The ratio of 2nd to 4th digit length and male homosexuality

Robinson, Susan; Manning, John T.

doi:10.1016/s1090-5138(00)00052-0

Cited by 164 publications

(128 citation statements)

References 36 publications

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“…Although reliability coefficients were consistently higher when image analysis was used, they were not significantly better than measurements made with Vernier calipers on photocopied images. Comparable levels of intra and interobserver reliability when using computer-guided methods and photocopies, corroborates the observation that photocopy technology generates accurate and clear images from which to measure finger lengths Robinson and Manning, 2000;Voracek et al, 2005Voracek et al, , 2007. However, despite close reliability, computer-assisted analysis has several advantages over photocopy technology.…”

Section: Discussionsupporting

confidence: 65%

“…Unfortunately, these associations with 2D:4D have been dampened by the enormous amount of nonreplication that has been reported among studies investigating similar study populations (e.g. Male and female homosexuality- Lippa, 2003;Robinson and Manning, 2000;Williams et al, 2000; Polycystic ovary syndrome-Bloski et al., 2008;Cattrall et al, 2005; Aggression-Bailey and Hurd, 2005;Hampson et al, 2008).Studies designed to test the notion that prenatal androgens program certain traits and phenotypes require a standardized, validated method of measuring fingers and determining 2D:4D . This is particularly important as effect sizes on 2D:4D are generally only moderate to low (Kemper and Schwerdtfeger, in press).…”

mentioning

confidence: 99%

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Digit ratios (2D:4D) determined by computer‐assisted analysis are more reliable than those using physical measurements, photocopies, and printed scans

Allaway

Bloski

Pierson

et al. 2009

American J Hum Biol

111

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Prenatal androgens influence the second to fourth digit ratio (2D:4D) of hands with men having lower ratios than women. Numerous methods are used to assess 2D:4D including, physical measurements with calipers, and measurements made from photocopies, scanned images, digital photographs, radiographs, and scaled tubes. Although each method appears relatively reliable, agreement upon a gold standard is necessary to better explore the putative effects of prenatal androgens. Our objective was to assess the level of intra and interobserver reliability when evaluating 2D:4D using four techniques: (1) physical measurements, (2) photocopies, (3) printed scanned images, and (4) computer-assisted image analysis. Physical measurements, photocopies, and printed scanned images were measured with Vernier calipers. Scanned images were also measured with computer-based calipers. Measurements were made in 30 men and 30 women at two different time points, by three experienced observers. Intraclass correlation coefficients were used to assess the level of reliability. Intraobserver reliability was best for computer-assisted (0.957), followed by photocopies (0.939), physical measurements (0.925), and printed scans (0.842; P = 0.015). Interobserver reliability was also greatest for computer-assisted (0.892), followed by photocopies (0.858), physical measurements (0.795), and printed scans (0.761; P = 0.001). Mean 2D:4D from physical measurements were higher than all other techniques (P < 0.0001). Digit ratios determined from computer-assisted, physical measurements, and printed scans were more reliable in men than women (P = 0.009, P = 0.017, and P = 0.012, respectively).In summary, 2D:4D determined from computer-assisted analysis yielded the most accurate and consistent measurements among observers. Investigations of 2D:4D should use computer-assisted measurements over alternate methods whenever possible.Prenatal androgen exposure influences development of the fingers and leads to distinct differences in hand patterns among men and women. In general, the ratio between the second (2D = index finger) and fourth (4D = ring finger) digits in men is lower than that observed in women (Lutchmaya et al., 2004;Manning et al., 1998). Anatomical evidence of prenatal androgen exposure has gained significance in recent times because there is growing evidence in animal models that adult traits and behaviors including, disease susceptibility may be programmed during fetal development (Abbott et al., 2006;Manikkam et al., 2004 Manning and Bundred, 2000;Robinson, 2006). Previous studies in humans have shown low digit ratios (2D:4D) to be associated with a variety of traits including, enhanced visual spatial ability (Burton et al., 2005;van Anders and Hampson, 2005), increased athleticism (Honekopp et al., 2006a), female homosexuality (Brown et al., 2002;Hall and Love, 2003;Kraemer et al., 2006;Williams et al., 2000), decreased susceptibility to coronary artery disease (Fink et al., 2003;Manning and Bundred, 2000), and greater fertility potent...

