Scholars Academic Journal of Biosciences Gender Variation in Digit Ratio of the Igbo Ethnic Group in Eastern Nigeria

Abstract

Original Research Article Background: This study was aimed at investigating gender variation in digit ratios of the Igbo ethnic group. The study was an analytical cross-sectional design with volunteers age ranging from 18-60 years. For the purpose of this study, an individual was considered to be a Nigeria of a particular ethnic group if the parents and four grandparents are of the same ethnic group. Materials and Methods: Cluster sampling method was used for the study. The selection and collection of required parameters relied on informed consent of volunteers. This was done by giving them a copy of the informed consent letter which was signed and dated. A total of 460 subjects (230 males, 230 females) subjects were recruited for the study. The fingerprints were obtained using print scanner (Hp G3110 Photo scanner). Results and Discussion: Descriptive statistics of digit lengths and ratios of Igbo ethnic group. In the males the following Mean±SD were seen: Males Left L2D (cm) 7.05±0.72, Right L2D(cm), 7.07±0.69, Left L4D(cm) 8.14±1.23, Right L4D(cm) 8.10±1.27, In females: Left L2D (cm) 7.50±1.01, Right L2D(cm) 7.48±0.99, Left L4D(cm) 8.20±1.06, Right L4D(cm) 8.21±1.21. The males on the left had the Digit Ratio 0.87±0.04, while on the Right Digit Ratio was 0.87±0.02; In the females, the Left Digit Ratio was 0.91±0.03, Right Digit Ratio 0.91±0.04. In the total population, the Left Digit Ratio was 0.88±0.02 while the Right Digit Ratio was 0.87±0.04. Sexual dimorphism was seen in the mean lengths of the digits with the females having higher values than the men. It suggests that there could be hormonal contribution in the formation of the digit lengths. These implies that averagely, females have longer digit than men which could be used in forensic investigation where the sex of victim or assailant is unknown. Conclusion: The longer digits in women is thought to be a typical feminine feature. The result of the study depicted sexual dimorphism again in the digit ratios with the females having higher digit ratios than the males. This dimorphism results from the difference in androgen level between both genders. The more exposure to testosterone, the lower the digit ratio. This further strengthens what has been reported in the digit lengths.

