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Jorjani Biomed J 2025, 13(2): 3-8 |
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Gwunireama I U, Uchechukwu Collins G. Comparative study of the digit ratio and hand pattern of the Ogoni and Ikwerre ethnic groups in Rivers state, Nigeria. Jorjani Biomed J 2025; 13 (2) :3-8
URL: http://goums.ac.ir/jorjanijournal/article-1-1013-en.html
URL: http://goums.ac.ir/jorjanijournal/article-1-1013-en.html
1- Department of Anatomy, Faculty of Basic Medical Sciences, University of Port Harcourt, Nigeria , israel.gwunireama@uniport.edu.ng
2- Department of Anatomy, Faculty of Basic Medical Sciences, University of Port Harcourt, Nigeria
2- Department of Anatomy, Faculty of Basic Medical Sciences, University of Port Harcourt, Nigeria
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Discussion
The present study evaluated the comparative analysis of digit ratios and hand patterns of Ikwerre and Ogoni ethnic groups of the Southern Nigerian population. There is adequate literature on digit ratios concerning 2D (Second digit) and 4D (Fourth digit) in the various Nigerian populations (11,23-25). However, none of these studies evaluated the digit ratio and hand patterns of the Ikwerre and Ogoni ethnic groups. In addition, previous studies have evaluated the relationship between the 2D:4D ratio and biological factors such as prenatal testosterone or estrogen, birth weight, metabolic syndrome, cardiovascular diseases, vitiligo, etc. (5,26-28). Some reports have depicted that the morphological and anthropometric relationships existing between different parts of the body, as well as between genders, ethnicity, and race, have been of great interest to forensic anthropologists due to the increase in cases of mass disasters, crimes, homicides and other causes of fatal catastrophes (29,30).
The reports of previous studies done by researchers on digit ratio suggest that the digit ratio of a male is lower compared to a female, even of the same ethnic and racial population (6-11). This is in agreement with the result of the present study, Tables 1-2 revealed that the digit ratios of Ikwerre and Ogoni male subjects were lower compared to females of both ethnic groups. This observation has been maintained across various Nigerian ethnic groups, as well as other racial populations (11,23-25,31,32). The study conducted by Nayak et al. (1) showed that the mean right 2D:4D ratio was higher compared to the mean left 2D:4D ratio in their male subjects. This was in contrast to the results of the present study. However, the results in their female category are in agreement with those of the present study, which showed the mean right 2D:4D ratio was significantly lower than the mean left 2D:4D ratio.
As shown in Table 1, the digit ratios of both right and left hands for the male and female Ikwerre groups were 0.95±0.04 and 0.96±0.05, and 0.97±0.08 and 0.98±0.05, respectively. Similarly, Table 2 shows the digit ratios of both right and left hands for the male and female Ogoni groups, which were 0.95±0.05 and 0.96±0.05, and 0.97±0.05 and 0.97±0.05, respectively. In previous studies on Nigerian subjects, morphometric variations in digit ratios have been recorded across different ethnic groups. The Igbo males were reported to have a mean value of 0.96 ± 0.02, while the females had a mean of 1.0 ± 0.06; the Urhobos: Males = 0.96 ± 0.02, Females = 1.0 ± 0.02 (23). As for the Ikwerres in a previous study done by Gwunireama and Ihemelandu (24), their males had mean right and left 2D:4D values of 0.96 ± 0.003 and 0.96± 0.002, respectively, while the females had a right and left mean 2D:4D value of 1.0 ± 0.001 and 1.0 ± 0.005, respectively. The male category of the Andoni ethnic group had a right and left 2D:4D of 0.95± 0.002 and 0.95 ± 0.002, while the females had 0.96± 0.002 (Right hand) and 0.96 ± 0.002 (Left hand), respectively. In all reports, in addition to the present study, it is observed that females have a higher digit ratio (2D:4D) than males. The sexual dimorphism on the digit ratio in the subjects of this study summarized in Tables 3-8 was statistically significant (P-value <0.05). The same observations were made in a study by Gwuanireama et al. (11) on the digit ratio of the Andoni (Obolo) group of Ijaw ethnic nationality. The consistency in this observation buttresses the point suggested by Manning (6) that differences in the digit ratios are caused by variability in hormonal secretions between males and females. The testosterone secretion levels in male subjects had a negative relationship with their 2D:4D values, in contrast to that of estrogen secretion levels, having a slightly positive relationship with 2D:4D values in their female subjects. A window for exposure to androgens, especially testosterone, during pregnancy can be found in the sexually dimorphic digit ratio (6,33).
This study showed that there were no significant ethnic differences in digit ratios (2D:4D) between the Ikwerre and Ogoni males. However, in the female category, the left 2D:4D showed significant ethnic differences between Ikwerre and Ogoni subjects; there were no significant differences in the right. In a related study done by Gwunireama and Ihemelandu (24) on Ikwerre and Andoni ethnic subjects in a southern Nigerian population, significant ethnic differences were observed in the same geographic area attributd to the digit ratio, which was discovered to be an inherited trait from the ancestral origins. However, the present study agrees with Manning et al. (34), who stated that location has an impact on 2D:4D.