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Section: Discussionsupporting

confidence: 65%

mentioning

confidence: 99%

Digit ratios (2D:4D) determined by computer‐assisted analysis are more reliable than those using physical measurements, photocopies, and printed scans

Allaway

Bloski

Pierson

et al. 2009

American J Hum Biol

111

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“…As many somatic sex differences result from prenatal androgen masculinization, it has been suggested that prenatal testosterone is responsible for the sex difference in mean 2D:4D ratio, with the latter being negatively correlated with testosterone [2,4]. Strong evidence for the role of androgen comes from the association between the 2D:4D ratio and congenital adrenal hyperplasia (CAH), a condition of elevated androgen production, as both males and females with CAH have smaller 2D:4D than controls [5,6].…”

Section: Introductionmentioning

confidence: 99%

Digit ratio (2D:4D) in newborns: Influences of prenatal testosterone and maternal environment

Ventura

Gomes

Pita

et al. 2013

Early Human Development

158

171

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Introduction: The 2D:4D digit ratio is sexually-dimorphic, probably due to testosterone action through the perinatal period. We characterize the 2D:4D ratio in newborn (NB) infants, in between the pre-and postnatal surges of testosterone, and relate it to the mother's 2D:4D and to testosterone levels in the amniotic fluid (AF). Subjects and methods: Testosterone was assayed in samples of maternal plasma and AF collected at amniocentesis. Shortly after birth, 106 NBs and their mothers were measured for 2D:4D ratio. Results: NB males had lower mean 2D:4D ratios than females but this dimorphism was significant only for the left hand (males: 0.927; females: 0.950; p =0.004). Mothers who had sons had lower 2D:4D ratios than those who had daughters and the mother's 2D:4D were higher than those of NBs regardless of sex. Both hands of NB females were negatively correlated with AF testosterone and positively correlated with the mother's 2D:4D, but males showed no significant associations. Maternal plasma testosterone also showed a negative weak correlation with NB's digit ratio in both sexes. Conclusions: Sexual dimorphism at birth was only significant for the left hand, in contrast with reports of greater right hand dimorphism, suggesting that postnatal testosterone is determinant for 2D:4D stabilization. The lower 2D:4D ratios in mothers who had sons support claims that hormone levels in parents are influential for determining their children's sex. NB female's digit ratio, but not males', was associated to the level of AF testosterone. The mother's 2D:4D ratios were positively correlated with their daughters' 2D:4D, but the same was not observed for male NBs, suggesting that prenatal testosterone levels in male fetus lead their 2D:4D ratios to stray from their mothers' with high individual variability.

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“…In the case of male sexual orientation, this would imply that up to a certain point, increased levels of testosterone are masculinizing, but after that point increased levels are feminizing. Robinson and Manning's (2000) study of heterosexual and homosexual men assessed a relatively ethnically homogeneous population (mostly White British and Scottish men), whereas the Williams et al (2000) and Brown et al (2002) studies likely did not (because they used convenience samples in ethnically diverse California). The ethnic background of participants is important because recent research shows that 2D:4D ratios vary substantially across ethnic and nationality groups (Manning, 2002).…”

mentioning

confidence: 99%

Are 2D:4D finger-length ratios related to sexual orientation? Yes for men, no for women.

Lippa

2003

Journal of Personality and Social Psychology

174

115

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The ratio of index and ring finger lengths (2D:4D) is thought to be a marker of prenatal androgen exposure. In a sample of over 2,000 participants, men had significantly lower 2D:4D ratios than women (d ϭ .36 and .23 for right and left hands, respectively), and these results were consistent across ethnic groups. Heterosexual men had significantly lower (more male typical) 2D:4D ratios than gay men (d ϭ .32 and .31 for right and left hands, respectively), and these results tended to be consistent across ethnic groups. Heterosexual and lesbian women showed no significant differences in 2D:4D ratios, after ethnicity was taken into account. The current findings add to evidence that prenatal hormonal factors may be linked to men's sexual orientation.

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The ratio of 2nd to 4th digit length and male homosexuality

Cited by 164 publications

References 36 publications

Digit ratios (2D:4D) determined by computer‐assisted analysis are more reliable than those using physical measurements, photocopies, and printed scans

Digit ratios (2D:4D) determined by computer‐assisted analysis are more reliable than those using physical measurements, photocopies, and printed scans

Digit ratio (2D:4D) in newborns: Influences of prenatal testosterone and maternal environment

Are 2D:4D finger-length ratios related to sexual orientation? Yes for men, no for women.

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