The study of ancient insects can inform about past human activities in a variety of ways, for example, as palaeoclimatic indicators that increase our understanding of climate and environmental change, or as testimonies of human impact on past environments, including detailed information on introductions and extinctions, human environments, health and disease.
Insects can provide a wealth of information about biogeographic change. The last glaciation in northwest Europe was accompanied with insect regional extinctions and faunas dominated by cold-adapted species interspersed with warmer ones. The warming climate at the beginning of the Holocene saw also extensive changes in the distribution of the insect fauna. Human impact resulting from the development of agriculture in turn promoted further biogeographic changes. Human mobility during this time, and the domestication of plants and animals were accompanied by uninvited insect guests (Panagiotakopulu & Buckland 2017). The study of these synanthropic and anthropochorous insect species from archaeological contexts can provide important information on human mobility, the introduction of farming, trade, and the spread of insect borne diseases (Simpson et al. 2020).
In this context, the genetic characterisation of fossil insects from natural and archaeological contexts emerges as a powerful tool to study inter and intraspecific variability patterns to allow a refined mapping of the distribution of these species in the past. This can provide information and a better understanding of biogeographic patterns which includes evidence for survival in refugia, re-immigration, synanthropic introductions, their geographic origins, dispersal patterns of insects associated with disease, etc. This database coupled with stable isotope analysis of insect chitin will provide valuable information with respect to palaeoclimatic/ palaeoenvironmental changes.
Historically, biogeographic genetic research on insects has been based primarily on modern DNA studies. While there are few studies of fossil insect DNA; these have until recently provided rather limited results (e.g. Heintzman et al. 2014). Very little research has so far been applied to archaeological insect specimens using stable isotope geochemistry (e.g. Gröcke et al. 2010). Recently, we have successfully extracted DNA from desiccated specimens of Musca domestica L., the house fly, which has probable origins in the Nile Valley and has become virtually cosmopolitan. This technical success has indicated the potential application of the technique and the importance of this research for understanding long-term biogeographic change (Simpson et al 2020).
The proposed PhD project, by using specimens from a variety of contexts and geographic areas, aims to further develop a methodology for the extraction of ancient DNA from fossil insects addressing complications arising from specimen size, differential preservation, contamination, etc. It will then use the genetic information obtained from the specimens to explore patterns of expansion of important synanthropic insects during different periods. Subsequently, stable isotope analysis of the specimens will be used to reconstruct palaeoclimatic conditions at the time the insects lived.
The PhD candidate will further compare these results with a database of modern and ancient DNA data in order to better understand pathways for dispersal, human mobility patterns and the processes behind the current cosmopolitan status of many synanthropic insects.