Abstract: Anthropometry is a series of systemized measuring techniques that express quantitatively the dimensions of the human body and skeleton. Anthropometry is the study of the science of measurement basic to physical anthropology. It is often viewed as a traditional and perhaps the basic tool of biological anthropology. Satisfactory characterization has been established for some racial groups and especially for Caucasian and Negroes where a number of measurements are treated by discriminant analysis, an accuracy of over 90% expected. The aims of this research are to establish cephalometric indices of Hausa and the Yoruba ethnic groups of Nigeria and to compare these indices among the two ethnic groups. Eight indices were calculated, compared and discussed based on proposal by Bass. These indices are cephalic, nasal upper facial, cephalic modules, cephalic Length-Height (L-HI), cephalic Breadth-Height (B-HI), Mean Height (M-HI) and Mean Basion Height (M-BHI) indices. Hausa and Yoruba have mesocephalic heads. Hausa have the highest value for cephalic length height index, cephalic breadth height index, mean height index and mean basion height than the Yoruba All show the high skull characteristics of Negroes skull.

INTRODUCTION

Anthropometry is a series of systemized measuring techniques that express quantitatively the dimensions of the human body and skeleton. Anthropometry is the study of the science of measurement basic to physical anthropology. It is often viewed as a traditional and perhaps the basic tool of biological anthropology. It started as not only a science that utilizes measurable parameters to define physical characteristics of different tribes but it 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. All human beings in this world belong to the same species, Homo sapiens. No two individuals are the same in all their measurable traits, even genetically identical twins, differ in some respects. Since a number of factors producing differences in skeletal proportions between different geographical areas influences skeletal development, it is desirable to have some means of giving quantitative expression to variations which such traits exhibit. Anthropometry constitutes that means as it is the technique of expressing quantitatively the form of the human body. In other words, anthropometry means the measurement of human beings, whether living or dead or on skeletal material. Anthropometric data are believed to be objective and they allow the forensic examiner to go beyond subjective assessments such as similar or different. With measurement data, the examiner is able to quantify the degree of difference or similarity and state how much confidence can be placed in this interpretation (Adams and Bryd, 2002). Satisfactory characterization has been established for some racial groups and especially for Caucasian and Negroes where a number of measurements are treated by discriminant analysis, an accuracy of over 90% expected. Variations in the Cl have little utility in distinguishing skulls from different geographic regions and mostly reflect interactions between the width of the cranial base and the volume of the brain (Lieberman et al., 2002). Hence the need to include other indices in the differentiation.

Several major studies have assessed variation in cranial shape among and between populations (Howells, 1973; Lahr, 1996). All the somatometric measurements (including measurements of the head and face) and standard procedures described by Oliver (1969), Weiner and Lourie (1969), Lohman et al. (1988) and Hall et al. (2003) can be used for estimating stature from different body segments. Using a strictly skull based categorization method; anthropologists organized three to four racial groups. Caucasoids were characterized by a doliocephalic shape with rceded zygomas, large browridge and a narrow nasal aperture. Secondly, Negroids were characterized by a mesocephalic head shape, with receded zygomas and wide nasal aperture. Third, Mongoloids were characterized as a brachycephalic head shape, absent browridges, small nasal aperture and projecting zygomas. Additionally, Australoids whose craniofacial type fell between Negroids and Caucasoids was added. With the addition of this category, Thomas Huxley considered India to fall in this group’s craniofacial measurements (Huxly, 2006). As with the genotype, variation in human cranial shape is far greater within than between populations (Relenford, 1994).

Summarizing the studies by (Howells, 1973; Lahr, 1996), there is more variation in Africa than elsewhere with marked differences between Bushmen, Bantu and other groups. On average, African crania are broader, with taller upper faces; more inferiorly positioned nasal regions and more prognathic mandibular and maxillary arches than crania from other parts of the globe.

European skulls tend to be narrow, with concomitantly narrow faces, retracted zygomatic arches, tail nasal regions and prominent midlaces. Europeans and American Indians share many cranial similarities. Asian skulls are typically wide (brachycephalic), with wide faces, a high degree of facial flatness and flat supranasal regions.

