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International Journal of Morphology

On-line version ISSN 0717-9502

Int. J. Morphol. vol.34 no.3 Temuco Sept. 2016

http://dx.doi.org/10.4067/S0717-95022016000300028 

Int. J. Morphol., 34(3):986-989, 2016.

 

Ethnic Difference in Brain Weight of 17-20 Year-Old Males in Northern Iran

 

Diferencias Étnicas en el Peso del Cerebro en Hombres de 17 a 20 Años de Edad del Norte de Irán

 

Kamran Haidari*; Mehrdad Jahanshahi**; Mohammad Jafar Golalipour***

* Assistant Professor, Medical Cellular and Molecular Research Center & Department of Anatomical Sciences, Golestan University of Medical Sciences, Gorgan, Iran.

** Associated Professor, Department of Anatomical Sciences, Golestan University of Medical Sciences, Gorgan, Iran.

*** Professor, Gorgan Congenital Malformations Research Center, Department of Anatomical Sciences, Golestan University of Medical Sciences, Gorgan, Iran.

Correspondence to:


SUMMARY: Cranial capacity and brain weight are important measurements in the study of racial/ethnic differences. Using linear (Lee­Pearson's) formula, brain weight and cranial capacity were estimated in 398 normal 17 to 20-year-old males (200 native Fars and 198 Turkman) males in Northern Iran. The dimensions of the head measured with spreading caliper and auricular head spanner. The mean±S.D of brain weight and cranial capacity in native Fars males were 1343.45±102.37 cm3, and 1390.47±105.95 g, and that of Turkmans were 1163.02±115.76 cm3 and 1203.73±119.81 g, respectively. Cerebral Index was 3.40 ±0.37 % and 2.52 ±0.37 % in Native Fars and Turkmans, respectively and cerebral quotient was higher in Turkmans (8.34) than Native Fars males (7.95). This study showed, the effect of ethnic factor influences the brain weight of 17-20 year-old males in Northern Iran.

KEY WORDS: Anthropometry; Cephalometry; Brain weight; Cranial capacity; Cerebral index; Cerebral quotient; Male; Iran.


RESUMEN: La capacidad craneal y el peso del cerebro son mediciones importantes en el estudio de las diferentes etnias. Se estimó el peso del cerebro y la capacidad craneal usando la fórmula lineal de Lee-Pearson, en 398 hombres de 17 a 20 años de edad (200 nativos Fars y 198 Turcomanos) en el norte de Irán. Las dimensiones de la cabeza se midieron con caliper deslizante y con una llave de Todd, para la medición auricular. La media ± D.S. del peso del cerebro y la capacidad craneal en hombres nativos Fars fue de 1343,45±102,37 cm3, y 1390,47±105,95 g, y la de los turcomanos fue de 1163,02±115,76 cm3 y 1203,73 ± 119,81 g, respectivamente. El índice cerebral fue de 3,40± 0,37 % y 2,52 ± 0,37 % en nativos Fars y turcomanos, respectivamente, y el cociente cerebral fue mayor en los turcomanos (8,34) que en los hombres Fars (7.95). Este estudio demostró que el efecto del factor étnico influye en el peso del cerebro en hombres de 17-20 años del norte de Irán.

PALABRAS CLAVE: Antropometría; Cefalometría; Peso del cerebro; Capacidad craneal; Índice cerebral; Cociente cerebral; Hombre; Irán.


 

INTRODUCTION

The dimensions of the head and face are measured by Cephalometry which is one of the important tools in human anthropometry (Grau et al., 2001; El-Feghi et al., 2004).

These dimensions are affected by geographical, racial, ethnical, sex and age factors (Williams & Bannister et al., 1995; Golalipour et al., 2003; Okupe et al., 1984; Irmak et al., 2004).

Cranial capacity which is in close correlation with brain volume reflects racial characteristics and thus has been thought to be one of the most common items in physical anthropological studies (Von Bonin, 1934; Hwang et al., 1995). The studies using different methods on the different samples reveal the same strong pattern. These methods apply measuring brain size using MRI, endocranial volume measured from empty skulls, wet brain weight at autopsy, and external head size measurements which all of them produce the same results (Dekaban, 1978; Peters et al., 2000;

Svennerholm et al., 1997; Mayhew & Olsen., 1991; Cotter et al., 1999; Nooranipoor & Masteri Farahani, 2008).

Regarding to the lack of documented studies and also the importance of acquiring information on brain weight in male living subjects in order to obtain baseline data, this study was carried out on living subjects to determine the linear dimensions of the heads measured by a classic cephalometry method as a baseline study for determining the brain weight and the effect of ethnic factor on normal 17-20 years-old males in Northern Iran.

MATERIAL AND METHOD

Three hundred ninety eight healthy 17-20 years old males of Turkman group (200 native Fars 198 Turkmans) in Gorgan, South-East Caspian Sea border (North of Iran) were designated for this study.

Turkman population has been living in this area for more than two centuries, having immigrated from central Asia. They are exclusively marring in intra-group because of religious and ethnic beliefs so are a nearly pure ethnic group.

The native Fars group are the main and original inhabitants of the Gorgan region who had been selected from among the last three generations living in this area.

Body weight and height were determined in each case. Body weights were measured by spring weighing-machine (Soehnle, Germany) while the individual swearing light clothes, with an accuracy of 1kg for weight and 1cm for height.

At the same time in each individual the following linear dimensions of the head were measured:

1. Maximum head length (L) (Glabella inion length).

2. Maximum head breath (B) (measured between parietal eminences).

One and two parameters measured with a spreading caliper.

