Second to Fourth Digit Ratio(2D:4D) in North-West Indians: Sexual Dimorphism

The index (2D) to ring finger (4D) ratio less than one (2D:4D < 1) has been considered as a “male finger pattern” and 2D:4D more than or equal to one (2D:4D≥1) has been considered as a “female finger pattern”. The present study was conducted on 100 young adults (m=56, f=44) from northwest population of India to find out the sexual dimorphism and right-left asymmetry in WAD ratio by three different methods namely visual, direct and scan methods. Visual method showed that significantly more number of males were having Type 3 hand i.e. index finger smaller than ring finger compared to females who more often had Type 1 hand i.e. index finger longer than ring finger (p< 0.001). The mean 2D:4D ratios in males were observed to be 0.97 by direct method and 0.96 by scan method. In females the ratio was 1.00 and 0.99 by direct and scan methods respectively; sex difference being statistically significant (p <0.001).Mean values by direct method were slightly higher than scan method but the difference was statistically insignificant. In both sexes there was no significant right left asymmetry.     

Metacarpophalangeal relations in 21 Danish patients with achondroplasia

Hand radiographs of 21 Danish patients suffering from achondroplastic chondrodystrophia were obtained to study the metacarpophalangeal relations. Mean pattern profiles based on z-scores were made for males, females, children, and adults. Metacarpal index and relative slenderness for metacarpals and proximal phalanges were calculated. The second to fourth metacarpals and third and fourth proximal phalanges were disproportionately short, and the distal phalanges were disproportionately long. The relation between hand size and height seemed to be the same for the achondroplasts as for normal persons. The metacarpal sign was found in four of the 21 patients.     

猕猴掌骨和指骨长度性差

目的探讨在1个猕猴种群中用掌骨和指骨的长度鉴定性别。方法采用直接测量法对11例雄性和25例雌性猕猴的掌骨和指骨长度进行测量。数据处理分析采用SPSS 20.0统计学软件。结果手骨的性别正确判别率从近侧掌骨到远侧指骨逐渐增加。5根掌骨和5根远节指骨长度的性别判别率分别是88.9%和100.0%,第1根手骨(包括1节掌骨和2节指骨)和第5根手骨(包括1节掌骨和3节指骨)总长度的性别判别率分别是90.3%和100.0%。因子分析结果显示,19根手骨形态分组是以排(掌骨、近节指骨、中节指骨和远节指骨)为单位,而不是以列(5根指骨)为单位。结论猕猴掌骨和指骨长度变量可以有效地识别性别,对非人灵长类的生物系统演化关系有一定的理论意义和应用价值。     

The Ratio of Second to Fourth Digit Length (2D:4D) and Coronary Artery Disease in a Han Chinese Population

Background: The association between index finger to ring finger length ratio (2D:4D) and cardiac disorders has been reported, however it has not been discussed in terms of coronary artery disease (CAD). We investigated whether 2D:4D could be used as a marker for predisposition to CAD as assessed by coronary angiography in Chinese men and women.Methods: This study included 1764 persons divided into 4 groups, 441 cases with CAD and 441 persons without CAD as control in each sex of the same age. Finger lengths were measured twice for both hands using electronic calipers. Student t test was used to detect the difference of 2D:4D among groups. The receiver operator characteristic curves (ROCs) were used to detect the diagnostic effect of 2D:4D for CAD.Results: There were no significant differences in age among the four groups. A significant difference of 2D:4D ratios between right and left hand were observed only in men in both control and CAD groups. On the right hand in the control group and on both hands in the CAD group, the 2D:4D ratios were higher in women than in men (all, P < 0.001). In men with CAD, mean 2D:4D was higher than mean 2D:4D in control men (right hand 0.962±0.042:0.927±0.038; left hand 0.950±0.044:0.934±0.048; both hands, P < 0.001), but this was not observed in women. No relationship was found between 2D:4D and age (all, P >0.05). The area under the curve of right hand 2D:4D in male was 0.72 (95% CI 0.683-0.753, p<0.001), while it was 0.602 (95% CI 0.565-0.639, p<0.001) in left hand.Conclusions: The present study showed an association between high 2D:4D ratio and CAD in both hands in men. There were no significant differences in mean 2D:4D between women with CAD and controls.     

