 mg T propionate. Such gestational exposures are known to enhance male-typical behavior. In this study, compared to control females (n = 19), only early-to-mid gestation T exposure virilizes female external genitalia while increasing 2D:4D ratio in the right hand (RH) by male-like elongation of RH2D. RH2D length and 2D:4D positively correlate with androgen-dependent anogenital distance (AG), and RH2D and AG positively correlate with duration of early-to-mid gestation T exposure. Male monkeys (n = 9) exhibit a sexually dimorphic 2D:4D in the right foot, but this trait is not emulated by early-to-mid or late gestation T exposed females. X-ray determined phalanx measurements indicate elongated finger and toe phalanx length in males, but no other phalanx-related differences. Discrete T exposure during early-to-mid gestation in female rhesus monkeys thus appears to increase RH2D:4D through right-side biased, non-skeletal tissue growth. As variation in timing and duration of gestational T exposure alter male-like dimensions of RH2D independently of RH4D, postnatal RH2D:4D provides a complex biomarker for fetal T exposure.
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Affiliation(s)
- Andrew D Abbott
- Wisconsin National Primate Research Center, University of Wisconsin, Madison, Wisconsin, United States of America.
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Beaton AA, Magowan SV, Rudling NG. Does handedness or digit ratio (2D:4D) predict lateralised cognitive ability? PERSONALITY AND INDIVIDUAL DIFFERENCES 2012. [DOI: 10.1016/j.paid.2011.12.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Gamliel M, Ebstein R, Yirmiya N, Mankuta D. Minor Fetal Sonographic Findings in Autism Spectrum Disorder. Obstet Gynecol Surv 2012; 67:176-86. [DOI: 10.1097/ogx.0b013e31824bb5d6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Abstract
AbstractThe principle of symmetry-asymmetry is widely presented in the structural and functional organization of the nonliving and living nature. One of the most complex manifestations of this principle is the left-right asymmetry of the human brain. The present review summarizes previous and contemporary literary data regarding the role of brain asymmetry in neuroimmunomodulation. Some handedness-related peculiarities are outlined additionally. Brain asymmetry is considered to be imprinted in the formation and regulation of the individual’s responses and relationships at an immunological level with the external and internal environment. The assumptions that the hemispheres modulate immune response in an asymmetric manner have been confirmed in experiments on animals. Some authors assume that the right hemisphere plays an indirect role in neuroimmunomodulation, controlling and suppressing the left hemispheric inductive signals.
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Loehlin JC, Medland SE, Martin NG. Is CAG sequence length in the androgen receptor gene correlated with finger-length ratio? PERSONALITY AND INDIVIDUAL DIFFERENCES 2012. [DOI: 10.1016/j.paid.2011.09.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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Hill R, Simpson B, Millet G, Manning J, Kilduff L. Right-left digit ratio (2D:4D) and maximal oxygen uptake. J Sports Sci 2011; 30:129-34. [PMID: 22141747 DOI: 10.1080/02640414.2011.637947] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
A low digit ratio (2D:4D) and low 2D:4D in the right compared with the left hand (right-left 2D:4D) are thought to be determined by high in utero concentrations of testosterone, and are related to "masculine" traits such as aggression and performance in sports like running and rugby. Low right-left 2D:4D is also related to sensitivity to testosterone as measured by the number of cytosine-adenine-guanine triplet repeats in exon 1 of the androgen receptor gene. Here we show that low right-left 2D:4D is associated with high maximal oxygen uptake (VO2(max)), high velocity at VO2(max), and high maximum lactate concentration in a sample of teenage boys. We suggest that low right-left 2D:4D is linked to performance in some sports because it is a proxy of high sensitivity to prenatal and maybe also circulating testosterone and high VO2(max).