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John N. Paul et al., Sch Acad J Biosci, Nov, 2019; 7(11): 412-415
© 2019 Scholars Academic Journal of Biosciences | Published by SAS Publishers, India
412
Scholars Academic Journal of Biosciences
Abbreviated Key Title: Sch Acad J Biosci
ISSN 2347-9515 (Print) | ISSN 2321-6883 (Online)
Journal homepage: http://saspublisher.com/sajb/
Gender Variation in Digit Ratio of the Igbo Ethnic Group in Eastern
Nigeria
John N. Paul1, Thank God C. Omuruka1, Deborah A. Akinola1, Tarimobo M. Otobo2*
1Department of Anatomy, Faculty of Basic Medical Sciences, College of Health Sciences, University of Port Harcourt, Nigeria
2Department of Anatomy, Faculty of Basic Medical Sciences, College of Health Sciences, Niger Delta University, Wilberforce Island, Bayelsa State,
Nigeria
DOI: 10.36347/SAJB.2019.v07i11.005 | Received: 07.11.2019 | Accepted: 17.11.2019 | Published: 28.11.2019
*Corresponding author: Tarimobo M. Otobo
Abstract
Original Research Article
Background: This study was aimed at investigating gender variation in digit ratios of the Igbo ethnic group. The study
was an analytical cross-sectional design with volunteers age ranging from 18-60 years. For the purpose of this study, an
individual was considered to be a Nigeria of a particular ethnic group if the parents and four grandparents are of the same
ethnic group. Materials and Methods: Cluster sampling method was used for the study. The selection and collection of
required parameters relied on informed consent of volunteers. This was done by giving them a copy of the informed
consent letter which was signed and dated. A total of 460 subjects (230 males, 230 females) subjects were recruited for
the study. The fingerprints were obtained using print scanner (Hp G3110 Photo scanner). Results and Discussion:
Descriptive statistics of digit lengths and ratios of Igbo ethnic group. In the males the following Mean±SD were seen:
Males Left L2D (cm) 7.05±0.72, Right L2D(cm), 7.07±0.69, Left L4D(cm) 8.14±1.23, Right L4D(cm) 8.10±1.27, In
females: Left L2D (cm) 7.50±1.01, Right L2D(cm) 7.48±0.99, Left L4D(cm) 8.20±1.06, Right L4D(cm) 8.21±1.21. The
males on the left had the Digit Ratio 0.87±0.04, while on the Right Digit Ratio was 0.87±0.02; In the females, the Left
Digit Ratio was 0.91±0.03, Right Digit Ratio 0.91±0.04. In the total population, the Left Digit Ratio was 0.88±0.02
while the Right Digit Ratio was 0.87±0.04. Sexual dimorphism was seen in the mean lengths of the digits with the
females having higher values than the men. It suggests that there could be hormonal contribution in the formation of the
digit lengths. These implies that averagely, females have longer digit than men which could be used in forensic
investigation where the sex of victim or assailant is unknown. Conclusion: The longer digits in women is thought to be
a typical feminine feature. The result of the study depicted sexual dimorphism again in the digit ratios with the females
having higher digit ratios than the males. This dimorphism results from the difference in androgen level between both
genders. The more exposure to testosterone, the lower the digit ratio. This further strengthens what has been reported in
the digit lengths.
Keywords: Gender, Digit ratio, Igbo, Eastern, Nigeria.
Copyright @ 2019: This is an open-access article distributed under the terms of the Creative Commons Attribution license which permits unrestricted
use, distribution, and reproduction in any medium for non-commercial use (NonCommercial, or CC-BY-NC) provided the original author and source are
credited
INTRODUCTION
Digit ratio is defined as the ratio of the second
digit length (2D) to the fourth digit length (4D) of the
hand [1].
Digit Ratio= 
= 

Digit ratio as a subject matter have been widely
explored by different researchers in indigenous and
foreign populations with very remarkable findings. Digit
ratio has also been used to investigate interpopulation
affinity stating tribal or population similarity [2].
It has been speculated that sexual differences in
2D:4D are mainly caused by the shift along the common
allometric line with non-zero intercept, which means
2D:4D necessarily decreases with increasing finger
length, and the fact that men have longer fingers than
women (which may be the basis for the sex difference in
digit ratios and/or any putative hormonal influence on
the ratios [3-5].
This gender has not been investigated in the
Igbo tribe yet as such the study was carried out to know
whether this characteristic is present in the Igbo
extraction. This study will add to the body of knowledge
Anatomy