In the present study, the hand patterns were categorized into three types: Type A (2D < 4D), Type B (2D = 4D), and Type C (2D > 4D). The results of this study showed that hand pattern Type A (2D < 4D) was the most prevalent in all sexes in both ethnic groups at the right hands and left hands. The next prevalent hand pattern was Type C (2D > 4D) in all genderes in both ethnic groups at the right hand and left hand. The least prevalent hand pattern was Type B (2D = 4D) in both genders across the ethnic groups, at the right hand and left hand. Nayak et al. (1) analyzed the hand patterns in selected ethnic groups in Malaysia. They noted that Type A was more prevalent compared to others, which is in strong agreement with the results of the present study. Furthermore, a study reported by Al-Qattan et al. (35) on variations in hand patterns among Saudi medical students noted that hand pattern Type A was significantly higher in males and Type C was significantly higher in females. The observation in the male category was in agreement with the present study. However, the female observation does not agree with the present study; this may be a result of the racial differences (35).
Conclusion
The findings of this study show that the 2D:4D ratios of the male and female members of the Ogoni and Ikwerre ethnic groups differ significantly. Females tend to have a higher value in this ratio. However, no significant differences in the digit ratio (2D:4D) were observed between the Ikwerre and Ogoni males and females. Hand pattern A was the most common in both ethnic groups for both genders, followed by pattern C, while pattern B was the least observed. There were no significant differences in hand patterns between the two ethnic groups, suggesting a close ancestral relationship. The findings of this study can be used as a foundation for exploring potential correlations with various physiological, psychological, and behavioral traits among the Ikwerre and Ogoni ethnic groups in Nigeria. Additionally, a solid understanding of digit ratios and hand patterns can serve as a useful tool in identifying gender differences for forensic investigations.
Acknowledgement
The authors sincerely appreciate all those who volunteered as participants in this research.
Funding sources
The writers declare that no organization ever provided them with any form of financial support.
Ethical statement
This study was approved by the Research Ethics Committee of the University of Port Harcourt (UPH/CEREMAD/REC/MM71/008).
Conflicts of interest
The authors declare no conflict of interest.
Author contributions
They all contributed to various components of the study, including research design, data collection and analysis, initial and final manuscript drafting. All authors read and approved the final manuscript.
Data availability statement
The datasets used or analyzed during the current study are available from the corresponding author on reasonable request.
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Introduction
The ratio of a hand's various digits or fingers is known as the "digit ratio," and its study has historically been regarded as pseudoscience. It is calculated by dividing the length of a hand's index finger by the length of its ring finger, the 2D:4D ratio is the most studied digit ratio. The shape of the palm and fingers when they are adducted is referred to as the hand pattern (1-3). The length of the digits is measured from the middle of the bottom crease to the fingertip (4). The male pattern, also referred to as the "A" pattern, occurs when the ratio is less than one, indicating that the ring finger is longer than the index finger. The female pattern, or "C" pattern, is when the index finger is longer than the ring finger; this ratio is greater than one. The pattern is known as a "B" pattern and can occur in both sexes when the lengths of the two fingers are equal (Ratio equal to one). According to several studies, male or female hand patterns are thought to result from prenatal exposure to either testosterone or estrogen (5).
Individuals' gender and race are the two most important factors that influence hand patterns, according to previous research documentation on hand patterns and digit ratios (6). Women have a higher value than men in the sexually dimorphic 2D:4D ratio. Men typically have a digit ratio of 0.96, whereas women typically have a digit ratio of 1.0. This indicates that the length of the index and ring fingers is nearly equal in females (6-11). It has been demonstrated that a low 2D:4D ratio is associated with high testosterone levels, which are typical of men, whereas a high 2D:4D ratio is associated with low testosterone levels, which are characteristic of women. The sexual difference in the digit ratio (2D:4D) is generally fixed in utero between the 13th and 14th weeks of gestation, and influenced by the prenatal secretion of testosterone and estrogen and then present in newborns. It is genetically regulated by HOX genes, which also regulate urogenital system differentiation. As a result, it may have an indirect impact on the development of the digits and the production of testicular androgen during pregnancy. Over time, an individual's 2D:4D ratio stays largely constant (6,12-15). Manning et al. (8) proposed that the 2D:4D ratio is unstable and only stabilizes after two years of age. Other population and longitudinal studies have discovered that an individuals' 2D:4D digit ratios increase with age (16). Hand patterns and the 2D:4D ratio have a direct correlation with a number of human phenotypic characteristics (Autism, physical aggression) in the medical field, special abilities (Soccer ability, musical ability), fertility, health conditions (Breast cancer, congenital adrenal hyperplasia) and behavioral skills (6,17-22).
Research conducted by experts has demonstrated that digit ratios and hand patterns may differ among various ethnic and racial groups (6,23). The Ikwerre and Ogoni are two distinct ethnic groups situated in Rivers State, South-Southern Nigeria. Despite this, there is currently no comparative research examining the digit ratios and hand patterns of these two ethnic groups. This study is designed to address this gap and aims to provide a comprehensive comparison and documentation of the relationship between digit ratios (2D:4D) and hand patterns between the Ogoni and Ikwerre ethnic groups in Rivers State, Nigeria.