Australian aborigines are often characterized by narrow skulls (dolichocephaly) and large, low projecting faces with prominent subnasal regions. Attempts to differentiate crania by region of geographic origin using multivariate methods such as discriminant function analysis can have accuracies of over 90%. The study of this research are:

MATERIALS AND METHODS

The study was carried out in two locations in 2006. Kano, this is state in Nigeria with highest population of the Hausa. Ilorin, this is a capital of Kwara state in Nigeria with a Yoruba as the dominant ethnic group. In both cases each subject must have his or her grandparents all of same ethnic group. The following instruments were used:

The following parameters were measured and recorded:

These measurements were recorded with the subjects sitting in upright Frankfurt horizontal position. The measurements and other parameters were the entered in the form head length (Fig. 1) is the maximum dimension of the sagittal axis of the skull head width (Fig. 2) is the maximum biparietal diameter Bizygomatic distance (Fig. 3) is the maximal distance between the most lateral points of the zygomatic arches (zygion).

Fig. 1:	Measurement of head length

Fig. 2:	Measurement of head width

Fig. 3:	Measurement of bizygomatic distance

Fig. 4:	Measurement of skull height

Fig. 5:	Measurement of upper facial height (Nasal length)

Skull height (Fig. 4) is the distance from the root of the nose (nasion) to the highest point of the head (vertex).

Fig. 6:	Measurement of lower facial height

Fig. 7:	Measurement of facial height (Total) distance

Upper facial height (Fig. 5) this is the distance from the root of the nose (nasion) to the base of the nose (sub nasion), Lower facial height (Fig. 6) this is the length of the lower one third of the craniofacies, Total Facial height (Fig. 7) is the distance from the root of the nose to the lowest median landmark on the lower border of the mandible. Nose width (Fig. 8) is the distance between the alae of the two nostrils.

Head length: It is the maximum dimension of the sagittal axis of the skull.

Land marks: Measure between the glabella and the opithocranuim (the most prominent portion of the occiput, close to the midline on the posteriorim of the foremen magnum.

Instrument: Wide spreading calipers.

Fig. 8:	Measurement of nose width

Head width: This is the maximum biperietal diameter.

Land marks: Measure between the most lateral points of the parietal bones (eurion on each of the head).

Instrument: Wide spreading calipers.

Bizygomatic distance: This is the maximal distance between the most lateral points of the zygomatic arches (zygion).

Land marks: Measure between the most lateral points of the zygomatic arches (zygion) localized by palpation.

Instrument: Wide spreading calipers.

Skull height: This is the distance from the root of the nose (nasion) to the highest point of the head (vertex).

Land marks: Measure from the depth of nasal roots to the superior most point the skull in the vertical plane.

Instrument: Sliding calipers.

Upper facial height (nasal length): This is the distance from the root of the nose (nasion) to the base of the nose (sub nasion).

Land marks: Measure from the deepest part of the nasal root to the deepest point of cavity at the base of the nose (subnasion) in a vertical plane.

Instrument: Sliding calipers.

Lower facial height: This is the length of the lower one third of the craniofacies.

Land marks: Measure from the base of the nose (subnasion) to the lowest median landmarks on the lower border of the mandible (mentron).

Instrument: Spreading calipers.

Remarks: This measurement can also be obtained from the lateral radiograph.

Facial height (total): This is the distance from the root of the nose to the lowest median landmark on the lower border of the mandible.

Instrument: Sliding calipers.

Nose width: This is the distance between the alae of the two nostrils.

Land mark: Measure the distance between the alae of the two nostrils in a straight line.

Instrument: The graduated transparent ruler.

RESULTS AND DISCUSSION

A total of 820 were used. This is made up 410 each for Hausa and Yoruba with age range between 13 years and 30 years. Mean weight 56.6 kg for the Hausa and 56.4 kg for the Yoruba.

Mean height range 169.50 cm for the Hausa cm and 164.84 cm for the Yoruba. Calculation of the various Cephalometric indices is carried out using the following equation.

Cranial (cephalic) Length-Height Index:

Cranial (cephalic) Breath-Height Index:

Mean-Height Index:

Hausa:

Yoruba:

Table 1:	Summary of the calculated indices of both Hausa and Yoruba

Eight indices were calculated, compared and discussed based on proposal by Bass (1995). These indices are cephalic, nasal upper facial, cephalic modules, cephalic Length-Height (L-HI), cephalic Breadth-Height (B-HI), Mean Height (M-HI) and mean basion height (M-BHI) indices Ethnicity is a variable that affects craniofacial dimension. Again specifically variables that affect for instance nose shape include race, tribe, environment and climatic conditions with narrower noses in warm, moist climate (Last, 1981). Cephalic index is an important parameter for deciding the race and sex of an individual whose identity is unknown (Shah and Jadhav, 2004).

