Higher Digit Ratio Research Articles

Evaluation of Digit Ratios in Youth With Polycystic Ovary Syndrome.

Polycystic ovary syndrome (PCOS) is a common syndrome often observed during adolescence, characterized by ovulatory dysfunction and hyperandrogenism. It is determined that, when female fetuses are exposed to high levels of androgens, it increases their likelihood of developing PCOS in later ages. The 2D:4D digit ratio, which measures the length of the index finger compared to the ring finger, is a precise anatomical indicator of the degree of prenatal androgen exposure. Higher digit ratios in individuals have been associated with outcomes typically attributed to females. In the adolescent age group, the relationship between PCOS and androgen exposure during the antenatal period is not clear. The study was aimed to evaluate digit ratios in adolescents with PCOS. The study included 38 adolescent girls with PCOS, and 40 healthy adolescent girls were selected as the control group. The digit ratio (2D:4D) was evaluated by digital calipers, and the digit ratios of the patient and control groups were compared. The mean age in the PCOS group was 15.99±1.18 years, while the control group had a mean age of 16.02±1.06 years. The right-hand 2D:4D digit ratio was significantly lower in the PCOS group (0.93±0.02) compared to the control group (1.00±0.01, p<0.001). Similarly, the left-hand 2D:4D digit ratio was also lower in the PCOS group (0.98±0.03) compared to the control group (1.00±0.01, p<0.001). There was a moderate negative correlation between the left-hand 2D:4D ratio and the modified Ferriman-Gallwey score (mFGS) (r=0.53, p=0.01). Nevertheless, there was not a significant association found between the 2D:4D ratio of the right hand and mFGS. This study demonstrates that PCOS patients have significantly lower both-hand 2D:4D ratios than healthy controls, suggesting prenatal androgen exposure. Recognizing anatomic markers in adolescence may predict the development of PCOS. The findings align with previous research linking low digit ratios to androgen exposure and various reproductive outcomes.

2D:4D digit ratio as a potential marker for prostate cancer risk

BackgroundThe second-to-fourth digit ratio (2D:4D) is thought to reflect prenatal exposure to sex steroids. We investigated the relationship between 2D:4D and odds of prostate cancer. MethodData were collected in PROtEuS, a population-based case-control study conducted in Montréal, Canada (2005–2012), including 1931 incident prostate cancer cases aged < 76 years and 1994 population controls. In-person interviews elicited information on potential risk factors. Digit lengths were measured by interviewers applying a standard protocol. Odds ratios (OR) and 95 % confidence intervals (CI) were estimated using unconditional logistic regression adjusting for potential confounders. ResultsThe OR of prostate cancer for a standard deviation increase in 2D:4D was 0.91 (95 % CI: 0.85–0.98). For less and more aggressive cancers, ORs were 0.93 (95 % CI: 0.87–1.00) and 0.85 (95 % CI: 0.77–0.93), respectively. There was an interaction with ancestry (p=0.04), whereas the OR among men of African descent was 1.23 (95 % CI: 0.96–1.57, based on 128 cases). ConclusionFindings suggest an inverse association between 2D:4D and odds of overall prostate cancer, more pronounced for aggressive cancers. This supports the notion that high levels of testosterone in utero, estimated by a low 2D:4D ratio, are associated with a higher risk of prostate cancer. Contrastingly, a high digit ratio was associated with greater cancer odds among participants of African descent. Upon replication, 2D:4D could prove to be an easily measured marker of prostate cancer risk.

High digit ratio (2D:4D) is associated with attack frequency and severity in hereditary angioedema patients

BackgroundHereditary angioedema (HAE) caused by a deficiency or dysfunction of the plasma protease C1-inhibitor is a rare autosomal-dominant disorder. We explored a possible correlation between the ratio of the second and fourth finger lengths (2D:4D) and the frequency of HEA attacks, and whether the ratio might predict laryngeal attack. MethodWe evaluated 35 HEA patients aged 19 to 66 years; 3 were subsequently excluded. The 2D:4D ratio was calculated by dividing the length of the second finger by that of the fourth finger of both hands. A structured clinical questionnaire exploring HAE course and treatment over the prior year was administered. ResultsOf the 32 participants, 56.25 % (n = 18) were female. Of them, those with high 2D:4D ratios suffered significantly more laryngeal attacks than others; 93.3% of patients with high 2D:4D ratios experienced ≥5 attacks annually, significantly more than those with low ratios. Among type 2 HEA patients, 75 % of those experiencing ≥5 attacks annually had high 2D:4D ratios; all patients with low 2D:4D ratios reported <5 attacks annually. These significant effects were found for right-hand 2D:4D ratios and not left-hand 2D:4D ratios. ConclusionThe data suggest that intrauterine sex hormone exposure, which affects the 2D:4D ratio, is significantly associated with HEA attack frequency and severity, and laryngeal edema.