Methods
This study employed a cross-sectional descriptive design in Rivers State, Nigeria, with a specific focus on the Ikwerre and Ogoni ethnic groups. This study was approved by the Research Ethics Committee of the University of Port Harcourt (UPH/CEREMAD/REC/MM71/008). A total of 1,925 subjects between the ages of 15 and 60 years were recruited using a simple random sampling technique. The participants gave informed consent and were voluntarily recruited for the study. Those having any form of hand deformity were excluded from the study.
The index finger (2D) and ring finger (4D) lengths were measured from the basal crease to the tips using a Digital Vernier Caliper. Participants wearing rings were asked to remove their finger rings before taking measurements. The patterns were assessed and grouped based on the digit ratios as A (The ring finger is longer than the index finger), B (When both fingers are equal in length), and C (The index finger is longer than the ring finger) types. The 2D:4D ratios were then calculated for each subject on both hands. All data obtained were segregated according to gender and ethnicity.
Data were analyzed using SPSS version 24.0. Gender and ethnic differences were determined using the independent sample T-test, while side differences were determined using paired sample T-test. In addition, gender and ethnic differences in hand patterns were determined using the Chi-square (χ2) test of association. The confidence interval was set at 95% and statistical significance level was set at 0.05
Results
A total of 1,925 subjects were involved in the study, of which 1,010 (52%) were from Ogoni group, while 915 (48%) were from the Ikwerre ethnic group. In the distribution of the subjects according to gender and ethnicity, Ikwerre males were more (460, accounting for 50.27%) than females (455 [49.73%]) in the study, compared to the Ogonis, where there were more females (515 [50.99%]) than males (495 [49.01%]).
The male Ikwerre subjects had a digit ratio of 0.95±0.04 and 0.96±0.05 on the right and left, respectively. This is a normal masculine digit ratio (5). A digit ratio of 0.97±0.08 (Right) and 0.98±0.05 (Left) was observed in the female Ikwerre subjects. The females were observed to have a higher digit ratio than the males (Table 1).
Table 2 explains the descriptive statistics of the Ogoni study group's digit lengths and digit ratios. The digit ratios of both right and left hands for the male Ogoni groups were 0.95±0.05 and 0.96±0.05, respectively. The digit ratios of both right and left hands for the female Ogoni groups were 0.97±0.05 and 0.97±0.05, respectively. The female Ogoni subjects were observed to have higher digit ratios than the males.
In both Ikwerre and Ogoni groups, the Digit Ratio of 2D:4D, the Second Digit Length (2D), and the Fourth Digit Length (4D) were significant in relation to gender, according to the T-test results (Table 3).
Additionally, the Right 2D-Left 2D and Right 2D:4D-Left 2D:4D in Ikwerre ethnicity were statistically significant in both males and females, according to the paired sample T-test (Table 4).
The Ogoni male population's Right 2D-Left 2D, Right 4D-Left 4D, and Right 2D:4D-Left 2D:4D were all statistically significant, while the Ogoni female population's Right 4D-Left 4D parameter was not (Table 5).
Table 6 shows the results based on ethnic differences between Ikwerre and Ogoni males concerning digit lengths and digit ratios. Significant differences were observed in the digit lengths of both hands. No significant difference was seen in the digit ratio (t = -0.01; P-Value = 0.99) and (t = 0.83; P-Value = 0.41) of right and left hands, respectively.
However, in the female category in Table 7, parameters such as left 4D length (t = -2.58; P-Value = 0.01) and left 2D:4D (t = 3.19; P-Value < 0.001) showed significant ethnic differences between Ikwerre and Ogoni groups.
There is a difference in the pattern between the two genders (Table 8) (Right (x2 = 33.29; P-Value < 0.001), and Left (x2 = 32.59; P-Value < 0.001)) of Ikwerre subjects. Pattern A was predominant in both hands (Right [A = 82.1%], and Left [74.5%]), followed by C (Right [A = 17.5%], and Left [24.8%]) and B (Right [A = 0.4%], and Left [0.7%]) was the least observed pattern.
The ratio of a hand's various digits or fingers is known as the "digit ratio," and its study has historically been regarded as pseudoscience. It is calculated by dividing the length of a hand's index finger by the length of its ring finger, the 2D:4D ratio is the most studied digit ratio. The shape of the palm and fingers when they are adducted is referred to as the hand pattern (1-3). The length of the digits is measured from the middle of the bottom crease to the fingertip (4). The male pattern, also referred to as the "A" pattern, occurs when the ratio is less than one, indicating that the ring finger is longer than the index finger. The female pattern, or "C" pattern, is when the index finger is longer than the ring finger; this ratio is greater than one. The pattern is known as a "B" pattern and can occur in both sexes when the lengths of the two fingers are equal (Ratio equal to one). According to several studies, male or female hand patterns are thought to result from prenatal exposure to either testosterone or estrogen (5).