Finger lengths, 2D:4D ratios, and their relation to gender-related personality traits and the Big Five

Finger lengths and the ratio of index finger to ring finger length (2D:4D) may be markers of gonadal hormone exposure. The current study investigated possible associations between absolute finger lengths, 2D:4D ratios, and gender-related personality traits in over 2000 participants. Regression analyses showed no associations between men's 2D:4D ratios and gender-related personality traits and weak associations between women's 2D:4D ratios and gender-related occupational preferences. Men's absolute finger lengths were weakly associated with self-ascribed masculinity, and women's absolute finger lengths were weakly associated with masculine occupational preferences. Big Five personality traits were assessed in a subsample of over 1000 participants. Analyses showed a weak positive association between 2D:4D and extraversion and a weak negative association between 2D:4D and openness to experience. Absolute finger lengths showed a weak negative association with agreeableness and a tendency to be associated with women's but not men's openness. Overall, associations between finger-length measures and personality were weak and inconsistent.     

Human 2D (index) and 4D (ring) digit lengths: their variation and relationships during the menstrual cycle

It is known that there are sexually dimorphic differences in relative and absolute lengths of the index (2nd) and ring (4th) fingers and that the sizes of laterally-paired soft tissues (e.g. ears and fingers) show changes across the menstrual cycle. The aim of the present study was to determine whether cyclical changes in the digit lengths of the index and ring fingers also occur and, if so, to what extent these are related to changing patterns of circulating sex steroids. Digit lengths were assessed over two cycles in groups of right-handed females (19-21 years of age) who were divided on the basis of whether or not they were taking oral contraceptive pills (n = 13 and n = 6 respectively). Using callipers, finger lengths were measured on photocopy images of both hands taken at 4-day intervals for a total of 56 days. We tested the following null hypotheses: (1) digit length measurements do not exhibit fluctuations across the menstrual cycle; (2) there is no evidence of lateral asymmetry between measurements made on both hands; (3) the lengths of digits 2 and 4 do not differ in either hand. Null hypotheses were tested using Page's L trends test for related samples (cyclical fluctuations) and paired Student's t tests (left-right asymmetries and within-hand digital differences). In those not taking oral contraceptives, finger lengths and 2D:4D digit ratios fluctuated across the cycle with values tending to increase in the pre-ovulatory period and decline thereafter. Left-right asymmetries varied in a similar fashion with lengths generally being larger, and lateral asymmetries smaller, in the dominant hand. Although sample sizes were smaller, some of these patterns were retained but others were perturbed in those practising oral contraception. We conclude that finger lengths are cycle-dependent and that account should be taken of this, and of oral contraceptive usage, in future studies on female digit lengths and their ratios.     

Radiographic 2D:4D index in females: no relation to anthropometric, behavioural, nutritional, health-related, occupational or fertility variables

Background  

The ratio of index finger to ring finger length (2D:4D index) may be an indicator of gonadal hormone exposure, because the differentiation of gonads, fingers and toes is influenced by the same HOXA and HOHD genes. Some previous studies have found significant associations between the 2D:4D index and sexual, psychological or behavioural variables. We studied the usability of the radiographic 2D:4D index as a potential predictor of several features in a large female sample.     

Morphometric analysis of the second through fifth metacarpal through posteroanterior X-Rays

Over the past 10 years, metacarpal fractures have had an annual incidence of 13.6 per 10,000 individuals. Literature has not reviewed anatomical variations through radiographic imaging, which may play a role in reducing postoperative complications. The purpose of this study was to use radiographic imaging to provide a detailed anatomy of the second through fifth metacarpals. This retrospective study measured length, neck width, narrowest body width, and narrowest medullary canal width of the second through fifth metacarpals through the use of posteroanterior X-rays. Patients who were ≥18 years and received hand radiographs from January 2015 to July 2019 were included in this study. Those with acute injury or fracture of the metacarpal were excluded. Five hundred and seventy-two metacarpals were included in this study, with 143 metacarpals measured each for the second through fifth metacarpal. The second metacarpal had the largest measured length, neck width, and narrowest body width at 68.72, 12.34, and 8.74 mm, respectively. The fifth metacarpal had the greatest average medullary canal width at 4.15 mm. This is the largest study in literature to comprehensively examine the anatomical variation of the second through fifth metacarpals. The second metacarpal had greatest dimensions except for canal width, which was the fifth metacarpal. Men almost consistently had greater metacarpal size when compared to women, and age was associated with second and third metacarpal canal width. The increased knowledge of metacarpal anatomy may potentially lay the foundation of further improvement of metacarpal implants and potentially reduce postoperative complications. Clin. Anat., 33:1014–1018, 2020. © 2019 Wiley Periodicals, Inc.     

