Anatomical-anthropological study of cranial capacity from prehistoric to recent times at the area of the present-day Bosnia and Herzegovina

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1 Original article Anatomical-anthropological study of cranial capacity from prehistoric to recent times at the area of the present-day Bosnia and Herzegovina Aida Sarač-Hadžihalilović¹*, Jasmin Kulenović², Amela Kulenović¹, Adnan Busuladžić³, Aida Hasanović¹ 1 Department of Anatomy, Faculty of Medicine, University of Sarajevo 2 Department of Neurology, General Hospital Prim. Dr. Abdulah Nakaš 3 Department of History and Archeology, Faculty of Philosophy, University of Sarajevo Submitted: / Accepted: Abstract Objectives: The development of bipedal position anatomically changed the entire skeleton, not only the legs and pelvis, but also the spine, feet and skull. By studying the changes in the appearance of the skull and its volume we can monitor the changes of brain volume, intelligence development and human evolution. Methods: The research was conducted on a specimen of 196 macerated and degreased skulls, 82 of which belong to the osteological collection of the Archeology Department, Prehistory, Classical Antiquity and the Middle Ages Sections of the National Museum of Bosnia and Herzegovina in Sarajevo. The remaining 114 skulls, half male and half female, belong to the osteological collection of the Department of Anatomy of the Faculty of Medicine in Sarajevo. We estimated the cranial capacity of each of the examined skulls by applying the craniometric method. Results: Regardless of the period, we found the highest variability in the cranial capacity category. It is a natural development due to the impact of all three linear dimensions (length, width and height) of the skull on its formation. Conclusion: There is a positive correlation between the cranial capacity and the period that the skulls originate from, with the tendency of growth in more recent periods of time, with the exception of a slight decline in the Middle Ages. Keywords: skull, cranial capacity, craniometry, prehistoric skull, antiquity period skull, middle ages skull, recent period skull 2016 Folia Medica Facultatis Medicinae Universitatis Saraeviensis. All rights reserved. *Corresponding Author: Aida Sarač Hadžihalilović Department of Anatomy Faculty of Medicine University of Sarajevo Bosnia and Herzegovina aida.sarac@mf.unsa.ba Introduction Human evolution is a part of primate evolution, more precisely, the development of Homo species and appearance of Homo sapiens as a kind of hominids or large anthropomorphic monkeys. Characteristics of human evolution are numerous changes in anatomic appearance, physiology, behavior and cognitive functions development. The main evolutionary changes are walking on two feet or bipedal walking, enlargement of brain volume or encephalization, extension of pregnancies and decrease in gender anatomical differences [1]. Development of bipedal walking anatomically changed the whole skeleton, not just the lower extremities and the pelvis, but also the spine, feet and skull. Researching the changes in skull appearance and volume we can track brain volume changes, intelligence development and human evolution. It is impossible to follow all these changes in evolutionary development of human species without the basic knowledge of the cranial capacity enlargement. This process resulted in a larger space for development of encephalon. Cranial base kyphosis (cranial base flexion) is expressed as sphenoidal angle that is formed by sphenoid area and clivus. This process increases the neurocranium volume at the expense of viscerocranium [2]. This process contributes to axial skeleton adjustment and vertical posture [3] that causes optimal setting of sensory organs. The eye is set in such a way that it can see far away horizons in the dominant position that the vertical posture brought to humans. Due to cranial base flexion (cranial base kyphosis) creation of superior orbital fissure, pyramid torsion and torsion of the whole temporal bone have been observed [2]. Lowering of skull fossae follows, with the posterior cranial fossa being set posterior and deep, and the anterior cranial fossa set superior and frontal, which should be borne in mind when monitoring certain skull distances lim- 30