3. Auricular height (HT) (external acoustic meatus to the highest point of the vertex) using an auricular head spanner.

Each measurement was taken to the nearest millimeter at least three times and the average was considered for computation.

The cranial capacity was calculated using the following formula given by Williams & Bannister et al., and Manjunath, (2002b).

Males: 0.000337(L-11) (B-11) (HT-11) +406.01

Brain weight in grams and cerebral index (CI) were determined by the following formulas: brain weight = cranial capacity X 1.035.

Where 1.035 is the mass density of the brain (Courchesne et al., 2000; Frontera, 1958; Golalipour & Hosseinpour, 2006).

Also index: "cerebral quotient (cm2) = brain volume/height", was determined.

The data for each person was recorded on a special form and then analyzed by Epi6 and comparison of the means of anthropometric measurements by T student Test (a=0.05) was used.

RESULTS

The Mean ± SD of Head Length and width and also auricular height in Native Fars and Turkman groups are depicted in Table I so that Head Length and width in Turkmans were more than that of Native Fars males but auricular height in the former was less than the latter.

Brain weight was 1417.30 ±147.42 g and 1470.33 ±88 g in Native Fars and Turkman males, respectively (p<0.05). The means ± SD of cranial capacity was in Turkmans more than Native Fars males, significantly (p< 0.05) (Table II).

Cerebral quotient was significantly higher in Turkmans (8.34) than Native Fars males (7.95); (p < 0.05).

Table I. Cranial capacity, brain weight, head length and width and also auricular
height in 17-20 years old Native Fars and Turkman males in Northern Iran.

Table II Cranial capacity, brain weight and cerebral index
in 17-20 years old Native Fars and Turkman Males in Northern Iran.

DISCUSSION

In this study, cranial capacity of the Turkman was higher than native Fars groups. Other researchers such as Manjunath (2002a), and Hwang et al. indicated cranial capacity in Indian, Korean male populations. Also Harvey et al. (1994) showed that 41 Africans and West Indians had a smaller average brain volume than that of 67 Caucasians.

In another study Morton (1849) using the method of measuring endocranial volume on 1000 skulls with packing material found that Blacks cranial capacity averaged about 5 in 3 less than Whites. More recently,

Beals et al. (1984) carried out a large study on the endocranial volume, with measurements of up to 20,000 skulls from all around the world. He reported that East Asians, Europeans, and Africans averaged cranial volumes of 1415, 1362, and 1268 cm3 respectively and the skulls from East Asia were 3 in 3 larger than those from Europe, which in turn were 5 in 3 larger than those from Africa. Broca (1873) corroborated the Black­White difference using endocranial volume and also found that East Asians averaged larger cranial capacities than Whites.

Also in this study, brain weight of Turkman populations (1470.33 g) was higher than native Fars males (1417.30 g) so that according to our findings, the brain weight was more than Nooranipoor and Masteri Farahani study results. In their study which was done on 320 18-22 year-old males in Tehran, the center of Iran, the brain weight reported 1390.47 g.

Also Hartman-Ramseir et al., (1994) reported that the mean brain weight was 1336 g in adult males with using brain autopsy method.On the other hand, Broca reported that Whites averaged heavier brains than Blacks with more complex convolutions and larger frontal lobes using the method of weighting brains at autopsy. Subsequent other studies have found an average Black­White difference of about 100 g (Bean, 1906; Mall, 1909; Pearl, 1934; Vint, 1934).

Furthermore, some studies have reported that the more White admixture (judged independently from skin color), the greater the average brain weight in Blacks (Bean; Mall; Pearl) and similarly Ho et al., (1980) determined in an autopsy study of 1261 American adults, that 811White Americans averaged 1323 g and 450 Black Americans averaged 1223 g, a difference of 100 g. Since the Blacks and Whites of the study were similar in body size, differences in body size cannot explain away the differences in brain weight. The overall size of the human brain (determined by weight) differs by almost 30% among normal subjects (Pakkenberg & Voigt, 1964; Dekaban.

In this study Cerebral quotient was 8.34 and 7.95 in Turkmans and Native Fars males, respectively which was higher than the findings of Nooranipooe & Farahani's (2008) study (7.75).

Cerebral quotient = brain volume/height", which can be useful for anthropometric and clinical applications and also the pattern of the relation of brain volume and height is less affected by gender in comparison with brain weight and body weight's relation, as well.

In addition, unlike body weight, height of an individual is not affected by being underweight, overweight, or obese (Nooranipoor & Masteri Farahani).

Genetic and racial/ethnic characteristics and environmental factors can affect brain weight and cranial capacity. Regarding the genetic and racial/ethnic factor, anthropometric parameters such as cranial capacity have been shown to depend on gene expression (Okupe et al.,). In addition, different racial and ethnic groups may exhibit different patterns of gene expression. Therefore, Gene expression may be used as an important determining factor.

Several decades ago, Hooton (1926) reported that racial characteristics are best defined in the skull. Indeed, cranial capacity and subsequently brain weight constitutes one of the most important parameters for determining racial differences. Also, Okupe reported the higher fetal biparietal diameter in Nigerian than Europeans. Indeed, our previous studies revealed the important role of ethnicity in head dimentions (Golalipour et al.,;Golalipour & Hosseinpour, 2006).

In conclusion this study showed that the ethnic factor can affect on brain weight and cranial capacity of 17-20 years old Males in Northern Iran.

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Correspondence:

Dr. Mohammad Jafar Golalipour

Gorgan Congenital Malformations Research Center
Department of Anatomical Sciences (Embryology and Histology)
Golestan University of Medical Sciences
P.O. Box: 49175-553
Gorgan - IRAN

E-mail: mjgolalipour@yahoo.com

Received:15-03-2016
Accepted:04-07-2016

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