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Richardson T. No association between adult sex steroids and hand preference in humans. Am J Hum Biol 2021; 34:e23605. [PMID: 33949024 DOI: 10.1002/ajhb.23605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 03/26/2021] [Accepted: 03/27/2021] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND There is ongoing debate about the effects of hormones on the lateralization of the developing brain. In humans, there are conflicting theories of how testosterone during development should affect lateralization. Empirical studies linking prenatal and postnatal testosterone levels to hand preference (a proxy for lateralization) are similarly mixed. Links between hand preference and health may also suggest a mediating role of steroid hormones such as testosterone and estradiol. Studies to date of adult steroid hormones and handedness have been hindered by samples that contain small numbers of non-right-handers. RESULTS In the largest study of the phenomenon to date, I find that the testosterone (n = 7290) and estradiol (n = 3700) levels of left- and mixed-handed adults are no different to those of right-handers. All Bayesian 95% highest density intervals contained 0. DISCUSSION AND CONCLUSIONS The results have implications for studies that show elevated risk of hormonal-related mental and physical disorders in left-handed individuals.
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Affiliation(s)
- Thomas Richardson
- School of Earth and Environmental Sciences, The University of Manchester, Manchester, UK
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2
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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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van der Feen FE, Zickert N, Groothuis TG, Geuze RH. Does hand skill asymmetry relate to creativity, developmental and health issues and aggression as markers of fitness? Laterality 2019; 25:53-86. [DOI: 10.1080/1357650x.2019.1619750] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Fleur E. van der Feen
- Clinical and Developmental Neuropsychology, University of Groningen, Groningen, Netherlands
| | - Nele Zickert
- Behavioral Biology, the Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, Netherlands
| | - Ton G.G. Groothuis
- Behavioral Biology, the Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, Netherlands
| | - Reint H. Geuze
- Clinical and Developmental Neuropsychology, University of Groningen, Groningen, Netherlands
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Hoppler S, Walther A, La Marca-Ghaemmaghami P, Ehlert U. Lower birthweight and left-/mixed-handedness are associated with intensified age-related sex steroid decline in men. Findings from the Men's Health 40+ Study. Andrology 2018; 6:896-902. [PMID: 29993200 PMCID: PMC6585816 DOI: 10.1111/andr.12516] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 04/29/2018] [Accepted: 05/26/2018] [Indexed: 11/29/2022]
Abstract
In males, age‐related decline in free testosterone (T) and dehydroepiandrosterone (DHEA) by 2–3% per year has been reported. Estradiol (E2) and progesterone (P) seem to decrease as well, but to a lesser extent. Lower sex steroid levels in men have been related to physical and mental symptoms. Low birthweight and left‐/mixed‐handedness (L/MH) are indicators of an adverse fetal environment during pregnancy, and both have been linked to morbidity in later life. The aim of this study is to examine the relationship between lower birthweight as well as L/MH and age‐related sex steroid decline. In a cross‐sectional study design, saliva samples were collected under standardized conditions from healthy men for subsequent steroid hormone analysis using standard luminescence immunoassays. T (M = 67.57 pg/mL), DHEA (M = 247.91 pg/mL), E2 (M = 1.29 pg/mL), and P (M = 28.20 pg/mL) have been quantified leading to a final sample of 256 men providing complete data on sex hormones (MAge=57.8; SDAge = 10.8). Information on participants’ birthweight was obtained from birth reports (N = 134), and participants were asked about their handedness (right‐handed, left‐handed, mixed‐handed) (N = 256). Multivariate‐adjusted linear regression models relating each sex hormone individually and the principal component of declining steroid hormones (DSH)—an integrated hormonal parameter—with handedness and birthweight did not identify significant associations except for handedness and E2. Moderation analysis using robust regression accounting for bias due to influential data points detected a significant association between age and DSH for handedness (β = −0.0314, p = 0.040) but only a trend for birthweight (β = 0.0309, p = 0.073). For lower birthweight, a trend toward intensified age‐related sex steroid decline in men was observed, while for L/MH, a significant association with intensified age‐related sex steroid decline was identified. These results indicate that L/MH and potentially also lower birthweight might be considered as early risk factors for endocrine health in later life.
