Date Thesis Awarded
Honors Thesis -- Open Access
Bachelors of Science (BS)
Shantá D. Hinton
Kurt E. Williamson
During the first decade of settlement in Barbados, slaves were not the dominant labor force; rather, indentured servitude was the most common source of labor. After the failure of tobacco and cotton crops, however, the successful implementation of sugar crops necessitated more and cheaper labor, and Barbados plantation owners turned to the Atlantic slave trade. Slaves imported to Barbados from Africa belonged to as many as nineteen tribes, originating from all across Africa, but concentrated in the West African coast. The overall objective of this thesis was to use molecular archaeology techniques to determine the origin of the remains discovered during an emergency excavation in Fontabelle, St. Michael, Barbados. To discover the origin of the unidentified remains, mitochondrial DNA (mtDNA) was extracted in a separate facility to reduce the risk of contamination by modern DNA sources. Because of its maternal inheritance, mtDNA is used to establish lineages across generations. The mitochondrial genome is separated into a coding region and non-coding region; the non-coding region which has a mutation rate higher than nuclear DNA, particularly in two regions, hypervariable regions I and II (HV I and HV II). Certain mutations in these hypervariable regions are more likely to be found in certain ethnic groups, to the extent that ethnic groups can be identified by their specific set of mtDNA mutations, or haplogroups. Haplogroups have been compiled into a comprehensive phylogenetic tree representing human migration patterns and tracing back to the first maternal ancestor. After extraction, HV I of each bone sample was amplified. However, due to post-mortem damage sustained by the DNA, sequences were obtained from only 3 of the 5 bones analyzed, only one of which was reproducible. MtDNA from the cheek cells of laboratory personnel interacting with the bones was sequenced as a positive contamination control. All sample sequences were compared to the revised Cambridge Reference Sequence (rCRS), the first complete mitochondrial genome sequence, to determine their haplogroup. Laboratory personnel were haplotyped as belonging to haplogroups T2b, H and J1b1, all haplogroups of European origin. The ancient sample with reproducible sequencing results was haplotyped as haplogroup C1, a Native American haplogroup of North and South America, which suggests this sample belongs to the descendant of one of forty Amerindians from South America enslaved by the settlers of Barbados. Establishing the origin of the other two samples was less conclusive as there was no additional sequence for determining which mutations were true and which were the result of sequencing errors. The majority of the mutations from both samples, however, when compared with worldwide frequencies of mtDNA mutations, showed the highest match probabilities with Kenyan and African populations, suggesting the samples belong to the remains of African slaves. Ideally, at least three separate extractions, each producing amplified mtDNA and mtDNA sequences, is obtained from each ancient sample in order to identify and authenticate haplogroup results. Despite attempts at optimizing the extraction protocol—by reducing then increasing the mass of each sample, by increasing incubation time for bone dissolution and cell lysis, by performing repeat extractions to remove PCR inhibitors, and by utilizing mtDNA amplification kits—most extractions did not yield DNA suitable for extraction. This suggests DNA in the bone samples either exists in such low concentrations or has sustained so much damage that it cannot act as the DNA template in PCR reactions. It is unlikely further attempts at extraction with these remains will produce positive results.
Hoptay, Katherine, "Analyzing Ancient Mitochondrial DNA from Fontabelle Emergency Excavation Site Remains" (2013). Undergraduate Honors Theses. William & Mary. Paper 637.
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