Digit ratio (2D : 4D) and prosocial behaviour in economic games: no direct correlation with generosity, bargaining or trust-related behaviours

Prenatal exposure to sex hormones exerts organizational effects on the brain which have observable behavioural correlates in adult life. There are reasons to expect that social behaviours—fundamental for the evolutionary success of humans—might be related to biological factors such as prenatal sex hormone exposure. Nevertheless, the existing literature is inconclusive as to whether and how prenatal exposure to testosterone and oestrogen, proxied by the second-to-fourth digit ratio (2D : 4D), may predict non-selfish behaviour. Here, we investigate this question using economic experiments with real monetary stakes and analyse five different dimensions of social behaviour in a comparatively large sample of Caucasian participants ( n = 560). For both males and females, our results show no robust association between right- or left-hand 2D : 4D and generosity, bargaining or trust-related behaviours. Moreover, no differences in behaviour were found according to sex. We conclude that there is no direct correlation between 2D : 4D and these social behaviours.

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Digit ratio (2D:4D) and amniotic testosterone and estradiol: an attempted replication of Lutchmaya et al. (2004)

Journal of Developmental Origins of Health and Disease ◽

10.1017/s2040174420001294 ◽

2021 ◽

pp. 1-6

Author(s):

Gareth Richards ◽

Wendy V. Browne ◽

Mihaela Constantinescu

Keyword(s):

Amniotic Fluid ◽

Digit Ratio ◽

Second Trimester ◽

Left Hand ◽

Digit Ratios ◽

Hormone Exposure ◽

The Right ◽

Digit Length ◽

Attempted Replication

Abstract The ratio of length between the second (index) and fourth (ring) fingers (digit ratio or 2D:4D) is frequently employed as a retrospective marker of prenatal sex hormone exposure. Lutchmaya et al. (2004) reported that the ratio of testosterone (T) to estradiol (E) present in second-trimester amniotic fluid was negatively correlated with digit ratios for the right hand (but not the left hand) in a sample of 29 children at 2-year follow-up. This observation is frequently cited as evidence for the measure’s validity but has not been replicated. We therefore present the findings of another study of amniotic T and E that did not find evidence for these effects at 4½-year follow-up. The confidence intervals were large, the direction of correlations observed was generally erratic, and the overall findings question the premise that second-trimester sex hormones affect the development of digit length ratios in humans.

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Digit Ratio (2D:4D) and Amniotic Testosterone and Estradiol: An Attempted Replication of Lutchmaya et al. (2004)

10.1101/2020.07.10.197269 ◽

2020 ◽

Author(s):

Gareth Richards ◽

Wendy V. Browne ◽

Mihaela Constantinescu

Keyword(s):

Amniotic Fluid ◽

Digit Ratio ◽

Second Trimester ◽

Left Hand ◽

Digit Ratios ◽

Hormone Exposure ◽

The Right ◽

Digit Length ◽

Attempted Replication

AbstractThe ratio of length between the second (index) and fourth (ring) fingers (digit ratio or 2D:4D) is frequently employed as a retrospective marker of prenatal sex hormone exposure. Lutchmaya et al. (2004) reported that the ratio of testosterone (T) to estradiol (E) present in second trimester amniotic fluid was negatively correlated with digit ratios for the right hand (but not the left hand) in a sample of 29 children at 2-year follow-up. This observation is frequently cited as evidence for the measure’s validity but has not been replicated. We therefore present the findings of another study of amniotic T and E that did not find evidence for these effects at 4½-year follow-up. The confidence intervals were large, the direction of correlations observed was generally erratic, and the overall findings therefore question the premise that second trimester sex hormones affect the development of digit length ratios in humans.

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2D:4D and Self-Employment: A Preregistered Replication Study in a Large General Population Sample

Entrepreneurship Theory and Practice ◽

10.1177/1042258720985478 ◽

2021 ◽

pp. 104225872098547

Author(s):

Frank M. Fossen ◽

Levent Neyse ◽

Magnus Johannesson ◽

Anna Dreber

Keyword(s):

General Population ◽

Population Sample ◽

In Utero ◽

Replication Study ◽

Digit Ratio ◽

General Population Sample ◽

Left Hand ◽

Self Employment ◽

Fourth Finger ◽

German Socioeconomic Panel

The 2D: 4D digit ratio, the ratio of the length of the second finger to the length of the fourth finger, is often considered a proxy for testosterone exposure in utero. A recent study reported, among other things, an association between the left-hand 2D:4D and self-employment in a sample of 974 adults. In this preregistered study, we replicate the 2D:4D results on a sample of more than 2100 adults from the German Socioeconomic Panel-Innovation Sample (SOEP-IS). We find no statistically significant associations between 2D:4D and self-employment.

