Digit ratio (2D:4D), dominance, reproductive success, asymmetry, and sociosexuality in the BBC Internet study. American Journal of Human Biology, 20, 451-461

Department of Psychology, University of Central Lancashire, Preston, United Kingdom.
American Journal of Human Biology (Impact Factor: 1.7). 07/2008; 20(4):451-61. DOI: 10.1002/ajhb.20767
Source: PubMed


Digit ratio (2D:4D) may be a correlate of prenatal sex steroids, and has been linked to traits, which are influenced by fetal testosterone and estrogen. Here we consider such links in a large Internet study of sex differences (the BBC Internet Study) in which finger lengths were self-measured. Consistent with lab-based findings the 2D:4D in this study shows sexual dimorphism, ethnic differences and higher dimorphism of right 2D:4D than left, thereby indicating that 2D:4D does measure real between-participant variation. High error in self-measurement of fingers reduces effect sizes. However, the large sample size gives assurance that significant effects are likely to be real. We controlled for ethnicity and sexual orientation by considering White heterosexuals only (153,429 participants). Sexual dimorphism was confirmed in 2D:4D and for the difference of right-left 2D:4D. After Bonferroni correction we found highly significant relationships with low effect sizes as follows. In males and females there were negative associations between 2D:4D and dominance. In males there were negative associations between 2D:4D and family size and factors associated with reproductive success. For females these associations were positive. For asymmetry we found U-shaped relationships with 2D:4D in both males and females. We found no relationship between 2D:4D and promiscuity (sociosexuality). In total, we considered 48 relationships and found 29 to be significant. We compare our findings with a similar study reported by Putz et al. (2004), which found only 2 out of 57 correlations to be significant and discuss possible reasons for the discrepancies between the studies.

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Available from: Bernhard Fink, Sep 30, 2015
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    • "Consistent with our specific hypotheses, feminist activists exhibited a significantly more masculinized 2D:4D ratio relative to both Swedish and aggregate comparison groups, a substantially higher level of Directiveness than both the male and female Australian samples, and within-sample correlations between these variables. Consistent with previous research, there were also significant correlations between the hands (Hampson et al., 2008; Manning and Fink, 2008; Butovskaya et al., 2010) and stronger correlations "
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    ABSTRACT: The feminist movement purports to improve conditions for women, and yet only a minority of women in modern societies self-identify as feminists. This is known as the feminist paradox. It has been suggested that feminists exhibit both physiological and psychological characteristics associated with heightened masculinization, which may predispose women for heightened competitiveness, sex-atypical behaviors, and belief in the interchangeability of sex roles. If feminist activists, i.e., those that manufacture the public image of feminism, are indeed masculinized relative to women in general, this might explain why the views and preferences of these two groups are at variance with each other. We measured the 2D:4D digit ratios (collected from both hands) and a personality trait known as dominance (measured with the Directiveness scale) in a sample of women attending a feminist conference. The sample exhibited significantly more masculine 2D:4D and higher dominance ratings than comparison samples representative of women in general, and these variables were furthermore positively correlated for both hands. The feminist paradox might thus to some extent be explained by biological differences between women in general and the activist women who formulate the feminist agenda.
    Frontiers in Psychology 09/2014; 5(1011). DOI:10.3389/fpsyg.2014.01011 · 2.80 Impact Factor
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    • "Thus, our data support one of the outlined approaches, showing that women with rather masculine body traits also tend to have a higher number of sexual partners and start earlier with sexual activities, and have thus more unrestricted sexual behavior (Clark, 2004; Mikach and Bailey, 1999). On the other hand, we also supported the other possibility (Manning and Fink, 2008; Rahman et al., 2005), by showing that rather more feminine women have higher sociosexual desires. Sociosexual desires do not need to reflect behaviors (Penke and Asendorpf, 2008), but they can increase, for example, flirting behavior with men who are willing to provide immediate resources or status. "
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    ABSTRACT: One of the possible explanations for human within-sex variation in promiscuity stems from conditional strategies dependent on the level of body sex-dimorphism. There is some evidence that masculine men and feminine women are more promiscuous than their sex-atypical counterparts, although mixed results persist. Moreover, another line of evidence shows that more promiscuous women are rather sex-atypical. We tested whether diverse sex-dimorphic body measures (2D:4D, WHR/WSR, handgrip strength, and height and weight) influence sociosexual desires, attitudes, promiscuous behavior, and age of first intercourse in a sex-typical or sex-atypical direction. Participants were 185 young adults, 51 men and 54 women from Brazil, and 40 men and 40 women from the Czech Republic. In men stronger handgrip and more feminine 2D:4D predicted higher sociosexual behaviors, desires, and lower age of the first sexual intercourse. While in women, sociosexual desires were predicted by lower handgrip strength and more feminine 2D:4D. It thus seems that it is rather a mixture of masculine and feminine traits in men, and feminine traits in women that increase their sociosexuality. Masculine traits (height) predicting female promiscuous behavior were specific for only one population. In conclusion, a mosaic combination of sex-typical but also sex-atypical independent body traits can lead to higher promiscuity, particularly in men. Limitations, implications, and future directions for research are considered.
    Behavioural Processes 08/2014; 109. DOI:10.1016/j.beproc.2014.07.010 · 1.57 Impact Factor
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    • "reproductive success, pre-natal hormonal environment (reflected in 2D:4D value) seems to play a role as well. Variables associated with male fertility such as sperm number (Manning et al., 1998), sex drive, level of sexual excitement (Manning & Fink, 2008), number of sexual partners per individual (Honekopp et al., 2006) and age at first marriage (Sorokowski et al., 2012) were all related to 2D:4D. These results might suggest that digit ratio might be widely associated with traits related to male reproductive strategy. "
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    ABSTRACT: Objectives: The 2nd to 4th digit ratio (2D:4D) is thought to reflect exposure to androgens during foetal development. This study examined the relationship between low (more masculine) and high (more feminine) 2D:4D and body size at different stages of the life course, adult testosterone levels and number of children among males. Methods: Five hundred and fifty-eight men from rural Poland at the Mogielica Human Ecology Study Site participated in this study. Life history data and anthropometric measurements were collected. Salivary morning and evening testosterone levels among 110 men from the same population were measured. Results: Low 2D:4D was related to higher birth weight (p = 0.04), higher birth length (p = 0.01), higher body mass during childhood and adolescence (p = 0.01), higher BMI (borderline significance, p = 0.06), higher number of children among fathers (p = 0.04) and higher testosterone levels during adulthood (p = 0.04). Conclusions: This study shows, for the first time in a single population, that digit ratio is related to sub-adult body size at different stages of the life course, adult testosterone levels and number of children. The observed results suggest that digit ratio might be a valuable predictor of male body size and reproductive characteristics.
    Annals of Human Biology 04/2014; 41(6). DOI:10.3109/03014460.2014.902993 · 1.27 Impact Factor
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