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Affiliation(s)
- S Hoppler
- Clinical Psychology and Psychotherapy, University of Zurich, Zurich, Switzerland
| | - A Walther
- Clinical Psychology and Psychotherapy, University of Zurich, Zurich, Switzerland.,University Research Priority Program - Dynamics of Healthy Aging, University of Zurich, Zurich, Switzerland.,Biological Psychology, TU Dresden, Dresden, Germany
| | | | - U Ehlert
- Clinical Psychology and Psychotherapy, University of Zurich, Zurich, Switzerland.,University Research Priority Program - Dynamics of Healthy Aging, University of Zurich, Zurich, Switzerland
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Zickert N, Geuze RH, van der Feen FE, Groothuis TG. Fitness costs and benefits associated with hand preference in humans: A large internet study in a Dutch sample. EVOL HUM BEHAV 2018. [DOI: 10.1016/j.evolhumbehav.2018.01.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Abstract
OBJECTIVE Mixed-handedness among children has recently been proposed as a marker of neurodevelopmental disorder and ADHD. This study expanded this initial evidence to the questions of whether mixed-handedness as well as mixed-footedness are similarly associated with ADHD among adults. METHOD Self-reported ADHD symptoms, handedness, footedness, and current depression and anxiety were assessed in a large, heterogeneous general population sample ( N = 2,592). Latent variable analysis was used to investigate the structure and measurement properties of ADHD symptoms, the dimensionality of footedness, and the classification of lateral preferences. RESULTS Mixed-footedness was associated with probable ADHD (odds ratio [OR] = 1.76 [1.07, 2.89], p = .026). Left- and mixed-footedness were associated with higher inattention and impulsivity scores. CONCLUSION Developmental continuities of the associations of mixed lateral preferences with ADHD from child to adult age seem to exist. In particular, mixed-footedness, rather than mixed-handedness, appears to be an ADHD marker among adults.
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Androgen Levels and Body Size Are Associated with Directional as Well as Fluctuating Asymmetry Patterns in Adult !Kung San and Kavango Males from Northern Namibia. Symmetry (Basel) 2017. [DOI: 10.3390/sym9050072] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Tran US, Voracek M. Footedness Is Associated with Self-reported Sporting Performance and Motor Abilities in the General Population. Front Psychol 2016; 7:1199. [PMID: 27559326 PMCID: PMC4978716 DOI: 10.3389/fpsyg.2016.01199] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 07/28/2016] [Indexed: 11/13/2022] Open
Abstract
Left-handers may have strategic advantages over right-handers in interactive sports and innate superior abilities that are beneficial for sports. Previous studies relied on differing criteria for handedness classification and mostly did not investigate mixed preferences and footedness. Footedness appears to be less influenced by external and societal factors than handedness. Utilizing latent class analysis and structural equation modeling, we investigated in a series of studies (total N > 15300) associations of handedness and footedness with self-reported sporting performance and motor abilities in the general population. Using a discovery and a replication sample (ns = 7658 and 5062), Study 1 revealed replicable beneficial effects of mixed-footedness and left-footedness in team sports, martial arts and fencing, dancing, skiing, and swimming. Study 2 (n = 2592) showed that footedness for unskilled bipedal movement tasks, but not for skilled unipedal tasks, was beneficial for sporting performance. Mixed- and left-footedness had effects on motor abilities that were consistent with published results on better brain interhemispheric communication, but also akin to testosterone-induced effects regarding flexibility, strength, and endurance. Laterality effects were only small. Possible neural and hormonal bases of observed effects need to be examined in future studies.
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Affiliation(s)
- Ulrich S Tran
- Department of Basic Psychological Research and Research Methods, School of Psychology, University of Vienna Vienna, Austria
| | - Martin Voracek
- Department of Basic Psychological Research and Research Methods, School of Psychology, University of Vienna Vienna, Austria
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Papadatou-Pastou M, Martin M, Mohr C. Salivary testosterone levels are unrelated to handedness or cerebral lateralization for language. Laterality 2016; 22:123-156. [DOI: 10.1080/1357650x.2016.1149485] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Abstract
Abstract
In boxing, athletes choose between two strategies: the orthodox stance characteristic of right handed competitors, or the southpaw stance characteristic of left-handers. Despite a conviction popular among the practitioners of this sport that fighting against a southpaw opponent constitutes a handicap, the effectiveness of the type of stance has so far not been examined. We extracted the statistics of the top twenty active male professionals boxing in each of the seventeen weight divisions. Out of the 340 boxers who composed our group, 75% used the orthodox stance and 25% were southpaw. Generally, we found that boxing stance had no effect on the percentage of 340 top professional boxers’ victories. However, both the southpaw and the orthodox athletes had a higher percentage of victories against orthodox boxers than against southpaws.
