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Butovskaya M, Adam Y, Batsevich V, Shackelford TK, Fink B. Direct and radiographic digit ratio (2D:4D) measurements of Tuvan children and adolescents from Southern Siberia: Sex differences and skeletal maturation. Early Hum Dev 2023; 184:105835. [PMID: 37517120 DOI: 10.1016/j.earlhumdev.2023.105835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 07/26/2023] [Accepted: 07/26/2023] [Indexed: 08/01/2023]
Abstract
BACKGROUND In Mongolian-origin ethnic groups digit ratio (2D:4D; a proxy for prenatal sex-steroids) is sexually dimorphic (males < females), as reported for other ethnicities. Most studies measured 2D:4D from soft tissue (directly from the digits, or indirectly from hand scans), or from radiographs. Evidence on the correspondence of 2D:4D measurements from soft tissue with measurements from radiographic images is scarce and has not been reported for a Mongolian-origin sample. In addition, previous research has not considered relationships between 2D:4D and measures of skeletal maturity. AIM To examine (i) associations between 2D:4D measured directly from the palms with those obtained from radiographic images of the same individuals in a sample of children and adolescents from the Tuvan population in Siberia (Russian Federation), and ii) associations between 2D:4D measurements with chronological and skeletal age. SUBJECTS AND METHODS Participants were Tuvan boys and girls aged 7 to 18 years. 2D:4D of the right and left hand was measured from soft tissue (directly from the palm) and compared with radiographic images (left hand only). In addition to finger length 2D:4D, we examined 2D:4D of the phalanges from measurements of radiographs. Skeletal age was assessed using the Tanner-Whitehouse method. RESULTS Sex differences (boys < girls) in measurements of 2D:4D from soft tissue and radiographs were found for total finger length and phalanges. In addition, 2D:4D measurements from radiographs correlated positively and significantly with those obtained from soft tissue. Sex predicted 2D:4D measurements from soft tissue and radiographs, but no effects of chronological/skeletal age and body height were detected. In girls (but not in boys), earlier skeletal maturity (relative to chronological age) was associated with higher 2D:4D in soft tissue measurements of both hands, radiographic 2D:4D, and 2D:4D of the proximal phalanges. CONCLUSION Consistent with reports from other ethnic groups, 2D:4D in young Tuvans was sexually dimorphic, with boys having lower 2D:4D than girls. For girls, higher 2D:4D was found for participants whose skeletal age was more advanced than chronological age. This finding was obtained from direct soft tissue and indirect radiographic measurements. Age and body height were not associated with 2D:4D, which suggests differences in hormone developmental trajectories for 2D:4D and height.
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Affiliation(s)
- Marina Butovskaya
- Institute of Ethnology and Anthropology, Russian Academy of Sciences, Moscow, Russian Federation; National Research University Higher School of Economics, Moscow, Russian Federation; Russian State University for the Humanities, Moscow, Russian Federation
| | - Yulia Adam
- Institute of Ethnology and Anthropology, Russian Academy of Sciences, Moscow, Russian Federation
| | - Valery Batsevich
- Anuchin Research Institute and Museum of Anthropology, Lomonosov Moscow State University, Moscow, Russian Federation
| | | | - Bernhard Fink
- Department of Evolutionary Anthropology, University of Vienna, Vienna, Austria; Human Evolution and Archaeological Sciences (HEAS), University of Vienna, Vienna, Austria; Biosocial Science Information, Biedermannsdorf, Austria.
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Khan SA, Raza Kazmi SM, Ahmed S, Hani U, Choudhry Z, Sukkurwala A. Correlation of index finger length to vertical dimensions of occlusion for edentulous patients and their satisfaction: a randomized controlled trial. Sci Rep 2023; 13:7414. [PMID: 37150797 PMCID: PMC10164741 DOI: 10.1038/s41598-023-33722-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 04/18/2023] [Indexed: 05/09/2023] Open
Abstract
The prevalence of edentulism is pandemic and people resort to complete dentures for the restoration of missing teeth and esthetics. However, the determination of the correct occlusal vertical dimensions (OVD) constitutes to play an important role in overall patient satisfaction. The objective of this study was to apply anthropometric methods to correlate the length of index finger (2D) to measure the OVD from base of the nose to the base of the chin (Sn-Me) and to assess satisfaction by comparing both the methods. A total of 80 edentulous patients were randomized and controlled for this trial into experimental and control groups. A correlation was found between Sn-Me and finger measurements, dentures' satisfaction was assessed after a 1-week follow-up and marked according to the Visual Analog Scale. Our findings established that finger measurements are greater among males, and in both genders, positive, and statistically significant correlations exist between the facial and finger length measurements. Moreover, 97.0% patients from experimental group were satisfied with the use of complete dentures through the new anthropometric method. Hence measuring the length of index finger can be an adjunct method for the restoration of OVD and is a relatively time-effective and simple method with a satisfactory follow-up.Trial registration: ID: NCT05153213 ( https://clinicaltrials.gov/ct2/show/NCT05153213 ).
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Affiliation(s)
- Shujah Adil Khan
- Department of Prosthodontics, Liaquat College of Medicine and Dentistry, Karachi, Pakistan.
| | - Syed Murtaza Raza Kazmi
- Section of Dentistry, Department of Surgery, Aga Khan University Hospital, Karachi, Pakistan
| | - Shahbaz Ahmed
- Department of Operative Dentistry, Dr. Ishrat-Ul-Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences, Karachi, Pakistan
| | - Ume Hani
- Department of Oral Biology, Dr. Ishrat-Ul-Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences, Karachi, Pakistan
| | - Ziaullah Choudhry
- Department of Prosthodontics, Dr. Ishrat-Ul-Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences, Karachi, Pakistan
| | - Adnan Sukkurwala
- Department of Community Dentistry, Dow Dental College, Dow University of Health Sciences, Karachi, Pakistan
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Finley B, Kalwij A, Kapteyn A. Born to be wild: Second-to-fourth digit length ratio and risk preferences. ECONOMICS AND HUMAN BIOLOGY 2022; 47:101178. [PMID: 36084390 DOI: 10.1016/j.ehb.2022.101178] [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: 05/10/2022] [Revised: 07/20/2022] [Accepted: 08/22/2022] [Indexed: 06/15/2023]
Abstract
The second-to-fourth digit length ratio of an individual's hand (digit ratio) is a putative biomarker for prenatal exposure to testosterone. We examine the hypothesized negative association between the digit ratio and the preference for risk taking within a large U.S. population survey. Our statistical framework provides a cardinal proxy for the true digit ratio based on ordinal digit ratio measurements and accounts for measurement error under the assumptions of Gaussianity and time-invariant true digit ratios. Our empirical findings support the hypothesis and suggest a meaningful biological basis for risk preferences.
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Affiliation(s)
| | - Adriaan Kalwij
- Utrecht University School of Economics, The Netherlands.
| | - Arie Kapteyn
- Center for Economic and Social Research at the University of Southern California, United States.