No association between two candidate markers of prenatal sex hormones: Digit ratios (2D:4D and other) and finger‐ridge counts

The second‐to‐fourth digit ratio (2D:4D), putatively indexing prenatal androgen levels retrospectively, has become increasingly popular as an easily applied measure in research into the prenatal sex‐hormonal bases of behavior, health, and disease. However, its validity has not yet been conclusively demonstrated and in fact is currently debated, because validation tests of 2D:4D with other, prenatally established, presumed markers for prenatal sex‐hormone action have yielded mixed evidence or still are unavailable. Hence, the associations of 2D:4D with finger‐ridge counts, one such further under‐researched marker, were examined in this study. In a sample of 75 male and 75 female normal healthy adults, the six possible finger‐length ratios of the human hand (from 2D:3D to 4D:5D, including the classic 2D:4D ratio) were ascertained with two commonly used measurement methods (imaged‐based vs. fingers measured directly), along with two traditional dermatoglyphic traits (total and absolute finger‐ridge counts). Sex differences in finger‐length ratios (lower in men) generally were of moderate size (about .5 SD units), whereas those in finger‐ridge counts (higher in men) were small to negligible (about .2 SD units). Within‐sex analysis did not indicate theory compliant (i.e., negative) correlations between these two sets of traits that were consistent, noteworthy, or reliable. Finger‐length ratios and finger‐ridge counts are ontogenetically overlapping in their prenatal formation and anatomically adjacent. Hence, possible temporal and localized sex‐hormonal effects in prenatal life are unlikely to account for their nonassociation. The current findings cast some doubt on the validity of these retrospective pointers to prenatal androgen levels. © 2010 Wiley Periodicals, Inc. Dev Psychobiol 53: 69–78, 2011.     

A comparison of self-measured and researcher-measured digit ratio (2D:4D)

Abstract

The largest investigation of digit ratio (2D:4D), the BBC Internet Study, reported on finger lengths measured by participants themselves, yet data validating this technique are scarce and the reliability has been questioned. The current study aimed to calculate reliability and repeatability statistics for self-measured 2D:4D and to examine the correlations with researcher-measures. One hundred and seventy-eight undergraduate psychology students attending a practical class self-measured their finger lengths with rulers; a researcher using digital Vernier calipers measured the second and fourth fingers of a random sub-sample (n?=?97). Reliability and repeatability of self-measured 2D:4D were high, as were correlations with researcher-measurements. In each case, lower values were observed for the right–left difference in 2D:4D (D_[R-L]). Self-measured L2D:4D and M2D:4D were significantly higher than the equivalent researcher measurements, suggesting that direct comparison could be problematic. Self-measurements and directly made researcher-measurements of 2D:4D are strongly correlated, though self-measured D_[R-L] is unreliable.     

A 72-year-old Danish puzzle resolved--comparative analysis of phenotypes in families with different-sized HOXD13 polyalanine expansions

A phenotype-genotype correlation was previously described for carriers of different sized of polyalanine expansions in HOXD13. We report on a detailed comparison of 55 members (approximately 220 limbs) from 4 Danish families with duplications of 21 or 27 bp, expanding the polyalanine repeat from 15 to 22 and 24 residues, respectively. Two of these were previously described by Danish pioneers of human genetics, Tage Kemp and Oluf Thomsen. A clinical score was assigned to each limb based on manifestations assumed to represent different degrees of a duplication defect in hand rays 3-4 and foot rays 4-5. The length of metacarpals and phalangeal bones in rays 1, 2, and 5 was measured on hand radiographs and converted to Z-scores. The relative difference between corresponding right and left bones and directional, total, and fluctuating asymmetry was calculated for each individual. All of these parameters were compared between carriers of the +9 alanine expansion, the +7 alanine expansion, and non-mutation carriers with affected parents from the two families. Upper limb scores and the rate of abnormal bones (>2SD) were significantly higher in the first group than in the others. The first metacarpal and the middle phalanx of the little finger were significantly shorter, and the proximal phalanx of the index finger was significantly longer in this group than in the others. An increased level of total and fluctuating asymmetry was observed in long expansion carriers. Thus, our data have added evidence to the phenotype-genotype correlation previously reported, which was further extended to include lesser involvement of bones in ray 1, 2, and 5.     