John N. Paul et al., Sch Acad J Biosci, Nov, 2019; 7(11): 412-415
© 2019 Scholars Academic Journal of Biosciences | Published by SAS Publishers, India
413
information on the population characteristics of
indigenous population especially in Sub-Saharan Africa.
The Igbo people, historically spelt Ibo, are an
ethnic group of south eastern Nigeria. They speak Igbo,
which includes various Igbo languages and dialect. Igbo
people are one of the largest ethnic groups in Africa. In
rural Nigeria, Igbo people are mostly craftsmen, farmers
and traders. They are found majorly in the five eastern
states (Abia, Imo, Enugu, Anambara and Ebonyi), but
have some minor settlements in some other states like
Rivers, Delta, Kogi and Edo states. They have been
estimated to have a population of 22,000,000 million [6,
7].
There are some reports on investigations by
other researchers on digit ratios in various indigenous
populations [8-19].
There is paucity of information on digit ratio in
Igbo tribe under investigation.
Aim and Objective: This study was aimed at gender
variation in digit ratio of the Igbo ethnic group.
Scope of the Study: This study was done specifically on
the second- and fourth-digit lengths.
Significance of the Study: This study will benefit the
body of knowledge on population studies of ethnic
groups in Nigeria which will be significant to historians,
sociologists, anthropologists, the Igbo people
specifically.
METHODS
Research Design
The study was descriptive and cross-sectional.
For the purpose of this study, an individual was
considered to be a Nigeria of a particular ethnic group if
the parents and four grandparents are of the same ethnic
group. Volunteers with age ranging from 18-60 years
from the Igbo extractions were recruited for this study by
random sampling. The study was conducted from March
6 - October 20, 2019.
Data Collection
The lengths of the second and fourth digits of
the left and right hands were measured on the ventral
(inferior) surface of the hand from the basal crease of the
2nd and 4th digits to the tip of the finger of the subjects.
In situations where there was a band of creases at the
base of the digit, the most proximal crease was used. All
measurements were done with a digital vernier caliper
having an accuracy of ±0.2mm [1-3]. The measurements
were done three times and the average value was
recorded. The lengths of the second digits were divided
by the lengths of the fourth digits to obtain the digit
ratios [1-3].
Fig-1: Digit ratio measurement from the study
Data Analysis: Data obtained were inputted into
Microsoft excel 2010 for data analysis using independent
t test to determine the mean values in the males and
females.
Criteria for Subject Selection: Volunteers recruited
were indigenes of the ethnic groups under investigation
with no form of anatomical abnormality of the hands.
Ethical Consideration
Ethical clearance was obtained from the
Research Ethics Committee of the University of Port
Harcourt with REC Number:
UPH/CEREMAD/REC/MM59/036 before
commencement of the study.
RESULTS
In Table-1, descriptive statistics of digit lengths
and ratios of Igbo ethnic group. In the males the
following Mean±SD were seen: Males Left L2D (cm)
7.05±0.72, Right L2D(cm), 7.07±0.69, Left L4D(cm)
8.14±1.23, Right L4D(cm) 8.10±1.27, In females: Left
L2D (cm) 7.50±1.01, Right L2D(cm) 7.48±0.99, Left
L4D(cm) 8.20±1.06, Right L4D(cm) 8.21±1.21.
In Table-2, the males, the Left Digit Ratio was
0.87±0.04, Right Digit Ratio was 0.87±0.02; In the
females, the Left Digit Ratio was 0.91±0.03, Right Digit
Ratio 0.91±0.04. In the total population, the Left Digit
Ratio was 0.88±0.02 while the Right Digit Ratio was
0.87±0.04.