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Chen WC, Hsu WL, Chen JYF, Shih NH, Wu CY. Second-to-fourth digit ratio and age predicting the severity of androgenetic alopecia: a cross-sectional study. Aging Male 2022; 25:242-248. [PMID: 36628519 DOI: 10.1080/13685538.2022.2119954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Purpose: Androgenetic alopecia (AGA) is a common type of hair loss. Previous studies indicated that the relative length of the index and ring finger (2D:4D ratio) of AGA patients was lower than control. However, the correlation between 2D:4D ratio and disease severity is unclear. In this study, we sought to evaluate the relationship between digit ratio of the right hand and AGA severity in male patients.Materials and methods: The cross-sectional study was performed. Hamilton-Norwood scale was used to assess severity. The finger lengths of the right hand were measured using a digital caliper.Results: Our study found that the lower the right-handed 2D:4D ratio, the greater the risk of developing AGA and that the severity of AGA increases with age. Patients with moderate and severe AGA (grade 3 and above) had lower 2D:4D ratios and higher average age compared with patients with mild AGA (Norwood grade 2). Patients aged ≥37.5 with a 2D:4D ratio <0.947 were six times more likely to have moderate-to-severe androgenetic alopecia compared with the reference group (OR: 6.11; 95% CI: 1.96-19.04).Conclusions: Combining 2D:4D ratio and older age may help predict the severity risk of AGA, and offer a clinically accessible, non-invasive approach for patients to easily predict their future severity.
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Affiliation(s)
- Wei-Chiao Chen
- College of Medicine, Department of Dermatology, Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan
- Department of Environmental Science and Engineering, College of Engineering, National Pingtung University of Science and Technology, Pingtung, Taiwan
| | - Wen-Li Hsu
- College of Medicine, Department of Dermatology, Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan
- Regenerative Medicine and Cell Therapy Research Center, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Jeff Yi-Fu Chen
- Department of Biotechnology, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Nai-Hua Shih
- Department of Laboratory Medicine, Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung, Taiwan
| | - Ching-Ying Wu
- College of Medicine, Department of Dermatology, Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan
- Department of Cosmetic Science, Chang Gung University of Science and Technology, Taoyuan, Taiwan
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Pickering GJ, Anger N, Baird J, Dale G, Tattersall GJ. Use of crowdsourced images for determining 2D:4D and relationship to pro-environmental variables. Acta Ethol 2022; 25:165-178. [PMID: 36097527 PMCID: PMC9452876 DOI: 10.1007/s10211-022-00401-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 06/28/2022] [Accepted: 08/16/2022] [Indexed: 01/02/2023]
Abstract
The primary purpose of this study was to examine whether 2D:4D ratios (a putative measure of prenatal androgen exposure) could be determined using participant-submitted hand images. The secondary purpose was to examine whether 2D:4D ratio was associated with pro-environmental behaviors, attitudes, and empathy, given the recent literature linking sex to environmental attitudes and actions. Participants (N = 1065) were asked via an online survey to submit a clear photograph of their right hand, palm side up. Participants also completed a questionnaire to assess (a) demographics, (b) dispositional empathy, and (c) environmental attitudes and behavior. A 2D:4D ratio was calculated for each participant, and the quality of each image was classified as poor, moderate, or good. We then examined the reliability of the 2D:4D image measurements, and the relationship between 2D:4D and our environmental measures. 2D:4D ratios fell somewhat outside of previously reported ranges, but the measurements did show acceptable intra-rater consistency. Although we did not find a sex difference in 2D:4D, we did find a sex by ratio interaction for both empathy and the number of pro-environmental behaviors in which individuals had engaged. Specifically, as 2D:4D ratio increased, males reported lower empathy and less engagement in pro-environmental behaviors, whereas females reported more engagement in pro-environmental behaviors (but no differences in empathy). These findings were contrary to expectations, as we anticipated that greater digit ratios (i.e., feminized) would be associated with greater empathy and pro-environmental behaviors. Overall, the findings of this study present a preliminary examination of the utility of measuring digit ratio with online samples. Furthermore, our results provide information regarding the complex relationship between sex and pro-environmental behaviors.
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Affiliation(s)
- Gary J. Pickering
- Department of Biological Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON L2S 3A1 Canada
- Psychology Department, Brock University, St. Catharines, Canada
- Environmental Sustainability Research Centre, Brock University, St. Catharines, Canada
- Sustainability Research Centre, University of the Sunshine Coast, Sippy Downs, Australia
| | - Nicholas Anger
- Centre for Digital Humanities, Brock University, St. Catharines, Canada
| | - Julia Baird
- Environmental Sustainability Research Centre, Brock University, St. Catharines, Canada
- Sustainability Research Centre, University of the Sunshine Coast, Sippy Downs, Australia
- Department of Geography and Tourism Studies, Brock University, St. Catharines, Canada
| | - Gillian Dale
- Environmental Sustainability Research Centre, Brock University, St. Catharines, Canada
| | - Glenn J. Tattersall
- Department of Biological Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON L2S 3A1 Canada
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Ernsten L, Körner LM, Heil M, Richards G, Schaal NK. Investigating the reliability and sex differences of digit lengths, ratios, and hand measures in infants. Sci Rep 2021; 11:10998. [PMID: 34040007 PMCID: PMC8155043 DOI: 10.1038/s41598-021-89590-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 04/23/2021] [Indexed: 11/08/2022] Open
Abstract
Hands and digits tend to be sexually dimorphic and may reflect prenatal androgen exposure. In the past years, the literature introduced several hand and digit measures, but there is a lack of studies in prepubertal cohorts. The available literature reports more heterogeneous findings in prepubertal compared to postpubertal cohorts. The comparability of the available studies is further limited by the study design and different measurement techniques. The present study compared the reliability and sex differences of available hand and digit measures, namely digit lengths of 2D, 3D, 4D, 5D, digit ratios 2D:4D, 2D:5D, 3D:4D, 3D:5D, 4D:5D, relative digit lengths rel2, rel3, rel4, rel5, directional asymmetry of right and left 2D:4D (Dr-l), hand width, length, and index of 399 male and 364 female 6-month-old German infants within one study using only indirect and computer-assisted measurements. The inter-examiner reliability was excellent while the test-retest reliability of hand scans was only moderate to high. Boys exhibited longer digits as well as wider and longer hands than girls, but smaller digit ratios, with ratios comprising the fifth digit revealing the largest effect sizes. Other hand and digit ratios revealed sex differences to some extent. The findings promote the assumption of sexual dimorphic hand and digit measures. However, by comparing the results of the available literature, there remains an uncertainty regarding the underlying hypothesis. Specifically in prepubertal cohorts, i.e. before the influence of fluctuating hormones, significant effects should be expected. It seems like other factors than the influence of prenatal androgens contribute to the sexual dimorphism in hand and digit lengths.