Associations between digit ratio (2D4D), mood,and autonomic stress response in healthy men

The ratio between the length of the second (index) and the fourth (ring) finger (2D4D) is a putative biomarker of prenatal testosterone (T) exposure, with higher exposure leading to a smaller ratio. 2D4D has further been linked to mental and somatic disorders. Healthy male Swiss recruits (N = 245; M_age = 20.30 years) underwent a psychosocial stress test. Mood and salivary alpha‐amylase (sAA) were assessed before and after the stress test, while heart rate (HR) and heart rate variability (HRV) were measured continuously. Additionally, 2D4D (right: R2D4D; left: L2D4D) was determined and divided into quartile groups. Correlation analysis showed no associations between R/L2D4D and outcome measures. Comparing calculated quartiles for R2D4D, subjects in the lowest R2D4D quartile expressed trendwise (p < 0.10) lower positive and higher negative affect, significantly elevated sAA activity (p < 0.05), but no HR and HRV differences at baseline as compared to subjects in the upper three quartiles. With regard to acute stress, subjects in the lowest as compared to subjects in the upper three R2D4D quartiles showed a higher increase of negative affect and a stronger cardiac response (p < 0.05), but no alterations in positive affect and sAA activity. Young healthy men in the lowest R2D4D quartile revealed a more negative affect and increased physiological activity at baseline and in response to acute stress. An exposure to high levels of prenatal T might constitute a risk factor potentially increasing vulnerability to stress‐related disorders in men.     

Metacarpophalangeal pattern profile analysis in Sotos and Marfan syndrome

Patients with Sotos and Marfan syndrome have unusually long metacarpals and phalanges which may make the differential diagnosis difficult in younger children. Using Q-scores, we compared metacarpophalangeal pattern profile (MCPP) analysis in these two syndromes and identified distinct and different pattern profiles. This illustrates that the MCPPs are specific in these syndromes, even at an early age, and not related solely to the unusually long metacarpals and phalanges. For this study we used data from 50 Sotos patients (34 from the United Kingdom and 16 from the Netherlands, with a total of 95 hand films) and 36 Marfan patients (from the Netherlands, with 98 hand films). Of all patients over age 3 years the bone length (including the epiphysis) was determined. The patients under 7½ years (29 Sotos and 12 Marfan) were also measured without inclusion of the epiphysis. The patients measured without epiphysis had a relative short metacarpal 1 (MC1) and long distal phalanx 1 (DPh1) in Sotos syndrome, and a relative long MC1 and short DPh1 in Marfan syndrome. Between age 3 and 7½ years more than 90% of the films could be classified correctly using these two variables. Of the roentgenograms measured with epiphyses, about 80% were classified correctly. © 1994 Wiley-Liss, Inc.     

Computed tomographic analysis of the internal structure of the metacarpals and its implications for hand use,pathology, and surgical intervention

The variation of bone structure and biomechanics between the metacarpals is not well characterized. It was hypothesized that their structure would reflect their common patterns of use (i.e., patterns of hand grip), specifically that trabecular bone density would be greater on the volar aspect of all metacarpal bases, that this would be most pronounced in the thumb, and that the thumb diaphysis would have the greatest bending strength. Cross-sections at basal and mid-diaphyseal locations of 50 metacarpals from 10 human hands were obtained by peripheral quantitative computed tomography. The volar and dorsal trabecular densities of each base were measured and characterized using the volar/dorsal density ratio. The polar stress–strain index (SSIp), a surrogate measure of torsional/bending strength, was measured for each diaphysis and standardized for bone length and mass. Comparisons were made using mixed-model analyses of variance (ANOVAs) and post hoc tests. Volar/dorsal trabecular density ratios showed even distribution in all metacarpal bases except for the thumb, which showed greater values on the volar aspect. The thumb, second, and third metacarpals all had high bending strength (SSIp), but the thumb’s SSIp relative to its length and trabecular mass was much higher than those of the other metacarpals. Trabecular density of the metacarpal bases was evenly distributed except in the thumb, which also showed higher bending strength relative to its length and mass. Understanding of how these indicators of strength differ across metacarpals may improve both fracture diagnosis and treatment and lays the groundwork for investigating changes with age, hand dominance, and occupation.     