Prenatal exposure to bisphenol analogues and digit ratio in children at ages 4 and 6 years: A birth cohort study.

Bisphenol analogues (BPs), including bisphenol A (BPA), have been shown to exhibit similar endocrine disrupting activities. However, epidemiological evidence on the reproductive and developmental toxicities of BPs other than BPA is scarce. The second to fourth digit ratio (2D:4D), an endocrine-sensitive endpoint, has been suggested to be a biomarker of prenatal sex steroid exposure and associated with reproductive outcomes in later life. Using the data of 545 mother-child pairs from the Shanghai-Minhang Birth Cohort Study, we prospectively assessed the effects of prenatal exposure to BPs on 2D:4D in children at ages 4 and 6 years. Single-spot urine samples were collected in the third trimester and analyzed for BPs. Digit lengths were measured using a vernier caliper in children at ages 4 and 6 years, and the 2D:4D values for both hands were calculated. A multivariable linear regression model was applied to examine associations between prenatal BPs exposure and 2D:4D digit ratios at each age separately. The generalized estimating equation (GEE) model was used to deal with repeated 2D:4D measures obtained at ages 4 and 6 years. We found that prenatal exposure to BPA alternatives including BPF, BPS, and BPAF was associated with higher digit ratio in boys and/or girls (feminizing), while TCBPA, a halogenated bisphenol, was associated with lower 2D:4D in boys (masculinizing). These associations were more pronounced at 4 years of age, and tended to remain after further considering the potential confounding from prenatal co-exposure to other BPs and childhood BPs exposure. Our study provides epidemiological evidence that BPs exposure during pregnancy may alter the digit development in children, indicative of disrupted reproductive development in later life. Given these new findings, further studies are needed to corroborate our results.

Assessing the Relationship between Digit Ratio as a Marker for Prenatal Androgen Exposure and Different Blood Pressure Components among North Indian Males: A Pilot Study

Introduction: Digit ratio (2D:4D) has been associated with cardiovascular diseases using association with surrogate markers. Studies showing an association of digit ratio with cardiovascular parameters within normal limits are scarce. Aim: To explore the relation between different blood pressure components and digit ratio in normal young males within physiological range. Materials and Methods: In this cross-sectional pilot study, 25 apparently healthy male volunteers were included. Digit ratio (2D:4D) was measured. Body Mass Index (BMI) was estimated. Peripheral blood pressure, central aortic blood pressure and all four limb blood pressures were measured using periscope arterial health and cardiovascular analysis system. Blood pressure was measured using oscillometric method from all peripheral sites and estimated central aortic pressure by a validated transfer function. Pearson’s correlation studies were performed to assess any preliminary association. Two groups were formed of low and high digit ratio and Student’s t-test was performed to assess any significant difference between the groups. Results: Digit ratio of both hands correlated best with peripheral Diastolic Blood Pressure (DBP) (Right 2D:4D r=0.43, p&lt;0.05/Left 2D:4D r=0.40, p&lt;0.05). No significant association observed for peripheral systolic pressure (p&gt;0.05) and digit ratio of both hands. Significant association observed for all four limb blood pressure components and digit ratio. Pulse pressure components did not show any association with digit ratio. Significant difference of blood pressure components was observed when low and high digit ratio groups were compared. It was observed that blood pressure components were on higher side within the normal limits among the subjects with high digit ratio. Conclusion: Preliminary observations from this pilot study suggests that in normal young adult males digit ratio associate positively with different blood pressure components in normotensive males and has the potential to be used as a potent marker for early changes in cardiovascular diseases.

