Digit Ratio 2D Research Articles

Soccer Passing Accuracy Differentiates Between High and Low Digit Ratio (2D:4D) Soccer Players

The purpose of the present study was to know soccer passing accuracy performances between the national youth level soccer players possessing high digit ratio and low digit ratio (2D:4D). The study was carried out in 108 male soccer players of Bangladesh aged between 16 to 19 years for measured the digit ratio. To find out the high and low digit ratio groups of participant quartile deviation has been used. Participants belonged to 0.973 and above (N=28) were categorized into high digit ratio group and 0.942 and below (N=28) were categorized into low digit ratio group. Soccer passing accuracy performance was assessed (N=56) by using Loughborough Soccer Passing Test (LSPT). Digit ratio (2D:4D) was measured by digital vernier caliper, Mitutoyo Corporation, Japan measuring to 0.01 mm. The length of the index finger (2D) and ring finger (4D) measured in millimeters from the second metacarpophalangeal crease of the finger to the fingertip. The mean digit ratio was calculated as dividing the length of the 2D by the length of the 4D for the left and right hand one by one and then computes the mean of these two ratios. To find out the significance of differences of soccer passing accuracy between the high digit ratio and the low digit ratio groups independent t-test was used. It was observed that the mean score in soccer passing accuracy performance, i.e., LSPT Total performance (TP) of the lower digit ratio, group was a significantly better performer than that of the high digit ratio group. A higher level of fetal testosterone, characterized by lower values of the digit finger ratio (2D:4D), may be associated with a higher performance of soccer passing accuracy in multifaceted aspects including passing, dribbling, controlling, turning, decision-making, and cognition.

2D:4D and Self-Employment Using SOEP Data: A Replication Study

The 2D:4D digit ratio, the ratio of the length of the 2nd digit to the length of the 4th digit, is often considered a proxy for testosterone exposure in utero. A recent study by Nicolaou et al. (2018) reported an association between the left-hand 2D:4D and self-employment (in a sample of about 1,000 adults). In this preregistered study we replicate these results on a new and larger sample of about 2,600 adults from the German Socioeconomic Panel-Innovation Sample (SOEP-IS). We find no statistically significant associations between 2D:4D and self-employment and thus cannot confirm the findings of Nicolaou et al. (2018) for left-hand 2D:4D. Our estimated 99.5% confidence intervals are within an about 2 percentage points change in self-employment for a one standard deviation change in the 2D:4D when we pool results for men and women (the association does not differ significantly between men and women). Even larger studies are needed to rule out smaller effect sizes.

2d:4d and Self-Employment Using SOEP Data: A Replication Study

The 2 D:4D digit ratio, the ratio of the length of the 2nd digit to the length of the 4th digit, is often considered a proxy for testosterone exposure in utero. A recent study by Nicolaou et al. (2018) reported an association between the lefthand 2D:4D and self-employment (in a sample of about 1,000 adults). In this preregistered study we replicate these results on a new and larger sample of about 2,600 adults from the German Socioeconomic Panel-Innovation Sample (SOEP-IS). We find no statistically significant associations between 2D:4D and self-employment and thus cannot confirm the findings of Nicolaou et al. (2018) for left-hand 2D:4D. Our estimated 99.5% confidence intervals are within an about 2 percentage points change in self-employment for a one standard deviation change in the 2D:4D when we pool results for men and women (the association does not differ significantly between men and women). Even larger studies are needed to rule out smaller effect sizes.

Gender determination analysis using anthropometrical dimensions of 2D:4D, foot index and mandibular canine index.

Introduction:Sex determination is a challenge for forensic experts during mass disasters. Teeth are an excellent source in both living and nonliving population, where bodies are mutilated beyond recognition. Mandibular canines can be employed for gender determination in such situations. Similarly, second-to-fourth digit ratio (2D:4D) and foot index (FI) are sexually dimorphic and differ in males and females. Mandibular canine index (MCI), 2D:4D and FI are considered quick, easy and reproducible methods for determining the sex of an individual.Aim:This study aimed to determine the combined role of MCI, 2D:4D and FI in denoting gender identity and establish their correlation.Materials and Methods:The present study comprised of 100 dental students (50 males and 50 females) of our institution, aged 19–25 years, with specific inclusion and exclusion criteria. The measurements were done using a Vernier caliper, a divider and a ruler, and MCI, 2D:4D and FI were calculated using their specific formulae. The calculated values of FI, MCI and 2D:4D were subjected to statistical analysis.Results:There was a statistically significant difference observed between left MCI (P < 0.05), right and left 2D:4D and FI (P < 0.05). The results revealed that 2D:4D was less, whereas MCI and FI were higher in males than in females. The observed MCI was compared with standard MCI, and left MCI revealed higher sexual dimorphic characteristics (15.2%). Although the overall correlation between 2D:4D, FI and MCI was insignificant, the measurements were comparable.Conclusion:This study indicated that the anthropometric dimensions of 2D:4D, FI and MCI can be used for sex determination independently with accurate results.