In-utero androgen exposure and 2nd to 4th digit length ratio-comparisons between healthy controls and females with classical congenital adrenal hyperplasia

BACKGROUND: Soft tissue measurements from the hand reveal lower second to fourth finger digit ratios (2D:4D) in males compared with females. The relatively longer 4th finger observed in males may be related to increased fetal exposure to androgens influencing the expression of Hox genes. METHODS: We have measured 2D:4D ratios in 69 healthy females [median age 9.3 (range 1.9-17) years], 77 control males [median age 13.86 (2.1-20.3) years] and in 66 females with classical virilizing congenital adrenal hyperplasia (CAH) (median age 8.5 (1.1-16.2) years] who are known to be exposed to high concentrations of androgens in utero. Measurements were determined from X-rays of the left hand using vernier callipers. Intra-observer variability in measurement technique was 0.01%. RESULTS: Control males had a significantly lower mean (SD) 2D:4D ratio [0.918 (0.029)] compared with female patients [0.927 (0.029), ANOVA P = 0.02]. No difference in 2D:4D ratio was observed between CAH females [0.925 (0.021)] and control females [0.927 (0.029)]. In contrast, 2D:4D ratio in males were significantly lower compared with CAH females (P = 0.03). CONCLUSIONS: 2D:4D ratios determined directly from radiographs of the left hand confirm significant differences between males and females. However, female patients with virilizing CAH do not have a male digit ratio pattern suggesting that in the left hand digit ratio development is not influenced by in-utero exposure to androgens.     

Second to fourth digit ratio, body mass index, waist-to-hip ratio, and waist-to-chest ratio: their relationships in heterosexual men and women

BACKGROUND: Prenatal sex steroids have been broadly discussed in terms of their possible effect on brain differentiation, whereas pubertal/adult sex hormones are thought to be the main regulators of sexually dimorphic physical features in males and females. Assessing prenatal steroid exposure has previously been difficult but evidence now suggests that finger length ratio may provide a 'window' into prenatal hormone exposure. The length of the second digit (the index finger) relative to the length of the fourth digit (the ring finger) is sexually dimorphic as males have a lower second to fourth digit ratio (2D:4D). The sexual dimorphism is determined as early as the 14th week of fetal life, and remains unchanged at puberty. There is evidence that sex differences in 2D:4D arise from in utero concentrations of sex steroids, with a low 2D:4D (male typical ratio) being positively related to prenatal testosterone, while a high 2D:4D (female typical ratio) is positively associated with prenatal oestrogen. AIM: The studied aimed to determine whether, and to what extent, adult sexually dimorphic physical traits, which are largely determined at puberty, relate to traits that are largely determined in utero. This work examined the relationship between three sexually dimorphic traits--body mass index (BMI), waist-to-hip ratio (WHR) and waist-to-chest ratio (WCR)--and digit ratio. PARTICIPANTS AND METHODS: BMI, WHR and WCR were assessed in 30 heterosexual male and 50 heterosexual female participants by recording their body height, weight, and measuring their waist, hip and chest circumference. Digit lengths of the second and fourth fingers were measured from photocopies of the ventral surface of the hand and by actual finger measurements. RESULTS: Digit ratio was found to be significantly lower in men than in women. Significant negative correlations were found between female's left and right hand 2D:4D, waist and hip circumference, and WCR. In males, BMI was found to be positively related to digit ratio but remained significant only for left hand 2D:4D. Generally, the relationships were stronger for females than for males. Although not all relationships were found to be significant, they were in accord with our predictions. CONCLUSION: In addition to an activational effect of sex hormones at puberty, the present data suggest an early organizational effect of sex hormones through the association between indices of female body shape, male BMI, and human finger length patterns.     

Normal length changes in hand bones during adulthood: exploratory study of ray two

A longitudinal analysis was made of total length changes of the four epiphyseal bones of ray two, the index finger, during adulthood. Matched pairs of standardized hand-wrist radiographs on 37 individuals between earlier (means = 22 years) and later (means = 54 years) adult age-grades show that the distal and middle phalanges continue to increase in overall length; the proximal phalange exhibits no change; and the metacarpal significantly decreases in size. The changes in these normal adults are also discernible in cross-sectional data but are not obvious statistically. Causes of the specific increases and decreases remain speculative.     