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Testosterone measured from amniotic fluid and maternal plasma shows no significant association with directional asymmetry in newborn digit ratio (2D:4D)

Journal of Developmental Origins of Health and Disease ◽

10.1017/s2040174418000752 ◽

2018 ◽

Vol 10 (3) ◽

pp. 362-367 ◽

Cited By ~ 17

Author(s):

G. Richards ◽

M. Gomes ◽

T. Ventura

Keyword(s):

Amniotic Fluid ◽

Secondary Analysis ◽

Relative Length ◽

Maternal Plasma ◽

Mean Value ◽

Digit Ratio ◽

Directional Asymmetry ◽

Second Trimester ◽

Maternal Circulation ◽

Left Hand

AbstractFoetal sex hormones can have powerful and far-reaching effects on later phenotype. However, obtaining accurate measurements is difficult for ethical reasons, and researchers often employ proxy variables to examine their effects. The relative length of the second and fourth fingers (digit ratio or 2D:4D) is frequently used for this purpose, as it is hypothesized to index variance in prenatal androgen and oestrogen exposure. Most studies employing this method examine digit ratio for the right hand (R2D:4D) and/or left hand (L2D:4D), though the mean value (M2D:4D) (i.e., the average of R2D:4D and L2D:4D) and directional asymmetry (D[R–L]) (i.e., R2D:4D minus L2D:4D) are also commonly used. As no published studies have examined M2D:4D or D[R-L] in relation to testosterone measured from amniotic fluid, we conducted a secondary analysis of data published by Ventura et al. The sample comprises 106 mothers from Portugal who underwent amniocentesis during the second trimester and their neonates. Newborn M2D:4D was negatively correlated with amniotic testosterone in females (P<0.05) but not in males; no significant association was observed between amniotic testosterone and D[R–L] in either sex. In addition, we examined testosterone measured from maternal circulation during the second trimester, and found that it was not a significant predictor of M2D:4D or D[R–L] in male or female infants. Further research should aim to measure the ratio of testosterone to oestradiol present in amniotic fluid and maternal plasma, to examine whether either is a predictor of digit ratio variables at different stages of postnatal development.

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EVIDENCE FOR ASSORTATIVE MATING ON DIGIT RATIO (2D:4D), A BIOMARKER FOR PRENATAL ANDROGEN EXPOSURE

Journal of Biosocial Science ◽

10.1017/s0021932006001647 ◽

2007 ◽

Vol 39 (4) ◽

pp. 599-612 ◽

Cited By ~ 32

Author(s):

MARTIN VORACEK ◽

STEFAN G. DRESSLER ◽

JOHN T. MANNING

Keyword(s):

Assortative Mating ◽

Age Differences ◽

Research Programme ◽

Digit Ratio ◽

Left Hand ◽

Right Hand ◽

Androgen Exposure ◽

The Right ◽

Prenatal Androgen ◽

Spousal Similarity

SummaryThe second-to-fourth digit ratio (2D:4D) presents an anatomical sex difference in humans. On average, men tend to have lower 2D:4D compared with women. There is fairly strong evidence for a role of the 2D:4D ratio as a biomarker for the organizational (permanent) effects of prenatal testosterone on the brain and behaviour. Recently, an accumulating research programme has shown 2D:4D to be related to a multitude of sex-dependent, hormonally influenced biosocial traits and phenotypes which reach into the domains of ability, behaviour, fertility, health, personality and sexuality. This study investigated the degree of assortative mating (spousal similarity) in a sample of 239 native Austrian couples of parental or grandparental age, all of them having reproduced. Results included: (i) significant spousal correlations of +0·19 and +0·18 for right-hand and left-hand 2D:4D, respectively, and +0·24 for average 2D:4D; (ii) no assortative mating effect on the right-minus-left difference in 2D:4D; (iii) indications consistent with a possible generational decrease of spousal similarity in 2D:4D; (iv) a prevalence of couples with a lower right-hand 2D:4D observed in the husband compared with his wife; and (v) relations of spousal 2D:4D patterns to spousal age differences, such that matings of men with more male-typical trait expressions (namely, a generally low right-hand 2D:4D or showing a lower right-minus-left 2D:4D difference than their wives) implicated larger male-minus-female age differences, i.e. younger wives. It is argued that assortative mating on 2D:4D operates indirectly and may be mediated through the assortment on other, more perceptible, physical traits and psychological phenotypes that entertain associations with 2D:4D and are relevant for courtship and mate choice.