Higher digit ratio (2D:4D) associated with dementia in women

AbstractBackgroundWomen have higher prevalence and risk for developing Alzheimer’s disease (AD) than men. The reason(s) underlying this sex difference in AD has not been definitively established but has been theorized to reflect sex‐specific patterns in age‐related depletion of sex steroid hormones, primarily the loss of estrogens in women. Not well considered is the possible role of developmental actions of sex steroids, which drive sexual differentiation of the brain. We investigated the hypothesis that early life differences in sex hormone exposure yield a female brain that is inherently more vulnerable to AD and related dementias.MethodRelative group differences in prenatal sex steroid hormone exposure were indirectly assessed by the ratio of the index (2nd digit) and ring (4th digit) fingers (2D:4D). The subjects were a community sample of non‐demented and demented men (N=66; 31 non‐demented, 35 demented) and women (N=73; 39 non‐demented, 34 demented) aged &gt;65 years. Subjects’ right hands were scanned, finger length determined by caliper measurement, and 2D:4D calculated. Data were analyzed by two‐way ANOVA with sex and dementia status as the variables.ResultThere were no significant differences in age between men (age range: 65‐97 years; mean age=82.8 years) and women (age range: 65‐104 years; mean age=84.5). Men had a significantly lower mean 2D:4D than women (0.948 versus 0.964; p=0.006), which is expected since relatively higher androgen exposure in utero has been linked with lower 2D:4D. Among men, there was no significant difference in 2D:4D between non‐demented and demented subjects (0.954 versus 0.943; p=0.57). Importantly, women with dementia showed a significantly higher 2D:4D than non‐demented women (0.979 versus 0.951; p=0.005).ConclusionThe data demonstrate a higher (more feminine) 2D:4D in women with dementia in comparison to non‐demented women. Similar effects were not observed in men. These results suggest that developmental events that yield relatively more feminine phenotypes increase vulnerability of women to dementia. The findings support the hypothesis that the female bias in AD risk is due in part to developmental sex differences. (Support: RF1AG058068 [NIH] and SAGA‐17‐419408 [Alzheimer’s Association].)

Asymmetric Behavior in Ptyodactylus guttatus: Can a Digit Ratio Reflect Brain Laterality?

The digit ratio, an indicator of brain laterality, is the ratio of the second and fourth digits on the left (L24) or right foot (R24). Much of the research on the digit ratio and brain laterality focuses on primates, rather than other species such as reptiles. We tested whether the digit ratio in the gecko Ptyodactylus guttatus was associated with behaviors attributed to brain laterality. We examined risk-taking behavior (time spent under cover), foot preference (which foot was the first to start moving) and the side from which geckos bypassed an obstacle, in relation to the digit ratio. Geckos with longer fourth digits on their left hind foot (higher digit ratio) spent more time under cover. Geckos starting to move with their left leg were much more likely to bypass obstacles from the right side, and vice versa. This is the first evidence of laterality being associated with the digit ratio in reptiles. Comparisons among vertebrates are needed in order to decipher the evolutionary origin of the commonalities and peculiarities of brain asymmetry and disentangle the patterns and drivers of our evolutionary tree.

Sand lizards Lacerta agilis with higher digit ratios are more likely to autotomy.

Digit ratio is a morphological feature regarded as a biomarker of the balance of sex hormones during early development. The exposure of embryos to a set of sex hormones and the mutual relations between those hormones cause the emergence of individual morphological and/or behavioural characteristics as well as differences between sexes. We have thus hypothesised that differences in one of these morphological traits-digit ratio-may be a proxy representing a tendency towards tail autotomy. The aim of this study is to investigate the digit ratio (2D:3D, 2D:4D, 3D:4D) of the sand lizard, Lacerta agilis, Lacertidae, a species characterised by well-developed sexual dimorphism, whereby females are larger than males. We also tested associations between patterns in digit ratio and caudal autotomy, a common defensive mechanism among lizards. To our knowledge, the relationship between a tendency towards autotomy and digit ratio pattern has never been researched. To date, studies on autotomy have mainly focused on the consequences, costs or evolutionary background of tail loss. Hence, researchers examined mostly the frequency of autotomy in the context of predatory pressure or habitat conditions, omitting an individual's behavioural tendency to shed its tail. However, behavioural traits can affect an individual's exposure to predator attack and consequently the need to use an anti-predator strategy. Thus, following this logic, dropping the tail may be the result of the lizard's intraspecific personality characteristics, resulting from the effect of hormones on behaviour or innate traits. Therefore, we suggest that the inclusion of autotomy as a factor explaining observed digit ratio patterns and their variability between taxa has great potential. We used computerised measurements of photographed limbs to determine the length of digits. We found that the digit ratios for all four limbs were significantly lower in females than in males, excluding the 3D:4D ratio for the right hindlimbs. Therefore, the results confirmed the pattern already observed for most lizards. The novel element in our study is the detection of the relationship between a tendency towards caudal autotomy and digit ratio. Individuals with a tendency towards autotomy have a higher 2D:4D ratio in the right forelimbs and a lower 2D:3D ratio in the right hindlimbs. Obtained results suggest that these morphological characteristics are most likely related to intraspecific differences (between bold and shy individuals) which consequently may determine an individual's reaction or susceptibility to be a prey and escape behaviour. Thus, our results are probably the first attempt to link digit ratio to the susceptibility of lizards to tail autotomy.