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Affiliation(s)
- Luisa Ernsten
- Department of Experimental Psychology, Heinrich-Heine-University, Universitätsstraße 1, 40225, Düsseldorf, Germany.
| | - Lisa M Körner
- Department of Experimental Psychology, Heinrich-Heine-University, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Martin Heil
- Department of Experimental Psychology, Heinrich-Heine-University, Universitätsstraße 1, 40225, Düsseldorf, Germany
| | - Gareth Richards
- School of Psychology, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Nora K Schaal
- Department of Experimental Psychology, Heinrich-Heine-University, Universitätsstraße 1, 40225, Düsseldorf, Germany
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Kyselicová K, Belica I, Vidošovičová M, Janšáková K, Neščáková E, Špajdel M, Navarová S, Ostatníková D. Autism spectrum disorder and new perspectives on the reliability of second to fourth digit ratio. Dev Psychobiol 2021; 63:e22122. [PMID: 33942898 DOI: 10.1002/dev.22122] [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: 06/12/2020] [Revised: 02/01/2021] [Accepted: 03/19/2021] [Indexed: 11/06/2022]
Abstract
The second to fourth digit ratio (2D:4D) is according to previous studies a likely biomarker for prenatal testosterone exposure and its effect on the human brain. It was found to be linked to autism spectrum disorders (ASD). Recently, 2D:4D raised a lot of questions with regard to its stability and autism-related behaviors. Here, we present a cross-sectional study of 2D:4D in boys (N = 91, mean age 7.63) and adults (N = 36 mean age 22.8) with ASD as well as neurotypical students, 506 participants in total. Digit ratio was assessed by taking measurements from digital scans, compared between groups and correlated with the autism quotient. Significant differences were found in the digit ratio of children and adults. Both girls and boys had 2D:4D ratio lower than women and men, both on the right (p = 0.000 in females, p = 0.000 in males) and left hand (p = 0.018 in females, p = 0.011 in males). No significant differences were found in digit ratios between neurotypical subjects and those with ASD nor was there a relationship with the reported autistic traits, which leads us to question the reliability of 2D:4D and its relation to ASD.
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Affiliation(s)
- Klaudia Kyselicová
- Institute of Physiology, Academic Research Center for Autism, Faculty of Medicine, Comenius University, Bratislava, Slovakia
| | - Ivan Belica
- Institute of Physiology, Academic Research Center for Autism, Faculty of Medicine, Comenius University, Bratislava, Slovakia
| | - Mária Vidošovičová
- Institute of Physiology, Academic Research Center for Autism, Faculty of Medicine, Comenius University, Bratislava, Slovakia
| | - Katarína Janšáková
- Institute of Physiology, Academic Research Center for Autism, Faculty of Medicine, Comenius University, Bratislava, Slovakia
| | - Eva Neščáková
- Department of Anthropology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
| | - Marián Špajdel
- Department of Psychology, Faculty of Philosophy and Arts, Trnava University, Trnava, Slovakia
| | - Simona Navarová
- Department of Psychology, Faculty of Philosophy and Arts, Trnava University, Trnava, Slovakia
| | - Daniela Ostatníková
- Institute of Physiology, Academic Research Center for Autism, Faculty of Medicine, Comenius University, Bratislava, Slovakia
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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: 8] [Impact Index Per Article: 2.7] [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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Abstract
Background Despite the global increase in the prevalence of autism spectrum disorders (ASD), relevant research studies are lacking in Brunei Darussalam. Various studies have shown a significant association between a lowered 2D:4D ratio (ratio of second digit/index finger to the fourth digit/ring finger) and ASD, making it one of the potential phenotypic biomarkers for early detection of autism, which is important for early intervention and management. Objective The objective of this study is to explore the association between 2D:4D ratio and ASD in Brunei Darussalam, as a potential tool to complement early ASD diagnosis. Methods We conducted a case–control study comprising 28 ASD and 62 typically developing (TD) children in the case and control group, respectively (age range: 3–11 years old; median age: 6 years old). Median 2D:4D ratios were measured, compared and analysed between the two groups. Logistic regression models were used to explore potential associations between the median 2D:4D ratio and ASD in respective gender, for both left and right hands, independently. Results Our study shows that the median 2D:4D ratio of left hand in ASD males is significantly lower than those in TD males, after adjusting for ethnicity and age [Odds Ratio (OR) = 0.57 (95% Confidence Interval (CI): 0.31–0.96); p = 0.044]. For females, there is no association of ASD with the median left hand 2D:4D ratio [OR = 3.09 (95% CI: 0.98–19.86); p = 0.144] or the median right hand 2D:4D ratio [OR = 1.23 (95% CI: 0.42–3.88); p = 0.702]. Our study also shows a significant positive correlation and/or a reduced asymmetry between the average 2D:4D ratio of left hands and right hands in ASD males (Pearson’s correlation (r) = 0.48; 95% CI: 0.076–0.75, p = 0.023). Conclusions There is significant association between a lowered median 2D:4D ratio of the left hand (in males only) and ASD diagnosis. Once validated in a larger sample size, a lowered median 2D:4D ratio on the left hand may be a potential tool to complement ASD diagnosis for males in our study population. There is no association between the median 2D:4D ratio (left or right hands) and ASD in females, which could be due to the small female sample size and/or the possibility of different aetiology for ASD in females. Reduced asymmetry between the average 2D:4D ratio of left and right hands observed in ASD males only (not in ASD females) also suggests the importance of considering gender-specific biomarkers for ASD diagnosis. Supplementary Information The online version contains supplementary material available at 10.1007/s10803-021-04899-9.
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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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Association patterns between 2D:4D ratio and age at menarche: the impact of methodology. ANTHROPOLOGICAL REVIEW 2020. [DOI: 10.2478/anre-2020-0026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
The ratio of index finger to ring finger length (2D:4D) is a sexually dimorphic feature and widely used as an indicator of prenatal androgen-estrogen exposure. Several studies have investigated the relationship between the 2D:4D ratio and the onset of the first menstrual period (menarche) in women.
The present study tested the association patterns between 2D:4D ratio and age at menarche. Furthermore, the impact of methods of measuring finger lengths was considered.
Two samples were used to conduct the study. One sample consisted of 110 women who self-measured their finger lengths. The finger length measurements in the second sample (88 women) were taken from one trained observer using the caliper-based technique. Age at menarche was determined using a retrospective method.
Women from the first sample reported an average age for the onset of the first menstrual bleeding at 12.9 (SD = 1.4) years of age. There was no significant association between the left and right 2D:4D ratio and the age at menarche. The second sample showed a mean age at menarche at 12.8 (SD = 1.3) years of age. Here, the right hand 2D:4D ratio and age at menarche were significantly correlated (p<0.001).
A more feminine 2D:4D ratio was significantly associated with an earlier menarcheal age only in the sample with direct finger length measurements by a trained investigator. The sample using self-measurements yielded no significant associations between menarcheal age and 2D:4D. The use of a reliable and well-founded methodology is essential for obtaining meaningful results.