Individuals' gender and race are the two most important factors that influence hand patterns, according to previous research documentation on hand patterns and digit ratios (6). Women have a higher value than men in the sexually dimorphic 2D:4D ratio. Men typically have a digit ratio of 0.96, whereas women typically have a digit ratio of 1.0. This indicates that the length of the index and ring fingers is nearly equal in females (6-11). It has been demonstrated that a low 2D:4D ratio is associated with high testosterone levels, which are typical of men, whereas a high 2D:4D ratio is associated with low testosterone levels, which are characteristic of women. The sexual difference in the digit ratio (2D:4D) is generally fixed in utero between the 13th and 14th weeks of gestation, and influenced by the prenatal secretion of testosterone and estrogen and then present in newborns. It is genetically regulated by HOX genes, which also regulate urogenital system differentiation. As a result, it may have an indirect impact on the development of the digits and the production of testicular androgen during pregnancy. Over time, an individual's 2D:4D ratio stays largely constant (6,12-15). Manning et al. (8) proposed that the 2D:4D ratio is unstable and only stabilizes after two years of age. Other population and longitudinal studies have discovered that an individuals' 2D:4D digit ratios increase with age (16). Hand patterns and the 2D:4D ratio have a direct correlation with a number of human phenotypic characteristics (Autism, physical aggression) in the medical field, special abilities (Soccer ability, musical ability), fertility, health conditions (Breast cancer, congenital adrenal hyperplasia) and behavioral skills (6,17-22).
Research conducted by experts has demonstrated that digit ratios and hand patterns may differ among various ethnic and racial groups (6,23). The Ikwerre and Ogoni are two distinct ethnic groups situated in Rivers State, South-Southern Nigeria. Despite this, there is currently no comparative research examining the digit ratios and hand patterns of these two ethnic groups. This study is designed to address this gap and aims to provide a comprehensive comparison and documentation of the relationship between digit ratios (2D:4D) and hand patterns between the Ogoni and Ikwerre ethnic groups in Rivers State, Nigeria.
Methods
This study employed a cross-sectional descriptive design in Rivers State, Nigeria, with a specific focus on the Ikwerre and Ogoni ethnic groups. This study was approved by the Research Ethics Committee of the University of Port Harcourt (UPH/CEREMAD/REC/MM71/008). A total of 1,925 subjects between the ages of 15 and 60 years were recruited using a simple random sampling technique. The participants gave informed consent and were voluntarily recruited for the study. Those having any form of hand deformity were excluded from the study.
The index finger (2D) and ring finger (4D) lengths were measured from the basal crease to the tips using a Digital Vernier Caliper. Participants wearing rings were asked to remove their finger rings before taking measurements. The patterns were assessed and grouped based on the digit ratios as A (The ring finger is longer than the index finger), B (When both fingers are equal in length), and C (The index finger is longer than the ring finger) types. The 2D:4D ratios were then calculated for each subject on both hands. All data obtained were segregated according to gender and ethnicity.
Data were analyzed using SPSS version 24.0. Gender and ethnic differences were determined using the independent sample T-test, while side differences were determined using paired sample T-test. In addition, gender and ethnic differences in hand patterns were determined using the Chi-square (χ2) test of association. The confidence interval was set at 95% and statistical significance level was set at 0.05
Results
A total of 1,925 subjects were involved in the study, of which 1,010 (52%) were from Ogoni group, while 915 (48%) were from the Ikwerre ethnic group. In the distribution of the subjects according to gender and ethnicity, Ikwerre males were more (460, accounting for 50.27%) than females (455 [49.73%]) in the study, compared to the Ogonis, where there were more females (515 [50.99%]) than males (495 [49.01%]).
The male Ikwerre subjects had a digit ratio of 0.95±0.04 and 0.96±0.05 on the right and left, respectively. This is a normal masculine digit ratio (5). A digit ratio of 0.97±0.08 (Right) and 0.98±0.05 (Left) was observed in the female Ikwerre subjects. The females were observed to have a higher digit ratio than the males (Table 1).
Table 2 explains the descriptive statistics of the Ogoni study group's digit lengths and digit ratios. The digit ratios of both right and left hands for the male Ogoni groups were 0.95±0.05 and 0.96±0.05, respectively. The digit ratios of both right and left hands for the female Ogoni groups were 0.97±0.05 and 0.97±0.05, respectively. The female Ogoni subjects were observed to have higher digit ratios than the males.
In both Ikwerre and Ogoni groups, the Digit Ratio of 2D:4D, the Second Digit Length (2D), and the Fourth Digit Length (4D) were significant in relation to gender, according to the T-test results (Table 3).
Additionally, the Right 2D-Left 2D and Right 2D:4D-Left 2D:4D in Ikwerre ethnicity were statistically significant in both males and females, according to the paired sample T-test (Table 4).
The Ogoni male population's Right 2D-Left 2D, Right 4D-Left 4D, and Right 2D:4D-Left 2D:4D were all statistically significant, while the Ogoni female population's Right 4D-Left 4D parameter was not (Table 5).
Table 6 shows the results based on ethnic differences between Ikwerre and Ogoni males concerning digit lengths and digit ratios. Significant differences were observed in the digit lengths of both hands. No significant difference was seen in the digit ratio (t = -0.01; P-Value = 0.99) and (t = 0.83; P-Value = 0.41) of right and left hands, respectively.