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.

Association of Hormonal Fingerprints and Dental Caries: A Pilot Study.

Context:Dental caries remains the most widespread oral disease among all age groups. Hormonal fingerprints (second digit: fourth digit ratio or 2D:4D ratio) are biomarkers displaying sexual dimorphism and diverse human phenotypic traits. A person's genetic makeup may influence the occurrence of dental caries.Aim:The present study aimed to evaluate the influence of digit ratio on the incidence of dental caries.Settings and Design:Two hundred patients between 18 and 55 years, reporting for restorations or endodontic therapy, participated in the study.Subjects and Methods:Hormonal fingerprints (2D:4D ratio) were measured with the help of a digital vernier caliper. Caries incidence was recorded using the DMFT index.Statistical Analysis used:Data obtained were tabulated and statistically analyzed using Independent t-test and Chi-square test.ResultsMales had a less mean 2D:4D ratio than females, which was statistically significant (p-value = 0.003). Chi-square test was applied, and there was a statistically significant correlation between high digit ratio and caries experience (p-value = 0.002). Females with a high digit ratio and males with a low digit ratio were in the moderate and low caries risk groups with a p-value of 0.029 and 0.001 in the respective risk groups.ConclusionThe present study displayed a correlation between hormonal fingerprints (2D:4D ratio) and dental caries. An indicator of caries risk will help prevent caries by implementing oral hygiene measures, which will reduce its incidence as the most occurring oral disease.

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.

Measurement of 2D:4D ratios in patients with major depressive disorders: A pilot study

Introduction: Digit ratio or 2D:4D ratio is a sexually dimorphic trait. It is a proxy marker of prenatal androgen exposure and is negatively correlated to prenatal androgens especially, testosterone. Literature search revealed significant correlations between digit ratios and various physiological, psychological or performance traits in adulthood. Objectives: The pilot study was conducted to measure 2D:4D ratios of patients with Major Depressive Disorder (MDD) and to compare it with normal (non-depressed) individuals and also to evaluate the correlation between digit ratios & depression scores. Materials and Methods: The present study was conducted in adults of age group belonging to 25-40 years with MDD (Group 1: n=30), from a tertiary care centre for Psychiatry. Using digital vernier calipers 2D:4D ratio was measured. Diagnosis of depression was done by the psychiatrist using DSM –IV criteria and depression scores were calculated by Hamilton depression rating scale (HDRS). Depression scores using Beck’s Depression Inventory and digit ratios were measured in age and sex matched healthy controls (Group 2: n=30). Results: The Mean ratios of Group 1 (0.9659 0.04161) was found to be lower than Group 2 (0.9788 0.0371). Using standard cutoffs, Group 1 was divided into Low and High digit ratios. The proportion of Group 1 patients with high ratios (84%) was significantly more than those with than low ratios (16%) (p Discussion: The outcomes of the present study were synchronous with reports of higher incidence of depression in females, nationally and globally. This was concurrent with the other reports of the previous studies. This would help us to conduct the future studies even on large study population. Keywords: Digit ratio, 2D:4D ratio, Prenatal testosterone, Depression, Vernier Caliper, Beck’s Inventory.

2D 4D ratio differences between 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.

Is There a Rationale behind Pharmacotherapy in Idiopathic Gynecomastia?