ASSOCIATION BETWEEN HAND DIGIT RATIO (2D:4D) AND ORAL SQUAMOUS CELL CARCINOMA

ASSOCIATION BETWEEN HAND DIGIT RATIO (2D:4D) AND ORAL SQUAMOUS CELL CARCINOMA

2nd to 4th Digit Ratio (2D:4D) – Is It a Marker for Dyslexia ?

2nd to 4th Digit Ratio (2D:4D) – Is It a Marker for Dyslexia ?

Low digit ratio (2D:4D) is associated with early natural menopause.

ObjectivesIntrauterine environmental conditions may affect the number of primordial follicles and in this way the timing of menopause. The aim of the present study was to investigate association patterns between right hand digit ratio, that is, 2D:4D ‐ as an indicator of prenatal androgen and estrogen exposure, and age at menopause.MethodsOne hundred sixty‐nine women, who had experienced natural menopause, were enrolled in the study. Length of second and fourth finger were measured directly from the palmar side and digit ratios of both hands were calculated. For further analyses the digit ratio of the right hand was used only. Additionally, smoking habits, body weight and body height, body mass index and the number of children were determined. Multiple regression analyses were used to test association patterns between digit ratio and age at menopause, body height, BMI, nicotine consumption as well as number of births and age at menopause.ResultsAge at menopause correlated significantly positively with the digit ratio. A more feminine digit ratio is associated with a higher age at menopause, while a low digit ratio, interpreted as a hint of a higher androgen exposure during prenatal phase was associated with a lower age at menopause.ConclusionsLow digit ratio is associated with an earlier onset of natural menopause.

Lower Digit Ratio (2D:4D) Indicative of Excess Prenatal Androgen Is Associated With Increased Sociability and Greater Social Capital.

Positive social interactions are crucial for human well-being. Elevated prenatal exposure to testosterone as indicated by a low second-to-fourth finger length ratio (2D:4D) relates to more aggressive/hostile behavior in men of low 2D:4D, especially in challenging situations. How much people enjoy interacting with others is determined by the personality trait sociability. Given its role in approach and avoidance behavior, sociability might also be influenced by prenatal sex hormones, but studies are inconclusive so far. Here, we investigated the association between 2D:4D and the personality trait sociability complemented by personal social capital and personal social network size, in a population-based cohort of 4998 men. Lower 2D:4D correlated significantly with higher trait sociability, bigger personal social capital, and larger personal social network size. These effects were consistent across both hands separately and their mean value. Furthermore, both factors of sociability (1) liking party and company of friends and (2) isolation intolerance, correlated significantly with the prenatal testosterone marker. The exploratory analysis revealed no link between 2D:4D and responses to the personality trait aggression items or items of anti-social-personality disorder. Our data suggest that prenatal androgen exposure organizes the brain with lasting effects on social behavior.

Relationship between parental consanguinity and digit ratios (2D:4D) among Turkish newborns in Sivas.

The aim of this study was to investigate the effects of parental consanguinity on the 2D:4D digit ratio of newborn infants, whose parents were the first cousins. The study included healthy and full-term newborn infants, delivered in a hospital, at the gestational ages from 37 to 41 weeks. A total of 225 newborns and their parents were included in the study. Of these 225 newborns; 100 were inbred and 125 were outbred infants. We used a Vernier caliper to measure the length of the second and fourth digits of the newborns (accuracy: 0.01 mm). Controlling for education and number of pregnancies, male newborns had lower digit ratios than female newborns, for both left and right hands. There were, moreover, differences between inbred and outbred samples. We determined that inbreeding was related to a reduction in the digit ratios regardless of the side of the hand and the sex of the infant, showing a consistent tendency to appear more masculine. Interaction between marriage type*sex was highly significant. Parental consanguinity appears to cause fetal masculinization of digit ratios by increasing fetal stress among Turkish newborns.