In this study the cephalic index for the Yoruba, 79.52% (Table 1) is higher than the Hausa with value of 75.85%. Table 1 which compares favorably with what Taura (2002) obtained in Kano for the Hausa which is 75.40%. Both Hausa and Yoruba therefore have mesocephalic crania. Hausa and Yoruba have mesocephalic crania.

As for nasal index Yoruba have value of 94.26% but Hausa have value of 90.05% (Table 1). The values obtained by Taura (2002) was 68.87% and Umar et al. (2006) obtained 67.14% in Jos. These values for the Hausa are typically leptorrhine which is close to Europeans which have long and narrow nose. The reason for the values in Jos could be climatic wherein it is close to a temperate climatic condition. The upper facial height obtained by tribe showed that the Hausa have the higher value of 64.92% than Yoruba with value of 51.65% (Table 1).

The value for the Hausa obtained in this study lower than what Taura (2002) got for the same Hausa with value of 71.00%. Again the reason is that though the Hausa have the highest upper facial height but they have the lowest bizygomatic distance (Table 2). The Yoruba have the highest bizygomatic distance but about the same upper facial height (Table 3).

We first calculated the following indices amongst Nigerians (Umar et al., 2006). These indices are cephalic module, Cephalic Length-Height Index (CL-HI), Cephalic Breath-Height Index (CB-HI), Mean cephalic Height Index (M-HI) and Mean Basion-Height Index (M-BHI). These indices when calculated give a description of the shape of head and its characteristic features as proposed by Bass (1995).

Cephalic module indicates the numerical value for the size of the cranial vault Cephalic Length-Height Index (CL-HI), Cephalic breath-Height Index ( CB-HI), Mean Cephalic Height Index(M-HI) and Mean basion-Height Index (M-BHI) are interpreted as either low, average or high skull.

In this study the cephalic module obtained for all the two tribes showed a high skull with the Yoruba having a higher value than the Hausa with values 154.99 and 150.47, respectively (Table 1). This compares favorably with what Umar et al. (2006) obtained, 151.47 for general population of Nigerians. This is because for the Yoruba, the values of all the three parameters in the calculation of cephalic module are highest as compared with the Hausa (Table 2 and 3).

For cephalic length height index the Hausa have higher value than the value obtained for Yoruba. These values are 95.80 and 86.27%, respectively (Table 1). The reason is that the Hausa have highest total facial height than the Yoruba (Table 2). However, the Yoruba with the lower cephalic length height index has the highest maximum head length (Table 3).

Regarding cephalic breath height index the Hausa have higher value of 117.08% than the Yoruba with value 115.47% (Table 1). The reason was that the Hausa has the higher value of total facial height (Table 2). Calculation of mean height index showed that the Hausa have higher value as compared with Yoruba values 60.60 and 58.07%, respectively (Table 1).

This is because the Hausa have the highest total facial height as compared with the other two tribes (Table 2). The same explanation for mean height index also applies for mean basion height.

With these results obtained for various tribes in respect to the indices calculated, (cephalic module, Cephalic Length-Height Index (CL-HI), Cephalic Breath-Height Index (CB-HI), Mean Cephalic Height Index (M-HI) and Mean Basion-Height Index (M-BHI). All show the high skull characteristics of Negroes skull, Bass (1995). Except for mean height index, this showed a medium value for the two tribes. When these eight indices were subjected to t-test, it was found out that there is no statistical difference, p<0.05 (Table 4).

Table 2:	Cephalometric variables used in calculating the indices-Hausa ethnic group

Table 3:	Cephalometric variables used in calculating the indices-Yoruba ethnic group

Table 4:	The t-test for Hausa and Igbo

CONCLUSION

It is therefore, concluded that these two Nigerian tribes belong to the Negroids skull Bass (1995). Future studies on discriminant function could be carried out as the two conditions necessary (normal distribution and no significant difference in the variances of the two tribes) are fulfilled.