However, in the female category in Table 7, parameters such as left 4D length (t = -2.58; P-Value = 0.01) and left 2D:4D (t = 3.19; P-Value < 0.001) showed significant ethnic differences between Ikwerre and Ogoni groups.
There is a difference in the pattern between the two genders (Table 8) (Right (x2 = 33.29; P-Value < 0.001), and Left (x2 = 32.59; P-Value < 0.001)) of Ikwerre subjects. Pattern A was predominant in both hands (Right [A = 82.1%], and Left [74.5%]), followed by C (Right [A = 17.5%], and Left [24.8%]) and B (Right [A = 0.4%], and Left [0.7%]) was the least observed pattern.
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Table 1. Descriptive statistics of digit length and ratio of the Ikwerre ethnic group
.PNG) 2D = Second Digit length, 4D = Fourth Digit length, 2D:4D = Digit Ratio, N = Number of subjects, Min = Minimum, Max = Maximum, SD = Standard Deviation Table 2. Descriptive statistics of digit length and ratio of the Ogoni ethnic group .PNG) 2D = Second Digit length, 4D = Fourth Digit length, 2D:4D = Digit Ratio, N = Number of subjects, Min = Minimum, Max = Maximum, SD = Standard Deviation |
There is a difference in the pattern between the two genders (Right (x2 = 25.56; p <0.001), and Left (x2 = 15.05; p <0.001)) of the Ogoni subjects. Just like in the Ikwerre subjects, pattern A was predominant in both hands (Right [A = 80.5%], and Left [77.4%]), followed by C (Right [A = 19.4%], and Left [22.3%]) and B (Right [A = 0.1%], and Left [0.3%]) was the least observed pattern.
The results of Chi-square test showed the association for gender-ethnic differences in the hand patterns of Ikwerre and Ogoni male subjects, which was not statistically significant (P-value >0.05). Ethnic differences were not observed in the hand patterns between Ikwerre and Ogoni males. In addition, Ikwerre and Ogoni females did not show ethnic differences in the hand patterns.
The results of Chi-square test showed the association for gender-ethnic differences in the hand patterns of Ikwerre and Ogoni male subjects, which was not statistically significant (P-value >0.05). Ethnic differences were not observed in the hand patterns between Ikwerre and Ogoni males. In addition, Ikwerre and Ogoni females did not show ethnic differences in the hand patterns.
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Table 3. Independent sample T-test for gender differences in the digit length and ratio of the Ikwerre and Ogoni ethnic groups
.PNG) 2D = Second Digit length, 4D = Fourth Digit length, 2D:4D = Digit Ratio, MD = Mean Difference, SEMD = Standard Error of Mean Difference, CI = Confidence Interval, df = Degree of freedom Table 4. Paired sample T-test for side differences in the digit length and ratio of Ikwerre male and female subjects .PNG) 2D = Second Digit length, 4D = Fourth Digit length, 2D:4D = Digit Ratio, MD = Mean Difference, SEMD = Standard Error of Mean Difference, CI = Confidence Interval, df = Degree of freedom Table 5. Paired sample T-test for side differences in the digit length and ratio of Ogoni male and female subjects .PNG) 2D = Second Digit length, 4D = Fourth Digit length, 2D:4D = Digit Ratio, MD = Mean Difference, SEMD = Standard Error of Mean Difference, CI = Confidence Interval, df = Degree of freedom |
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Table 6. Independent sample T-test for ethnic differences in the digit length and ratio of Ikwerre and Ogoni male subjects
.PNG) 2D = Second Digit length, 4D = Fourth Digit length, 2D:4D = Digit Ratio, N = Number of subjects, Min = Minimum, Max = Maximum, SD = Standard Deviation Table 7. Independent sample T-test for ethnic differences in the digit length and ratio of Ikwerre and Ogoni female subjects .PNG) 2D = Second Digit length, 4D = Fourth Digit length, 2D:4D= Digit Ratio, N = Number of subjects, Min = Minimum, Max = Maximum, SD = Standard Deviation Table 8. Chi-square test of association for gender differences in hand patterns between Ikwerre and Ogoni groups .PNG) A = (2D < 4D), B = (2D = 4D), C = (2D > 4D), N = Number of Subjects, df = Degree of freedom, X2 = Chi-square |
Discussion
The present study evaluated the comparative analysis of digit ratios and hand patterns of Ikwerre and Ogoni ethnic groups of the Southern Nigerian population. There is adequate literature on digit ratios concerning 2D (Second digit) and 4D (Fourth digit) in the various Nigerian populations (11,23-25). However, none of these studies evaluated the digit ratio and hand patterns of the Ikwerre and Ogoni ethnic groups. In addition, previous studies have evaluated the relationship between the 2D:4D ratio and biological factors such as prenatal testosterone or estrogen, birth weight, metabolic syndrome, cardiovascular diseases, vitiligo, etc. (5,26-28). Some reports have depicted that the morphological and anthropometric relationships existing between different parts of the body, as well as between genders, ethnicity, and race, have been of great interest to forensic anthropologists due to the increase in cases of mass disasters, crimes, homicides and other causes of fatal catastrophes (29,30).