Relationships Between the 2D:4D Digit Ratio, Waist Circumference, Hand Preferences, Weight, Height, Waist-to-Height Ratio and BMI in a Turkish Population

Relationships Between the 2D:4D Digit Ratio, Waist Circumference, Hand Preferences, Weight, Height, Waist-to-Height Ratio and BMI in a Turkish Population

Prenatal hormones (2D:4D), intrasexual competition, and materialism in women

AbstractWe explore the relationship between digit ratios (2D:4D) and materialism in women. Digit ratio is a sexually dimorphic trait that is indicative of prenatal testosterone and estrogen exposure. Across two studies, we found that masculinized digit ratios (i.e., exposure to a high testosterone‐to‐estrogen ratio) were associated with the happiness dimension of materialism. Furthermore, we show that women with feminized digit ratios (i.e., high estrogen‐to‐testosterone ratio) who were assigned to an intrasexually competitive condition scored higher on the success dimension of materialism. Overall, these findings suggest that prenatal testosterone exposure promotes stronger beliefs that possessions are an important source of happiness, while prenatal estrogen exposure promotes stronger beliefs that possessions are an important means of signaling success. Thus, prenatal hormone exposure not only influences masculinized and feminized behavior but also shapes consumers’ materialistic beliefs.

2D:4D digit ratios in males and females and its correlation with simple reaction time: A cross sectional Study at Combined Military Hospital (CMH), Lahore, Pakistan.

A cross-sectional study was conducted on 86 medical students between the ages of 18 to 25 years studying at the Combined Military Hospital (CMH) in Lahore, Pakistan. They were assessed for height, weight, digit length of the 2nd and 4th fingers of both hands and reaction time (response time to auditory stimulus as measured by BIOPAC). Of the 86 students, 42 (49%) were male and 44 (51%) were female, with a mean age of 19.55±1.017 and 19.86±0.905 years, respectively. There was a significant difference in the height, weight and Body Mass Index (BMI) of the students. The mean 2D:4D ratio for males on the left hand was 0.958±0.029 and for females it was 0.979±0.363 (p=0.004). The ratio for the right hand for males was 0.958±0.031 and for the females it was 0.977±0.035 (p=0.011). There was a significant correlation between the 2D: 4D ratio in the left hand with the reaction time in the dominant hand at random intervals (r= -0.240, p= 0.027) and with reaction time in the non-dominant hand at fixed intervals (r= -0.232, p= 0.03). Our results concluded that there is a negative correlation between the digit ratio and the reaction time. Those individuals who had lower digit ratios had faster reaction times than those who had higher digit ratios.

The digit ratio (2D:4D) and economic preferences: no robust associations in a sample of 330 women.

Many studies report on the association between 2D:4D, a putative marker for prenatal testosterone exposure, and economic preferences. However, most of these studies have limited sample sizes and test multiple hypotheses (without preregistration). In this study we mainly replicate the common specifications found in the literature for the association between the 2D:4D ratio and risk taking, the willingness to compete, and dictator game giving separately. In a sample of 330 women we find no robust associations between any of these economic preferences and 2D:4D. We find no evidence of a statistically significant relation for 16 of the 18 total regressions we run. The two regression specifications which are statistically significant have not previously been reported and the associations are not in the expected direction, and therefore they are unlikely to represent a real effect.

Association between second to fourth digit ratio and personality among Indian men.

To examine the relationship between the personality domains with the second to fourth digit ratio (2d:4d); a prenatal testosterone exposure marker. The 2d:4d for both hands was measured for the Indian male subjects' (n = 994). Ten-item personality inventory and displaced aggression questionnaire data were collected in a self-reported proforma in this cross sectional study with a convenient sampling approach. The personality traits, namely openness to new experiences, carelessness, and self-discipline were significantly differed between lower-half and higher-half of 2d:4d by median split. The right hand 2d:4d was positively correlated with open to new experiences and negatively correlated with disorganization, carelessness, and revenge planning. The left hand 2d:4d was positively correlated with aggression. On binary logistic regression, openness was positively associated while carelessness was negatively associated with the right hand 2d:4d and self-discipline trait was negatively associated with the left hand 2d:4d. This study affirmed the link between 2d:4d and domains of Big Five personality factors among Indian men and inverse relationship between 2d:4d and more "female" hands in the domains of disorganization, carelessness, and revenge planning even in men, emphasizing the effect of prenatal testosterone exposure on human personality.

Digit Ratio and Soccer

The peripheral blood cannot be extracted in utero from fetuses [1]. The second to fourth digit ratio (2D:4D) was therefore suggested as a prenatal testosterone marker.

Digit ratio (2D:4D) and its behavioral correlates in infant rhesus macaques (Macaca mulatta).

