Assessments of Cranial Capacities in a North-Eastern Adult Nigerian Population
Cranial capacity is a measure of the volume of the interior of the cranium which is sometimes used as a rough indicator of the size of the brain and is mostly affected by environmental, geographical, gender, age, nutritional and racial factors. A survey of available literature indicates a lack of study on cranial capacities in adults resident in Maiduguri North Eastern Nigeria, this study was therefore undertaken to determine the Cranial Capacities (CC) of 300 (150 males, 150 females) aged 18-35 years adults resident in Maiduguri Metropolis using a random stratified method. Linear measurements of cranial length, width, height and head circumference were undertaken and their cranial capacities calculated. The Mean (±SD) of cranial capacity was significantly (p<0.0001) higher in males (1424.4±137.9) than in females (1331.3±201.8). Cranial length and height were also found to be significantly higher in males than in females. The results obtained from this study confirms that the cranial volume of males is higher than that of the females and also suggest that the cranial capacity of adult males and females were slightly higher than those of similar studies carried out in some ethnic groups indigenous to the southern part of Nigeria.
Received: September 10, 2010;
Accepted: February 18, 2011;
Published: June 07, 2011
The influence of genetic, physiological and anatomical differences between
males and females had been well documented in various studies (Guyton
and Hall, 2006; Moore and Dalley, 1999; Chandrashekar
et al., 2005) although, some differences are indistinctive, most
are related to body dimensions which are determined by anthropometry (Chamela,
1997; Williams et al., 1995). Craniometric
study is an important fraction of anthropometry that can be employed in the
determination of the cranial capacity of an individual. Cranial capacity like
several bodily dimensions are affected by environmental, ecological, biological,
geographical, racial, gender and age factors (Heidari et
al., 2006; Golalipour and Kamran, 2004; Golalipour
et al., 2003, 2005; Okupe
et al., 1984; Tuli et al., 1995;
Rajlakshmi et al., 2001). The capacity of the
cranium has in many studies been used to indirectly reflect the volume of the
brain and to predict mental ability (Gault et al.,
1988; Wolf et al., 2003; Mazonakis
et al., 2004). Anthropometric studies carried out on the cranium
as it relates to gender have shown a lot of variations with males possessing
higher values than females in both adults and neonates (Manjunath,
2002b; Acer et al., 2007; Garba
et al., 2008; Raji et al., 2010;
Odokuma et al., 2010a).
Most studies carried out to determine cranial capacities in a population are
done with the aim of detecting the effect of various fundamental parameters
such as racial, geographic, ethnic and dietary factors etc. (Manjunath,
2002b). Such studies can also provide useful results in the field of forensic
anthropology and paediatrics as an indicator of skull development in both female
and male individuals (Pereira et al., 2008).
It is also a good determinant of normal or abnormal skull; because, living humans
have a cranial capacity ranging from about 950 to 1800 cc, with an average of
about 1400 cc (Milner, 1990). Against this background
this study was carried out to determine if healthy adults resident in Maiduguri
Metropolis of Borno State a very hot and arid region in the North Eastern Region
of Nigeria will concur or differ from few studies carried out in other part
of Nigeria (Umar et al., 2006; Odokuma
et al., 2010b). The objective of the study is to determine the cranial
capacities in males and females and to compare our results with similar studies
carried out in the southern part of Nigeria.
MATERIALS AND METHODS
Subjects: This study was conducted on 300 (150 males, 150 females) volunteers
whose ages ranged between 18 and 33 years. The subjects were randomly selected
from persons whose parents and grand parents were of Nigerian origin and showed
no obvious physical craniofacial deformity and resident in Maiduguri metropolis,
north eastern Nigerian from April to November 2009.
|| Comparison of the means of cranial capacity and head measurements
between males and females
|*Significant level p<0.05; **Significant level p<0.001;
***Significant level p<0.0001, n = 150 males, 150 females
|| Linear Regression between cranial capacity and head measurements
|n = 150 Males, 150 Females
|| Mean cranial capacity in southern and north eastern nigerian
male and female adult population
|***Significant level p<0.0001
Prior and informed consent was obtained from the subjects and the study was
carried out after dully obtaining clearance from the ethical committee of the
College of Medical Sciences, University of Maiduguri, Nigeria.
Craniometric measurements: Standardised measurements of cranial length, cranial width, cranial height and Head circumference were taken with the subject sitting relaxed on a chair, with the head in anatomical position using a spreading calliper and measuring tape.