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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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Fowler KD, Ross J, Walker E, Barritt-Cleary C, Greenfield HJ, Maeir AM. Fingerprint evidence for the division of labour and learning pottery-making at Early Bronze Age Tell eṣ-Ṣâfi/Gath, Israel. PLoS One 2020; 15:e0231046. [PMID: 32302320 PMCID: PMC7164663 DOI: 10.1371/journal.pone.0231046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 03/14/2020] [Indexed: 11/22/2022] Open
Abstract
The organization of craft production has long been a marker for broader social, economic and political changes that accompanied urbanism. The identity of producers who comprised production groups, communities, or workshops is out of reach using conventional archaeological data. There has been some success using epidermal prints on artefacts to identify the age and sex of producers. However, forensic research indicates that a combination of ridge breadth and ridge density would best identify the age and sex of individuals. To this end, we combine mean ridge breadth (MRB) and mean ridge density (MRD) to distinguish the age and sex of 112 fingerprints on Early Bronze Age (EB) III pottery from the early urban neighbourhood at Tell eṣ-Ṣâfi/Gath, Israel, dating to a 100 year time span. Our analysis accounts for the shrinkage of calcareous fabrics used to make six type of vessels, applies a modified version of the Kamp et al. regression equation to the MRB for each individual print, and infers sex by correlating MRD data to appropriate modern reference populations. When the results are combined, our analyses indicate that most fingerprints were made by adult and young males and the remainder by adult and young females. Children’s prints are in evidence but only occur on handles. Multiple prints of different age and sex on the same vessels suggest they were impressed during the training of young potters. Production appears dominated by adult and young males working alone, together, and in cooperation with adult and/or young females. Vessels with prints exclusively by females of any age are rare. This male dominant cooperative labour pattern contrasts recent studies showing that adult women primarily made Neolithic figurines in Anatolia, and more females than males were making pottery prior to the rise of city-states in northern Mesopotamia.
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Affiliation(s)
- Kent D. Fowler
- Department of Anthropology Ceramic Technology Laboratory, The University of Manitoba, Winnipeg, Canada
- St. John’s College, The University of Manitoba, Winnipeg, Canada
- Department of Anthropology, The University of Manitoba, Winnipeg, Canada
- * E-mail:
| | - Jon Ross
- Department of Anthropology Ceramic Technology Laboratory, The University of Manitoba, Winnipeg, Canada
- Department of Anthropology, The University of Manitoba, Winnipeg, Canada
- St. Paul’s College, Near Eastern Biblical Archaeology Laboratory, The University of Manitoba, Winnipeg, Canada
| | - Elizabeth Walker
- Department of Anthropology Ceramic Technology Laboratory, The University of Manitoba, Winnipeg, Canada
- Department of Anthropology, The University of Manitoba, Winnipeg, Canada
| | - Christian Barritt-Cleary
- Department of Anthropology Ceramic Technology Laboratory, The University of Manitoba, Winnipeg, Canada
- Department of Anthropology, The University of Manitoba, Winnipeg, Canada
| | - Haskel J. Greenfield
- Department of Anthropology, The University of Manitoba, Winnipeg, Canada
- St. Paul’s College, Near Eastern Biblical Archaeology Laboratory, The University of Manitoba, Winnipeg, Canada
| | - Aren M. Maeir
- The Institute of Archaeology, The Martin (Szusz) Department of Land of Israel Studies and Archaeology, Bar-Ilan University, Ramat Gan, Israel
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Nafakhi H, Al-Mosawi AA, Mudhafar MM, Al-Nafakh HA, Alsaady R. Digit ratio and hair color relationships with coronary atherosclerotic markers. Asian Cardiovasc Thorac Ann 2019; 27:362-368. [PMID: 31018656 DOI: 10.1177/0218492319847379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Objective We aimed to investigate the association between body phenotype markers and coronary atherosclerosis markers. Methods Eighty-nine patients (mean age 57 ± 9 years, 50.5% male) who were assessed for coronary artery disease by 64-slice multidetector computed tomography angiography were enrolled in the study. Results A significant positive association was observed between coronary artery calcification and the second to fourth digit ratio ( r = 0.2, p = 0.00); more notably in males compared to females ( p = 0.03 vs. p = 0.08). There was a significant association between coronary artery calcification and pure white hair ( p = 0.00). There was no significant association between pericardial fat volume and second to fourth digit ratio ( p = 0.8). Pericardial fat volume was significantly associated with pure white hair ( p = 0.02). A significant association was observed between coronary plaque and a higher second to fourth digit ratio ( p = 0.01) and this was more notable in males ( p = 0.04). A significant association was observed between pure white hair and coronary plaque ( p = 0.00). After adjustment for conventional cardiac risk factors, the association of coronary artery calcification and coronary plaque with the second to fourth digit ratio did not persist, whereas the association of pericardial fat volume and coronary artery calcification with pure white hair remained significant ( p = 0.01 and p = 0.00, respectively). Conclusion These results suggest a possible predictive value of hair color, rather than digit ratio, in assessing increased risk of coronary atherosclerosis and cardiac fat deposition.
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Affiliation(s)
- Hussein Nafakhi
- 1 Internal Medicine Department, Medicine College, University of Kufa, Najaf, Iraq
| | | | - Mundher M Mudhafar
- 3 Radiology Department, Jabir Ibn Hayyan Medical University, Najaf, Iraq
| | - Hasan A Al-Nafakh
- 2 Radiology Department, Medicine College, University of Kufa, Najaf, Iraq
| | - Rana Alsaady
- 2 Radiology Department, Medicine College, University of Kufa, Najaf, Iraq
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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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Familial digit ratio (2D:4D) associations in a general population sample from Wales. Early Hum Dev 2017; 112:14-19. [PMID: 28668648 PMCID: PMC5566275 DOI: 10.1016/j.earlhumdev.2017.06.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 06/13/2017] [Accepted: 06/20/2017] [Indexed: 11/30/2022]
Abstract
BACKGROUND The relative length of the second and fourth fingers (2D:4D) may be a sex-linked correlate of prenatal androgen exposure. However, the nature of the sex-linkage is controversial, with evidence for both X- and Y-linkage of the 2D:4D phenotype. AIMS To examine transgenerational effects relating to sex-linkage. In addition, assortative mating on 2D:4D was considered, as well as associations between 2D:4D and age and sex. STUDY DESIGN A family study was conducted. Parents and offspring completed a demographic questionnaire, and digit ratios were calculated from photocopies of participants' hands. SUBJECTS We recruited and phenotyped 585 individuals attending a cultural festival in Wales. 2D:4D information was available for 47 mother-son dyads, 70 mother-daughter dyads, 31 father-son dyads and 30 father-daughter dyads. OUTCOME MEASURES Correlations between 2D:4D of parents and children, as well as between mothers and fathers were conducted. 2D:4D was also examined in relation to age and sex. RESULTS AND CONCLUSIONS There was a sex difference in 2D:4D (males<females). Within the dyads, there was a significant positive correlation between mother and daughter 2D:4D, but no significant correlation between mother and son ratios, nor between father and offspring ratios. The overall pattern of correlations (with emphasis on father-son dyads) was not supportive of Y-linkage. There was a positive correlation between 2D:4D and age in children, and a negative correlation between 2D:4D and age in adults, and no evidence of assortative mating. Our data are consistent with the notion of 2D:4D as a sexually-dimorphic, mildly age-sensitive, and transgenerationally-transmitted trait that is more likely to be X- than Y-linked.