2 ited by anthropometric points within the frame of the referenced topographic areas. All of these could have a crucial impact on the creation of certain categories such as the cephalic index, the head length or width and, finally, on the forming of different categories of head shapes. Materials and methods The research was conducted on the sample of 196 macerated and degreased skulls, 82 of which belong to the osteological collection at the Archeology Department, Sections for Prehistory, Classical Antiquity and the Middle Ages of the National Museum of Bosnia and Herzegovina in Sarajevo. The skulls originated from different periods and locations as follows: Prehistory 16 skulls (locations: Grujin-Gradac, Glasinac and Klakar Neolithic settlements); Antiquity 9 skulls (locations: Breza and Skelani); the Middle Ages 57 skulls in total (locations: Županjac, Bobovac crkvica, Lupnica-Jajce, Bila-Travnik, Čelebići). From the osteological collection that belongs to the Department of Anatomy of the Faculty of Medicine in Sarajevo, 114 skulls were treated 57 male and 57 female skulls. On each of the treated skulls we applied osteometric methodology and determined the skull s length, width and height. Prior to the measurement, each skull was set in the Frankfurt horizontal position. The skull length was measured using cephalometer and it represents the maximal sagittal distance between glabella and opisthion. The skull width was measured using cephalometer and it represents the maximal transverse distance between the left and right porion. The skull height was observed by setting on the vertex a ruler long enough to run perpendicular to the ear canal. The distance between the ruler and external acoustic meatus (external acoustic pore) was determined by sliding caliper. To determine the height value of the skull, the value of ruler s thickness was subtracted from the measured height. All results are shown in centimeters. The skull capacity was estimated by applying the craniometric method. Craniometric method is based on the measuring of the length, width, and height of the skull, and gender specific knowledge of empiric constant [4]. It was determined according to the following Pearson formula: not determined, within the referenced formula we used the average value for gender specific constants. Bioanthropological methods and instruments Anthropometry includes numerous methods of researching quantitative properties of human organism. Anthropometric methods are primarily applied in research of quantitative (measurable) properties [4]. In our prospective study we used the following instruments: Cephalometer is constructed on the same principle as pelvimeter. Its scale is on a horizontal crossbar that joints two arms, with span of 30 centimeters divided into millimeters. It is used for measurement of small values of length and width, such as head measurement. Readings are on the line that fits the inner edge of the arm (Figure 1) [4]. Figure 1. Cephalometer Sliding caliper has several different constructions; the Martin type sliding caliper has a span of 20 centimeters, while it s variant with nonius has a span of 15 centimeters. In both cases the scale is graded to 0.1 centimeter. It is used for measuring small spans. The ends of its arms are sharper. Prior to measurement, anthropometric points should be marked with sliding caliper. The obtained dimension is read on the line that fits the inner edge of the arm (Figure 2) [4]. Considering the fact that the gender of the skulls from the osteological collection at the Archeology Department of the National Museum of B-H in Sarajevo was Figure 2. Sliding caliper 31

3 Results Cranial capacity Average value of cranial capacity trend during the observed period is presented in Figure 3. We observed a slight increase in the average cranial capacity value in the period of Antiquity compared with the period of Prehistory. After the Antiquity period the cranial capacity value showed a decreasing tendency but the male skulls value showed an increasing tendency in the recent period. Table 1 showed that cranial capacity values were significantly different for observed periods (p<0.001). Table 1. Results of ANOVA test in different periods, cranial capacity variable Period Average cranial capacity Prehistory Antiquity Middle Ages Recent, male skull Recent, female skull ANOVA F = p <0.001 The difference in cranial capacity values is significant between the Prehistory and the recent period for female skulls; the Antiquity and the Middle Ages; and the Antiquity and the recent period for female skulls; the Middle Ages and the recent period for male skulls, and between the Middle Ages and the recent period for female skulls. Significant difference between male and female skulls was observed in the recent period. Figure 4. Cranium frontal view, osteological collection at Archeology Department, Prehistory Section, National Museum of B-H in Sarajevo 1550 Cranial capacity (m 3 ) Prehistory Antic Middle age Recent male Recent female Figure 3. Average cranial capacity value trend 32