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Affiliation(s)
- Randy Hill
- HP Sports and YSC Sports, Philadelphia, Pennsylvania, USA
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Lenz B, Müller CP, Stoessel C, Sperling W, Biermann T, Hillemacher T, Bleich S, Kornhuber J. Sex hormone activity in alcohol addiction: integrating organizational and activational effects. Prog Neurobiol 2011; 96:136-63. [PMID: 22115850 DOI: 10.1016/j.pneurobio.2011.11.001] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2011] [Revised: 11/03/2011] [Accepted: 11/08/2011] [Indexed: 01/06/2023]
Abstract
There are well-known sex differences in the epidemiology and etiopathology of alcohol dependence. Male gender is a crucial risk factor for the onset of alcohol addiction. A directly modifying role of testosterone in alcohol addiction-related behavior is well established. Sex hormones exert both permanent (organizational) and transient (activational) effects on the human brain. The sensitive period for these effects lasts throughout life. In this article, we present a novel early sex hormone activity model of alcohol addiction. We propose that early exposure to sex hormones triggers structural (organizational) neuroadaptations. These neuroadaptations affect cellular and behavioral responses to adult sex hormones, sensitize the brain's reward system to the reinforcing properties of alcohol and modulate alcohol addictive behavior later in life. This review outlines clinical findings related to the early sex hormone activity model of alcohol addiction (handedness, the second-to-fourth-finger length ratio, and the androgen receptor and aromatase) and includes clinical and preclinical literature regarding the activational effects of sex hormones in alcohol drinking behavior. Furthermore, we discuss the role of the hypothalamic-pituitary-adrenal and -gonadal axes and the opioid system in mediating the relationship between sex hormone activity and alcohol dependence. We conclude that a combination of exposure to sex hormones in utero and during early development contributes to the risk of alcohol addiction later in life. The early sex hormone activity model of alcohol addiction may prove to be a valuable tool in the development of preventive and therapeutic strategies.
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Affiliation(s)
- Bernd Lenz
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander-University of Erlangen-Nuremberg, Germany.
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Cherbuin N, Sachdev PS, Anstey KJ. Mixed handedness is associated with greater age-related decline in volumes of the hippocampus and amygdala: the PATH through life study. Brain Behav 2011; 1:125-34. [PMID: 22399092 PMCID: PMC3236539 DOI: 10.1002/brb3.24] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Accepted: 08/05/2011] [Indexed: 11/07/2022] Open
Abstract
Handedness has been found to be associated with structural and functional cerebral differences. Left handedness and mixed handedness also appear to be associated with an elevated risk of some developmental and immunological disorders that may contribute to pathological processes developing in ageing. Inconsistent reports show that left handedness may be more prevalent in early-onset as well as late-onset Alzheimer's disease, but might also be associated with slower decline. Such inconsistencies may be due to handedness being usually modeled as a binary construct while substantial evidence suggests it to be a continuous trait. The aim of this study was to investigate the relationship between brain structures known to be implicated in pathological ageing and strength and direction of handedness. The association between handedness and hippocampal and amygdalar atrophy was investigated in 327 cognitively healthy older individuals. Handedness was measured with the Edinburgh Inventory. Two measures were computed from this index, one reflecting the direction (left = 0/right = 1) and the other the degree of handedness (ranging from 0 to 1). Hippocampal and amygdalar volumes were manually traced on scans acquired 4 years apart. Regression analyses were used to assess the relationship between strength and direction of handedness and incident hippocampal and amygdalar atrophy. Analyses showed that strength but not direction of handedness was a significant predictor of hippocampal (Left: beta = 0.118, P = 0.013; Right: beta = 0.116, P = 0.010) and amygdalar (Right: beta = 0.105, P = 0.040) atrophy. The present findings suggest that mixed but not left handedness is associated with greater hippocampal and amygdalar atrophy. This effect may be due to genetic, environmental, or behavioural differences that will need further investigation in future studies.