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Mendes PHC, Barbosa CR, da Silva MTME, Paranaíba LMR, Martelli DRB, de Barros LM, Swerts MSO, Silveira MF, Júnior HM. Association Between Hand Digit Ratio (2D:4D) and Nonsyndromic Orofacial Clefts. Cleft Palate Craniofac J 2016; 54:595-601. [PMID: 27148640 DOI: 10.1597/15-266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
OBJECTIVES Digit ratio (2D:4D) has been considered to be a marker in studies evaluating an individual's susceptibility to diseases, especially those diseases that show sex differences in their occurrence. We aimed to assess whether 2D:4D ratios are associated with nonsyndromic cleft lip and/or palate (NSCL/P) and verify the existence of a specific pattern of 2D:4D ratio in individuals affected by orofacial clefts. DESIGN This was a case-control study. METHODS Digital measurements of index and ring finger lengths of both hands of patients with NSCL/P (n = 54) and age- and gender-matched controls (n = 54) were obtained using a digital vernier caliper. Mean ratios between the second and fourth digits were compared. Data were analyzed by Student's t test and Mann-Whitney test with a significance level of 5%. RESULTS No significant difference was found between the mean digit ratios of the right and left hands between the groups for any analysis (P > .05), neither for the whole sample nor for the distributions by type of cleft and by gender. CONCLUSIONS Although the development of the fingers and the occurrence of NSCL/P can be regulated by the actions of similar genes, our results are not consistent with an association between 2D:4D ratio and this craniofacial deformity. This suggests that intrauterine exposure to fetal androgens, assessed using this marker, is similar between patients with NSCL/P and healthy individuals. We highlight the need for further studies in populations with different ancestries.
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Ellis L, Skorska MN, Bogaert AF. Handedness, sexual orientation, and somatic markers for prenatal androgens: Are southpaws really that gay? Laterality 2016; 22:157-180. [DOI: 10.1080/1357650x.2016.1151024] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Ellis L, Lykins A, Hoskin A, Ratnasingam M. Putative Androgen Exposure and Sexual Orientation: Cross-Cultural Evidence Suggesting a Modified Neurohormonal Theory. J Sex Med 2015; 12:2364-77. [PMID: 26663858 DOI: 10.1111/jsm.13070] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
INTRODUCTION According to neurohormonal theory, prenatal androgens are key determinants of sexual orientation. As a reputed marker for prenatal androgens, the 2D:4D finger length ratio has been used in more than a dozen studies to test the hypothesis that prenatal androgens influence sexual orientation. Findings have been very inconsistent. AIM The present study sought to retest the hypothesis that 2D:4D and sexual orientation are related is a manner consistent with neurohormonal theory. METHODS A 2D:4D measure (of the right hand) along with four additional somatic markers of androgen exposure (height, physical strength, muscularity, and athletic ability) with samples of college students in Malaysia (N = 2,058) and the United States (N = 2,511). The five androgen measures were factor analyzed, resulting in a two-factor solution: Factor 1 consisted of strength, muscularity, and athletic ability (the muscular coordination factor), and Factor 2 was comprised of the r2D:4D and adult height (the bone growth factor). MAIN OUTCOME MEASURES Sexual orientation was measured by asking each respondent the extent to which they were sexually attracted to males and the extent to which they were sexually attracted to females, both on 11-point scales. RESULTS When the countries and sexes were analyzed separately, neither the r2D:4D measure nor Factor 2 correlated with sexual orientation to significant degrees. Instead, it was the muscular coordination factor that correlated the best. Support was found for the hypothesis that prenatal androgens influence sexual orientation, but the nature of these influences was more complex than neurohormonal theory predicted. CONCLUSION A modified theory is needed and presented to accommodate the results from this study.
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Affiliation(s)
- Lee Ellis
- University of Malaya, Kuala Lumpur, Malaysia
| | - Amy Lykins
- University of New England, Armidale, NSW, Australia
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Portnoy J, Raine A, Glenn AL, Chen FR, Choy O, Granger DA. Digit ratio (2D:4D) moderates the relationship between cortisol reactivity and self-reported externalizing behavior in young adolescent males. Biol Psychol 2015; 112:94-106. [PMID: 26463360 DOI: 10.1016/j.biopsycho.2015.09.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 09/30/2015] [Accepted: 09/30/2015] [Indexed: 12/22/2022]
Abstract
Although reduced cortisol reactivity to stress and increased circulating testosterone level are hypothesized to be associated with higher levels of externalizing behavior, empirical findings are inconsistent. One factor that may account for the heterogeneity in these relationships is prenatal testosterone exposure. This study examined whether the second-to-fourth digit ratio (2D:4D), a putative marker of prenatal testosterone exposure, moderates the relationships of testosterone and cortisol reactivity with externalizing behavior. Left and right hand 2D:4D and self-reported externalizing behavior were measured in a sample of 353 young adolescents (M age=11.92 years; 178 females; 79.7% African American). Saliva samples were collected before and after a stress task and later assayed for cortisol. Testosterone levels were determined from an AM saliva sample. 2D:4D interacted with cortisol reactivity to predict externalizing behavior in males, but not females. In males, low cortisol reactivity was associated with higher levels of aggression and rule-breaking behavior, but only among subjects with low 2D:4D (i.e., high prenatal testosterone). Findings suggest the importance of a multi-systems approach in which interactions between multiple hormones are taken into account. Furthermore, results demonstrate the importance of considering the organizational influence of prenatal testosterone in order to understand the activational influence of circulating hormones during adolescence.
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Affiliation(s)
- Jill Portnoy
- University of Pennsylvania, Department of Criminology, 3809 Walnut St., Philadelphia, PA 19104, USA.
| | - Adrian Raine
- Departments of Criminology, Psychology, and Psychiatry, University of Pennsylvania, USA
| | - Andrea L Glenn
- Center for the Prevention of Youth Behavior Problems, Department of Psychology, University of Alabama, USA
| | - Frances R Chen
- Department of Criminology, University of Pennsylvania, USA
| | - Olivia Choy
- Department of Criminology, University of Pennsylvania, USA
| | - Douglas A Granger
- Institute for Interdisciplinary Salivary Bioscience Research, Arizona State University, Johns Hopkins University School of Nursing, Johns Hopkins University Bloomberg School of Public Health, USA
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Furuya S, Hisasue SI, Kato H, Shimamura S. Novel insight for midline cyst formation in prostate: The involvement of decreased prenatal testosterone suggested by second-to-fourth digit ratio study. Int J Urol 2015; 22:1063-7. [PMID: 26290162 DOI: 10.1111/iju.12892] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 07/07/2015] [Indexed: 11/29/2022]
Abstract
OBJECTIVES To clarify the relationship between midline cyst formation and second to fourth finger length ratio. METHODS The present study included 95 benign prostatic hyperplasia patients and 61 healthy male college students. All midline cysts were identified by transrectal ultrasonography. In the benign prostatic hyperplasia group, 45 midline cyst (+) men (M(age) = 67.2 years) and age-matched 50 midline cyst (-) men (M(age) = 67.1 years) were included. In the university student group, 12 midline cyst (+) men (M(age) = 21.7 years) and age-matched 49 midline cyst (-) men (Mage = 21.1 years) were included. We took photocopies of the participants' bilateral hands, and measured the second and fourth finger length was measured by one examiner in a blind manner. RESULTS Second to fourth finger length ratios in the benign prostatic hyperplasia group (right/left mean ± SD) were higher bilaterally in midline cyst (+) (0.95 ± 0.03/0.95 ± 0.03) than those in midline cyst (-) (0.92 ± 0.03/0.92 ± 0.03; P < 0.0001/P = 0.0010). Second to fourth finger length ratios in students were higher only in the right hand in midline cyst (+) (0.96 ± 0.03/0.94 ± 0.03) than those in midline cyst (-) (0.93 ± 0.03/0.94 ± 0.03; P = 0.0018/P = 0.9968). The second to fourth finger length ratio of midline cyst (+) men was significantly higher than that in midline cyst (-) men. CONCLUSIONS The second to fourth finger length ratio is higher in subjects with midline cyst of the prostate. It can be speculated that the prostatic utricle dilates in cases less exposed to male hormones during fetal development.
