A genetic history of mobility in the Iron Age and Roman Mediterranean

My aim in this dissertation is two-fold. First, to present the research I have had the opportunity to conduct during my Ph.D. on the genetic history of Rome and the Iron Age and Roman Imperial Mediterranean as part of an interdisciplinary team of anthropologists, archaeologists, geneticists, and biologists. Second, is to explore the dynamic body of theory and praxis being built around the rapidly growing field of ancient DNA research, in which this study is situated. From a single genome in 2010 to what has been hailed as a "scientific revolution" today, the field of paleogenomics has expanded rapidly. At the crossroads of genetics and archaeology, it is bringing together disciplines in new and unique ways, and reviving old debates. In the first chapter of this dissertation, I will trace how studies of the human past have drawn on evolutionary models and theories, starting with their intertwined beginnings in the mid-1800s and how they have developed - at times in dialogue and at times in isolation - since. I will pay special attention to the recent emergence of theories in the 21st century that challenge the Darwinian-centrism of the Modern Synthesis and highlight the central role of other genetic, epigenetic, behavioral and symbolic processes as mechanisms of inheritance from generation to generation. I will explore how ancient DNA, by its interdisciplinary nature, bridges questions about cultural and biological change and this nascent field is positioned to contribute to theory-building within the framework of the Extended Evolutionary Synthesis. In the second chapter, I will discuss the collaborative research I have contributed to on the genetics of the Iron Age and Roman Mediterranean, paying special attention to the insights ancient DNA can shed on patterns of mobility and interaction in the ancient world. By building a time series of ancient genomes from Rome and central Italy that spans the last 12,000 years, from the Mesolithic to the present, our multidisciplinary team explored genomic changes through time contextually-situated within research from allied fields about changing mobility patterns in the Mediterranean. We observe two major prehistoric ancestry shifts, one at the Neolithic transition with the introduction of farming into Italy and the second coinciding with increased movement of people across the Mediterranean following technological developments in seafaring and horse-drawn transport in the Bronze Age and Iron Ages. A new research project focused on Iron Age sites in Tunisia and Italy adds detail to the patterns of mobility across the Mediterranean that we observed in the time series data. We also saw evidence that even in Rome's early days, the population of the region exhibited high levels of ancestry diversity. As Rome grew from a small city to an empire encompassing the entirety of the Mediterranean - or Mare Nostrum, 'our sea', as the Romans called it - and beyond, the city became a mosaic of inhabitants from across the empire and remained so even after the fragmentation of the Western Roman Empire. Furthermore, we found that gene flow between Rome and surrounding regions closely mirrored Rome's geopolitical interactions. I will explore these general trends and discuss case studies, such as the Roman ports of Ostia and Portus, the catacombs of Saints Marcellino and Pietro, Late Antique burials at Crypta Balbi, and Medieval Villa Magna. Contextualizing archaeological and textual evidence from these sites has been instrumental in understanding the genetic structure of the Roman population in our study. In the third chapter, I highlight how ancient DNA research can shed light on questions of health and disease in the archaeological record. This chapter will pay special attention to the case study of malaria in the Iron Age and Roman Mediterranean. Malaria is known to have afflicted the Romans since at least the 2nd century CE, and possibly much. Recent paleo-biomolecular evidence and numerous ancient literary sources confirm the malaria pathogen's ancient presence and hint at the disease's devastation. Given this growing body of knowledge, archaeologists and ancient historians increasingly are taking the disease into consideration when studying ancient Rome. Yet much remains unknown about the disease's changing prevalence over time and its impact on the population. Research on modern populations has made clear that malaria has been a major selective force in human history, shaping human genomes and resulting in high frequencies of malaria resistant alleles in regions where the disease has long been endemic. Information on the frequency of these alleles in the past complements existing lines of evidence regarding malaria's historical impact in Italy. In this chapter I examine the frequencies of known malaria resistance alleles using the time-series data from Rome and central Italy described above and take a closer look at the timing and context of these allele frequency changes, exploring how selection, migration, or both might be driving these allele frequency changes. I also examine the changing disease ecology of ancient Rome and how this may have played a role in the trends observed. In the final chapter, I explore possible futures for the field of ancient DNA in terms of ethics, practice, and theory. 10 years after the sequencing of the first human genome, I explore how the field is grappling with emerging issues related to ethical and responsible research, including sampling practices, collaborative community partnerships, and accessibility of research findings to the broader public. As a field bridging disciplines in the social and natural sciences, I examine how these new alliances formed around paleogenomics inform the ethics of sampling, participation, and interpretation

Keywords: Anthropology.
Advisor: Seetah Krish
Bauer Andrew M. 
Hodder Ian
Liu Li
Pritchard Jonathan (Jonathan K.)