The reports of previous studies done by researchers on digit ratio suggest that the digit ratio of a male is lower compared to a female, even of the same ethnic and racial population (6-11). This is in agreement with the result of the present study, Tables 1-2 revealed that the digit ratios of Ikwerre and Ogoni male subjects were lower compared to females of both ethnic groups. This observation has been maintained across various Nigerian ethnic groups, as well as other racial populations (11,23-25,31,32). The study conducted by Nayak et al. (1) showed that the mean right 2D:4D ratio was higher compared to the mean left 2D:4D ratio in their male subjects. This was in contrast to the results of the present study. However, the results in their female category are in agreement with those of the present study, which showed the mean right 2D:4D ratio was significantly lower than the mean left 2D:4D ratio.
As shown in Table 1, the digit ratios of both right and left hands for the male and female Ikwerre groups were 0.95±0.04 and 0.96±0.05, and 0.97±0.08 and 0.98±0.05, respectively. Similarly, Table 2 shows the digit ratios of both right and left hands for the male and female Ogoni groups, which were 0.95±0.05 and 0.96±0.05, and 0.97±0.05 and 0.97±0.05, respectively. In previous studies on Nigerian subjects, morphometric variations in digit ratios have been recorded across different ethnic groups. The Igbo males were reported to have a mean value of 0.96 ± 0.02, while the females had a mean of 1.0 ± 0.06; the Urhobos: Males = 0.96 ± 0.02, Females = 1.0 ± 0.02 (23). As for the Ikwerres in a previous study done by Gwunireama and Ihemelandu (24), their males had mean right and left 2D:4D values of 0.96 ± 0.003 and 0.96± 0.002, respectively, while the females had a right and left mean 2D:4D value of 1.0 ± 0.001 and 1.0 ± 0.005, respectively. The male category of the Andoni ethnic group had a right and left 2D:4D of 0.95± 0.002 and 0.95 ± 0.002, while the females had 0.96± 0.002 (Right hand) and 0.96 ± 0.002 (Left hand), respectively. In all reports, in addition to the present study, it is observed that females have a higher digit ratio (2D:4D) than males. The sexual dimorphism on the digit ratio in the subjects of this study summarized in Tables 3-8 was statistically significant (P-value <0.05). The same observations were made in a study by Gwuanireama et al. (11) on the digit ratio of the Andoni (Obolo) group of Ijaw ethnic nationality. The consistency in this observation buttresses the point suggested by Manning (6) that differences in the digit ratios are caused by variability in hormonal secretions between males and females. The testosterone secretion levels in male subjects had a negative relationship with their 2D:4D values, in contrast to that of estrogen secretion levels, having a slightly positive relationship with 2D:4D values in their female subjects. A window for exposure to androgens, especially testosterone, during pregnancy can be found in the sexually dimorphic digit ratio (6,33).
This study showed that there were no significant ethnic differences in digit ratios (2D:4D) between the Ikwerre and Ogoni males. However, in the female category, the left 2D:4D showed significant ethnic differences between Ikwerre and Ogoni subjects; there were no significant differences in the right. In a related study done by Gwunireama and Ihemelandu (24) on Ikwerre and Andoni ethnic subjects in a southern Nigerian population, significant ethnic differences were observed in the same geographic area attributd to the digit ratio, which was discovered to be an inherited trait from the ancestral origins. However, the present study agrees with Manning et al. (34), who stated that location has an impact on 2D:4D.
In the present study, the hand patterns were categorized into three types: Type A (2D < 4D), Type B (2D = 4D), and Type C (2D > 4D). The results of this study showed that hand pattern Type A (2D < 4D) was the most prevalent in all sexes in both ethnic groups at the right hands and left hands. The next prevalent hand pattern was Type C (2D > 4D) in all genderes in both ethnic groups at the right hand and left hand. The least prevalent hand pattern was Type B (2D = 4D) in both genders across the ethnic groups, at the right hand and left hand. Nayak et al. (1) analyzed the hand patterns in selected ethnic groups in Malaysia. They noted that Type A was more prevalent compared to others, which is in strong agreement with the results of the present study. Furthermore, a study reported by Al-Qattan et al. (35) on variations in hand patterns among Saudi medical students noted that hand pattern Type A was significantly higher in males and Type C was significantly higher in females. The observation in the male category was in agreement with the present study. However, the female observation does not agree with the present study; this may be a result of the racial differences (35).
Conclusion
The findings of this study show that the 2D:4D ratios of the male and female members of the Ogoni and Ikwerre ethnic groups differ significantly. Females tend to have a higher value in this ratio. However, no significant differences in the digit ratio (2D:4D) were observed between the Ikwerre and Ogoni males and females. Hand pattern A was the most common in both ethnic groups for both genders, followed by pattern C, while pattern B was the least observed. There were no significant differences in hand patterns between the two ethnic groups, suggesting a close ancestral relationship. The findings of this study can be used as a foundation for exploring potential correlations with various physiological, psychological, and behavioral traits among the Ikwerre and Ogoni ethnic groups in Nigeria. Additionally, a solid understanding of digit ratios and hand patterns can serve as a useful tool in identifying gender differences for forensic investigations.