2D:4D ratios are typically lower in adult human males than females and are linked to numerous sex-differentiated behaviors. 2D:4D ratios are considered an indicator of prenatal androgen exposure; if so, children's 2D:4D ratios would arguably be even better indicators of prenatal androgen exposure since children have experienced fewer postnatal influences than adults. However, sex differences in 2D:4D ratios as well as associations between 2D:4D ratios and sex-typed behaviors in children have been inconsistent. Several studies also report sex differences and behavioral correlates of 2D:4D ratios in adult non-human primates, but little is known about 2D:4D ratios in infant non-human primates. This study examined sex differences in 2D:4D ratios over the first month of life, and associations with behavioral outcomes at 12-24weeks of age, in N=304 infant rhesus macaques. An increase in 2D:4D ratios over the first month of life was found, as well as associations with aggression and play behaviors, but no sex differences in 2D:4D ratios were observed. These results highlight the need for future developmental studies of 2D:4D ratios in order to determine not only their stability and predictive value, but also to discern the mechanism connecting prenatal androgen exposure, 2D:4D ratios, and behavioral outcomes.

Digit ratio (2D:4D) and testosterone supplementation

BackgroundTestosterone (T) is taken or prescribed to enhance appearance, increase athletic performance and libido and to treat hypogonadism. Digit ratio (2D:4D) is thought to be a negative correlate of prenatal T. Here we consider the relationship between 2D:4D and T supplementation. AimsOur sample was taken from the BBC internet study. Respondents were asked (y/n) if they were taking; (i) T, (ii) hormone replacement therapy with T (HRTwT). We removed extreme 2D:4D values and age and considered the most numerous ethnic group (i.e. “Whites”). Analyses were performed with a two-factor (sex*T) analysis of variance with covariate age and dependent variables 2D:4D or right-left 2D:4D (Dr-l). ResultsOut of 197,589 respondents, 793 (598 males) reported taking T. There was a significant main effect for right 2D:4D such that T supplementing males had higher 2D:4D than those who did not. The sex*T interaction was significant, but the effect reversed in females. There were 22,576 (661 males) participants who reported taking HRTwT. We found a significant main effect for right 2D:4D, males taking HRTwT had higher 2D:4D than those who did not. This was reversed in females. The sex*HRTwT interaction was significant, a high Dr-l was also found in males reporting HRTwT. ConclusionMales who reported taking T or HRTwT had high right 2D:4D and/or Dr-l. The situation with females may be the reverse of that found in males but effect sizes are less. The health implications of an association between high (feminized) 2D:4D and T supplementation in males are discussed.

The 2nd to 4th digit ratios (2D:4D) in patients with bipolar disorder

BackgroundThe ratio of the index finger to the ring finger (2D:4D) is a reflection of the intrauterine hormonal environment and a lower ratio has been shown to be associated with male gender, impulsive behaviors, substance abuse, and aggression. Bipolar illness is characterized by increased impulsivity and increased rates of co-morbid substance abuse, but the 2D:4D ratios have not been examined in this disorder. MethodsWe measured digit length of both hands in subjects with bipolar disorder and age- and gender-matched non-bipolar controls (n = 50 in each group). Diagnosis was confirmed with structured diagnostic interviews (MINI) and all subjects also completed Barratt Impulsivity Scale-version 11. ResultsThe patients did not vary significantly from the controls in demographic variables. Subjects with bipolar disorder had a higher right hand 2D:4D ratio compared to controls (0.967 ± .029 vs. 0.953 ± .035, t = 2.18, p = .03). Despite clearly higher measures of impulsivity in the bipolar group, no relationship could be documented between digit ratio and measures of impulsivity in either group. However, the right hand 2D:4D ratios and total impulsivity scores predicted bipolar disorder diagnosis status. LimitationsThe predominantly white racial composition of the study sample may limit generalizability to other groups. Only three patients were diagnosed with bipolar type 2, limiting the generalizability of the findings to all bipolar disorder types. ConclusionsThe data confirm previous observations of increased measures of impulsivity in euthymic bipolar individuals, and suggest that the mechanism of this increased impulsivity is different than in impulsivity seen in other conditions such as personality disorders.

Differential Placing of Flexion Creases Contributes to Sex Differences in the Second-to-Fourth Digit Ratio (2D:4D).

The present research examined whether differential placing of the basal flexion creases contributes to the occurrence of sex differences in digit ratio (2D:4D) derived from palmar digit lengths. The ratio of palmar-to-dorsal digit length, a measure of the placing of the basal flexion crease in the finger, was derived for the digits 2 and 4 of the right hand in two independent samples (Study I: N = 100; Study II: N = 200), in accordance with discovery-replication sample approach. The results show that men have lower palmar-to-dorsal digit ratios than women, and this effect is significantly stronger for digit 2 than for digit 4. Thus, the present study supports the likelihood that differential placing of flexion creases in the digits contributes to the occurrence of sex differences in palmar 2D:4D. In addition (Study II), the measurement procedure assessing the placing of flexion creases was validated. In conclusion, this evidence highlights potential conceptual shortcomings and technical limitations in the measurement conventions and methods currently employed in the field of 2D:4D research.

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.