4 Table 2. The difference in cranial capacity values across different historical time periods Prehistory Antiquity Middle Ages Recent, male skulls Recent, female skulls Prehistory Antiquity Middle Ages Recent, male skulls t = p = t = p = t = p = t = p = t = P = t = p < t = p = t = p < t = p = t = p < Figure 5. Cranium - frontal view, osteological collection at Archeology Department, Classical Antiquity Section, National Museum of B-H in Sarajevo Figure 7. Cranium - side view, osteological collection from Department of Anatomy of the Faculty of Medicine in Sarajevo Figure 6. Cranium - frontal and back view, osteological collection at Archeology Department, Middle Ages Section, National Museum of B-H in Sarajevo 33

5 Discussion The question of biogenesis and ethnogenesis in the territory of the present day Bosnia and Herzegovina is very complex and specific; it is a subject of research of both natural sciences and the humanities. The relevant subject may be regarded on several levels: the anatomic, anthropologic, archeological, and so on. One of the postulates of medical anthropology is skull typing. The most important methods for determining a range of variables that could be considered in typing are anthropometry and anthroposcopy, as well as psychometrics. We applied the first two methods in this study. We know from literature that anthropometry and anthroposcopy are the main methods of physical and medical anthropology. Anthropometry s task is to present morphological features of human body in quantitative terms. Anthroposcopy on the other hand is an anthropology method that presents features of human body in qualitative terms. These two methods may be applied to study humans and human groups from the ontogenic and philogenic aspect [1]. In this research we endeavor to identify the autochthonous skull types in our country over a long period of time, from Prehistory the Bronze and the Iron Ages, the Classical Antiquity, the Middle Ages until the present time. We also endeavor to research the correlations between the cranial capacity parameter and the period that the skull originates from. In that way we would like to give a modest contribution to the understanding of evolutive processes in this field in the territory of the present day Bosnia and Herzegovina. Thus we would help to understand the fragments of the complete picture of development of human society through a very long period of time in our parts which many other authors dealt with from various points of view [5]. Our results indicate that in the territory of present day Bosnia and Herzegovina the average value of cranial capacity was on the slight increase from the period of Prehistory to the period of Antiquity, after which the value was on the decrease, but there is an increase of the value for male skulls in the recent period. Variability of the sample from Prehistory is expressed the most with the cranial capacity variable that ranged from the minimum of 1090 cm 3 to the maximum of 1699 cm 3. The variation coefficient was 11.02%. The results similar to ours were found in a study that dealt with cranial features of the Sima de los Huesos people in Spain. Their cranial capacity mean value was 1337 cm 3 while the same parameter in our study was 1397 cm 3 [6]. Many authors concluded that at the very beginning of the Early Bronze Age there existed very heterogeneous groups and groups that lived in isolation that could accept the material culture of the Bronze Age through cultural diffusion. Using anthropometric methods authors concluded that the tested skulls belonged to the Nordic and the Mediterranean types [7]. The variability of cranial capacity was lower in the Antiquity than in Prehistory and it ranged from 1318 cm 3 to 1810 cm 3. The variation coefficient was 9.90%. In this sample from the Antiquity, the cephalic index and cranial capacity are in significant correlation with width only which can be explained by the prevalence of narrow skulls of 67%, unlike Prehistory when the referenced variables (cephalic index and cranial capacity) were in correlation, to a higher or lesser degree, with all three linear dimensions of the skull. In the Middle Ages, variability within the referenced sample was the most expressed at cranial capacity variable (variable coefficient is 8.9%), but it is lower compared with the previous two periods (Prehistory and Antiquity). In the recent period the variability of male skull was the most expressed at cranial capacity (variable coefficient is 7.59%) ranging from 1216 cm 3 to 1729 cm 3. In the recent period the variability of female skull was also the most expressed at cranial capacity (variable coefficient is 6.34%) ranging from 1121 cm 3 to 1541 cm 3. Therefore, we notice that regardless of the observed period, the highest variability is in the category of cranial capacity. It