Doctoral Dissertation Improvement Award: DNA Analysis As A Tool For Understanding Population Movement

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Research on migration in Archaeology has largely focused on its role as an agent of cultural change. However, migration and genetic admixture are also drivers of biological change and adaptation. Consequently, characterizing how ancient migrations shape genetic diversity is vital to inform understanding of biological ancestry, cultural evolution, and health outcomes in admixed human populations. But, because modern populations do not retain all the genomic diversity of ancient groups, genetic research with contemporary individuals provides limited resolution for reconstructing ancient demographic events. This limitation can be addressed by combining archaeological questions with ancient DNA. This investigation characterizes the genetic diversity of ancient human groups and test hypotheses about their relationships to other ancient and modern populations. Specifically, ancient DNA obtained from human skeletal remains in three archaeological sites (Tibes, Punta Candelero and Paso del Indio) will be analyzed to investigate the role of migration and genetic admixture in the history of pre-Columbian populations from the Caribbean island of Puerto Rico. The project incorporates training of undergraduate students in laboratory and analytical methods and contributes to the participation of underrepresented groups in the sciences through training of a female, Puerto Rican doctoral student. The researchers will engage the public by disseminating project findings through Ask-A Biologist, an online resource for students, teachers and the public, and by collaborating with archaeologists and the Ceremonial Center of Tibes site museum to integrate findings in public site tours. A significant aspect of this research is the optimization of protocols for DNA recovery from degraded skeletal remains. This methodological development improves ancient DNA recovery from remains in tropical environments, and can be extended to forensic applications where DNA may be damaged due to corpse deposition in adverse preservation contexts. Debate remains about how many migrants settled the island of Puerto Rico in antiquity, where they came from, and how these processes influenced social interaction networks across the ancient Caribbean basin. This investigation compares ancient mitochondrial and nuclear DNA from skeletal remains dated A.D. 500-1300, with data from other modern and ancient indigenous populations of the Americas to determine: (1) How were ancient populations in Puerto Rico related to continental Native American groups, and what may this indicate about their origins? (2) What was the extent of gene flow in the pre-contact Caribbean, and what may this indicate about local social interaction? Project findings reassess existing models for the peopling of Puerto Rico and the Caribbean, and explore how migration and admixture shaped the biocultural diversity of ancient Caribbean populations. By also examining the extent of inter-island migration and genetic exchange, this investigation elucidates the role of kinship, residence patterns and mobility in the maintenance of interaction networks across the pre-Columbian Caribbean. Lastly, this study also sheds light on the genetic relationships between pre-Columbian populations and modern Puerto Ricans, the second largest Hispanic group in the USA. Given the growing role that Native American ethnicity plays in contemporary Puerto Rican culture, project results have implications for the construction and experience of modern Puerto Rican identity.