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Affiliation(s)
| | - Shin-Ichi Hisasue
- Department of Urology, Graduate School of Medicine, Juntendo University, Tokyo, Japan
| | - Haruaki Kato
- Department of Urology, School of Medicine, Shinshu University, Matsumoto, Nagano, Japan
| | - Shogo Shimamura
- Department of Urology, Sapporo Jieitai Hospital, Sapporo, Hokkaido, Japan
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Anthropometric aspects of hand morphology in relation to sex and to body mass in a Turkish population sample. HOMO-JOURNAL OF COMPARATIVE HUMAN BIOLOGY 2014; 65:338-48. [DOI: 10.1016/j.jchb.2014.03.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2013] [Accepted: 03/06/2014] [Indexed: 11/17/2022]
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Valla K, Halazonetis DJ. Correlation of 2D:4D digit ratio and craniofacial shape in prepubertal children. Am J Hum Biol 2014; 26:337-46. [PMID: 24470061 DOI: 10.1002/ajhb.22512] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2013] [Revised: 12/23/2013] [Accepted: 01/08/2014] [Indexed: 12/13/2022] Open
Abstract
OBJECTIVES The 2D:4D ratio is sexually dimorphic and is considered a proxy of prenatal androgen levels, or, according to recent evidence, is related to genes involved in ocular and palate development. Our aim was to investigate correlation between the 2D:4D ratio and the shape of the craniofacial skeleton in a population of prepubertal children. METHODS We conducted a cross-sectional study in a group of 58 male and 59 female prepubertal children aged 7-12 years. Craniofacial shape was evaluated using 15 skeletal landmarks on lateral cephalometric radiographs and fingers were measured with a computer-assisted procedure that involved tracing the finger outline. Geometric morphometric analysis was applied to the craniofacial landmarks and multivariate regression between digit ratios and craniofacial shape was computed in shape space and form space. RESULTS The male 2D:4D ratio was smaller than the female ratio (Cohen's d: 0.275 left hand, 0.126 right hand), but the difference was not statistically significant. Craniofacial shape did not show sexual dimorphism, but males were larger than females. No correlation was found between digit ratio and craniofacial shape in prepubertal children, either for the whole sample or for any of the two sex groups. CONCLUSIONS As several factors might be involved in the development and growth of both the craniofacial complex and fingers, the 2D:4D ratio, a putative proxy for fetal sex-hormone levels, is probably unable to impose a measurable effect within the variation of a normal population. Future research needs to examine an adult sample for potential covariation arising after the pubertal growth spurt.
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Affiliation(s)
- Kalliopy Valla
- Department of Orthodontics, School of Dentistry, National and Kapodistrian University of Athens, Greece
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Nikolic D, Cvjeticanin S, Petronic I, Milincic Z, Brdar R, Karan R, Konstantinovic L, Dragin A, Cutovic M. Population genetic analyses of susceptibility to increased body weight. Arch Med Sci 2012; 8:998-1002. [PMID: 23319973 PMCID: PMC3542489 DOI: 10.5114/aoms.2012.32405] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2010] [Revised: 03/14/2011] [Accepted: 04/24/2011] [Indexed: 11/19/2022] Open
Abstract
INTRODUCTION Obesity is a complex condition with multifactorial origin. Assuming that such a state is genetically controlled, the aim of our study was to evaluate the degree of genetic homozygosity among overweight and obese individuals by the homozygously recessive characteristics (HRC) test. MATERIAL AND METHODS We analysed the presence, distribution and individual combination of 15 selected genetically controlled recessive phenotype traits in a sample of 140 individuals with increased body mass index (overweight individuals n = 100 and obese individuals n = 40) and a control group of normal weight individuals (n = 300). RESULTS OBESE INDIVIDUALS HAVE SIGNIFICANTLY HIGHER MEAN VALUES FOR GENETIC HOMOZYGOSITY THAN THOSE WITH NORMAL WEIGHT (NORMAL WEIGHT: 3.61 ±1.48; obese: 4.13 ±1.47, p < 0.05) and difference in the presence of certain individual combinations of evaluated phenotype traits (Σχ(2) = 76.9; p < 0.01). There was no difference in average homozygosity of such genetic markers between groups of normal weight and overweight individuals (normal weight: 3.61 ±1.48; overweight: 3.93 ±1.51, p > 0.05) and between groups of overweight and obese individuals (overweight: 3.93 ±1.51; obese: 4.13 ±1.47, p > 0.05). There is no difference in the presence of certain individual combinations of evaluated phenotype traits between overweight and obese individuals (Σχ(2) = 20.6; p > 0.05). CONCLUSIONS There is a populational genetic difference in the degree of genetic homozygosity and variability between the group of normal weight and group of obese individuals, indicating a possible genetic component. Overweight and obese individuals have a genetic predisposition, but different expression of genetic loads could be one of the possible explanations for different susceptibility to increase of fat mass and body mass index.
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Affiliation(s)
- Dejan Nikolic
- Physical Medicine and Rehabilitation Department, University Children's Hospital, Belgrade, Serbia
| | - Suzana Cvjeticanin
- Faculty of Medicine, University of Belgrade, Serbia
- Institute for Human Genetics, Faculty of Medicine, Belgrade, Serbia
| | - Ivana Petronic
- Physical Medicine and Rehabilitation Department, University Children's Hospital, Belgrade, Serbia
- Faculty of Medicine, University of Belgrade, Serbia
| | | | - Radivoj Brdar
- Faculty of Medicine, University of Belgrade, Serbia
- Pediatric Surgery Department, University Children's Hospital, Belgrade, Serbia
| | - Radmila Karan
- Cardiac Surgery Clinic, Clinical Centre of Serbia, Belgrade, Serbia
| | - Ljubica Konstantinovic
- Faculty of Medicine, University of Belgrade, Serbia
- Clinic for Rehabilitation, School of Medicine, Belgrade, Serbia
| | - Aleksandra Dragin
- Faculty of Medicine, University of Belgrade, Serbia
- Clinic for Rehabilitation, School of Medicine, Belgrade, Serbia
| | - Milisav Cutovic
- Faculty of Medicine, University of Belgrade, Serbia
- Clinic for Rehabilitation, School of Medicine, Belgrade, Serbia
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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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Mayhew TM. Cross-sectional data on soft tissue morphometry of the growing hand and fingers of dextral individuals 5-65 years old. J Anat 2012; 221:373-81. [PMID: 22881364 DOI: 10.1111/j.1469-7580.2012.01553.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/17/2012] [Indexed: 11/26/2022] Open
Abstract
This study examines both hands of right-handed (dextral) subjects 5-65 years old in order to define the separate growth trajectories of digit lengths (2D-5D) and hand widths; to assess how 2D : 4D and other digit ratios also vary with age; and to test whether lengths are influenced by gender dimorphism and lateral (right/left) asymmetry. Calliper measurements were made from hand photocopies. Growth patterns were analysed by linear regression and correlation, main and interaction effects of age and gender were resolved by analysis of variance, and lateral asymmetries were identified by paired tests. All digits, and hand width, grew in a biphasic pattern in both hands, and inflection points between phases showed gender dimorphism. In the early fast-growing phase, male digits grew over a longer period than those in females, before switching to a slower growth phase during which gender dimorphism became more exaggerated. In right hands, age differences in digit ratios were confined to 2D : 4D and, except for 4D : 5D, females tended to show larger ratios than males. In left hands, all ratios (except 3D : 5D) varied with age and gender influenced only 2D : 4D, 2D : 5D and 3D : 5D. Again, ratios were greater in females. In females, 2D was longer in the right hand of older subjects, whilst 3D, 4D and 5D tended to be shorter in the right hand of younger subjects. No asymmetries were seen in 2D, 3D or 4D in males, but 5D tended to be shorter on the right in the group 9-12 years old. Finally, hand width tended to be greater in females on the right at 9-65 years old, and in males on the right at 18-23 years old. A further novel finding was that certain relationships (inflection points, correlation coefficients and gender differences in digit lengths) seemed to follow gradients running from 2D to 5D. It is tempting to speculate that these are manifestations of the antero-posterior gradients established by signalling events that control digit development and patterning in utero.
