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Waves of history in the South Pacific: A gene-culture coevolutionary approach

Periodic Reporting for period 2 - Waves (Waves of history in the South Pacific: A gene-culture coevolutionary approach)

Reporting period: 2019-07-01 to 2020-12-31

The human prehistory of the Pacific region is relatively short yet extremely complex, comprising not only multiple waves of colonization but also wide and ongoing interaction spheres through which both seafaring peoples and their cultures maintained long-distance connections. While great progress has been made in understanding this history within a number of disciplines – often working within their disciplinary boundaries – the Waves project is providing the means to formally integrate these insights in a single inferential framework. Our dual inheritance systems of genetics and culture interact in unique and unexpected ways, making human prehistory vastly more difficult to infer than for any other species. The Waves project is building the computational tools necessary to model the interplay of genes and culture, providing a cohesive inferential framework for human prehistory that integrates data from across genomics, archaeogenetics, archaeology and historical linguistics. The Waves project comprises two major elements: first, the generation of ancient human genetic data across the Pacific (Archaeogenetics); and second, the development and application of a novel gene-culture inference framework (Gene-culture modelling). The aims of Waves are to integrate these two streams of research, providing both a deeper understanding of Pacific prehistory and developing tools and methods as a proof-of-concept to apply to other regions of the world.
In 2018 we published a major interdisciplinary study on the prehistory of Vanuatu bringing together ancient and modern genetics, archaeology and historical linguistics (Posth et al. 2018, Nature Ecology & Evolution). This high-profile study – which demonstrated the possibly unique phenomenon of genetic replacement despite linguistic continuity in post-Lapita Vanuatu – itself became the subject of a forum discussion in Archaeology in Oceania, allowing us to follow-up with a detailed elaboration of our results and integrated approach to prehistory (Posth et al. 2019, Archaeology in Oceania). The 2018 study involved modern genetic sampling in multiple communities in Vanuatu, and we have continued to provide feedback on the research across participating villages – with the latest trip in February / March 2020 (see attached research summary in Bislama, the local lingua franca). Our Vanuatu research was central to a prominent New York Times Magazine cover story, published in February 2019, on the field of ancient DNA and its relationship with the other sciences of the human past. The Archaeogenetics subteam has continued to generate new genome-wide ancient DNA data from over 230 human skeletal remains provided by our Pacific archaeology partners. In collaboration with colleagues in the Department of Archaeogenetics at MPI-SHH, we now envisage the data we are generating leading to multiple separate regional subprojects, similar to our initial Vanuatu study.

The second component of Waves has focused on development and testing of cultural evolutionary / gene-culture coevolutionary models for demographic inference. The Modelling subteam has developed a framework for testing the accuracy and robustness of existing linguistic / cultural phylogenetic reconstruction methods. We have also developed a demic gene-culture model that allows us to explicitly test the various hypotheses on the complex population replacement in Vanuatu we identified in Posth et al. (2018). Both of these novel modeling frameworks are being fully integrated into DeMIGOD, the overarching GIS-based simulation software package that will be the major technical output of the Waves project. Development of DeMIGOD has now reached an initial application phase within the Waves team and with a small network of collaborators – this will lead to a number of publications on integrated human prehistory over the coming year. Public release of DeMIGOD to the broader population genetic and cultural evolutionary research community is planned for summer 2021.
The DeMIGOD software is already at the cutting-edge – integrating methods from GIS, ecology, archaeology, population genetics, phylogenetics and cultural evolution into a single gene-culture coevolutionary framework for inference on the human past. While the Waves project focuses on the prehistory of the Pacific region, the suite of DeMIGOD tools are already being applied to questions in other parts of the world. For example, examining in detail the heterogeneous interactions between hunter-gatherers and farmers in early Neolithic Europe as a core part of the ANR-DFG funded INTERACT project. Following publication of the proof-of-concept studies already in progress, I believe DeMIGOD will demonstrate its utility and become a core inference tool for many researchers in the sciences of human prehistory.
DeMIGOD GIS and cost-path
DeMIGOD GIS in Fuller projection
Posth et al. 2018 PCA & regional map
DeMIGOD Demographic model with genetic admixture
Posth et al. 2018 Vanuatu community feedback (in Bislama)