All measurements were carried out after careful palpation of the head for anatomical
landmarks and measurements were taken to the nearest 1mm by a single investigator
thrice and the average recorded for computation and subsequent analysis (Umar
et al., 2006).
||Cranial length: It was taken as the linear length from
the glabella to the Inion
||Cranial width: It was taken as the linear distance between the
||Cranial height: It was taken as the linear distance from the root
of nose (nasion) to highest point of head (vertex)
||Head circumference: It was measured by passing a measuring tape
across a point slightly above the glabella, superciliary arch and superior
margin of the external acoustic meatus round via the inion and back to the
point above the glabella
Cranial capacity in males and females were then calculated according to the
following formulae (Williams et al., 1995; Manjunath,
||Males: 0.000337(L-11) (W-11) (H-11)+406.01
||Females: 0.000400(L-11) (W-11) (H-11)+206.60
Statistical analysis: Data obtained from the subjects were recorded
in a specially designed form and then transferred into SPSS
(2001) 11.0.1 for analysis. The means obtained from this study were subjected
to analyses of variance (ANOVA) for comparison within gender and multivariate
analyses (MANOVA) was used between this study and similar studies for assessment
of statistical significance and linearity with a probability level of less than
0.05 considered significant.
RESULTS AND DISCUSSION
The Mean±SD of cranial volume obtained from this study was 1424.4±137.9 and 1331.3±201.8 cm3 in females (Table 1). Cranial length, width, height and circumference were 191.11±6.4, 135.90±12.9, 145.15±7.5 and 564.51±14.1 cm3, respectively in males while females presented with 183.53±9.9, 135.47±14.9, 141.29±7.6 and 570.03±26.7 cm3, respectively (Table 1). The results indicates that the values in males were significantly (p<0.05-0.0001) higher in males than in females. Analysis for Linear regression between cranial capacity and cranial length, width, height and circumference of males and females revealed a positive correlation in all cases (Table 2).
Comparison between our study and a study carried out by Odokuma
et al. (2010a) in three major ethnic groups resident in the southern
part of Nigeria is presented in Table 3. Comparison of the
male and female population of the three ethnic groups in the study of Odokuma
et al. (2010a) with our study showed a significantly (p<0.0001)
higher cranial capacity value of 1424.40±137.9 against 1310.65±124.57
and 1208.77±138.65 against 1331.30±201.8 cm3 in males
and females, respectively.
Anthropometric studies that have intercultural comparisons as a basis have
in many ways given insights into the homogeneity of the human population. The
knowledge of the cranium of either a dry skull or of a living being is of significant
importance to the study and comparison of populations with various fundamental
differences like racial, geographic, ethnic and dietary characteristics. Medically,
an analysis of cranial capacity expresses another aspect of growth and development
and permits critical evaluation of unusually large, small or misshapen crania
(Haack and Meihoff, 1971). Craniometric data is used
in mainstream science to compare modern-day animal species and to analyze the
evolution of the human species in archeology. Fossil hominids are often found
fragmented and are reconstructed upon a paradigm according to the law of correlation
(Jerrison, 1979; Odokuma et al.,
In this study, the Mean (±SD) of cranial capacity were 1424.4±137.9
and 1331.3±201.8 in males and females, respectively with the values significantly
(p<0.0001) higher in males than in females. These values were also higher
when compared to a study in North Iran by Golalipour et
al. (2005), who reported a cranial capacity of 1420.60±85 and
1227.2±120 cc in 17-20 years Turkman males and females and 1369.4±142
and 1215.8±125 cc in 17-20 years Fars males and females, respectively.
The findings also revealed that the cranial capacity were higher compared to
findings reported by Acer et al. (2007) who revealed
a cranial capacity of 1375.67±91.17 and 1237.32±95.12 cm3
in 17-26 years males and females Mugla University students in Turkey. It was
also higher than cranial volume of Indian males and females dissecting room
cadavers with 1152.813±279.16 and 1117.82±99.09 cc, respectively
(Manjunath, 2002a). But a work conducted by Hwang
et al. (1995) in Korea reported a cranial volume of 1470±107
in males and 1317±117 cc in females indicating that the male Korean skull
had a higher cranial volume than the males of our study but the results obtained
from their study on the female skulls were lower than the females in this study.
The observed higher mean cranial capacities of males than that of the females
observed in this study tends to agree with similar works conducted on brain
weight were the males had significantly higher values than that of the females
which could be explained by the generally bigger frame of the average male than
the average female. Moreover, it has been shown that gender differences in brain
weight could be attributed to activities in which the specific sex excelled
(Andy, 1992; Rushton and Osborne,
1995). The higher male values also corresponds with similar findings in
North-Iran (Golalipour et al., 2005), in Turkey
(Acer et al., 2007), in India (Manjunath,
2002a) and in Korea (Hwang et al., 1995).
However, contradictions do exist between the values of the mean cranial capacities
in both males and females in this study with other studies by Golalipour
et al. (2005), Acer et al. (2007),
Manjunath (2002a) and Hwang et
al. (1995). This is probably due to ecological, biological, geographical,
racial, gender and age factors which have been cited to influence several bodily
dimensions (Golalipour et al., 2003; Okupe
et al., 1984; Tuli et al., 1995;
Rajlakshmi et al., 2001).
The values obtained from this study have been able to demonstrate that cranial capacities are higher in males than in females and that the cranial capacity of adult males and females were slightly higher than those of similar studies carried out in some ethnic groups indigenous to the southern part of Nigeria.
We thank Yakaka Bukar Maina of Division of General Studies and Mohammad Buba of Department of Human Anatomy for their assistance.
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