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Affiliation(s)
- T M Mayhew
- School of Biomedical Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, UK.
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Hisasue SI, Sasaki S, Tsukamoto T, Horie S. The relationship between second-to-fourth digit ratio and female gender identity. J Sex Med 2012; 9:2903-10. [PMID: 22738413 DOI: 10.1111/j.1743-6109.2012.02815.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Gender identity and the second-to-fourth finger length ratio (2D : 4D) are discriminative between the sexes. However, the relationship between 2D : 4D and gender identity disorder (GID) is still controversial. AIM The aim of this study is to investigate the relationship between 2D : 4D and score on the Gender Identity Scale (GIS) in female-to-male (FtM) GID subjects. METHODS Thirty-seven GID-FtM with testosterone replacement therapy from our clinic were included in this study. As controls, 20 male and 20 female volunteers participated from our institution (medical doctors and nurses). We photocopied left and right hands of the participants and measured the second and fourth finger lengths. Gender identity was measured with the GIS. MAIN OUTCOME MEASURES 2D : 4D digit ratio and GIS in male, female, and GID-FtM subjects. RESULTS The 2D : 4D (mean ± standard deviation) in male, female, and GID-FtM were 0.945 ± 0.029, 0.999 ± 0.035, and 0.955 ± 0.029 in right hand and 0.941 ± 0.024, 0.979 ± 0.040, and 0.954 ± 0.036 in left hand, respectively. The 2D : 4D was significantly lower in male controls in both hands and GID-FtM in the right hand than in female controls (P < 0.05, analysis of variance). Multiple linear regression analysis revealed that "consistent gender identity" score in the higher domain in GIS and "persistent gender identity" score in the lower domain are statistically significant variables correlating with 2D : 4D in the right hands among biological females. CONCLUSIONS The finger length ratio 2D : 4D in GID-FtM was significantly lower than in female controls in the right hand in this study. 2D : 4D showed a positive correlation with GIS score. Because 2D : 4D influences are assumed to be established in early life and to reflect testosterone exposure, our results suggest a relationship between GID-FtM and perinatal testosterone.
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Affiliation(s)
- Shin-Ichi Hisasue
- Department of Urology, School of Medicine, Teikyo University, Itabashi-ku, Tokyo, Japan.
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Cherbuin N, Luders E, Chou YY, Thompson PM, Toga AW, Anstey KJ. Right, left, and center: how does cerebral asymmetry mix with callosal connectivity? Hum Brain Mapp 2012; 34:1728-36. [PMID: 22419524 DOI: 10.1002/hbm.22022] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Revised: 11/13/2011] [Accepted: 11/28/2011] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Prior research has shown that cerebral asymmetry is associated with differences in corpus callosum connectivity. Such associations were detected in histological and anatomical studies investigating callosal fiber size and density, in neuroimaging investigations based on structural and diffusion tensor imaging, as well as in neuropsychological experiments. However, little is known about typical associations between these factors, and even less about the relative influences of magnitude and direction of cerebral asymmetries. Here, we investigated relationships between callosal connectivity and cerebral asymmetry using precise measures of callosal thickness and selected cerebral structures. We considered both the direction and magnitude of the asymmetries. METHODS Associations between cerebral asymmetry and callosal thickness were investigated in 348 cognitively healthy older individuals. RESULTS The magnitude and direction of cerebral lateralization were significant independent predictors of callosal thickness. However, associations were small. Leftward asymmetry and increased magnitude of asymmetry were generally associated with increased callosal thickness, mostly in the callosal midbody and isthmus. CONCLUSIONS When a large sample of normal individuals is considered, cerebral asymmetries are only subtly associated with callosal thickness.
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Affiliation(s)
- Nicolas Cherbuin
- Centre for Research on Ageing, Health, and Wellbeing, Australian National University, Canberra, Australia.
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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; 9:354-70. [PMID: 22947980 PMCID: PMC10481021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Accepted: 07/28/2011] [Indexed: 06/01/2023] 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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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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Individual phenotype trait variability as genetic markers of gender susceptibility to spina bifida. Balkan J Med Genet 2011; 14:11-8. [PMID: 24052697 PMCID: PMC3776695 DOI: 10.2478/v10034-011-0012-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We compared individual trait variability in 65 male and 81 female patients with spina bifida occulta (SBO) or spina bifida aperta (SBA) against 170 male and 200 female subjects randomly selected Serbian subjects without these conditions. Variability was evaluated by direct observation of 15 homozygous recessive traits (HRT), while gender was evaluated separately. Individual trait variations between genders in SBO patients (4/15 HRT) and in SBA patients (12/15 HRT) showed remarkable differences. Individual trait variations between the male control group and SBO (9/15 HRT), between the female control group and SBO (5/15 HRT), between the male control group and SBA (8/15 HRT), between the female control group and SBA (9/15 HRT), between male SBO and SBA patients (6/15 HRT), between female SBO and SBA patients (6/15 HRT), also indicated remarkable differences. These differences could be explained by different expression of genes that may contribute to expression of spina bifida (SB).
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Ruuskanen S, Helle S, Ahola M, Adamczyck F, Möstl E, Laaksonen T. Digit ratios have poor indicator value in a wild bird population. Behav Ecol Sociobiol 2011; 65:983-994. [PMID: 21625648 PMCID: PMC3078308 DOI: 10.1007/s00265-010-1099-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Revised: 10/25/2010] [Accepted: 10/25/2010] [Indexed: 11/28/2022]
Abstract
Early androgen exposure is known to have long-lasting effects on phenotype, behaviour and even fitness, but difficulties in measuring the exposure hinders the study of its importance in evolutionary context. Digit ratios have been highlighted as a potential easy-to-measure indicator of early steroid exposure, as they have been suggested to reflect steroid, mainly testosterone levels during prenatal development. However, evidence for digit ratios reflecting early steroid levels is weak, as experimental studies, especially in wild populations, are scarce. We studied the association between maternally derived yolk androgens and digit ratios (2D:4D, 2D:3D and 3D:4D) using both correlative data and a rather high level of experimental elevation of yolk androgens in a passerine bird, the pied flycatcher (Ficedula hypoleuca). We also examined whether digit ratios have indicator value in an evolutionary context by studying correlations between digit ratios and reproductive traits, secondary sexual traits and exploratory behaviour. We did not find any association between digit ratios and yolk androgen level either in correlative or experimental data. Digit ratios were neither related to any of the reproductive and secondary sexual traits or exploratory behaviour measured. There was, however, a sex difference in 2D:3D and 3D:4D of adult birds (due to second and fourth digits being shorter in females), which was not apparent in fledglings or captivity-raised juveniles. This suggests that either the sex difference may develop as late as during the sexual maturation for breeding. These results indicate that, in this species, digit ratios are not reliable markers of maternally derived yolk androgen exposure and that they bear little relevance as correlates of the adaptive traits we measured.
