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Bridging continents across the sea: Multi-disciplinary perspectives on the emergence of long-distance maritime contacts in prehistory

Final Report Summary - SEALINKS (Bridging continents across the sea: Multi-disciplinary perspectives on the emergence of long-distance maritime contacts in prehistory)

The focus of the Sealinks Project has been on exploring the emergence of early contact, migration, and trade in the Indian Ocean, and their relationship to patterns of anthropogenic biological exchange. The project has involved a multidisciplinary approach that has brought together disciplines across the humanities-natural sciences divide, including in particular the fields of archaeology, molecular genetics and historical linguistics.

The project has involved archaeological fieldwork in India, Sri Lanka, Kenya, Tanzania, the Comoros and Madagascar, and has involved excavation at a total of 27 sites, as well as collaboration with researchers working on additional sites. A range of archaeobotanical, zooarchaeological, biomolecular, geochemical and chronometric studies have been undertaken. The project has undertaken the collection of ancient and modern specimens of taro (Colocasia esculenta), black rat (Rattus rattus), house mouse (Mus musculus) and Asian house shrew (Suncus murinus) from around the Indian Ocean for the purposes of phylogenetic study. Genetic study of other species, including humans, goats, cats, and rice from selected archaeological sites and locales, has also been undertaken in collaboration with other research projects. Linguistic studies have been conducted in Island Southeast Asia, South Asia and numerous Indian Ocean islands.

The results of this work can be discussed in terms of several broad themes:

Proto-globalisation

The project has examined the emergence of long-distance trade and exchange in the Indian Ocean, focusing in particular on southern Indian Ocean routes and the emergence of early connections between Africa and Asia. It has improved understanding of early chronologies and routes of contact and trade, particularly for eastern Africa. The project has explored the role of small-scale societies in the emergence of long-distance contacts across the Indian Ocean, challenging earlier narratives about the dominance of seafaring and trade by more organised, technologically advanced and state-based societies. In particular, the project has examined the poorly understood role of Austronesian language speakers from Southeast Asia in the early Indian Ocean, tracing their early movements through historical linguistic, archaeological and genetic approaches.

Research on proto-globalisation highlights the inter-connectivity of distant regions of the globe from an early time period, challenging notions of cultural isolation and demonstrating the role of cultural and biological exchange and hybridisation in the long-term shaping of present-day societies and landscapes.

Anthropocene

Anthropogenic impacts have emerged as a key area of interest for the project, and focus has been on two areas in particular:

a) Biological exchange. The Sealinks Project has highlighted the role of ancient biological exchange in creating cosmopolitan assemblages of organisms in many regions of the Indian Ocean. It has focused in particular on examining in detail the exchange of organisms between Africa and Asia via the Swahili coast, drawing on a range of traditional and cutting-edge methods to trace the arrival of plants and animals introduced to Africa from Asia.

b) Human impacts to islands. The Sealinks Project has examined the impact of human contact and settlement on the coastal islands of eastern Africa, which, with the exception of Madagascar, have seen little study of this kind. The project has demonstrated the impact of anthropogenic processes of species extirpation, extinction, and translocation in reshaping local ecologies from an early time period.

Studies of ancient anthropogenic impacts have an important role to play in understanding the onset of the Anthropocene, including its chronology and processes, as well as shaping how we understand, study and conserve landscapes that have seen long-term anthropogenic transformation.

Ancient human migration

The provision of insights into human migrations both in the Indian Ocean and in Africa has been possible as a result of new lines of evidence produced by the Sealinks Project. One key cross-oceanic migration that the project has examined is the colonisation of Madagascar by Austronesian-language speakers from Southeast Asia. This colonisation involved an extraordinary migration across the Indian Ocean by the mid-first millennium AD, but remains poorly understood and archaeologically invisible. The Sealinks Project has provided the first archaeological window into this colonisation, finding that Asian plants were moved to Madagascar by Southeast Asian colonists and thus allow tracking of their arrival and movements across the island. These ancient plant remains also highlight the fact that not just Madagascar but also the Comoros was colonised by early Southeast Asians, even though the Comoros no longer retain cultural or linguistic traces of this early settlement. Our results hint at an early role for the slave trade in driving linkages between Southeast Asia and eastern Africa.

The project’s findings are also providing insight into population movements within Africa, including the migration of both pastoralists and Bantu language speaking agriculturalists to eastern Africa. Our work highlights new processes of maritime Bantu expansion that led to rapid migration of Bantu language-speakers southwards. Ancient DNA is providing new insights into the human populations who inhabited eastern Africa prior to the Bantu expansion.

Research on ancient migrations, particularly as a result of the novel insights brought by genetic studies, is beginning to demonstrate radical reshaping of human populations through time through ongoing processes of population migration, replacement and mixing, usefully challenging pervasive ideas about cultural and biological homogeneity, as well as standard notions of ethnic and cultural identity.

Methods development

The project can be seen as part of an emerging landscape of studies that are highlighting the productive interplay between archaeology, historical linguistics and the rapidly developing fields of molecular genetics and ancient DNA studies. New synergetic studies across these fields are demonstrating the extraordinary mobility of ancient populations, and the role of both human migrations and species translocations in reshaping populations, cultures and ecologies. Our work has pioneered the application of ancient DNA and collagen fingerprinting methods in tropical, open-air contexts, highlighting the potential for the application of these methods even in such challenging environmental and climatic contexts.

Overall, the Sealinks Project findings serve to highlight the fact that societies have not evolved in isolation, and that biological and cultural processes have long been closely interwoven. The findings have implications for how we understand and contextualise the migrations happening today, including those currently affecting Europe. They emphasise the role of humans in actively shaping environments, and are part of an emerging story of long-term, widespread human transformation of environments that demands that we rethink not just our role in the past but also our role in shaping ecologies for the future.