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FC29-02 - Is prenatal exposure to alcohol a factor which re-program the brain?

European Psychiatry ◽

10.1016/s0924-9338(11)73681-1 ◽

2011 ◽

Vol 26 (S2) ◽

pp. 1978-1978

Author(s):

J.H. Sliwowska

Keyword(s):

Prenatal Exposure ◽

Hpa Axis ◽

Alcohol Exposure ◽

Hippocampal Neurogenesis ◽

Adult Hippocampal Neurogenesis ◽

Ovariectomized Rats ◽

List Type ◽

Depression And Anxiety ◽

Hpg Axis ◽

The Brain

IntroductionFetal programming refers to the concept that early environmental factors, including prenatal exposure to stress and drugs, can permanently organize or imprint physiological and behavioural systems and increase vulnerability to disorders such as depression and anxiety later in life.AimsIs prenatal exposure to alcohol a factor which re-programs the brain?ObjectivesEffects of prenatal alcohol exposure (PAE) on:1)the hypothalamus-pituitary-adrenal (HPA) axis;2)the hypothalamus-pituitary-gonadal (HPG) axis;3)serotonergic (5-HT) system and4)adult hippocampal neurogenesis are presented.MethodsOffspring from prenatal ethanol (PAE), pair-fed (PF) and ad lib-fed control (C) dams are studied across the development or in adulthood. Immunocytochemistry and in situ hybridization techniques are used.ResultsIn term of the HPA axis: PAE alters the balance of mineralocorticoids/glucocorticoids (MRs/GRs) receptor levels in the hippocampus of adult females. In the case of the HPG axis: PAE delays puberty and changes hormonal profiles in males and females. PAE also decreases numbers of 5-HT-immunoreactive neurons in the dorsal raphe nucleus of the brainstem in ovariectomized rats and estradiol and progesterone modulate those effects. Finally, in adult PAE males, but not females stress-induced decrease in neurogenesis is altered.ConclusionsIn our animal model PAE re-programs the brain. Effects of PAE are long-lasting, affect HPA and HPG axes, 5-HT system and adult hippocampal neurogenesis and if seen in humans could contribute to increased vulnerability to depression and anxiety.

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Interpreting Brain Waves

Handbook of Research on Machine Learning Innovations and Trends - Advances in Computational Intelligence and Robotics ◽

10.4018/978-1-5225-2229-4.ch030 ◽

2017 ◽

pp. 695-714

Author(s):

Noran Magdy El-Kafrawy ◽

Doaa Hegazy ◽

Mohamed F. Tolba

Keyword(s):

Support Vector Machine ◽

Feature Extraction ◽

Basis Function ◽

Brain Computer Interface ◽

Support Vector ◽

Left Hand ◽

Brain Waves ◽

Mode Decomposition ◽

Rbf Kernel ◽

The Brain

BCI (Brain-Computer Interface) gives you the power to manipulate things around you just by thinking of what you want to do. It allows your thoughts to be interpreted by the computer and hence act upon it. This could be utilized in helping disabled people, remote controlling of robots or even getting personalized systems depending upon your mood. The most important part of any BCI application is interpreting the brain signalsasthere are many mental tasks to be considered. In this chapter, the authors focus on interpreting motor imagery tasks and more specifically, imagining left hand, right hand, foot and tongue. Interpreting the signal consists of two main steps: feature extraction and classification. For the feature extraction,Empirical Mode Decomposition (EMD) was used and for the classification,the Support Vector Machine (SVM) with Radial Basis Function (RBF) kernel was used. The authors evaluated this system using the BCI competition IV dataset and reached a very promising accuracy.

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