K. M. Chandimal

ABSTRACT

This thesis explores morphology, morphometry and mitochondrial DNA polymorphisms of prehistoric and the Purana population at Sigiriya suburbs. The first part of the thesis contains the findings of morphometry and morphology of three human skeletons excavated from Potana Sigiriya that has been radio carbon dated as 4,000 years before present (YBP). The gender, age, stature, cause of death, health status, food habits and the way of life of Potana population have been explored. One skeleton unearthed from context no 10 of the excavation presently displayed at National Museum, Colombo is of female sex and age at death is around 25–35 years. The calculated stature of the individual is 170 cm. Other skeleton found at the same context presently displayed at Sigiriya Museum is of male sex and determined age at death is around 25–30 years. The calculated stature of the male is 173.61cm. The skeleton excavated in context no 03 presently stored at Osteology Laboratory, Postgraduate Institute of Archaeology, University of Kelaniya is determined as female and age at death is around 35 – 40 years. In general, the prehistoric population that lived in Potana is further identified as a hunter gatherer population that shared many biometrics and socioeconomic characteristics among contemporary prehistoric populations that lived in Sri Lanka such as Bellan bandi Palassa, Batadomba lena, Beli lena, Fa Hien lena etc.

Moreover archaeological remains contain genetic information that has capability to elucidate recent evolutionary history of humans. Ancient DNA (aDNA) recovered from archaeological remains is in minute amounts because of degradation which limits the successful retrieval of valuable historical genetic information. The preservation of ancient DNA (aDNA) in Sri Lanka has been reported to be low (Reed et al., 2003). In this study, an attempt was made to extract DNA from ancient human bones using reported aDNA extraction protocols (Newman et al., 2002; Mohendasan et al., 2004; Ariffin et al., 2007: DNA investigation Kit – QIAGEN, Germany). Mitochondrial DNA (mtDNA) of ancient bone samples taken from the prehistoric skeleton (4,000 YBP) excavated from Potana Sigiriya presently displayed at Sigiriya Museum along with the historic skeleton dated as 1,000 YBP displayed at Polonnaruwa Museum was extracted and analyzed. Genetic information of a 231 bp long mtDNA fragment was successfully recovered from human skeletons dated 1,000 YBP and 4,000 YBP excavated from Sri Lanka. Analysis revealed that the mtDNA haplotypes of ancient bone samples of 1,000 YBP and 4,000 YBP were unique.

The present human population living in Sigiriya suburbs with the Purana surnames such as Aluthgedara, Gamagedara, Undiyagedara, Millagahagedara, Kongahagedara etc are considered as the Purana population whose ancestry could be traced back to the times of Sinhalese Kings of 5th Century A.D (1,450 YBP). The quantitative (morphometrical) and qualitative (morphological) anthropological traits of the Purana populations (n=313) representing Purana villages: Pidurangala, Thalkote, Nagalawewa and Diyakepilla at Sigiriya suburbs were investigated. The quantitative anthropological traits such as height, cranial index, facial index, nasal index and qualitative traits such as skin colour, hair type and colour etc of the Purana population revealed that the Purana populations living in these four villages’ posses increased variations. Results analyzed by ANOVA showed higher variations of most of studied phenotypic characteristics (morphometrical) among Purana female populations living in four villages in Sigirya suburbs. Principle component analysis (PCA) confirmed that Purana male populations of Talkote and Diyakepilla are closer in terms of morphometrical characteristics while the inhabitants at Pidurangala and Nagalaweva are quite isolated from the rest of the population. In contrast to male population, PCA analysis of female populations living in four villages are morphometrically placed in different clusters. The gender, pedigree or caste system, geographical location and socioeconomic status have been identified as limiting factors for the extent of phenotypic divergence among the Purana population.

When comparing the present findings and other documented studies based on morphological and morphometrical traits of population groups in Sri Lanka, the analyzed percentage distribution of each blood groups (A, B, AB, O and Rh) of Sinhalese, Tamils, Muslims, Burgers and the Purana population showed that the Purana population was phenotypically different from the rest of Sri Lankans. The individual quantitative traits (stature, cranial length, cranial breadth, facial height, facial length etc) and qualitative anthropological traits (skin colour, hair type and colour) of the Purana population were observed to be different when compared with other Sri
Lankans.

Polymorphisms in the mitochondrial DNA hypervariable segment – 1 (HVS -1) of the Purana population was studied to explore the genetic affinity of them to modern Sri Lankans. The results of AMOVA confirmed that the four purana populations living in four villages were genetically isolated from each other and the rest of Sri Lankans and maternal gene flow was limited to them. This isolation was also collaborated with findings of morphological / morphometrical variations of the Purana population compared to modern Sri Lankans as observed in the percentage distribution of each blood group in the Purana population and modern Sri Lankans. The effects of isolation of the Purana population further demonstrated their other morphometrical and morphological findings.

Pedigree or caste system and geographical location are suggested as the limiting factors for restricted female gene flow among the Purana populations. Phylogenetic analysis based on mtDNA HVS – I polymorphism data revealed that the Purana population in Sigiriya was genetically closer to Sri Lankan Tamils than the Vedda and other modern Sri Lankans. This may have been as a result of genetic isolation and genetic drift. The genetic evidence did not support for existence of any genetic affinity between the Purana population and prehistoric population that lived in Potana Sigiriya. As the mtDNA represents the maternal gene flow, the finding of the present study restrict to the maternal lineage of the studied subjects. Hence the findings of the present study should be further verified with genetic data derived from nuclear and male specific Y chromosomal DNA markers.