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Background: The relationship between the second (2D) and fourth finger (4D) of the hand (2D:4D) is considered to be a proxy indicator of prenatal- testosterone (PT) and estrogen (PE) exposure in the first trimester of pregnancy. A lower 2D:4D indicates relatively higher PT exposure and vice versa. The 2D:4D is generally higher in women than in men. Lower 2D:4D is associated with greater physical ability, strength, better athletic performance, and a propensity for jobs that require more physical fitness and are more risky.
Aim: The aim of the present study was to examine the differences in 2D:4D, if any, between three groups of men in Poland: military students (N = 250), soldiers of the Land Forces (N = 106) and volunteers of the Territorial Defense Force (N = 202).
Method: This cross-sectional study was carried out in Military University of Land Forces (MULF) in Wroclaw, Poland. The measurements included body height, body weight and the lengths of the second and fourth fingers in both hand of each participant.
Results: The results showed significantly lower 2D:4D in land forces soldiers and military students than those belonged to the Territorial Defense Force.
Conclusion: The results indicated the possible impact of fetal androgens on specific human abilities as well as choices for challenging occupations.
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http://dx.doi.org/10.1016/j.earlhumdev.2025.106371 | DOI Listing |
Exp Anim
May 2025
Department of Biology, Faculty of Environmental, Life, Natural Science and Technology, Okayama University.
The ratio of the second and fourth digits (2D:4D) is a morphological marker reflecting fetal exposure to sex steroid hormones. This ratio exhibits sexual dimorphism, with males typically showing a significantly lower ratio than females, which results from higher androgen exposure during the fetal period. While studies in humans have suggested a relationship between sexual orientation and the 2D:4D ratio, this relationship in rodents remains elusive.
View Article and Find Full Text PDFNoro Psikiyatr Ars
August 2024
Department of Child and Adolescent Psychiatry, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey.
Introduction: It has been suggested that inhibin B (InhB), Anti-Müllerian hormone (Müllerian-inhibiting substance, AMH) levels, and 2D/4D finger length ratios are related to sex differences in neurodevelopmental disorders. The aim of this study is to investigate the role of InhB, AMH levels, and 2D/4D finger length ratios in male children with specific learning disorder (SLD).
Methods: The study included 38 male children diagnosed with SLD and 38 males of similar ages without SLD as the control group.
Noro Psikiyatr Ars
May 2024
Istanbul University, Istanbul Medical Faculty, Department of Child and Adolescent Psychiatry Istanbul, Turkey.
Introduction: There is a significant, but poorly understood, male preponderance in prevalence of autism spectrum disorder (ASD). The aim of this study was to examine the relationship between male preponderance in ASD and Inhibin B (InhB) and Anti-Müllerian hormone (AMH) levels and the 2D/4D finger ratio associated with fetal androgen exposure.
Methods: 42 patients with ASD and 42 neurotypical controls between the ages of 5 and 10 were included.
J Cosmet Dermatol
July 2022
Department of Dermatology, Selçuk University, Konya, Turkey.
Aims: Vitiligo is a multifactorial, acquired skin disease of unknown etiology characterized by depigmented patches caused by melanocyte loss. The ratio of the second to fourth digits (2D:4D) is believed to be a marker of prenatal androgen exposure. Among the many hypotheses for melanocyte loss, one is that sex hormones may play a role in the development of vitiligo.
View Article and Find Full Text PDFPsychophysiology
May 2019
Department of Clinical Psychology and Psychotherapy, University of Zurich, Zurich, Switzerland.
The ratio between the length of the second (index) and the fourth (ring) finger (2D4D) is a putative biomarker of prenatal testosterone (T) exposure, with higher exposure leading to a smaller ratio. 2D4D has further been linked to mental and somatic disorders. Healthy male Swiss recruits (N = 245; M = 20.
View Article and Find Full Text PDF