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Loffing F, Hagemann N. Pushing through evolution? Incidence and fight records of left-oriented fighters in professional boxing history. Laterality 2014; 20:270-86. [DOI: 10.1080/1357650x.2014.961471] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Knepp MM, Krafka ER, Boulton AN, Myers MP. Group administration influences design but not written word fluency testing. Laterality 2014; 19:615-37. [PMID: 24611866 DOI: 10.1080/1357650x.2014.892507] [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: 10/25/2022]
Abstract
Quicker assessments of right and left frontal lobe function, such as the examination of performance on design and language fluency tasks, respectively, lend themselves to a group administration setting. However, the influence of social facilitation factors on a dissociation model in these group settings is not well understood. One hundred college students (71 women) completed design and written word fluency tasks while sitting beside a faster or slower working confederate. Questionnaires related to trait worry, emotion regulation, state depression, anxiety and stress were completed following these tasks. Students in the fast condition produced significantly more unique designs, but there was no condition difference on written word fluency. This finding indicated that performance on a design task, which requires relative right frontal activation, may decrease if the subject is paired with a slow working confederate. High trait worriers demonstrated reduced performance on the design task (as indicated by higher design error ratios) but preserved performance on the word task. This supported a single dissociation in that performance on these tasks indicates compromised right hemisphere function and preserved left hemisphere function, respectively, in high trait worriers.
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Affiliation(s)
- Michael M Knepp
- a Department of Psychology and Neuroscience , University of Mount Union , Alliance , OH , USA
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Pollet TV, Stulp G, Groothuis TG. Born to win? Testing the fighting hypothesis in realistic fights: left-handedness in the Ultimate Fighting Championship. Anim Behav 2013. [DOI: 10.1016/j.anbehav.2013.07.026] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Groothuis TGG, McManus IC, Schaafsma SM, Geuze RH. The fighting hypothesis in combat: how well does the fighting hypothesis explain human left-handed minorities? Ann N Y Acad Sci 2013; 1288:100-9. [PMID: 23742682 DOI: 10.1111/nyas.12164] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The strong population bias in hand preference in favor of right-handedness seems to be a typical human trait. An elegant evolutionary hypothesis explaining this trait is the so-called fighting hypothesis that postulates that left-handedness is under frequency-dependent selection. The fighting hypothesis assumes that left-handers, being in the minority because of health issues, are still maintained in the population since they would have a greater chance of winning in fights than right-handers due to a surprise effect. This review critically evaluates the assumptions and evidence for this hypothesis and concludes that some evidence, although consistent with the fighting hypothesis, does not directly support it and may also be interpreted differently. Other supportive data are ambiguous or open for both statistical and theoretical criticism. We conclude that, presently, evidence for the fighting hypothesis is not particularly strong, but that there is little evidence to reject it either. The hypothesis thus remains an intuitively plausible explanation for the persistent left-hand preference in the population. We suggest alternative explanations and several ways forward for obtaining more crucial data for testing this frequently cited hypothesis.
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Affiliation(s)
- Ton G G Groothuis
- Behavioural Biology, Centre for Behaviour and Neuroscience, University of Groningen, Groningen, The Netherlands.
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Faurie C, Raymond M. The fighting hypothesis as an evolutionary explanation for the handedness polymorphism in humans: where are we? Ann N Y Acad Sci 2013; 1288:110-3. [DOI: 10.1111/nyas.12159] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Charlotte Faurie
- Institute of Evolutionary Sciences of Montpellier; University of Montpellier II; Montpellier France
| | - Michel Raymond
- Institute of Evolutionary Sciences of Montpellier; University of Montpellier II; Montpellier France
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