Background/Aims: The aim of this research was to analyze digit ratio in relation to estrogen receptor (ER) and progesterone receptor (PR) expression and to verify digit ratio (2D: 4D) as a marker of ER and PR overexpression in the male breast. Methods: This study included 35 patients who underwent breast reduction due to the idiopathic form of gynecomastia. The average age of the studied individuals was 25.7 years (SD = 7.8). ER and PR expression was detected in breasts, and digit ratios were calculated in patients with idiopathic gynecomastia. Results: ER expression did not correlate with the right (p = 0.51) and left 2D: 4D (p = 0.97). Also, there was no correlation between PR expression and 2D: 4D. A lack of correlation between these variables may result from the fact that the analyzed group of men with idiopathic gynecomastia was small in number, but at the same time, it appeared to be homogenous in these aspects (positive ER and/or PR expression and high digit ratio). Conclusion: High digit ratio in men with gynecomastia may tend to be a marker of overexpression of ER and PR. This may justify an early use of tamoxifen in men with gynecomastia and a high digit ratio.

Digit Ratio and Dental Caries: A Sexually Dimorphic Trait.

Dental caries is the most common oral health disease affecting all age groups, races, and geographic locations. The need for the study was to determine the anatomical marker that could predict the taste perception and caries at an early stage. Aim of the study was to determine the correlation between digit ratio and caries experience in school-going children of south Canara region. An observational and cross-sectional pattern was adopted for the present study. The study was then evaluated to find out the correlation between the digit ratio that is thought to be predetermined with caries experience in children of age group 6 to 16 years. In the total sample of 2,037 children, the total population was divided into two categories, i.e., high digit ratio and low digit ratio. Of the total population, 1,112 had low digit ratio and 925 had high digit ratio. Caries experience was highest in low-risk group, followed by moderate, high risk, low risk, and very high risk groups. In all the categories, low digit ratio was affected more than high digit ratio. The study clearly states a positive correlation between digit ratio, taste, social behavior, and dental caries.How to cite this article: Verma P, Hegde AM. Digit Ratio and Dental Caries: A Sexually Dimorphic Trait. Int J Clin Pediatr Dent 2018;11(1):1-6.

Association of Estrogen-Related Traits with Allergic Rhinitis.

Estrogen's role in allergic diseases has recently been of considerable interest. The present article seeks to determine the relationship between estrogen-dependent traits and allergic rhinitis. The following traits were considered: digit ratio, age at menarche, regularity of menstrual cycles, and the waist to hip ratio. The study consisted of surveys and measurement data collected from 768 female university undergraduates. One hundred and sixty eight undergraduates (21.9%) had been diagnosed with allergic rhinitis. The results of logistic regression show that in women with a high digit ratio, indicating exposure to a higher estrogen level in the prenatal period, the risk of allergic rhinitis was almost twice as high as that in those with an average value of the ratio. The difference in the digit ratio was greater for the right than left hand. A significantly higher risk of allergic rhinitis was also observed in women who experienced first menstruation at a younger age. No differences in risk of allergic rhinitis were noted due to general obesity, abdominal obesity, or irregularity of menstrual cycles. We conclude that a higher digit ratio is suggestive of a propensity to allergies in adulthood plausibly having to do with greater exposure to estrogen at early stages of ontogenetic development.

2D:4D ratio and its association with examination scores and cognitive abilities in adolescent students - A cross-sectional study

Background: 2D:4D ratio or the ratio of lengths of 2nd (index finger) and 4th (ring finger), a proxy marker for prenatal testosterone exposure, is known to be sexually dimorphic with males having lower values. Low digit ratio is associated with certain characteristics such as aggression in males and assertiveness in females. Similarly, high digit ratio in males is associated with increased sperm counts, increased risk for heart disease, obesity and metabolic syndrome, depression, and anxiety. Aims and Objectives: The objectives of the present study were to measure 2D:4D ratios of adolescent students and look for associations between 2D:4D ratios and their Higher Secondary School Board examination scores and their cognitive abilities such as attention, memory, spatial ability, and intelligence. Materials and Methods: The present study was conducted on 70 adolescents of 18-19 years age group pursuing their education in the campus of Saveetha University. The 2D:4D ratio was measured from the midpoint of bottom crease where the finger joins the hand to the tip of the finger using digital Vernier calipers. Selected few domains of cognition were evaluated using the tests for free and placement recall, category fluency tests, and visual N-back tests. Correlation between 2D:4D ratio and Higher Secondary Board examination scores and mean cognition test scores were tested using Pearson’s correlation test. Comparison of test scores between genders and low scorers versus normal scorers was performed using student t-test. Results: The mean 2D:4D ratio of the study population was 0.97 ± 0.034. The mean 2D:4D ratio of males (0.97 ± 0.32) was not significantly different from that of females (0.98 ± 0.035). There was no significant correlation between higher secondary scores and the 2D:4D ratio. Significant relationships with 2D:4D ratios and domains of cognition tested (free and placement recall, category fluency, and working memory) were not observed. Existing literature also revealed many inconsistencies within the pattern of associations between 2D:4D digit ratio and cognitive abilities. Conclusion: The future studies in a larger population with more and different tests for assessment of cognition would help us in ascertaining the role of 2D:4D ratio as a proxy marker for prenatal androgen exposure.