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Affiliation(s)
- Suvi Ruuskanen
- Section of Ecology, Department of Biology, University of Turku, Turku, Finland
| | - Samuli Helle
- Section of Ecology, Department of Biology, University of Turku, Turku, Finland
| | - Markus Ahola
- Section of Ecology, Department of Biology, University of Turku, Turku, Finland
| | - Freya Adamczyck
- Department of Animal Population Biology, Netherlands Institute of Ecology (NIOO-KNAW), Heteren, The Netherlands
| | - Erich Möstl
- University of Veterinary Medicine, Vienna, Austria
| | - Toni Laaksonen
- Section of Ecology, Department of Biology, University of Turku, Turku, Finland
- Finnish Museum of Natural History, University of Helsinki, Helsinki, Finland
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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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Hönekopp J, Watson S. Meta-analysis of digit ratio 2D:4D shows greater sex difference in the right hand. Am J Hum Biol 2011; 22:619-30. [PMID: 20737609 DOI: 10.1002/ajhb.21054] [Citation(s) in RCA: 323] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
OBJECTIVES Our aims are, first, to describe the sex difference in the length ratio of the second and fourth digits (2D:4D), which likely reflects prenatal testosterone levels in humans. Second, to infer the loss of reliability observed in 2D:4D based on self-measured finger lengths. METHODS We used random-effects meta-analysis of 2D:4D based on expert-measured finger lengths (116 samples with 13,260 females and 11,789 males). RESULTS We find a moderate sex difference (with lower 2D:4D for males), which shows substantial heterogeneity (which is unrelated to age). The sex difference is moderated by the type of finger length measurement and by hand. Measurement involving the distortion of soft tissue leads to a significantly larger sex difference than finger length measurement avoiding this. The sex difference in 2D:4D is larger in the right hand than in the left. The reliability of self-measured 2D:4D in the BBC internet study, by far the largest study on 2D:4D, is estimated to be 46% of that of expert-measured 2D:4D. CONCLUSIONS Right-hand 2D:4D might be a better indicator of prenatal androgenisation than left-hand 2D:4D. The view that 2D:4D has allometric properties (Kratochvil L, Flegr J. 2009. Differences in 2nd to 4th digit length ratio in humans reflect shifts along the common allometric line. Biol Lett 5:643-646.) is not supported. Bone lengths contribute to the sex difference in 2D:4D. In addition, there might be a sex difference in fingers' soft tissue, which should be investigated. Because of measurement unreliability, correlations between 2D:4D and variables of interest are about one-third smaller in the BBC internet study than in studies in which 2D:4D is based on expert-measured finger lengths.
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Affiliation(s)
- Johannes Hönekopp
- Department of Psychology, Northumbria University, Newcastle upon Tyne NE1 8ST, United Kingdom.
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Voracek M, Loibl LM. Scientometric analysis and bibliography of digit ratio (2D:4D) research, 1998-2008. Psychol Rep 2009; 104:922-56. [PMID: 19708418 DOI: 10.2466/pr0.104.3.922-956] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A scientometric analysis of modern research on the second-to-fourth digit ratio (2D:4D), a widely studied putative marker for prenatal androgen action, is presented. In early 2009, this literature totalled more than 300 publications and, since its initiation in 1998, has grown at a rate slightly faster than linear. Key findings included evidence of publication bias and citation bias, incomplete coverage and outdatedness of existing reviews, and a dearth of meta-analyses in this field. 2D:4D research clusters noticeably in terms of researchers, institutions, countries, and journals involved. Although 2D:4D is an anthropometric trait, most of the research has been conducted at psychology departments, not anthropology departments. However, 2D:4D research has not been predominantly published in core and specialized journals of psychology, but rather in more broadly scoped journals of the behavioral sciences, biomedical social sciences, and neurosciences. Total citation numbers of 2D:4D papers for the most part were not larger than their citation counts within 2D:4D research, indicating that until now, only a few 2D:4D studies have attained broader interest outside this specific field. Comparative citation analyses show that 2D:4D research presently is commensurate in size and importance to evolutionary psychological jealousy research, but has grown faster than the latter field. In contrast, it is much smaller and has spread more slowly than research about the Implicit Association Test Fifteen conjectures about anticipated trends in 2D:4D research are outlined, appendixed by a first-time bibliography of the entirety of the published 2D:4D literature.
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Affiliation(s)
- Martin Voracek
- Department of Basic Psychological Research, School of Psychology, University of Vienna, Liebiggasse 5, Rm 03-46, A-1010 Vienna, Austria.
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Voracek M, Dressler SG, Loibl LM. The contributions of Hans-Dieter Rösler: pioneer of digit ratio (2D:4D) research. Psychol Rep 2009; 103:899-916. [PMID: 19320227 DOI: 10.2466/pr0.103.3.899-916] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Over the past decade, the second-to-fourth digit ratio (2D:4D), a putative biomarker for the organizational (permanent) effects of prenatal androgens on the human brain, body, and behavior, has received extensive research attention in psychology. This account makes more widely accessible the contributions of the German psychologist, Hans-Dieter Rösler, an early, for a long time unnoticed, predecessor of modern 2D:4D research. In the mid-1950s, Rösler collected a massive sample of hand outline drawings, totalling nearly 7,000 individuals, ranging in age from 1 mo. to 70 yr. With regard to the distal finger-extent pattern, Rösler differentiated radial (longer index than ring finger), ulnar (reversed pattern), and intermediate hand types, which reflect higher (more female-typical), lower (more male-typical), and intermediate 2D:4D, respectively. Here is summarized Rösler's research. In a series of investigations into the hand types, he reported on their anatomical bases, unsuitability for paternity testing, developmental changes, heritability, sex, side, and occupational group differences, and associations with left-handedness, manual dexterity, mental retardation, and clinodactyly. Based on new data from 313 male and 316 female adults, hand type is further shown to be only a weak proxy of actual 2D:4D, leaving 75% of the interindividual variation in 2D:4D unexplained. Notwithstanding these shortcomings of the hand-type method, Rösler's work from the 1950s still has the potential to inform modern 2D:4D research, as it contains a multitude of testable hypotheses not yet picked up by current research.
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Affiliation(s)
- Martin Voracek
- Department of Basic Psychological Research, School of Psychology, University of Vienna, Liebiggasse 5, Rm 03-46, 1010 Vienna, Austria.
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