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Affiliation(s)
- Nicolas Cherbuin
- Centre for Mental Health Research, Australian National UniversityCanberra, Australia
| | | | - Kaarin J Anstey
- Centre for Mental Health Research, Australian National UniversityCanberra, Australia
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Voracek M. Special issue preamble: Digit ratio (2D:4D) and individual differences research. PERSONALITY AND INDIVIDUAL DIFFERENCES 2011. [DOI: 10.1016/j.paid.2011.04.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Faurie C, Llaurens V, Alvergne A, Goldberg M, Zins M, Raymond M. Left-Handedness and Male-Male Competition: Insights from Fighting and Hormonal Data. EVOLUTIONARY PSYCHOLOGY 2011. [DOI: 10.1177/147470491100900307] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Male-male competition can shape some behavioral or morphological traits of males. Here we investigate if this competition could play a role in the persistence of the polymorphism of handedness in human populations. A negative frequency-dependent selection mechanism has been hypothesized, based on the fact that left-handed men may benefit from a “surprise” advantage during fighting interactions because they are rare in human populations. This advantage may thereby enhance the probability of survival of left-handed men and/or their reproductive success through an increase in social status. In this study, we first explored the association between hand preference and lifetime fighting behavior in a population of 1,161 French men. No effect of hand preference on the probability of fighting was detected, suggesting that the innate propensity to fight does not differ between left- and right-handers. However, among men who had been involved in at least one fight during their lifetime, left-handers reported significantly more fights than right-handers. To explore the biological basis of this behavior, we also investigated the testosterone concentration in saliva samples from 64 French university students. Consistent with frequencies of fights, we found a significantly higher average testosterone concentration in left-handers than in right-handers. We suggest that these behavioral and hormonal differences may be acquired throughout life due to previous experiences in a social context and may favor the persistence of left-handers in humans.
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Affiliation(s)
- Charlotte Faurie
- CNRS, Institute of Evolutionary Sciences, Université de Montpellier 2, Montpellier cedex 5, France
| | - Violaine Llaurens
- CNRS, Institute of Evolutionary Sciences, Université de Montpellier 2, Montpellier cedex 5, France
| | - Alexandra Alvergne
- Human Evolutionary Ecology Group, Department of Anthropology, University College London, London, United Kingdom
| | - Marcel Goldberg
- INSERM Unit 687 –IFR 69, Hôpital National de Saint-Maurice, Saint-Maurice cedex, France
| | - Marie Zins
- INSERM Unit 687 –IFR 69, Hôpital National de Saint-Maurice, Saint-Maurice cedex, France
| | - Michel Raymond
- CNRS, Institute of Evolutionary Sciences, Université de Montpellier 2, Montpellier cedex 5, France
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Stoyanov Z, Nikolova P, Pashalieva I. Season of birth, Geschwind and Galaburda hypothesis, and handedness. Laterality 2011; 16:607-19. [PMID: 21287424 DOI: 10.1080/1357650x.2010.506689] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Geschwind and Galaburda (1985a, 1985b) suggested that the season of conception is a non-genetic random variable that may affect laterality and handedness, probably due to seasonal variations in the hormonal influences on the foetal brain. According to this suggestion it is logical to expect seasonal anisotropy in the incidence of birth of right- and non-right-handers. The present study analysed data obtained from a sample of 3182 young Bulgarians: 2825 right-handers and 357 non-right-handers. Significant difference in the seasonal distribution of births of right- and non-right-handers was found in males only. The incidence of non-right-handedness was highest among participants born in winter. In right-handers increased birth rate was observed in spring and summer. The results in males seem to support the Geschwind and Galaburda suggestion. One can speculate that the high levels of mother's androgens during spring and early summer play the role of a "left shift" factor for the male foetuses with genetic potential for non-right-handedness.
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Affiliation(s)
- Zlatislav Stoyanov
- Department of Physiology and Pathophysiology, Medical University Prof. Paraskev Stoyanov, Marin Drinov Str. 55, 9002 Varna, Bulgaria.