Does the Mother or Father Determine the Offspring Sex Ratio? Investigating the Relationship between Maternal Digit Ratio and Offspring Sex Ratio.

ObjectiveIn mammals, high parental testosterone levels present around the time of conception are thought to skew offspring sex ratio toward sons. The second to fourth digit ratio (digit ratio) is now widely accepted as a negative correlate of prenatal testosterone. Thus, we investigated the association between digit ratio and offspring sex ratio.MethodsA total of 508 Korean patients (257 males and 251 females) less than 60 years old who had one or more offspring were prospectively enrolled. The lengths of the 2nd and 4th digits of the right hand were measured by a single investigator using a digital vernier calliper. Next, the patients’ lifetime offspring birth sex ratios were investigated.ResultsMaternal (rather than paternal) digit ratio was significantly associated with the number of sons (r = -0.153, p = 0.015), number of daughters (r = 0.130, p = 0.039), and offspring sex ratio (r = -0.171, p = 0.007). And, the maternal digit ratio was a significant factor for predicting offspring sex ratio (B = -1.620, p = 0.008) on multiple linear regression analysis. The female patients with a lower digit ratio (< 0.95) were found to have a higher offspring sex ratio (0.609 versus 0.521, p = 0.046) compared to those with a higher digit ratio (≥ 0.95). Furthermore, females in the low digit ratio group have a probability 1.138 greater of having sons than females in the high digit ratio group.ConclusionsMaternal digit ratio was negatively associated with offspring sex ratio. Females with a lower digit ratio were more likely to have more male offspring compared to those with a higher digit ratio. Thus, our results suggest that the sex of offspring might be more influenced by maternal rather than paternal factors.

Testosterone at your fingertips: Digit ratios (2D:4D and rel2) as predictors of courtship-related consumption intended to acquire and retain mates

While hormones have been shown to impact a wide range of behaviors, little is known regarding their influence on consumer behavior. The current research examines the association between digit ratios and courtship-related consumption. Digit ratios (2D:4D and rel2) are indicators of prenatal testosterone exposure and are assessed by measuring finger length. In Study 1, masculinized digit ratios (low digit ratios, high prenatal testosterone) in men were associated with greater courtship-related consumption to acquire mates, and this association was stronger for men with high mating confidence. In women, feminized digit ratios (high digit ratios, low prenatal testosterone) were associated with greater courtship-related consumption to acquire mates. In Study 2, men with masculinized digit ratios engaged in greater courtship-related consumption by offering romantic gifts as a means of retaining mates. In women, feminized digit ratios were associated with greater romantic gift giving. Our findings suggest that high prenatal testosterone in men leads to greater courtship-related consumption, whereas low prenatal testosterone leads to greater courtship-related consumption in women.

2D:4D values are associated with mathematics performance in business and economics students

Prenatal testosterone has organizational effects on adult cognition. The second-to-fourth digit length ratio, which is a proxy of prenatal testosterone exposure, has been linked to a wide variety of sexually differentiated behaviors. We analyze the association between academic performance and the second-to-fourth digit ratio among students at the Faculty of Business and Economics of the University of Granada (Spain). In a sample of 516 freshmen (304 women), we find an inverted U-shaped relationship between digit ratio and mathematics grades. Males and females show the same pattern. Participants with both high and low digit ratios earn lower grades in mathematics, while participants which have intermediate digit ratios achieve the highest grades in mathematics. We also find that there is no statistically significant relationship between the digit ratio and the average grades earned by students in other courses except mathematics taken in the first semester at the Faculty of Business and Economics.