Acknowledgement
The authors sincerely appreciate all those who volunteered as participants in this research.
Funding sources
The writers declare that no organization ever provided them with any form of financial support.
Ethical statement
This study was approved by the Research Ethics Committee of the University of Port Harcourt (UPH/CEREMAD/REC/MM71/008).
Conflicts of interest
The authors declare no conflict of interest.
Author contributions
They all contributed to various components of the study, including research design, data collection and analysis, initial and final manuscript drafting. All authors read and approved the final manuscript.
Data availability statement
The datasets used or analyzed during the current study are available from the corresponding author on reasonable request.
Editorial: Original article |
Subject:
Basic Medical Sciences
Received: 2024/02/3 | Accepted: 2025/05/13 | Published: 2025/05/21
Received: 2024/02/3 | Accepted: 2025/05/13 | Published: 2025/05/21
References
1. Nayak SB, Nair D, Ravi V, Aithal AP. A comparative study on digit ratio and hand patterns of three ethnic races of Malaysia. Egypt J Forensic Sci. 2018;8:56. [View at Publisher] [DOI] [Google Scholar]
2. Hager-Ross C, Schieber MH. Quantifying the Independence of Human Finger Movements: Comparisons of Digits, Hands, and Movement Frequencies. J Neurosci. 2000;20(22):8542-50. [View at Publisher] [DOI] [PMID] [Google Scholar]
3. Mcardle BH, Anderson MJ. Fitting multivariate models to community data: a comment on distance-based redundancy analysis. Ecology. 2001;82(1):290-7. [View at Publisher] [DOI] [Google Scholar]
4. Alperovitch-Najenson D, Carmeli E, Coleman R, Ring H. Handgrip strength as a diagnostic tool in work-related upper extremity musculoskeletal disorders in women. ScientificWorldJournal. 2004:4:111-7 [View at Publisher] [DOI] [PMID] [Google Scholar]
5. Stein AD, Kahn HS, Lumey LH. The 2D:4D digit ratio is not a useful marker for prenatal famine exposure: Evidence from the Dutch hunger winter families study. Am J Hum Biol. 2010;22(6):801-6. [View at Publisher] [DOI] [PMID] [Google Scholar]
6. Manning JT. The ratio of 2nd to 4th Digit length and performance in skiing. J Sports Med Phy Fitness. 2002;42(4):446-50. [View at Publisher] [PMID] [Google Scholar]
7. Phelps VR. Relative Index Finger Length as a sex Influenced Trait in Man. Am J Hum Genet. 1952;4(2):72-89. [View at Publisher] [PMID] [Google Scholar]
8. Manning JT, Scutt D, Wilson J, Lewis-Jones DI. The Ratio of 2nd to 4th Digit Length: A Predictor of Sperm Number and Concentrations Testosterone, Luteinizing hormone and Oestrogen. Hum Reprod. 1998;13(11):300-2004. [View at Publisher] [DOI] [PMID] [Google Scholar]
9. Lutchmaya S, Baron-Cohen S, Raggatt P, Knickmeyer R, Manning JT. 2nd to 4th digit ratios, fetal testosterone, and estradiol. Early Hum Dev. 2004;77(1-2):23−8. [View at Publisher] [DOI] [PMID] [Google Scholar]
10. Manning JT. The Finger book: Sex, behavior, and disease revealed in the fingers. London: Faber & Faber. 2008. [View at Publisher] [Google Scholar]
11. Gwunireama IU, Osunwoke EA, Orish CN. Anthropometrical study of the second-and fourth-digit ratio of Andoni (Obolo) Groups of Ijaw Ethnic Nationality in Nigeria. J Appl Biosci. 2010;27:1732-5. [View at Publisher] [Google Scholar]
12. Viveka S, Sudha MJ, Udyavar A, Bidarkotimath S. Digit ratio and Down syndrome correlation with perinatal androgen levels. International Journal of Comprehensive Medical Physiology and Research. 2014;1(1):25-33. [View at Publisher] [Google Scholar]
13. Ventura T, Gomes MC, Pita A, Neto MT, Taylor A. Digit ratio (2D:4D) in newborns: Influences of prenatal testosterone and maternal environment. Early Hum Dev. 2013;89(2):107-12. [View at Publisher] [DOI] [PMID] [Google Scholar]
14. Trivers R, Manning J, Jacobson A. A longitudinal study of digit ratio (2D:4D) and other finger ratios in Jamaican children. Horm Behav. 2006;49(2):150-6. [View at Publisher] [DOI] [PMID] [Google Scholar]
15. Kanchan T, Pradeep Kumar G, Menezes RG. Index and ring finger ratio new sex determinant in south Indian population.Forensic Sci Int. 2008;181(1-3):53.e1-53.e4. [View at Publisher] [DOI] [PMID] [Google Scholar]