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Kornhuber J, Erhard G, Lenz B, Kraus T, Sperling W, Bayerlein K, Biermann T, Stoessel C. Low digit ratio 2D:4D in alcohol dependent patients. PLoS One 2011; 6:e19332. [PMID: 21547078 PMCID: PMC3081847 DOI: 10.1371/journal.pone.0019332] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Accepted: 03/26/2011] [Indexed: 11/23/2022] Open
Abstract
The ratio of the lengths of the second and fourth finger (2D∶4D) has been
described as reflecting the degree of prenatal androgen exposure in humans.
2D∶4D is smaller for males than females and is associated with traits such
as left-handedness, physical aggression, attention-deficit-hyperactivity
disorder and a genetic polymorphism of the androgen receptor. All of these
traits are known to be correlated to the vulnerability for alcohol dependency.
We therefore hypothesized low 2D∶4D in patients with alcohol dependency.
In the present study on 131 patients suffering from alcohol dependency and 185
healthy volunteers, we found that alcohol dependent patients had smaller
2D∶4D ratios compared to controls with preserved sexual dimorphism but
with reduced right-left differences. The detection of alcohol dependency based
on 2D∶4D ratios was most accurate using the right hand of males
(ROC-analysis: AUC 0.725, sensitivity 0.667, specificity 0.723). These findings
provide novel insights into the role of prenatal androgen exposure in the
development of alcohol dependency and for the use of 2D∶4D as a possible
trait marker in identifying patients with alcohol dependency.
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Affiliation(s)
- Johannes Kornhuber
- Department of Psychiatry and Psychotherapy, Friedrich-Alexander University of Erlangen-Nuremberg, Erlangen, Germany.
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Beaton AA, Rudling N, Kissling C, Taurines R, Thome J. Digit ratio (2D:4D), salivary testosterone, and handedness. Laterality 2011; 16:136-55. [DOI: 10.1080/13576500903410369] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Stein AD, Kahn HS, Lumey LH. The 2D:4D digit ratio is not a useful marker for prenatal famine exposure: Evidence from the Dutch hunger winter families study. Am J Hum Biol 2011; 22:801-6. [PMID: 20721977 DOI: 10.1002/ajhb.21085] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
OBJECTIVES Digit lengths, and in particular the ratio of the 2nd (2D) to 4th (4D) digit (2D:4D), are stable in adulthood and have been linked to characteristics thought to have developmental origins, but little research has focused on early life determinants of these measures. We examined whether exposure to acute famine during specific periods of gestation was associated with 2D, 4D or the 2D:4D ratio. METHODS We studied men and women (1) born in one of three hospitals in western Netherlands whose mothers were exposed to a limited period of famine immediately prior to or during the pregnancy (n = 337); (2) born in the same hospitals to mothers not exposed to famine during the pregnancy (n = 271) or same-sex siblings of individuals in Groups 1 and 2 (n = 295). We measured 2D and 4D on both hands using calipers and computed the 2D:4D ratio. RESULTS Mean 2D and 4D lengths were 73.5 (SD 5.1) and 75.0 (5.4) mm, respectively. The 2D:4D ratio was 0.981 (SD 0.030). Both 2D and 4D were associated with male gender and height (all P < 0.001), and weakly with BMI. The 2D:4D ratio was 0.0070 (95% confidence interval 0.0017, 0.0123) lower among males as compared with females, and was not significantly associated with height (0.0002 per cm; 95% -0.0001, 0.0005). The 2D:4D ratio was not significantly associated with exposure to famine, overall (-0.0010, 95% CI 0.0030, 0.0050) or within any period of gestation. CONCLUSIONS The 2D:4D ratio is not significantly affected by prenatal exposure to famine and therefore is not a useful marker for generalized prenatal undernutrition.
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Affiliation(s)
- Aryeh D Stein
- Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, Georgia 30322, USA.