John N. Paul et al., Sch Acad J Biosci, Nov, 2019; 7(11): 412-415
© 2019 Scholars Academic Journal of Biosciences | Published by SAS Publishers, India
414
Table-1: Descriptive statistics of digit lengths of Igbo ethnic group
IGBO ETHNIC GROUP
Parameters
Male [N = 230]
Female [N =230]
Total [N = 460]
Mean±SD
Mean±SD
Mean±SD
Left L2D (cm)
7.05±0.72
7.50±1.01
7.20±1.01
Right L2D(cm)
7.07±0.69
7.48±0.99
7.22±0.99
left L4D(cm)
8.14±1.23
8.20±1.06
8.18±0.89
Right L4D(cm)
8.10±1.27
8.21±1.21
8.21±0.90
L2D (cm) < L4D (cm), Females > Males
Table-2: Descriptive statistics of digit ratios of Igbo ethnic group
IGBO ETHNIC GROUP
Parameters
Male [N = 230]
Female [N =230]
Total [N = 460]
Mean±SD
Mean±SD
Mean±SD
Left Digit Ratio
0.87±0.04
0.91±0.03
0.88±0.02
Right Digit Ratio
0.87±0.02
0.91±0.04
0.87±0.04
L2D (cm) < L4D (cm), Females > Males
DISCUSSIONS
Sexual dimorphism was seen in the mean
lengths of the digits with the females having higher
values than the men. It suggests that there could be
hormonal contribution in the formation of the digit
lengths. These implies that averagely, females have
longer digit than men which could be used in forensic
investigation where the sex of victim or assailant is
unknown. The longer digits in women is thought to be a
typical feminine feature.
The result of the study depicted sexual
dimorphism again in the digit ratios with the females
having higher digit ratios than the males. This
dimorphism results from the difference in androgen level
between both genders. The more exposure to
testosterone, the lower the digit ratio. This further
strengthens what has been reported in the digit lengths.
The result of this present study agrees strongly with the
reports of previous investigators who have expressly
stated that there is sexual dimorphism in the digit ratios
[8-13]. In this study, it was found that the males
repeatedly had low digit ratios compared to the females.
This low digit ratio seen in men is considered a positive
trait as several other authors who have worked on this
subject reported that low digit ratios are typical
masculine traits. Alonso et al., [14] reported that low
digit ratio correlates with high social preference;
Aycinena et al., [15] in his study asserted that women
with low digit ratio tend to be more patient; motioned
that a low digit ratio positively correlates with static and
explosive strength, speed and agility which is a typical
masculine trait exemplified in digit ratio. Furthermore, it
was also mentioned that a study on sports activities
showed that those who got to the highest level of
competition in their respective games had low digit
ratios [16] which were mostly men. Another report had it
that women were more attracted to men with lower digit
ratios as compared to those with high digit ratio.
Recalling the rule of magnetism in physics that says
‘opposites attract’, it is not preposterous to say that
women were attracted to those men because men with
low digit ratios have typical and attractive masculine
features that is considered an ideal male feature. This
may also imply that women who have low digit ratios,
may possibly have more masculine features with high
testosterone level if investigated than the normal women
with high digit ratio. Just recently, in April 2018, a
female South African athlete by name Caster Semenya,
who was reported to have a higher than normal
testosterone level had serious issues with participating in
the games because of a new rule by the International
Association of Athletics Federations, that stipulates that
athletes should lower and maintain their testosterone
levels to no more than 5 nanomoles per liter of blood, the
IAAF said that’s half the amount previously allowed
[17]. They maintained that athlete who refuses to adhere
strictly to this rule should in the alternative compete with
men in sports instead of females.
Here, the knowledge of digit ratio can be
employed to screen athletes who have lower digit ratios
and exclude them from the games, till it has been proven
that they have stabilized their testosterone level
according to the IAAF standard. Finally, Warrington et
al., [18] said that it is possible that there is genetic
contribution to the formation of digit ratios. All these
reports from the previous authors affirm the results got
from this present study which showed that males had
lower digit ratios than the females.
CONCLUSION
The longer digits and higher digit ratios in
women are thought to be typical feminine features as
such could be used as a marker for gender differentiation
in a forensic investigation.

John N. Paul et al., Sch Acad J Biosci, Nov, 2019; 7(11): 412-415
© 2019 Scholars Academic Journal of Biosciences | Published by SAS Publishers, India
415
ACKNOWLEDGEMENTS
We want to appreciate the entire management
and staff of the Department of Anatomy, University of
Port Harcourt.
Conflict of Interest: We write to state that there is no
conflict of interest.
Source of Funding: Self-funding.
AUTHOR’S CONTRIBUTION
We write to state that all authors have
contributed significantly, and that all authors are in
agreement with the contents of the manuscript. ‘Authors
A’ (John Nwolim Paul) designed the study and protocol,
wrote the first draft of the manuscript; ‘Authors B’
(ThankGod C. Omuruka and Deborah A. Akinola)
‘reviewed the design, protocol; ‘Author C’ (Tarimobo
M. Otobo) examined the intellectual content of the
manuscript. All authors read and approved the final
manuscript.
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