The hand profile in de Lange syndrome: Diagnostic criteria

The hand pattern profiles of 18 previously published and 10 new cases of de Lange syndrome were compared to those of cases referred as suspects, but judged clinically and by numerical taxonomic methods not to have de Lange syndrome (non-de Lange). Based on a Poznanski metacarpophalangel profile of the 2 groups of patients, a simple scoring system using 11 measurements was devised using the 16 most marked differences within and between metacarpals and phalanges. Of the metacarpals, the first is shorter than the second, third, fourth, or fifth; and the second fifth are shorter than the third or fourth. Of the middle phalanges, the third and fourth are shorter than the respective metacarpal and than the second and fifth middle phalanx. Of the distal phalanges, the fifth is shorter than the second. The mean Z score for these 11 measurements is further below normal in the de Lange group than in the non-de Lange group. All 11 non-de Lange patients had a score less than 17, and all 28 de Lange patients had a score of 18 or more.     

The hand profile on de Lange syndrome: diagnostic criteria.

The hand pattern profiles of 18 previously published and 10 new cases of de Lange syndrome were compared to those of cases referred as suspects, but judged clinically and by numerical taxonomic methods not to have de Lange syndrome (non-de Lange). Based on a Poznanski metacarpophalangeal profile of the 2 groups of patients, a simple scoring system using 11 measurements was devised using the 16 most marked differences within and between metacarpals and phalanges. Of the metacarpals, the first is shorter than the second, third, fourth, or fifth; and the second and fifth are shorter than the third or fourth. Of the middle phalanges, the third and fourth are shorter than the respective metacarpal and than the second and fifth middle phalanx. Of the distal phalanges, the fifth is shorter than the second. The mean Z score for these 11 measurements is further below normal in the de Lange group than in the non-de Lange group. All 11 non-de Lange patients had a score less than 17, and all 28 de Lange patients had a score of 18 or more.     

Second to fourth digit ratio,body mass index,waist-to-hip ratio,and waist-to-chest ratio: their relationships in heterosexual men and women

Background: Prenatal sex steroids have been broadly discussed in terms of their possible effect on brain differentiation, whereas pubertal/adult sex hormones are thought to be the main regulators of sexually dimorphic physical features in males and females. Assessing prenatal steroid exposure has previously been difficult but evidence now suggests that finger length ratio may provide a ‘window’ into prenatal hormone exposure. The length of the second digit (the index finger) relative to the length of the fourth digit (the ring finger) is sexually dimorphic as males have a lower second to fourth digit ratio (2D:4D). The sexual dimorphism is determined as early as the 14th week of fetal life, and remains unchanged at puberty. There is evidence that sex differences in 2D:4D arise from in utero concentrations of sex steroids, with a low 2D:4D (male typical ratio) being positively related to prenatal testosterone, while a high 2D:4D (female typical ratio) is positively associated with prenatal oestrogen.

Aim: The studied aimed to determine whether, and to what extent, adult sexually dimorphic physical traits, which are largely determined at puberty, relate to traits that are largely determined in utero. This work examined the relationship between three sexually dimorphic traits—body mass index (BMI), waist-to-hip ratio (WHR) and waist-to-chest ratio (WCR)—and digit ratio.

Participants and methods: BMI, WHR and WCR were assessed in 30 heterosexual male and 50 heterosexual female participants by recording their body height, weight, and measuring their waist, hip and chest circumference. Digit lengths of the second and fourth fingers were measured from photocopies of the ventral surface of the hand and by actual finger measurements.

Results: Digit ratio was found to be significantly lower in men than in women. Significant negative correlations were found between female’s left and right hand 2D:4D, waist and hip circumference, and WCR. In males, BMI was found to be positively related to digit ratio but remained significant only for left hand 2D:4D. Generally, the relationships were stronger for females than for males. Although not all relationships were found to be significant, they were in accord with our predictions.

Conclusion: In addition to an activational effect of sex hormones at puberty, the present data suggest an early organizational effect of sex hormones through the association between indices of female body shape, male BMI, and human finger length patterns.