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Vuoksimaa E, Peter Eriksson CJ, Pulkkinen L, Rose RJ, Kaprio J. Decreased prevalence of left-handedness among females with male co-twins: evidence suggesting prenatal testosterone transfer in humans? Psychoneuroendocrinology 2010; 35:1462-72. [PMID: 20570052 PMCID: PMC2950868 DOI: 10.1016/j.psyneuen.2010.04.013] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Revised: 04/19/2010] [Accepted: 04/23/2010] [Indexed: 10/19/2022]
Abstract
Studies of singletons suggest that right-handed individuals may have higher levels of testosterone than do left-handed individuals. Prenatal testosterone levels are hypothesised to be especially related to handedness formation. In humans, female members from opposite-sex twin pairs may experience elevated level of prenatal exposure to testosterone in their intrauterine environment shared with a male. We tested for differences in rates of left-handedness/right-handedness in female twins from same-sex and opposite-sex twin pairs. Our sample consisted of 4736 subjects, about 70% of all Finnish twins born in 1983-1987, with information on measured pregnancy and birth related factors. Circulating testosterone and estradiol levels at age 14 were available on 771 and 744 of these twins, respectively. We found significantly (p=.006) lower prevalence of left-handedness in females from opposite-sex pairs (5.3%) compared to females from same-sex pairs (8.6%). The circulating levels of neither testosterone nor estradiol related to handedness in either females or males. Nor were there differences in circulating testosterone or estradiol levels between females from opposite-sex and same-sex twin pairs. Birth and pregnancy related factors for which we had information were unrelated to handedness. Our results are difficult to fully explain by postnatal factors, but they offer support to theory that relates testosterone to formation of handedness, and in a population-based sample, are suggestive of effects of prenatal testosterone transfer.
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Affiliation(s)
- Eero Vuoksimaa
- Department of Public Health, University of Helsinki, Finland.
| | - C. J. Peter Eriksson
- Department of Alcohol, Drugs and Addiction, National Institute for Health and Welfare, Helsinki, Finland
| | - Lea Pulkkinen
- Department of Psychology, University of Jyväskylä, Finland
| | - Richard J. Rose
- Department of Public Health, University of Helsinki, Finland, Department of Psychological and Brain Sciences, Indiana University, Bloomington, USA
| | - Jaakko Kaprio
- Department of Public Health, University of Helsinki, Finland, Department of Mental Health and Substance Abuse Services, National Institute for Health and Welfare, Helsinki, Finland, Institute for Molecular Medicine, University of Helsinki, Helsinki, Finland
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Voracek M, Dressler SG. Relationships of toe-length ratios to finger-length ratios, foot preference, and wearing of toe rings. Percept Mot Skills 2010; 110:33-47. [PMID: 20391868 DOI: 10.2466/pms.110.1.33-47] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Sexually differentiated digit ratios of the hand (2D:4D and other) are currently widely studied, owing to their presumed role as a retrospective diagnostic window into prenatal androgen action. This study was only the second one (following McFadden & Shubel, 2002) to examine all 6 possible finger-length ratios (excluding the thumb) and all 10 possible toe-length ratios (including the big toe). Data from a sample of 59 male and 69 female Austrian adults (M age = 27 yr., SD = 7.9) were collected. Replicating the prior study, the majority of toe-length ratios exhibited significant sex differences, which was similar to finger-length ratios, but of weaker effect size. Ipsilateral correlations of toe-length and finger-length ratios were largely absent, except for those of corresponding or adjacent length ratios of the right body side among women. However, these associations were directionally opposite, such that among women, feminized finger-length ratios corresponded to masculinized toe-length ratios. Foot preference (among both sexes) and wearing of toe rings (among women) were not correlates of toe-length ratios. Discussed are implications of these findings for digit ratio research, along with ideas for further inquiry on this topic.
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Affiliation(s)
- Martin Voracek
- Department of Basic Psychological Research, School of Psychology, University of Vienna, Austria.
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