16. Butovskaya M, Burkova V, Apalkova Y, Dronova D, Rostovtseva V, Karelin D, et al. Sex, population origin, age and average digit length as predictors of digit ratio in three large world populations. Sci Rep. 2021;11(1):8157 [View at Publisher] [DOI] [PMID] [Google Scholar]
17. Luxen MF, Buunk BP. Second to fourth digit ratio related to Verbal and Numerical Intelligence and the Big Five. Personality and Individual Differences. 2005; 39(5):959-66. [View at Publisher] [DOI] [Google Scholar]
18. Manning JT, Baron-Cohen S, Wheelwright S, Sanders G. The 2nd to 4th digit ratio and autism. Dev Med Child Neurol. 2001;43(3):160-4. [View at Publisher] [DOI] [PMID] [Google Scholar]
19. Allison AA, Hurd PL. The finger length ratio (2D:4D) correlates with physical aggression in men but not in women. Biol Psychol. 2005;68(3):215-22. [View at Publisher] [DOI] [PMID] [Google Scholar]
20. Manning JT, Taylor RP. Second to fourth digit ratio and male ability in sport: implications for sexual selection in humans. Evol Hum Behav. 2001;22(1):61-9. [View at Publisher] [DOI] [PMID] [Google Scholar]
21. Sluming VA, Manning JT. Second to fourth digit ratio in Elite Musicians: evidence for musical ability as an honest signal of male fitness. Evol Hum Behav. 2000;21(1):1-9. [View at Publisher] [DOI] [Google Scholar]
22. Brown WM, Hines M, Fore BA, Breed-love SM. Masculinized finger length patterns in human males and females with congenital adrenal hyperplasia. Horm Behav. 2002;42(4):380-6. [View at Publisher] [DOI] [PMID] [Google Scholar]
23. Gabriel S.O, Fawehinmi HB, Ezon-Ebidor E, Osunwoke EA, Ordu KS. Second to fourth digit ratio in Nigerian Igbos and Yorubas. Scientific Research and Essay. 2009;4(10):1146-8. [View at Publisher] [Google Scholar]
24. Gwunireama IU, Ihemelandu EC. Geographical Influence on Digit Ratio (2D:4D): A case study of Andoni and Ikwerre Ethnic Groups in Niger Delta. J.Appl. Biosci. 2010;27:1736-41. [View at Publisher] [Google Scholar]
25. Paul JN, Obiandu C, Ogbilikana PS, Akinola DA. Analytical Study of Ancestral Relationship between Ikwerre, Bini, and Igbo Ethnic Groups Using Digit Ratio (2d:4d). East African Scholars J Med Sci. 2020;3(1):16-20. [View at Publisher] [DOI]
26. Danborno B, Adebisi1 SS, Adelaiye AB, Ojo SA. Relationship between Digit Ratio (2D:4D) and Birth Weight in Nigerians. Anthropologist. 2010;12(2):127-30. [View at Publisher] [DOI] [Google Scholar]
27. Oyeyemi BF, Iyiola OA, Oyeyemi AW, Oricha KA, Anifowoshe AT, Alamukii NA. Sexual dimorphism in ratio of second and fourth digits and its relationship with metabolic syndrome indices and cardiovascular risk factors. J Res Med Sci. 2014;19(3):234-9. [View at Publisher] [PMID] [Google Scholar]
28. Gwunireama IU, Ukoba O, Ogoun TR. Anthropometric Study of the Length of Digits in the Left and Right Hands of the String Players in Port Harcourt. Saudi J Biomed Res. 2021;6(12):307-10. [View at Publisher]
29. Kanchan T, Krishan K, Sharma A, Menezes RG. A study of correlation of hand and foot dimensions for personal identification in mass disasters. Forensic Sci Int. 2010;199(1-3):112.e1-6. [View at Publisher] [DOI] [PMID] [Google Scholar]
30. Matheswaran G, Vallabhajosyula R. Digit length displays a significant fraction in stature estimation: a study from the coastal region of south India. Int J Anat Res. 2014;2(2):336-39. [View at Publisher] [Google Scholar]
31. Xu Y, Zheng Y. The Relationship Between Digit Ratio (2D:4D) and Sexual Orientation in Men from China. Arch Sex Behav. 2016;45(3):735-41. [View at Publisher] [DOI] [PMID] [Google Scholar]
32. Setiya M, Jehan M, Godwin R, Sastya A. Sexual Dimorphism of Digit Ratio (2D:4D) in Madhya Pradesh. Int J Sci Stud. 2017;4(10):155-9. [View at Publisher] [DOI] [Google Scholar]
33. Jeevanandam S, Muthu PK. 2D:4D Ratio and its Implications in Medicine. J Clin Diagn Res. 2016;10(12):CM01-CM03. [View at Publisher] [DOI] [PMID] [Google Scholar]
34. Manning JT, Bundred PE, Newton DT, Flanigan BF. The Second to Fourth Digit Ratio and Variation in the Androgen Receptor Gene. Evol Hum Behav. 2003;24(6):399-403. [View at Publisher] [DOI] [Google Scholar]
35. Al-Qattan NM, Al-Kharashi SK, Al-Hindi GK, Dammas NM, Kattan AE, Al-Qattan MM. Hand pattern based on second-to-fourth digit ratio: its sex relationship, body mass index, and physical activity. Plast Reconstr Surg Glob Open. 2019;7(5):e2144. [View at Publisher] [DOI] [PMID] [Google Scholar]
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