A Reanalysis of Five Studies on Sexual Orientation and the Relative Length of the 2nd and 4th Fingers (the 2D:4D Ratio)

McFadden, Dennis; Loehlin, John C.; Breedlove, S. Marc; Lippa, Richard A.; Manning, John T.; Rahman, Qazi

doi:10.1007/s10508-005-3123-9

Cited by 104 publications

(89 citation statements)

References 35 publications

(58 reference statements)

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“…The 2D:4D of gay males has been described as hypermasculinized (lower) in some reports or hypomasculinized (higher) in other studies (Lippa, 2003;Manning et al, 2007;McFadden et al, 2005;McFadden & Shubel, 2002;Rahman & Wilson, 2003;Robinson & Manning, 2000;Voracek, Manning, & Ponocny, 2005;Williams et al, 2000). The correlation between sexual orientation and 2D:4D in women seems more consistent.…”

Section: Introductionmentioning

confidence: 84%

“…Here, the 2nd to 4th finger length ratio (2D:4D) was suggested to represent prenatal testosterone levels based on the finding that men usually show lower 2D:4D than women (Manning, Scutt, Wilson, & Lewis-Jones, 1998;Peters, Mackenzie, & Bryden, 2002). This difference seems to be more pronounced for the right hand 2D:4D and for right-handed individuals (McFadden et al, 2005;Schneider, Pickel, & Stalla, 2006).…”

Section: Introductionmentioning

confidence: 99%

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Finger Length Ratio (2D:4D) in Adults with Gender Identity Disorder

et al. 2007

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From early childhood, gender identity and the 2nd to 4th finger length ratio (2D:4D) are discriminative characteristics between sexes. Both the human brain and 2D:4D may be influenced by prenatal testosterone levels. This calls for an examination of 2D:4D in patients with gender identity disorder (GID) to study the possible influence of prenatal testosterone on gender identity. Until now, the only study carried out on this issue suggests lower prenatal testosterone levels in right-handed male-to-female GID patients (MtF). We compared 2D:4D of 56 GID patients (39 MtF; 17 female-to-male GID patients, FtM) with data from a control sample of 176 men and 190 women. Bivariate group comparisons showed that right hand 2D:4D in MtF was significantly higher (feminized) than in male controls, but similar to female controls. The comparison of 2D:4D ratios of biological women revealed significantly higher (feminized) values for right hands of right handed FtM. Analysis of variance confirmed significant effects for sex and for gender identity on 2D:4D ratios but not for sexual orientation or for the interaction among variables. Our results indirectly point to the possibility of a weak influence of reduced prenatal testosterone as an etiological factor in the multifactorially influenced development of MtF GID. The development of FtM GID seems even more unlikely to be notably influenced by prenatal testosterone. Analysis of variance confirmed significant effects for sex and for gender identity on 2D:4D ratios but not for sexual orientation or for the interaction among variables. Our results indirectly point to the possibility of a weak influence of reduced prenatal testosterone as an etiological factor in the multifactorially influenced development of MtF GID. The development of FtM GID seems even more unlikely to be notably influenced by prenatal testosterone.

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Section: Introductionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Finger Length Ratio (2D:4D) in Adults with Gender Identity Disorder

et al. 2007

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“…Taking direct measurements from photocopies is a widely used approach in 2D:4D studies (e.g., McFadden et al, 2005), although the ratios are slightly lower compared to direct measurements . Digit lengths were means of three measurements done by one of the authors (AK) for each digit from the photocopy (working from the left 4 th digit to the right 2 nd digit, then repeating these measures twice over) to reduce measurement error.…”

Section: Materials and Proceduresmentioning

confidence: 99%

Body Odor Quality Predicts Behavioral Attractiveness in Humans

et al. 2011

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Growing effort is being made to understand how different attractive physical traits covary within individuals, partly because this might indicate an underlying index of genetic quality. In humans, attention has focussed on potential markers of quality such as facial attractiveness, axillary odor quality, the second-to-fourth digit (2D:4D) ratio and body-mass index (BMI). Here we extend this approach to include visually-assessed kinesic cues (nonverbal behavior linked to movement) which are statistically independent of structural physical traits. The utility of such kinesic cues in mate assessment is controversial, particularly during every day conversational contexts, as they could be unreliable and susceptible to deception. However, we show here that the attractiveness of nonverbal behavior, in 20 male participants, is predicted by perceived quality of their axillary body odor. This finding indicates covariation between two desirable traits in different sensory modalities. Depending on two different rating contexts (either a simple attractiveness rating, or a rating for long-term partners, by 10 female raters not using hormonal contraception), we also found significant relationships between perceived attractiveness of nonverbal behavior and BMI, and between axillary odor ratings and 2D:4D ratio. Axillary odor pleasantness was the single attribute that consistently predicted attractiveness of nonverbal behavior. Our results demonstrate that nonverbal kinesic cues could reliably reveal mate quality, at least in males, and could corroborate and contribute to mate assessment based on other physical traits.

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“…Females-Twenty-one correlations between 2D:4D and spatial ability were obtained from 11 published (Austin et al, 2002;Coolican & Peters, 2003;Csatho et al, 2003;Kempel, Gohlke et al, 2005 Csatho et al, 2005;Kempel, Burk et al, 2005;Loehlin et al, 2005;Peters & Manning, 2005) studies, involving a total of 101,488 subjects ( Table 2). The fixed effects model rendered an effect size estimate of −.028, and the random effects model produced a smaller effect size estimate in the opposite direction: .005 (Figure 3).…”

Section: D:4d Studiesmentioning

confidence: 99%

Spatial Ability and Prenatal Androgens: Meta-Analyses of Congenital Adrenal Hyperplasia and Digit Ratio (2D:4D) Studies

et al. 2007

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Hormonal manipulations indicate that early androgens organize sex differences in spatial ability in animal models. In humans, spatial ability is also sexually dimorphic, and information about the effects of prenatal androgens on spatial ability can be obtained from studies of congenital adrenal hyperplasia (CAH) and the ratio of the second and fourth finger lengths (2D:4D). CAH is a condition characterized by prenatal overproduction of adrenal androgens, and several lines of evidence suggest that 2D:4D reflects prenatal androgen exposure. Some studies have found that these proxy measures of prenatal androgenization predict spatial ability, others have found no significant relationship, and yet others have obtained results in opposite directions. In light of these mixed findings, we conducted meta-analyses of published literature and unpublished results to determine if, across studies, either of these indications of prenatal androgens predicts spatial ability. In addition, we applied a trim and fill analysis to the data in search of asymmetry that might be an indication of publication bias. Results indicate that females with CAH have significantly better spatial abilities, and CAH males have worse spatial abilities, than do controls. Little or no relationship exists between 2D:4D and spatial ability. Implications for possible hormonal contributions and the developmental timing of sex differences in spatial cognition are discussed.

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A Reanalysis of Five Studies on Sexual Orientation and the Relative Length of the 2nd and 4th Fingers (the 2D:4D Ratio)

Cited by 104 publications

References 35 publications

Finger Length Ratio (2D:4D) in Adults with Gender Identity Disorder

Finger Length Ratio (2D:4D) in Adults with Gender Identity Disorder

Body Odor Quality Predicts Behavioral Attractiveness in Humans

Spatial Ability and Prenatal Androgens: Meta-Analyses of Congenital Adrenal Hyperplasia and Digit Ratio (2D:4D) Studies

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