is a natural development due to the influence of all three linear dimensions (length, width and height) of the skull on its formation. Considering the fact that we have previously observed the variability of the span of skull s linear dimensions that causes a series of transition forms, these results were expected. It was stated in our results that length and height have significant and relatively high correlation coefficients with the calculations of cephalic index and cranial capacity, which was absolutely expected considering the model of the cephalic index and cranial capacity calculations. For the same reason the height is in high correlation with the value of cranial capacity. The relation between the skull length and the cephalic index is an indirect one considering the negative sign of correlation coefficient which is, again, consistent with the formula used for cephalic index calculation. We can ask a question here as to which of the linear dimensions has the strongest influence on the forming of the cranial capacity and thus constitutes a part of the complex mechanisms of the human skull formation, even though the question exceeds the topic of this paper. We observed a slight increase of the average cranial capacity value as we move from Prehistory to the Antiquity, after that the value has a decreasing tendency but it is on the increase in the recent period for male skulls. There is a statistically significant difference between different periods by the cranial capacity variable values. The difference is significant between Prehistory 34

6 and the recent period for female skulls; between the Antiquity and the Middle Ages as well as between the Antiquity and the recent period for female skulls; between the Middle Ages and the recent period for male skulls, and between the Middle Ages and the recent period for female skulls. There is a significant difference in the recent period between female and male skulls. The greater capacity of male skulls compared with female skulls has been observed in many articles, such as the study done in Sri Lanka. That study was done on the sample of 210 students, 118 males and 92 females. The parameters of length, width and height and the cranial capacity were followed in application of craniometric methods. The results showed that the skull length and width were larger in males compared with females, which led to the same conclusion with respect to the for cranial capacity [8]. Stephan Gold refers to his results of the cranial capacity analysis of 292 skulls, where he finds that male skulls have a 14-percent greater capacity in average [9]. Reference to greater cranial capacity of male skulls ( ± cm 3 ) related to female skulls ( ± cm3), and their correlation with brain volume and brain indexes is found in papers of Iranian scientists [10]. Conclusions Variability among samples, regardless of the period tested, was the most expressed in the cranial capacity category. There is a positive correlation between the cranial capacity and the period that the skulls originate from. There is a tendency of growth toward the more recent periods of time, with the exception of a slight decline in the Middle Ages. The capacity of the male skulls is greater than that of female skulls in the recent period. References [1] Boyd R, Silk JB. How Humans Evolved. 3rd ed. New York: Norton [2] Nikolić V, Rudan P. Morfološke i antropometrijske karakteristike posmatranih dijelova srednje lobanjske jame. Glasnik antropološkog društva Jugoslavije, SV : [3] Krmpotić Nemanjić Jelena, Keros P, Imančić Košuta M: Prilagodba aksijalnog skeleta uspravnom stavu. Glasnik antropološkog društva Jugoslavije SV : [4] Hadžiselimović R, Lelo S, Šljuka S. Bioantropološki praktikum. Sarajevo, [5] Benac A, Basler Đ, Čović B, Pašalić E, Miletić N, Anđelić P. Kulturna istorija Bosne i Hercegovine. 2nd ed. Sarajevo: SOUR Veselin Masleša [6] Lorenz C, Carretero JM, Arsuaga JL, et al. Intrapopulational Body Size Variation and Cranial Capacity Variation in Middle Pleistocene Humans: The Sima de los Huesos Sample, Sierra de Atapuerca, Spain. American Journal of Physical Anthropology 1998; 106: [7] Mikić Ž. Stanje i problemi fizičke antropologije u Jugoslaviji - prahistorijski periodi. Sarajevo: Centar za balkanološka ispitivanja [8] Ilayperuma I. Cranial Capacity in an Adult Sri Lankan Population: Sexual Dimorphism and Ethnic Diversity. Int. J. Morphol. 2011; 29(2): [9] Gould SJ. Mortons ranking of races by cranial capacity. Science 1978; 200(4341): [10] Nooranipour M, Farahani RM. Estimation of cranial capacity and brain weight in year old Iranian adults. Clinical Neurology and Neurosurgery, 2008; 110(10): Declaration of interest The authors declare no conflict of interest for this study. 35