G Oladipo, A Udoaka, E Afolabi, I Bob-Manuel
itsekiri and urhobo ethnic groups, nasal indices, platyrrhine
G Oladipo, A Udoaka, E Afolabi, I Bob-Manuel. Nasal Parameters Of Itsekiris And Urhobos Of Nigeria. The Internet Journal of Biological Anthropology. 2008 Volume 3 Number 1.
Variation is one of the most important phenomena occurring in humans, and is attributed to many factors such as mutation and natural selection. Many studies have emphasized the importance of anthropometric measurements as a means of studying variation in human populations as well as a veritable tool in forensic science for crime detection. This study investigates the nasal breadth, nasal length and nasal indices of individuals of Itsekiri and Urhobo ethnic extraction, as a baseline study which may be necessary for future reference in these regard. Nasal length and nasal breadth of 1000 living Itsekiri and Urhobo people, aged 25-45 years, were measured. From these data, nasal indices were calculated and results were compared with published standards for various world populations. The results showed that on the average, the Urhobos had a mean nasal index of 89.63 and the Itsekiri’s had a mean nasal index of 90.74. Sexual dimorphism was also observed in the ethnic groups studied with males having significantly higher nasal index values than the females (p < 0.05). Therefore, the two ethnic groups fall within the same nose type which is platyrrhine (short and broad nosed) expected of an African population. The findings of this study have confirmed anthropological differences amongst the two Nigerian ethnic groups examined.
The nose is the most prominent 3-dimensional structure located on the central area of the face. It is also the first part of the air channel to the lungs.1 Its shape including the nasal bridge, slope of the tip, the septum and nares differ from race to race, tribe to tribe and from one environmental region of the world to the other.23 The Urhobo and Itsekiri ethnic groups both inhabit Delta state, in the extreme Southern part of Nigeria. They both live in the westernmost part of the Niger Delta. This paper attempts to study the variations in nasal indices of these ethnic groups as a baseline study.
Anthropometry is a series of systematized measuring techniques that express quantitatively the dimensions of the human body and skeleton. Anthropometry, often viewed as a traditional and perhaps the basic tool of biological anthropology, has a long tradition of use in forensic sciences and it is finding increased use in medical sciences especially in the discipline of forensic medicine. It is highly objective and reliable in the hands of trained anthropometrist4. An anthropometric Index is a ratio between one related human measurement and another. Nasal index is a ratio of the greatest width of the nasal aperture to the height of the nasal skeleton multiplied by 100.5 The nasal index measurement is the most common nasal measurements which may be related to regional and climatic differences67 with variation in the nasal index supporting prior studies of selection of longer, narrower noses in cold and dry climates and broader noses in warmer, moister ones8. It exhibits sexual differences9 (Oladipo et al, 2006). A study on the Nasal Height (NH) for adult Igbo males was found to be 4.87 cm ± 0.84cm and 4.40 cm ± 0.76 for Adult Igbo Females10.
Besides, recent studies in India1112 and South Africa13 have used cephalo-facial measurements to determine stature.
Only a limited reference material for nasal measurements of African ethnic groups exists. Therefore the present study provides reference data for the Urhobo and Itsekiri ethnic groups of Nigeria, which could be of relevance in clinical practice, forensics, anthropological studies, treatment planning and other commercial applications1415.
Materials And Methods
The study population consisted of 1000 subjects (250 Urhobo women, 250 Urhobo men, 250 Itsekiri women, 250 Itsekiri men, with ages ranging from 25-45 years). Participants were of non-mixed direct and grand parentage and they were selected at random from various communities in Delta State, Nigeria. Subjects who had trauma of the nose, prior plastic or reconstructive surgery of the face or cleft lips and other congenital facial malformations were excluded in the study.
The height of the nose (NH) was measured with the help of a sliding caliper with an accuracy of 0.01 from nasion to nasospinale9. The nasal breadth (maximum breadth of the nose) was measured at right angles to the nasal height from ala to ala. All the measurements were taken with the subject sitting in a chair in a relaxed condition with the head in the anatomical position. The facial muscles were relaxed in order not to alter the size of the nose9.
The nasal index was calculated as follows; Nasal Index = (Nasal breadth/Nasal height) × 100.5 The data was subjected to statistical analysis. Errors were avoided to a large extent while measurements were recorded.
Data obtained was analyzed using simplified statistical formula like: mean (×), standard deviation (S.D.), standard error (S.E.), and Z-test. These were aptly represented in tables 1-4.
There are significant differences (p < 0.05) between the mean nasal length of the Urhobo and Itsekiri males, Urhobo and Itsekiri females, Urhobo males and females, and Itsekiri males and females (Table 1).
It is also evident that there were significant differences (p < 0.05) between the mean nasal breadth of the Urhobo and Itsekiri females, Urhobo males and females, and Itsekiri males and females. However there was no significant difference (p > 0.05) between the mean nasal breadth of the Urhobo males and Itsekiri males (Table 2).
Significant differences also were observed in the nasal indices of the Urhobos and Itsekiris except between the Urhobo females and Itsekiri females where the difference was not significant (p >0.05) (Table 3).
A number of studies have indicated racial and ethnic differences in nasal index amongst different populations16. Most western Europeans are leptorrhine, having long and narrow noses with a nasal index of 69.9 or less; the Bantus and Bushmen of Africa as well as indigenous Australians are platyrrhine, having broad noses with nasal index of 85.0 and above614. The Sudroid race has a nasal index similar to indigenous Africans South of the Sahara and Indigenous Australians with a nasal index of 85.0 and above i.e. Platyrrhine, while the German’s nasal index is similar to that of general Western European average of nasal index of 71.0 and below-leptorrhine6. Akpa et al7 showed that the mean nasal length and width of Nigerian Igbo’s were 6.22 and 7.26 respectively.
All authors above agree with racial differences in nasal index. Our results conform with them and especially with that of Risley6 on African population of nasal index of 90-100 (platyrrhine). The result shows that there were significant differences (p<0.05) between the mean nasal breadth of the Urhobo and Itsekiri female, Urhobo males and females and Itsekiri males and females. However, there was no significant difference (P> 0.05) between the nasal breadth of the Urhobo and Itsekiri males.
Also, the result shows that significant differences (P<0.05) were also observed in the mean nasal indices of the Urhobos and Itsekiri except between the Urhobo females and Itsekiri females where the difference was not significant (P>0.05). With the result of this study; it can be said that the Urhobo and Itsekiri ethnic group have the nose type called Platyrrhine (broad nose), but the Itsekiri males have a significantly broader (P<0.05) nose compared to that of the females, and the Urhobo males have a significantly broader (P<0.05) nose compared with that of the females. However no such difference (P>0.05) was found among the Itsekiri females and Urhobo females.
On the basis of anthropometric measurements, it can be concluded that ethnic differences exist in the nasal length, breadth and Index of the Urhobo and Itsekiri ethnic groups. This data is an important anthropometric tool in differentiating these ethnic groups, and also has tremendous relevance in forensic investigations, clinical practice and plastic surgery.